U.S. patent application number 10/992329 was filed with the patent office on 2005-12-08 for method and apparatus for document processing.
This patent application is currently assigned to Microsoft Corporation. Invention is credited to Anderson, Christopher L., Dunietz, Jerry, Foehr, Oliver, Hillberg, Mike, Jazdzewski, Charles P., Little, Robert A., Ornstein, David, Relyea, Rob, Ternasky, Joseph D..
Application Number | 20050273704 10/992329 |
Document ID | / |
Family ID | 35240754 |
Filed Date | 2005-12-08 |
United States Patent
Application |
20050273704 |
Kind Code |
A1 |
Dunietz, Jerry ; et
al. |
December 8, 2005 |
Method and apparatus for document processing
Abstract
Modular content framework and document format methods and
systems are described. The described framework and format define a
set of building blocks for composing, packaging, distributing, and
rendering document-centered content. These building blocks define a
platform-independent framework for document formats that enable
software and hardware systems to generate, exchange, and display
documents reliably and consistently. The framework and format have
been designed in a flexible and extensible fashion. In addition to
this general framework and format, a particular format, known as
the reach package format, is defined using the general framework.
The reach package format is a format for storing paginated
documents. The contents of a reach package can be displayed or
printed with full fidelity among devices and applications in a wide
range of environments and across a wide range of scenarios.
Inventors: |
Dunietz, Jerry; (Seattle,
WA) ; Jazdzewski, Charles P.; (Redmond, WA) ;
Ornstein, David; (Seattle, WA) ; Relyea, Rob;
(Bellevue, WA) ; Foehr, Oliver; (Mercer Island,
WA) ; Hillberg, Mike; (Beaux Arts, WA) ;
Ternasky, Joseph D.; (Mountain View, CA) ; Little,
Robert A.; (Redmond, WA) ; Anderson, Christopher
L.; (Redmond, WA) |
Correspondence
Address: |
LEE & HAYES PLLC
421 W RIVERSIDE AVENUE SUITE 500
SPOKANE
WA
99201
|
Assignee: |
Microsoft Corporation
Redmond
WA
98052
|
Family ID: |
35240754 |
Appl. No.: |
10/992329 |
Filed: |
November 18, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10992329 |
Nov 18, 2004 |
|
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10837043 |
Apr 30, 2004 |
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Current U.S.
Class: |
715/234 ;
715/255 |
Current CPC
Class: |
G06F 40/197 20200101;
G06F 40/143 20200101 |
Class at
Publication: |
715/513 |
International
Class: |
G06F 017/24; G06F
017/21 |
Claims
1. A memory for storing data for access by an application program
being executed on a processor, comprising: a data structure stored
in the memory, the data structure including a markup representation
associated with a plurality of document parts, the markup
representation including: a preferred content that is used by
applications capable of processing the preferred content; and a
fallback content that is used by applications incapable of
processing the preferred content.
2. The memory of claim 1, wherein the markup representation further
includes an element that controls a manner in which applications
handle unknown attributes.
3. The memory of claim 1, wherein the markup representation further
includes an element that identifies a namespace as ignorable.
4. The memory of claim 1, wherein the markup representation further
includes an element that identifies elements and attributes
associated with a namespace as ignorable.
5. The memory of claim 1, wherein the markup representation further
includes an element that specifies behavior for ignorable
content.
6. The memory of claim 1, wherein the markup representation further
includes an element that reverses the effect of a declaring a
namespace ignorable.
7. The memory of claim 1, wherein the preferred content and the
fallback content can be nested in an arbitrary manner.
8. A programming interface embodied on one or more
computer-readable media, comprising: a first group of services
related to identifying attributes contained in a document; a second
group of services related to determining a default handling
behavior associated with each attribute in the document; a third
group of services related to ignoring an attribute in the document
if the attribute is not understood and the attribute's default
handling behavior is set to ignore new features; and a fourth group
of services related to halting processing of the document if the
attribute is not understood and the attribute's default handling
behavior is set to require understanding of attributes.
9. The programming interface of claim 8, further comprising a fifth
group of services related to processing attributes in the document
if the attribute is understood.
10. The programming interface of claim 8, wherein the first group
of services includes a service for identifying elements contained
in the document.
11. The programming interface of claim 8, wherein the default
handling behavior may vary when processing different parts of the
document.
12. The programming interface of claim 8, wherein the third group
of services includes a service for maintaining the ignored
attribute for future use if a carry along parameter is active.
13. The programming interface of claim 8, wherein the third group
of services includes a service for discarding the ignored attribute
if a carry along parameter is not active.
14. The programming interface of claim 8, where in the third group
of services includes a service for storing the attribute for use in
a later process.
15. The programming interface of claim 8, wherein the first group
of services includes a service for determining compatibility rules
properties.
16. The programming interface of claim 8, further comprising a
fifth group of services related to identifying behavior associated
with ignorable content.
17. The programming interface of claim 8, wherein the first group
of services includes a service for identifying XML attributes.
18. A software architecture comprising the programming interface as
recited in claim 8.
19. A programming interface embodied on one or more
computer-readable media, comprising: a first group of services
related to defining a plurality of parts associated with a
document; and a second group of services related to associating a
markup representation with the plurality of parts, wherein the
second group of services includes: a service for identifying a
preferred content that is used by applications capable of
processing the preferred content; and a service for identifying a
fallback content that is used by applications incapable of
processing the preferred content.
20. The programming interface of claim 19, wherein the first group
of services includes a service for associating a name with each of
the plurality of parts.
21. The programming interface of claim 19, wherein the second group
of services includes a service for identifying an element that
controls how applications react to unknown attributes.
22. The programming interface of claim 19, wherein the second group
of services includes a service for identifying an element that
declares a namespace as ignorable.
23. The programming interface of claim 19, wherein the second group
of services includes a service for identifying an element that
declares all elements and attributes associated with a namespace as
ignorable.
24. The programming interface of claim 19, wherein the second group
of services includes a service for identifying an element that
specifies behavior for ignorable content.
25. The programming interface of claim 19, wherein the second group
of services includes a service for identifying an element that
reverses t he effect of a namespace declared ignorable.
26. A software architecture comprising the programming interface as
recited in claim 19.
27. A programming interface embodied on one or more
computer-readable media, comprising: a first group of services
related to identifying a document; a second group of services
related to determining a handling behavior associated with the
document, wherein the second group of services includes: a service
for determining behavior associated with ignorable content in the
document; a service for halting processing of the document if an
element in the document is not understood and the handling behavior
associated with the document requires an understanding of the
element; a third group of services related to rendering the
document.
28. The programming interface of claim 27, wherein the third group
of services includes a service for displaying the document on a
display device.
29. The programming interface of claim 27, wherein the third group
of services includes a service for printing the document on a
printing device.
30. The programming interface of claim 27, wherein the third group
of services includes a service for transmitting the document to
another device.
31. The programming interface of claim 27, wherein the second group
of services includes a service for identifying XML elements.
32. An apparatus comprising: means for identifying attributes
contained in a document; means for determining a default handling
behavior associated with each attribute in the document; and means
for processing the document, the means for processing the document
configured to: ignore an attribute in the document if the attribute
is not understood and the attribute's default handling behavior is
set to ignore new features; and halt processing of the document if
the attribute is not understood and the attribute's default
handling behavior is set to require an understanding of
attributes.
33. The apparatus of claim 32, wherein the means for processing the
document is further configured to process attributes in the
document that are understood.
34. The apparatus of claim 32, wherein the attributes include
elements contained in the document.
35. The apparatus of claim 32, wherein the default handling
behavior varies based on the portion of the document being
processed.
36. The apparatus of claim 32, wherein the means for processing the
document is further configured to: maintain the ignored attribute
for future use if a carry along parameter is active; and discard
the ignored attribute if a carry along parameter is not active.
37. The apparatus of claim 32, further comprising means for
identifying behavior associated with ignorable content.
38. The apparatus of claim 32, further comprising means for
rendering the document.
39. The apparatus of claim 32, further comprising means for
communicating the document to another device for rendering.
40. An apparatus comprising: means for defining a plurality of
parts associated with a document; means for identifying a preferred
content used by applications capable of processing the preferred
content; means for identifying a fallback content used by
applications incapable of processing the preferred content; and
means for defining a manner in which applications react to unknown
attributes in the document.
41. The apparatus of claim 40, further including means for defining
an element that declares a namespace as ignorable.
42. The apparatus of claim 40, further including means for defining
an element that declares all elements and attributes associated
with a namespace as ignorable.
43. The apparatus of claim 40, further including means for
determining an element that specifies behavior for ignorable
content.
Description
RELATED APPLICATIONS
[0001] This application is a Continuation of co-pending application
Ser. No. 10/837,043, filed Apr. 30, 2004, entitled "Method and
Apparatus for Document Processing", and incorporated herein by
reference.
TECHNICAL FIELD
[0002] This invention relates to a content framework, document
format and related methods and systems that can utilize both.
BACKGROUND
[0003] Typically today, there are many different types of content
frameworks to represent content, and many different types of
document formats to format various types of documents. Many times,
each of these frameworks and formats requires its own associated
software in order to build, produce, process or consume an i
associated document. For those who have the particular associated
software installed on an appropriate device, building, producing,
processing or consuming associated documents is not much of a
problem. For those who do not have the appropriate software,
building, producing, processing or consuming associated documents
is typically not possible.
[0004] Against this backdrop, there is a continuing need for
ubiquity insofar as production and consumption of documents is
concerned.
SUMMARY
[0005] Modular content framework and document format methods and
systems are described. The described framework and format define a
set of building blocks for composing, packaging, distributing, and
rendering document-centered content. These building blocks define a
platform-independent framework for document formats that enable
software and hardware systems to generate, exchange, and display
documents reliably and consistently. The framework and format have
been designed in a flexible and extensible fashion.
[0006] In addition to this general framework and format, a
particular format, known as the reach package format, is defined
using the general framework. The reach package format is a format
for storing paginated documents. The contents of a reach package
can be displayed or printed with full fidelity among devices and
applications in a wide range of environments and across a wide
range of scenarios.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a block diagram of components of an exemplary
framework and format in accordance with one embodiment.
[0008] FIG. 2 is a block diagram of an exemplary package holding a
document comprising a number of parts in accordance with one
embodiment.
[0009] FIG. 3 is a block diagram that illustrates an exemplary
writer that produces a package, and a reader that reads the
package, in accordance with one embodiment.
[0010] FIG. 4 illustrates an example part that binds together three
separate pages.
[0011] FIG. 5 is a diagram that illustrates an exemplary selector
and sequences arranged to produce a financial report containing
both an English representation and a French representation of the
report, in accordance with one embodiment.
[0012] FIG. 6 illustrates some examples of writers and readers
working together to communicate about a package, in accordance with
one embodiment.
[0013] FIG. 7 illustrates an example of interleaving multiple parts
of a document.
[0014] FIGS. 8 and 9 illustrate different examples of packaging the
multiple parts of the document shown in FIG. 7.
[0015] FIG. 10 illustrates an exemplary reach package and each of
the valid types of parts that can make up or be found in a package,
in accordance with one embodiment.
[0016] FIG. 11 illustrates an exemplary mapping of Common Language
Runtime concepts to XML in accordance with one embodiment.
[0017] FIG. 12 illustrates both upright and sideways glyph metrics
in accordance with one embodiment.
[0018] FIG. 13 illustrates a one-to-one cluster map in accordance
with one embodiment.
[0019] FIG. 14 illustrates a many-to-one cluster map in accordance
with one embodiment.
[0020] FIG. 15 illustrates a one-to-many cluster map in accordance
with one embodiment.
[0021] FIG. 16 illustrates a many-to-many cluster map in accordance
with one embodiment.
DETAILED DESCRIPTION
[0022] Overview
[0023] This document describes a modular content framework and
document format. The framework and format define a set of building
blocks for composing, packaging, distributing, and rendering
document-centered content. These building blocks define a
platform-independent framework for document formats that enable
software and hardware systems to generate, exchange, and display
documents reliably and consistently. The framework and format have
been designed in a flexible and extensible fashion. In various
embodiments, there is no restriction to the type of content that
can be included, how the content is presented, or the platform on
which to build clients for handling the content.
[0024] In addition to this general framework, a particular format
is defined using the general framework. This format is referred to
as the reach package format in this document, and is a format for
storing paginated or pre-paginated documents. The contents of a
reach package can be displayed or printed with full fidelity among
devices and applications in a wide range of environments and across
a wide range of scenarios.
[0025] One of the goals of the framework described below is to
ensure the interoperability of independently-written software and
hardware systems reading or writing content produced in accordance
with the framework and format described below. In order to achieve
this interoperability, the described format defines formal
requirements that systems that read or write content must
satisfy.
[0026] The discussion below is organized along the following lines
and presented in two main sections--one entitled "The Framework"
and one entitled "The Reach Package Format".
[0027] The section entitled "The Framework" presents an
illustrative packaging model and describes the various parts and
relationships that make up framework packages. Information about
using descriptive metadata in framework packages is discussed, as
well as the process of mapping to physical containers, extending
framework markup, and the use of framework versioning
mechanisms.
[0028] The section entitled "The Reach Package Format" explores the
structure of one particular type of framework-built package
referred to as the reach package. This section also describes the
package parts specific to a fixed payload and defines a reach
package markup model and drawing model. This section concludes with
exemplary reach markup elements and their properties along with
illustrated samples.
[0029] As a high level overview of the discussion that follows,
consider FIG. 1 which illustrates aspects of the inventive
framework and format generally at 100. Certain exemplary components
of the framework are illustrated at 102, and certain components of
the reach package format are illustrated at 104.
[0030] Framework 102 comprises exemplary components which include,
without limitation, a relationship component, a pluggable
containers component, an interleaving/streaming component and a
versioning/extensibility component, each of which is explored in
more detail below. Reach package format 104 comprises components
which include a selector/sequencer component and a package markup
definition component.
[0031] In the discussion that follows below, periodic reference
will be made back to FIG. 1 so that the reader can maintain
perspective as to where the described components fit in the
framework and package format.
[0032] The Framework
[0033] In the discussion that follows, a description of a general
framework is provided. Separate primary sub-headings include "The
Package Model", "Composition Parts: Selector and Sequence",
"Descriptive Metadata", "Physical Model", "Physical Mappings" and
"Versioning and Extensibility". Each primary sub-heading has one or
more related sub-headings.
[0034] The Package Model
[0035] This section describes the package model and includes
sub-headings that describe packages and parts, drivers,
relationships, package relationships and the start part.
[0036] Packages and Parts
[0037] In the illustrated and described model, content is held
within a package. A package is a logical entity that holds a
collection of related parts. The package's purpose is to gather up
all of the pieces of a document (or other types of content) into
one object that is easy for programmers and end-users to work with.
For example, consider FIG. 2 which illustrates an exemplary package
200 holding a document comprising a number of parts including an
XML markup part 202 representing the document, a font part 204
describing a font that is used in the document, a number of page
parts 206 describing pages of the document, and a picture part
representing a picture within the document. The XML markup part 202
that represents a document is advantageous in that it can permit
easy searchability and referencing without requiring the entire
content of a package to be parsed. This will become more apparent
below.
[0038] Throughout this document the notion of readers (also
referred to as consumers) and writers (also referred to as
producers) is introduced and discussed. A reader, as that term is
used in this document, refers to an entity that reads modular
content format-based files or packages. A writer, as that term is
used in this document, refers to an entity that writes modular
content format-based files or packages. As an example, consider
FIG. 3, which shows a writer that produces a package and a reader
that reads a package. Typically, the writer and reader will be
embodied as software. In at least one embodiment, much of the
processing overhead and complexities associated with creating and
formatting packages is placed on the writer. This, in turn, removes
much of the processing complexity and overhead from readers which,
as will be appreciated by the skilled artisan, is a departure from
many current models. This aspect will become apparent below.
[0039] In accordance with at least one embodiment, a single package
contains one or more representations of the content held in the
package. Often a package will ii be a single file, referred to in
this application as a container. This gives end-users, for example,
a convenient way to distribute their documents with all of the
component pieces of the document (images, fonts, data, etc.). While
packages often correspond directly to a single file, this is not
necessarily always so. A package is a logical entity that may be
represented physically in a variety of ways (e.g., without
limitation, in a single file, a collection of loose files, in a
database, ephemerally in transit over a network connection, etc.).
Thus containers hold packages, but not all packages are stored in
containers.
[0040] An abstract model describes packages independently of any
physical storage mechanism. For example, the abstract model does
not refer to "files", "streams", or other physical terms related to
the physical world in which the package is located. As discussed
below, the abstract model allows users to create drivers for
various physical formats, communication protocols, and the like. By
analogy, when an application wants to print an image, it uses an
abstraction of a printer (presented by the driver that understands
the specific kind of printer). Thus, the application is not
required to know about the specific printing device or how to
communicate with the printing device.
[0041] A container provides many benefits over what might otherwise
be a collection of loose, disconnected files. For example, similar
components may be aggregated and content may be indexed and
compressed. In addition, relationships between components may be
identified and rights management, digital signatures, encryption
and metadata may be applied to components. Of course, containers
can be used for and can embody other features which are not
specifically enumerated above.
[0042] Common Part Properties
[0043] In the illustrated and described embodiment, a part
comprises common properties (e.g., name) and a stream of bytes.
This is analogous to a file in a file system or a resource on an
HTTP server. In addition to its content, each part has some common
part properties. These include a name--which is the name of the
part, and a content type--which is the type of content stored in
the part. Parts may also have one or more associated relationships,
as discussed below.
[0044] Part names are used whenever it is necessary to refer in
some way to a part. In the illustrated and described embodiment,
names are organized into a hierarchy, similar to paths on a file
system or paths in URIs. Below are examples of part names:
1 /document.xml /tickets/ticket.xml /images/march/summer.jpeg
/pages/page4.xml
[0045] As seen above, in this embodiment, part names have the
following characteristics:
[0046] Part names are similar to file names in a traditional file
system.
[0047] Part names begin with a forward slash (`/`).
[0048] Like paths in a file-system or paths in a URI, part names
can be organized into a hierarchy by a set of directory-like names
(tickets, images/march and pages in the above examples).
[0049] This hierarchy is composed of segments delineated by
slashes.
[0050] The last segment of the name is similar to a filename a
traditional file-system.
[0051] It is important to note that the rules for naming parts,
especially the valid characters that can be used for part names,
are specific to the framework described in this document. These
part name rules are based on internet-standard URI naming rules. In
accordance with this embodiment, the grammar used for specifying
part names in this embodiment exactly matches abs_path syntax
defined in Sections 3.3 (Path Component) and 5 (Relative URI
References) of RFC2396, (Uniform Resource Identifiers (URI: Generic
Syntax) specification.
[0052] The following additional restrictions are applied to
abs_path as a valid part name:
[0053] Query Component, as it is defined in Sections 3 (URI
Syntactic Components) and 3.4 (Query Component), is not applicable
to a part name.
[0054] Fragment identifier, as it is described in Section 4.1
(Fragment Identifier), is not applicable to a part name.
[0055] It is illegal to have any part with a name created by
appending * ("/" segment ) to the part name of an existing
part.
[0056] Grammar for part names is shown below:
2 part_name = "/" segment * ( "/" segment ) segment = *pchar pchar
= unreserved .vertline. escaped .vertline. ":" .vertline. "@"
.vertline. "&" .vertline. "=" .vertline. "+" .vertline. "$"
.vertline. "," unreserved = alphanum .vertline. mark escaped = "%"
hex hex hex = digit .vertline. "A" .vertline. "B" .vertline. "C"
.vertline. "D" .vertline. "E" .vertline. "F" .vertline. "a"
.vertline. "b" .vertline. "c" .vertline. "d" .vertline. "e"
.vertline. "f" mark = "-" .vertline. "_" .vertline. "." .vertline.
"!" .vertline. ".about." .vertline. "*" .vertline. "'" .vertline.
"(" .vertline. ")" alpha = lowalpha .vertline. upalpha lowalpha =
"a" .vertline. "b" .vertline. "c" .vertline. "d" .vertline. "e"
.vertline. "f" .vertline. "g" .vertline. "h" .vertline. "i"
.vertline. "j" .vertline. "k" .vertline. "l" .vertline. "m"
.vertline. "n" .vertline. "o" .vertline. "p" .vertline. "q"
.vertline. "r" .vertline. "s" .vertline. "t" .vertline. "u"
.vertline. "v" .vertline. "w" .vertline. "x" .vertline. "y"
.vertline. "z" upalpha = "A" .vertline. "B" .vertline. "C"
.vertline. "D" .vertline. "E" .vertline. "F" .vertline. "G"
.vertline. "H" .vertline. "I" .vertline. "J" .vertline. "K"
.vertline. "L" .vertline. "M" .vertline. "N" .vertline. "O"
.vertline. "P" .vertline. "Q" .vertline. "R" .vertline. "S"
.vertline. "T" .vertline. "U" .vertline. "V" .vertline. "W"
.vertline. "X" .vertline. "Y" .vertline. "Z" digit = "0" .vertline.
"1" .vertline. "2" .vertline. "3" .vertline. "4" .vertline. "5"
.vertline. "6" .vertline. "7" .vertline. "8" .vertline. "9"
alphanum = alpha .vertline. digit
[0057] The segments of the names of all parts in a package can be
seen to form a tree. This is analogous to what happens in file
systems, in which all of the non-leaf nodes in the tree are folders
and the leaf nodes are the actual files containing content. These
folder-like nodes (i.e., non-leaf nodes) in the name tree serve a
similar function of organizing the parts in the package. It is
important to remember, however, that these "folders" exist only as
a concept in the naming hierarchy--they have no other manifestation
in the persistence format.
[0058] Part names can not live at the "folder" level. Specifically,
non-leaf nodes in the part naming hierarchy ("folder") cannot
contain a part and a subfolder with the same name.
[0059] In the illustrated and described embodiment, every part has
a content type which identifies what type of content is stored in a
part. Examples of content types include:
3 image/jpeg text/xml text/plain; charset="us-ascii"
[0060] Content types are used in the illustrated framework as
defined in RFC2045 (Multipurpose Internet Mail Extensions; (MIME)).
Specifically, each content type includes a media type (e.g., text),
a subtype (e.g., plain) and an optional set of parameters in
key=value form (e.g., charset="us-ascii"); multiple parameters are
separated by semicolons.
[0061] Part Addressing
[0062] Often parts will contain references to other parts. As a
simple example, imagine a container with two parts: a markup file
and an image. The markup file will want to hold a reference to the
image so that when the markup file is processed, the associated
image can be identified and located. Designers of content types and
XML schemas may use URIs to represent these references. To make
this possible, a mapping between the world of part names and world
of URIs needs to be defined.
[0063] In order to allow the use of URIs in a package, a special
URI interpretation rule must be used when evaluating URIs in
package-based content: the package itself should be treated as the
"authority" for URI references and the path component of the URI is
used to navigate the part name hierarchy in the package.
[0064] For example, given a package URI of
http://www.example.com/foo/some- thing.package, a reference to
/abc/bar.xml is interpreted to mean the part called /abc/bar.xml,
not the URI http://www.example.com/abc/bar.xml.
[0065] Relative URIs should be used when it is necessary to have a
reference from one part to another in a container. Using relative
references allows the contents of the container to be moved
together into a different container (or into the container from,
for example, the file system) without modifying the cross-part
references.
[0066] Relative references from a part are interpreted relative to
the "base URI" of the part containing the reference. By default,
the base URI of a part is the part's name.
[0067] Consider a container which includes parts with the following
names:
4 /markup/page.xml /images/picture.jpeg
/images/other_picture.jpeg
[0068] If the "/markup/page.xml" part contains a URI reference to
"../images/picture.jpeg", then this reference must be interpreted
as referring to the part name "/images/picture.jpeg", according to
the rules above.
[0069] Some content types provide a way to override the default
base URI by specifying a different base in the content. In the
presence of one of these overrides, the explicitly specified base
URI should be used instead of the default.
[0070] Sometimes it is useful to "address" a portion or specific
point in a part. In the URI world, a fragment identifier is used
[see, e.g. RFC2396]. In a container, the mechanism works the same
way. Specifically, the fragment is a string that contains
additional information that is understood in the context of the
content type of the addressed part. For example, in a video file a
fragment might identify a frame, in an XML file it might identify a
portion of the XML file via an xpath.
[0071] A fragment identifier is used in conjunction with a URI that
addresses a part to identify fragments of the addressed part. The
fragment identifier is optional and is separated from the URI by a
crosshatch ("#") character. As such, it is not part of a URI, but
is often used in conjunction with a URI.
[0072] The following discussion provides some guidance for part
naming, as the package and part naming model is quite flexible.
This flexibility allows for a wide range of applications of a
framework package. However, it is important to recognize that the
framework is designed to enable scenarios in which multiple,
unrelated software systems can manipulate "their own" parts of a
package without colliding with each other. To allow this, certain
guidelines are provided which, if followed, make this possible.
[0073] The guidelines given here describe a mechanism for
minimizing or at least reducing the occurrences of part naming
conflicts, and dealing with them when they do arise. Writers
creating parts in a package must take steps to detect and handle
naming conflicts with existing parts in the package. In the event
that a name conflict arises, writers may not blindly replace
existing parts.
[0074] In situations where a package is guaranteed to be
manipulated by a single writer, that writer may deviate from these
guidelines. However, if there is a possibility of multiple
independent writers sharing a package, all writers must follow
these guidelines. It is recommended, however, that all writers
follow these guidelines in any case.
[0075] It is required that writers adding parts into an existing
container do so in a new "folder" of the naming hierarchy, rather
than placing parts directly in the root, or in a pre-existing
folder. In this way, the possibility of name conflicts is limited
to the first segment of the part name. Parts created within this
new folder can be named without risking conflicts with existing
parts.
[0076] In the event that the "preferred" name for the folder is
already used by an existing part, a writer must adopt some strategy
for choosing alternate folder names. Writers should use the
strategy of appending digits to the preferred name until an
available folder name is found (possibly resorting to a GUID after
some number of unsuccessful iterations).
[0077] One consequence of this policy is that readers must not
attempt to locate a part via a "magic" or "well known" part name.
Instead, writers must create a package relationship to at least one
part in each folder they create. Readers must use these package
relationships to locate the parts rather than relying on well known
names.
[0078] Once a reader has found at least one part in a folder (via
one of the aforementioned package relationships) it may use
conventions about well known part names within that folder to find
other parts.
[0079] Drivers
[0080] The file format described herein can be used by different
applications, different document types, etc.--many of which have
conflicting uses, conflicting formats, and the like. One or more
drivers are used to resolve various conflicts, such as differences
in file formats, differences in communication protocols, and the
like. For example, different file formats include loose files and
compound files, and different communication protocols include http,
network, and wireless protocols. A group of drivers abstract
various file formats and communication protocols into a single
model. Multiple drivers can be provided for different scenarios,
different customer requirements, different physical configurations,
etc.
[0081] Relationships
[0082] Parts in a package may contain references to other parts in
that package. In general, however, these references are represented
inside the referring part in ways that are specific to the content
type of the part; that is, in arbitrary markup or an
application-specific encoding. This effectively hides the internal
linkages between parts from readers that don't understand the
content types of the parts containing such references.
[0083] Even for common content types (such as the Fixed Payload
markup described in the Reach Package section), a reader would need
to parse all of the content in a part to discover and resolve the
references to other parts. For example, when implementing a print
system that prints documents one page at a time, it may be
desirable to identify pictures and fonts contained in the
particular page. Existing systems must parse all information for
each page, which can be time consuming, and must understand the
language of each page, which may not be the situation with certain
devices or readers (e.g., ones that are performing intermediate
processing on the document as it passes through a pipeline of
processors on the way to a device). Instead, the systems and
methods described herein use relationships to identify
relationships between parts and to describe the nature of those
relationships. The relationship language is simple and defined once
so that readers can understand relationships without requiring
knowledge of multiple different languages. In one embodiment, the
relationships are represented in XML as individual parts. Each part
has an associated relationship part that contains the relationships
for which the part is a source.
[0084] For example, a spreadsheet application uses this format and
stores different spreadsheets as parts. An application that knows
nothing about the spreadsheet language can still discover various
relationships associated with the spreadsheets. For example, the
application can discover images in the spreadsheets and metadata
associated with the spreadsheets. An example relationship schema is
provided below:
5 <?xml version="1.0"?> <xsd:schema
xmlns:mmcfrels="http://mmcfrels-PLACEHOLDER"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <xsd:attribute
name="Target" type="xsd:string"/> <xsd:attribute name="Name"
type="xsd:string"/> <xsd:element name="Relationships">
<xsd:complexType> <xsd:sequence> <xsd:element
ref="Relationship" minOccurs="0" maxOccurs="unbounded"/>
</xsd:sequence> </xsd:complexType> </xsd:element>
<xsd:element name="Relationship"> <xsd:complexType>
<xsd:simpleContent> <xsd:extension base="xsd:string">
<xsd:attribute ref="Target"/> <xsd:attribute
ref="Name"/> </xsd:extension> </xsd:simpleContent>
</xsd:complexType> <xsd:element> <xsd:schema>
[0085] This schema defines two XML elements, one called
"relationships" and one called "relationship." This "relationship"
element is used to describe a single relationship as described
herein and has the following attributes: (1) "target," which
indicates the part to which the source part is related, (2) "name"
which indicates the type or nature of the relationship. The
"relationships" element is defined to allow it to hold zero or more
"relationship" elements and serves simply to collect these
"relationship" elements together in a unit.
[0086] The systems and methods described herein introduce a
higher-level mechanism to solve these problems called
"relationships". Relationships provide an additional way to
represent the kind of connection between a source part and a target
part in a package. Relationships make the connections between parts
directly "discoverable" without looking at the content in the
parts, so they are independent of content-specific schema and
faster to resolve. Additionally, these relationships are protocol
independent. A variety of different relationships may be associated
with a particular part.
[0087] Relationships provide a second important function: allowing
parts to be related without modifying them. Sometimes this
information serves as a form of "annotation" where the content type
of the "annotated" part does not define a way to attach the given
information. Potential examples include attached descriptive
metadata, print tickets and true annotations. Finally, some
scenarios require information to be attached to an existing part
specifically without modifying that part--for example, when the
part is encrypted and can not be decrypted or when the part is
digitally signed and changing it would invalidate the signature. In
another example, a user may want to attach an annotation to a JPEG
image file. The JPEG image format does not currently provide
support for identifying annotations. Changing the JPEG format to
accommodate this user's desire is not practical. However, the
systems and methods discussed herein allow the user to provide an
annotation to a JPEG file without modifying the JPEG image
format.
[0088] In one embodiment, relationships are represented using XML
in relationship parts. Each part in the container that is the
source of one or more relationships has an associated relationship
part. This relationship part holds (expressed in XML using the
content type application/PLACEHOLDER) the list of relationships for
that source part.
[0089] FIG. 4 below shows an environment 400 in which a "spine"
part 402 (similar to a FixedPanel) binds together three pages 406,
408 and 410. The set of pages bound together by the spine has an
associated "print ticket" 404. Additionally, page 2 has its own
print ticket 412. The connections from the spine part 402 to its
print ticket 404 and from page 2 to its print ticket 412 are
represented using relationships. In the arrangement of FIG. 4, the
spine part 402 would have an associated relationship part which
contained a relationship that connects the spine to ticket1, as
shown in the example below.
6 <Relationships xmlns="http://mmcfrels-PLACEHOLDER"&- gt;
<Relationship Target="../tickets/ticket1.xml"
Name="http://mmcf-printing-ticket/PLACEHOLDER"/>
</Relationships>
[0090] Relationships are represented using <Relationship>
elements nested in a single <Relationships> element. These
elements are defined in the http://mmcfrels (PLACEHOLDER)
namespace. See the example schema above, and related discussion,
for example relationships.
[0091] The relationship element has the following additional
attributes:
7 Attribute Required Meaning Target Yes A URI that points to the
part at the other end of the relationship. Relative URIs MUST be
interpreted relative to the source part. Name Yes An absolute URI
that uniquely defines the role or purpose of the relationship.
[0092] The Name attribute is not necessarily an actual address.
Different types of relationships are identified by their Names.
These names are defined in the same way that namespaces are defined
for XML namespaces. Specifically, by using names patterned after
the Internet domain name space, non-coordinating parties can safely
create non-conflicting relationship names--just as they can for XML
namespaces.
[0093] The relationships part is not permitted to participate in
other relationships. However, it is a first class part in all other
senses (e.g., it is URI addressable, it can be opened, read,
deleted, etc.). Relationships do not typically point at things
outside the package. URIs used to identify relationship targets do
not generally include a URI scheme.
[0094] A part and its associated relationship part are connected by
a naming convention. In this example, the relationship part for the
spine would be stored in /content/_rels/spine.xml.rels and the
relationships for page 2 would be stored in
/content/_rels/p2.xml.rels. Note two special naming conventions
being used here. First, the relationship part for some (other) part
in a given "folder" in the name hierarchy is stored in a
"sub-folder" called _rels (to identify relationships). Second, the
name of this relationship-holding part is formed by appending the
.rels extension to the name of the original part. In particular
embodiments, relationship parts are of the content type
application/xml+relationshipsP- LACEHOLDER.
[0095] A relationship represents a directed connection between two
parts. Because of the way that the relationship is being
represented, it is efficient to traverse relationships from their
source parts (since it is trivial to find the relationships part
for any given part). However, it is not efficient to traverse
relationships backwards from the target of the relationship (since
the way to find all of the relationships to a part is to look
through all of the relationships in the container).
[0096] In order to make backwards traversal of a relationship
possible, a new relationship is used to represent the other
(traversable) direction. This is a modeling technique that the
designer of a type of relationship can use. Following the example
above, if it were important to be able to find the spine that has
ticket1 attached, a second relationship would be used connecting
from the ticket to the spine, such as:
8 In content/_rels/p1.xml.rels: <Relationships
xmlns="http://mmcfrels-PLACEHOLDER"> <Relationship
Target="/content/spine.xml"
Name="http://mmcf-printing-spine/PLACEHOLDER"/>
</Relationships>
[0097] Package Relationships
[0098] "Package Relationships" are used to find well-known parts in
a package. This method avoids relying on naming conventions for
finding parts in a package, and ensures that there will not be
collisions between identical part names in different payloads.
[0099] Package relationships are special relationships whose target
is a part, but whose source is not: the source is the package as a
whole. To have a "well-known" part is really to have a "well-known"
relationship name that helps you find that part. This works because
there is a well-defined mechanism to allow relationships to be
named by non-coordinating parties, while certain embodiments
contain no such mechanism for part name--those embodiments are
limited to a set of guidelines. The package relationships are found
in the package relationships part and is named using the standard
naming conventions for relationship parts. Thus: it's named
"/_rels/.rels"
[0100] Relationships in this package relationships part are useful
in finding well-known parts.
[0101] The Start Part
[0102] One example of a package-level, well-known part is the
package "start" part. This is the part that is typically processed
when a package is opened. It represents the logical root of the
document content stored in the package. The start part of a package
is located by following a well-known package relationship. In one
example, this relationship has the following name:
http://mmcf-start-part-PLACEHOLDER.
[0103] Composition Parts: Selector and Sequence
[0104] The described framework defines two mechanisms for building
higher-order structures from parts: selectors and sequences.
[0105] A selector is a part which "selects" between a number of
other parts. For example, a selector part might "select" between a
part representing the English version of a document and a part
representing the French version of a document. A sequence is a part
which "sequences" a number of other parts. For example, a sequence
part might combine (into a linear sequence) two parts, one of which
represents a five-page document and one of which represents a
ten-page document.
[0106] These two types of composition parts (sequence and selector)
and the rules for assembling them comprise a composition model.
Composition parts can compose other composition parts, so one could
have, for example, a selector that selects between two
compositions. As an example, consider FIG. 5, which shows and
example of a financial report containing both an English
representation and a French representation. Each of these
representations is further composed of an introduction (a cover
page) followed by the financials (a spreadsheet). In this example,
a selector 500 selects between the English and French
representation of the report. If the English representation is
selected, sequence 502 sequences the English introduction part 506
with the English financial part 508. Alternately, if the French
representation is selected, sequence 504 sequences the French
introduction part 510 with the French financial part 512.
[0107] Composition Part XML
[0108] In the illustrated and described embodiment, composition
parts are described using a small number of XML elements, all drawn
from a common composition namespace. As an example, consider the
following:
9 Element: <selection> Attributes: None Allowed Child
Elements: <item> Element: <sequence> Attributes: None
Allowed Child Elements: <item> Element: <item>
Attributes: Target - the part name of a part in the composition
[0109] As an example, here is the XML for the example of FIG. 5
above:
10 MainDocument.XML <selection> <item
target="EnglishRollup.xml"/> <item
target="FrenchRollup.xml"/> </selection> EnglishRollup.XML
<sequence> <item target="EnglishIntroduction.xml"/>
<item target="EnglishFinancials.xml"/> </sequence>
FrenchRollup.XML <sequence> <item
target="FrenchIntroduction.xml"> <item
target="FrenchFinancials.xml"> </sequence>
[0110] In this XML, MainDocument.xml represents an entire part in
the package and indicates, by virtue of the "selection" tag, that a
selection is to be made between different items encapsulated by the
"item" tag, i.e., the "EnglishRollup.xml" and the
"FrenchRollup.xml".
[0111] The EnglishRollup.xml and FrenchRollup.xml are, by virtue of
the "sequence" tags, sequences that sequence together the
respective items encapsulated by their respective "item" tags.
[0112] Thus, a simple XML grammar is provided for describing
selectors and sequences. Each part in this composition block is
built and performs one operation--either selecting or sequencing.
By using a hierarchy of parts, different robust collections of
selections and sequences can be built.
[0113] Composition Block
[0114] The composition block of a package comprises the set of all
composition parts (selector or sequence) that are reachable from
the starting part of the package. If the starting part of the
package is neither a selector nor a sequence, then the composition
block is considered empty. If the starting part is a composition
part, then the child <item>s in those composition parts are
recursively traversed to produce a directed, acyclic graph of the
composition parts (stopping traversal when a non-composition part
is encountered). This graph is the composition block (and it must,
in accordance with this embodiment, be acyclic for the package to
be valid).
[0115] Determining Composition Semantics
[0116] Having established the relatively straight forward XML
grammar above, the following discussion describes a way to
represent the information such that selections can be made based on
content type. That is, the XML described above provides enough
information to allow readers to locate the parts that are assembled
together into a composition, but does not provide enough
information to help a reader know more about the nature of the
composition. For example, given a selection that composes two
parts, how does a reader know on what basis (e.g., language, paper
size, etc.) to make the selection? The answer is that these rules
are associated with the content type of the composition part. Thus,
a selector part that is used for picking between representations
based on language will have a different associated content type
from a selector part that picks between representations based on
paper sizes.
[0117] The general framework defines the general form for these
content types:
Application/XML+Selector-SOMETHING
Application/XML+Sequence-SOMETHING
[0118] The SOMETHING in these content types is replaced by a word
that indicates the nature of the selection or sequence, e.g. page
size, color, language, resident software on a reader device and the
like. In this framework then, one can invent all kinds of selectors
and sequences and each can have very different semantics.
[0119] The described framework also defines the following
well-known content types for selectors and sequences that all
readers or reading devices must understand.
11 Content Type Rules Application/XML + Pick between the items
based on their content Selector + types. Select the first item for
which SupportedContentType software is available that understands
the given content type.
[0120] As an example, consider the following. Assume a package
contains a document that has a page, and in the middle of the page
there is an area in which a video is to appear. In this example, a
video part of the page might comprise video in the form of a
Quicktime video. One problem with this scenario is that Quicktime
videos are not universally understood. Assume, however, that in
accordance with this framework and, more particularly, the reach
package format described below, there is a universally understood
image format--JPEG. When producing the package that contains the
document described above, the producer might, in addition to
defining the video as a part of the package, define a JPEG image
for the page and interpose a SupportedContentType selector so that
if the user's computer has software that understands the Quicktime
video, the Quicktime video is selected, otherwise the JPEG image is
selected.
[0121] Thus, as described above, the framework-level selector and
sequence components allow a robust hierarchy to be built which, in
this example, is defined in XML. In addition, there is a
well-defined way to identify the behaviors of selectors and
sequences using content types. Additionally, in accordance with one
embodiment, the general framework comprises one particular content
type that is predefined and which allows processing and utilization
of packages based on what a consumer (e.g. a reader or reading
device) does and does not understand.
[0122] Other composition part content types can be defined using
similar rules, examples of which are discussed below.
[0123] Descriptive Metadata
[0124] In accordance with one embodiment, descriptive metadata
parts provide writers or producers of packages with a way in which
to store values of properties that enable readers of the packages
to reliably discover the values. These properties are typically
used to record additional information about the package as a whole,
as well as individual parts within the container. For example, a
descriptive metadata part in a package might hold information such
as the author of the package, keywords, a summary, and the
like.
[0125] In the illustrated and described embodiment, the descriptive
metadata is expressed in XML, is stored in parts with well-known
content types, and can be found using well-known relationship
types.
[0126] Descriptive metadata holds metadata properties. Metadata
properties are represented by a property name and one or many
property values. Property values have simple data types, so each
data type is described by a single XML qname. The fact that
descriptive metadata properties have simple types does not mean
that one cannot store data with complex XML types in a package. In
this case, one must store the information as a full XML part. When
this is done, all constraints about only using simple types are
removed, but the simplicity of the "flat" descriptive metadata
property model is lost.
[0127] In addition to the general purpose mechanism for defining
sets of properties, there is a specific, well-defined set of
document core properties, stored using this mechanism. These
document core properties are commonly used to describe documents
and include properties like title, keywords, author, etc.
[0128] Finally, metadata parts holding these document core
properties can also hold additional, custom-defined properties in
addition to the document core properties.
[0129] Metadata Format
[0130] In accordance with one embodiment, descriptive metadata
parts have a content type and are targeted by relationships
according to the following rules:
12 Using Using Custom- Document Descriptive Metadata Discovery
defined Core Rules properties properties Content type of a
descriptive metadata part MUST
application/xml-SimpleTypeProperties- be: PLACEHOLDER Content type
of a source part which can have ANY ANY relationship targeting
descriptive metadata part may be: Name of the relationship
targeting descriptive *custom-defined Uri- http://mmcf- metadata
part may be either: namespace* DocumentCore- PLACEHOLDER Number of
descriptive metadata parts, which can UNBOUNDED 0 or 1 be attached
to the source part may be: Number of source parts which can have
the same UNBOUNDED UNBOUNDED descriptive metadata part attached
MUST be
[0131] The following XML pattern is used to represent descriptive
metadata in accordance with one embodiment. Details about each
component of the markup are given in the table after the
sample.
13 <mcs:properties xmlns:mcs="http://mmcf-core-services/
PLACEHOLDER" xmlns:xsd="http://www.w3.org/2001/XMLSchema"- >
<mcs:property prns:name = "property name" xmlns:prns="property
namespace" mcs:type="datatype" mcs:multivalued="true
.vertline.false"> <mcs:value> ... value ...
</mcs:value> </mcs:property>
</mcs:properties>
[0132]
14 Markup Component Description xmlns:mcs="http://mmcf-common-
Defines the MMCF common services namespace services/PLACEHOLDER"
xmlns:xsd="http://www.w3.org/2001/ Defines the XML schema
namespace. Many custom-defined XMLSchema" properties and the
majority of Document Core properties will have built-in data types
defined using an XSD. Although each property can have its own
namespace, the XSD namespace is placed on the root of the
descriptive metadata XML. mcs:properties Root element of the
descriptive metadata XML mcs:property Property element. A property
element holds a property qname and value. There may be an unbounded
number of property elements. Property elements are considered to be
immediate children of the root element. xmlns:prns Property
Namespace: For Document Core properties it is
http://mmcf-DocumentCore-PLACEHOLDER. For custom-defined properties
it will be a custom namespace. prns:name Property Name: string
attribute which holds property name mcs:type="datatype" Type is the
string attribute that holds the property datatype definition, e.g.
xsd:string mcs:value This component specifies the value of the
property. Value elements are immediate children of property
elements. If mcs:multivalued="true", then there may be an unbounded
number of value elements.
[0133] Document Core Properties
[0134] The following is a table of document core properties that
includes the name of the property, the property type and a
description.
15 Name Type Description Comments String, optional, single-valued A
comment to the document as a whole that an Author includes. This
may be a summary of the document. Copyright String, optional,
single-valued Copyright string for this document EditingTime Int64,
optional, single-valued Time spent editing this document in
seconds. Set by application logic. This value must have the
appropriate type. IsCurrentVersion boolean, optional, single-valued
Indicates if this instance is a current version of the document, or
an obsolete version. This field can be derived from VersionHistory,
but the derivation process may be expensive. Language Keyword (=
string256), optional, The language of the document (English,
French, multi-valued etc.). This field is set by the application
logic. RevisionNumber String, optional, single-valued Revision of
the document. Subtitle String, optional, single-valued A secondary
or explanatory title of the document TextDataProperties
TextDataProperties, optional, If this document has text, this
property defines a single-valued collection of the text properties
of the document, CharacterCount int64 such as paragraph count, line
count, etc LineCount int64 PageCount int64 ParagraphCount int64
WordCount int64 TimeLastPrinted datetime, optional, single-valued
Date and time when this document was last printed. Title String,
optional, single-valued The document title, as understood by the
application that handles the document. This is different than the
name of the file that contains the package. TitleSortOrder String,
optional, single-valued The sort order of the title (e.g. "The
Beatles" will have SortOrder "Beatles", with no leading "The").
ContentType Keyword (= string256), optional, Document type as set
by application logic. The multi-valued type that is stored here
should be a recognized "mime-type" This property may be useful for
categorizing or searching for documents of certain types.
[0135] Physical Model
[0136] The physical model defines various ways in which a package
is used by writers and readers. This model is based on three
components: a writer, a reader and a pipe between them. FIG. 6
shows some examples of writers and readers working together to
communicate about a package.
[0137] The pipe carries data from the writer to the reader. In many
scenarios, the pipe can simply comprise the API calls that the
reader makes to read the package from the local file system. This
is referred to as direct access.
[0138] Often, however, the reader and the writer must communicate
with each other over some type of protocol. This communication
happens, for example, across a process boundary or between a server
and a desktop computer. This is referred to as networked access and
is important because of the communications characteristics of the
pipe (specifically, the speed and request latency).
[0139] In order to enable maximum performance, physical package
designs must consider support in three important areas: access
style, layout style and communication style.
[0140] Access Style
[0141] Streaming Consumption
[0142] Because communication between the writer and the reader
using networked access is not instantaneous, it is important to
allow for progressive creation and consumption of packages. In
particular, it is recommended, in accordance with this embodiment,
that any physical package format be designed to allow a reader to
begin interpreting and processing the data it receives the data
(e.g., parts), before all of the bits of the package have been
delivered through the pipe. This capability is called streaming
consumption.
[0143] Streaming Creation
[0144] When a writer begins to create a package, it does not always
know what it will be putting in the package. As an example, when an
application begins to build a print spool file package, it may not
know how many pages will need to be put into the package. As
another example, a program on a server that is dynamically
generating a report may not realize how long the report will be or
how many pictures the report will have--until it has completely
generated the report. In order to allow writers like this, physical
packages should allow writers to dynamically add parts after other
parts have already been added (for example, a writer must not be
required to state up front how many parts it will be creating when
it starts writing). Additionally, physical packages should allow a
writer to begin writing the contents of a part without knowing the
ultimate length of that part. Together, these requirements enable
streaming creation.
[0145] Simultaneous Creation and Consumption
[0146] In a highly-pipelined architecture, streaming creation and
streaming consumption can occur simultaneously for a specific
package. When designing a physical package, supporting streaming
creation and supporting streaming consumption can push a design in
opposite directions. However, it is often possible to find a design
that supports both. Because of the benefits in a pipelined
architecture, it is recommended that physical packages support
simultaneous creation and consumption.
[0147] Layout Styles
[0148] Physical packages hold a collection of parts. These parts
can be laid out in one of two styles: simple ordering and
interleaved. With simple ordering, the parts in the package are
laid out with a defined ordering. When such a package is delivered
in a pure linear fashion, starting with the first byte in the
package through to the last, all of the bytes for the first part
arrive first, then all of the bytes for the second part, and so
on.
[0149] With interleaved layout, the bytes of the multiple parts are
interleaved, allowing for improved performance in certain
scenarios. Two scenarios that benefit significantly from
interleaving are multi-media playback (e.g., delivering video and
audio at the same time) and inline resource reference (e.g., a
reference in the middle of a markup file to an image).
[0150] Interleaving is handled through a special convention for
organizing the contents of interleaved parts. By breaking parts
into pieces and interleaving these pieces, it is possible to
achieve the desired results of interleaving while still making it
possible to easily reconstruct the original larger part. To
understand how interleaving works, FIG. 7 illustrates a simple
example involving two parts: content.xml 702 and image.jpeg 704.
The first part, content.xml, describes the contents of a page and
in the middle of that page is a reference to an image (image.jpeg)
that should appear on the page.
[0151] To understand why interleaving is valuable, consider how
these parts would be arranged in a package using simple ordering,
as shown in FIG. 8. A reader that is processing this package (and
is receiving bytes sequentially) will be unable to display the
picture until it has received all of the content.xml part as well
as the image.jpeg. In some circumstances (e.g., small or simple
packages, or fast communications links) this may not be a problem.
In other circumstances (for example, if content.xml was very large
or the communications link was very slow), needing to read through
all of the content.xml part to get to the image will result in
unacceptable performance or place unreasonable memory demands on
the reader system.
[0152] In order to achieve closer to ideal performance, it would be
nice to be able to split the content.xml part and insert the
image.jpeg part into the middle, right after where the picture is
referenced. This would allow the reader to begin processing the
image earlier: as soon as it encounters the reference, the image
data follows. This would produce, for example, the package layout
shown in FIG. 9. Because of the performance benefits, it is often
desirable that physical packages support interleaving. Depending on
the kind of physical package being used, interleaving may or may
not be supported. Different physical packages may handle the
internal representation of interleaving differently. Regardless of
how the physical package handles interleaving, it's important to
remember that interleaving is an optimization that occurs at the
physical level and a part that is broken into multiple pieces in
the physical file is still one logical part; the pieces themselves
aren't parts.
[0153] Communication Styles
[0154] Communication between writer and reader can be based on
sequential delivery of parts or by random-access to parts, allowing
them to be accessed out of order. Which of these communication
styles is utilized depends on the capabilities of both the pipe and
the physical package format. Generally, all pipes will support
sequential delivery. Physical packages must support sequential
delivery. To support random-access scenarios, both the pipe in use
and the physical package must support random-access. Some pipes are
based on protocols that can enable random access (e.g., HTTP 1.1
with byte-range support). In order to allow maximum performance
when these pipes are in use, it is recommended that physical
packages support random-access. In the absence of this support,
readers will simply wait until the parts they need are delivered
sequentially.
[0155] Physical Mappings
[0156] The logical packaging model defines a package abstraction;
an actual instance of a package is based on some particular
physical representation of a package. The packaging model may be
mapped to physical persistence formats, as well as to various
transports (e.g., network-based protocols). A physical package
format can be described as a mapping from the components of the
abstract packaging model to the features of a particular physical
format. The packaging model does not specify which physical package
formats should be used for archiving, distributing, or spooling
packages. In one embodiment, only the logical structure is
specified. A package may be "physically" embodied by a collection
of loose files, a .ZIP file archive, a compound file, or some other
format. The format chosen is supported by the targeted consuming
device, or by a driver for the device.
[0157] Components being Mapped
[0158] Each physical package format defines a mapping for the
following components. Some components are optional and a specific
physical package format may not support these optional
components.
16 Required or Component Description Optional Parts Name Names a
part. Required Content type Identified the kind of content stored
Required in the part. Part contents Stores the actual content of
the part. Required
[0159] Common Mapping Patterns
17 Access Styles Streaming Allows readers to begin processing
Optional Consumption parts before the entire package has arrived.
Streaming Allows writers to begin writing parts to Optional
Creation the package without knowing, in advance, all of the parts
that will be written. Simultaneous Allows streaming creation and
Optional Creation and streaming consumption to happen at
Consumption the same time on the same package. Layout Styles Simple
All of the bytes for part N appear in Optional Ordering the package
before the bytes for part N + 1. Interleaved The bytes for multiple
parts are Optional interleaved. Communication Sequential All of
part N is delivered to a reader Optional Styles Delivery before
part N + 1. Random- A reader can request the delivery of a Optional
Access part out of sequential order.
[0160] There exist many physical storage formats whose features
partially match the packaging-model components. In defining
mappings from the packaging model to such storage formats, it may
be desirable to take advantage of any similarities in capabilities
between the packaging model and the physical storage medium, while
using layers of mapping to provide additional capabilities not
inherently present in the physical storage medium. For example,
some physical package formats may store individual parts as
individual files in a file system. In such a physical format, it
would be natural to map many part names directly to identical
physical file names. Part names using characters which are not
valid file system file names may require some kind of escaping
mechanism.
[0161] In many cases, a single common mapping problem may be faced
by the designers of different physical package formats. Two
examples of common mapping problems arise when associating
arbitrary Content Types with parts, and when supporting the
Interleaved layout style. This specification suggests common
solutions to such common mapping problems. Designers of specific
physical package formats may be encouraged, but are not required,
to use the common mapping solutions defined here.
[0162] Identifying Content Types of Parts
[0163] Physical package format mappings define a mechanism for
storing a content type for each part. Some physical package formats
have a native mechanism for representing content types (for
example, the "Content-Type" header in MIME). For such physical
packages, it is recommended that the mapping use the native
mechanism to represent content types for parts. For other physical
package formats, some other mechanism is used to represent content
types. The recommended mechanism for representing content types in
these packages is by including a specially-named XML stream in the
package, known as the types stream. This stream is not a part, and
is therefore not itself URI-addressable. However, it can be
interleaved in the physical package using the same mechanisms used
for interleaving parts.
[0164] The types stream contains XML with a top level "Types"
element, and one or more "Default" and "Override" sub-elements. The
"Default" elements define default mappings from part name
extensions to content types. This takes advantage of the fact that
file extensions often correspond to content type. "Override"
elements are used to specify content types on parts that are not
covered by, or are not consistent with, the default mappings.
Package writers may use "Default" elements to reduce the number of
per-part "Override" elements, but are not required to do so.
[0165] The "Default" element has the following attributes:
18 Name Description Required Extension A part name extension. A Yes
"Default" element matches any part whose name ends with a period
followed by this attribute's value. ContentType A content type as
defined in Yes RFC2045. Indicates the content type of any matching
parts (unless overridden by an "Override" element; see below).
[0166] The "Override" element has the following attributes:
19 Name Description Required PartName A part name URI. An Yes
"Override" element matches the part whose name equals this
attribute's value. ContentType A content type as defined in Yes
RFC2045. Indicates the content type of the matching part.
[0167] The following is an example of the XML contained in a types
stream:
20 <Types xmlns="http://mmcfcontent-PLACEHOLDER"> <Default
Extension="txt" ContentType="plain/text" /> <Default
Extension="jpeg" ContentType="image/jpeg" /> <Default
Extension="picture" ContentType="image/gif" /> <Override
PartName="/a/b/sample4.picture" ContentType="image/jpeg" />
</Types>
[0168] The following table shows a sample list of parts, and their
corresponding content types as defined by the above types
stream:
21 Part Name Content Type /a/b/sample1.txt plain/text
/a/b/sample2.jpeg image/jpeg /a/b/sample3.picture image/gif
/a/b/sample4.picture image/jpeg
[0169] For every part in the package, the types stream contains
either (a) one matching "Default" element, (b) one matching
"Override" element, or (c) both a matching "Default" element and a
matching "Override" element (in which case the "Override" element
takes precedence). In general there is, at most, one "Default"
element for any given extension, and one "Override" element for any
given part name.
[0170] The order of "Default" and "Override" elements in the types
stream is not significant. However, in interleaved packages,
"Default" and "Override" elements appear in the physical package
before the part(s) they correspond to.
[0171] Interleaving
[0172] Not all physical packages support interleaving of the data
streams of parts natively. In one embodiment, a mapping to any such
physical package uses the general mechanism described in this
section to allow interleaving of parts. The general mechanism works
by breaking the data stream of a part into multiple pieces that can
then be interleaved with pieces of other parts, or whole parts. The
individual pieces of a part exist in the physical mapping and are
not addressable in the logical packaging model. Pieces may have a
zero size.
[0173] The following unique mapping from a part name to the names
for the individual pieces of a part is defined, such that a reader
can stitch together the pieces in their original order to form the
data stream of the part.
[0174] Grammar for deriving piece names for a given part name:
22 piece_name = part_name "/" "[" 1*digit "]" [ ".last" ]
".piece"
[0175] The following validity constraints exist for piece_names
generated by the grammar:
[0176] The piece numbers start with 0, and are positive,
consecutive integer numbers. Piece numbers can be
left-zero-padded.
[0177] The last piece of the set of pieces of a part contains the
".last" in the piece name before ".piece".
[0178] The piece name is generated from the name of the logical
part before mapping to names in the physical package.
[0179] Although it is not necessary to store pieces in their
natural order, such storage may provide optimal efficiency. A
physical package containing interleaved (pieced) parts can also
contain non-interleaved (one-piece) parts, so the following example
would be valid:
23 spine.xaml/[0].piece pages/page0.xaml spine.xaml/[1].piece
pages/page1.xaml spine.xaml/[2].last.piece pages/page2.xaml
[0180] Specific Mappings
[0181] The following defines specific mappings for the following
physical formats: Loose files in a Windows file system.
[0182] Mapping to Loose Files in a Windows File System
[0183] In order to better understand how to map elements of the
logical model to a physical format, consider the basic case of
representing a Metro package as a collection of loose files in a
Windows file system. Each part in the logical package will be
contained in a separate file (stream). Each part name in the
logical model corresponds to the name of the file.
24 Logical Component Physical Representation Part File(s) Part name
File name with path (which should look like URI, changes slash to
backslash, etc.). Part Content Type File containing XML expressing
simple list of file names and their associated types
[0184] The part names are translated into valid Windows file names,
as illustrated by the table below.
[0185] Given below are two character sets that are valid for
logical part name segments (URI segments) and for Windows
filenames. This table reveals two important things:
[0186] There are two valid URI symbols colon (:) and asterisk (*)
which we need to escape when converting a URI to a filename.
[0187] There are valid filename symbols {circumflex over ( )} { } [
] # which cannot be present in a URI (they can be used for special
mapping purposes, like interleaving).
[0188] "Escaping" is used as a technique to produces valid filename
characters when a part name contains a character that can not be
used in a file name. To escape a character, the caret symbol
({circumflex over ( )}) is used, followed by the hexadecimal
representation of the character.
[0189] To map from an abs_path (part name) to a file name:
25 remove first / convert all / to .backslash. escape colon and
asterisk characters
[0190] For example, the part name /a:b/c/d*.xaml becomes the
following file name a{circumflex over (
)}25b.backslash.c.backslash.d{circumflex over ( )}2a.xaml.
[0191] To perform the reverse mapping:
26 convert all .backslash. to / add / to the beginning of the
string unescape characters by replacing {circumflex over (
)}[hexCode] with the corresponding character
[0192]
27 From URI grammar rules Characters that are valid for naming
files, (RFC2396) folders, or shortcuts path_segments = segment *(
"/" segment ) Alphanum .vertline. {circumflex over ( )} Accent
circumflex (caret) segment = *pchar *( ";" param ) & Ampersand
param = *pchar ' Apostrophe (single quotation mark) pchar =
unreserved .vertline. escaped .vertline.":" .vertline. "@"
.vertline. "&" .vertline. @ At sign "=" .vertline. "+"
.vertline. "$" .vertline. "," { Brace left unreserved = alphanum
.vertline. mark } Brace right alphanum = alpha .vertline. digit [
Bracket opening mark = "-" .vertline. "_" .vertline. "." .vertline.
"!" .vertline. ".about." .vertline. "*" .vertline. "'"
.vertline."(" .vertline. ")" ] Bracket closing escaped = "%" hex
hex , Comma hex = digit .vertline. "A" .vertline. "B" .vertline.
"C" .vertline. "D" .vertline. "E" .vertline. "F" .vertline."a"
.vertline. $ Dollar sign "b" .vertline. "c" .vertline. "d"
.vertline. "e" .vertline. "f" = Equal sign ! Exclamation point -
Hyphen # Number sign ( Parenthesis opening ) Parenthesis closing %
Percent . Period + Plus .about. Tilde .sub.-- Underscore
[0193] Versioning and Extensibility
[0194] Like other technical specifications, the specification
contained herein may evolve with future enhancements. The design of
the first edition of this specification includes plans for the
future interchange of documents between software systems written
based on the first edition, and software systems written for future
editions. Similarly, this specification allows for third-parties to
create extensions to the specification. Such an extension might,
for example, allow for the construction of a document which
exploits a feature of some specific printer, while still retaining
compatibility with other readers that are unaware of that printer's
existence.
[0195] Documents using new versions of the Fixed Payload markup, or
third-party extensions to the markup, require readers to make
appropriate decisions about behavior (e.g., how to render something
visually). To guide readers, the author of a document (or the tool
that generated the document) should identify appropriate behavior
for readers encountering otherwise-unrecognized elements or
attributes. For Reach documents, this type of guidance is
important.
[0196] New printers, browsers, and other clients may implement a
variety of support for future features. Document authors exploiting
new versions or extensions must carefully consider the behavior of
readers unaware of those versions of extensions.
[0197] Versioning Namespace
[0198] XML markup recognition is based on namespace URIs. For any
XML-namespace, a reader is expected to recognize either all or none
of the XML-elements and XML-attributes defined in that namespace.
If the reader does not recognize the new namespace, the reader will
need to perform fallback rendering operations as specified within
the document.
[0199] The XML namespace URI `http://PLACEHOLDER/version-control`
includes the XML elements and attributes used to construct Fixed
payload markup that is version-adaptive and extensions-adaptive.
Fixed Payloads are not required to have versioning elements within
them. In order to build adaptive content, however, one must use at
least one of the <ver:Compatibility.Rules> and
<ver:AlternativeContent> XML-elements.
[0200] This Fixed-Payload markup specification has an xmlns URI
associated with it: `http://PLACEHOLDER/pdl`. Using this namespace
in a Fixed Payload will indicate to a reader application that only
elements defined in this specification will be used. Future
versions of this specification will have their own namespaces.
Reader applications familiar with the new namespace will know how
to support the superset of elements of attributes defined in
previous versions. Reader applications that are not familiar with
the new version will consider the URI of the new version as if it
were the URI of some unknown extension to the PDL. These
applications may not know that a relationship exists between the
namespaces, that one is a superset of the other.
[0201] Backward and "Forward" Compatibility
[0202] In the context of applications or devices supporting the
systems and methods discussed herein, compatibility is indicated by
the ability of clients to parse and display documents that were
authored using previous versions of the specification, or unknown
extensions or versions of the specification. Various versioning
mechanisms address "backward compatibility," allowing future
implementations of clients to be able to support documents based on
down-level versions of the specification, as illustrated below.
[0203] When an implemented client, such as a printer, receives a
document built using a future version of the markup language, the
client will be able to parse and understand the available rendering
options. The ability of client software written according to an
older version of a specification to handle some documents using
features of a newer version is often called "forward
compatibility." A document written to enable forward compatibility
is described as "version-adaptive."
[0204] Further, because implemented clients will also need to be
able to support documents that have unknown extensions representing
new elements or properties, various semantics support the more
general case of documents that are "extension adaptive."
[0205] If a printer or viewer encounters extensions that are
unknown, it will look for information embedded alongside the use of
the extension for guidance about adaptively rendering the
surrounding content. This adaptation involves replacing unknown
elements or attributes with content that is understood. However,
adaptation can take other forms, including purely ignoring unknown
content. In the absence of explicit guidance, a reader should treat
the presence of an unrecognized extension in the markup as an
error-condition. If guidance is not provided, the extension is
presumed to be fundamental to understanding the content. The
rendering failure will be captured and reported to the user.
[0206] To support this model, new and extended versions of the
markup language should logically group related extensions in
namespaces. In this way, document authors will be able to take
advantage of extended features using a minimum number of
namespaces.
[0207] Versioning Markup
[0208] The XML vocabulary for supporting extension-adaptive
behavior includes the following elements:
28 Versioning Element and Hierarchy Description
<Compatibility.Rules> Controls how the parser reacts to an
unknown element or attribute. <Ignorable> Declares that the
associated namespace URI is ignorable. <ProcessContent>
Declares that if an element is ignored, the contents of the element
will be processed as if it was contained by the container of the
ignored element. <CarryAlong> Indicates to the document
editing tools whether ignorable content should be preserved when
the document is modified. <MustUnderstand> Reverses the
effect of an element declared ignorable. <AlternateContent>
In markup that exploits versioning/extension features, the
<AlternateContent> element associates substitute "fallback"
markup to be used by reader applications that are not able to
handle the markup specified as Preferred. <Prefer> Specifies
preferred content. This content will that a client is aware of
version/extension features. <Fallback> For down-level
clients, specifies the `down-level` content to be substituted for
the preferred content.
[0209] The <Compatibility.Rules> Element
[0210] Compatibility.Rules can be attached to any element that can
hold an attached attribute, as well as to the Xaml root element.
The <Compatibility.Rules> element controls how the parser
reacts to unknown elements or attributes. Normally such items are
reported as errors. Adding an Ignorable element to a
Compatibilitiy.Rules property informs the compiler that items from
certain namespaces can be ignored.
[0211] Compatibility.Rules can contain the elements Ignorable and
MustUnderstand. By default, all elements and attributes are assumed
to be MustUnderstand. Elements and attributes can be made Ignorable
by adding an Ignorable element into its container's
Compatibility.Rules property. An element or property can be made
MustUnderstand again by adding a MustUnderstand element to one of
the nested containers. One Ignorable or MustUnderstand refers to a
particular namespace URI within the same Compatibility.Rules
element.
[0212] The <Compatibility.Rules> element affects the contents
of a container, not the container's own tag or attributes. To
affect a container's tag or attributes, its container must contain
the compatibility rules. The Xaml root element can be used to
specify compatibility rules for elements that would otherwise be
root elements, such as Canvas. The Compatibility.Rules compound
attribute is the first element in a container.
[0213] The <Ignorable> Element
[0214] The <Ignorable> element declares that the enclosed
namespace URI is ignorable. An item can be considered ignorable if
an <Ignorable> tag is declared ahead of the item in the
current block or a container block, and the namespace URI is
unknown to the parser. If the URI is known, the Ignorable tag is
disregarded and all items are understood. In one embodiment, all
items not explicitly declared as Ignorable must be understood. The
Ignorable element can contain <ProcessContent> and
<CarryAlong> elements, which are used to modify how an
element is ignored as well as give guidance to document editing
tools how such content should be preserved in edited documents.
[0215] The <Process Content> Element
[0216] The <ProcessContent> element declares that if an
element is ignored, the contents of the element will be processed
as if it was contained by the container of the ignored element.
29 <ProcessContent> Attributes Attribute Description Elements
A space delimited list of element names for which to process the
contents, or "*" indicating the contents of all elements should be
processed. The Elements attribute defaults to "*" if it is not
specified.
[0217] The <CarryAlong> Element
[0218] The optional <CarryAlong> element indicates to the
document editing tools whether ignorable content should be
preserved when the document is modified. The method by which an
editing tool preserves or discards the ignorable content is in the
domain of the editing tool. If multiple <CarryAlong> elements
refer to the same element or attribute in a namespace, the last
<CarryAlong> specified has precedence.
30 <CarryAlong> Attributes Attribute Description Elements A
space delimited list of element names that are requested to be
carried along when the document is edited, or "*" indicating the
contents of all elements in the namespace should be carried along.
The Elements attribute defaults to "*" if it is not specified.
Attributes A space delimited list of attribute names within the
elements that are to be carried along, or a "*" indicating that all
attributes of the elements should be carried along. When an element
is ignored and carried along, all attributes are carried along
regardless of the contents of this attribute. This attribute only
has an effect if the attribute specified is used in an element that
is not ignored, as in the example below. By default, Attributes is
"*".
[0219] The <MustUnderstand> Element
[0220] <MustUnderstand> is an element that reverses the
effects of an Ignorable element. This technique is useful, for
example, when combined with alternate content. Outside the scope
defined by the <MustUnderstand> element, the element remains
Ignorable.
31 <MustUnderstand> Attributes Attribute Description
NamespaceUri The URI of the namespace whose items must be
understood.
[0221] The <AlternateContent> Element
[0222] The <AlternateContent> element allows alternate
content to be provided if any part of the specified content is not
understood. An AlternateContent block uses both a <Prefer>
and a <Fallback> block. If anything in the <Prefer>
block is not understood, then the contents of the <Fallback>
block are used. A namespace is declared <MustUnderstand> in
order to indicate that the fallback is to be used. If a namespace
is declared ignorable and that namespace is used within a
<Prefer> block, the content in the <Fallback> block
will not be used.
[0223] Versioning Markup Examples
[0224] Using <Ignorable>
[0225] This example uses a fictitious markup namespace,
http://PLACEHOLDER/Circle, that defines an element Circle in its
initial version and uses the Opacity attribute of Circle introduced
in a future version of the markup (version 2) and the Luminance
property introduced in an even later version of the markup (version
3). This markup remains loadable in versions 1 and 2, as well as 3
and beyond. Additionally, the <CarryAlong> element specifies
that v3:Luminance MUST be preserved when editing even when the
editor doesn't understand v3:Luminance.
32 For a version 1 reader, Opacity and Luminance are ignored. For a
version 2 reader, only Luminance is ignored. For a version 3 reader
and beyond, all the attributes are used. <FixedPanel
xmlns="http://PLACEHOLDER/fixed-content"
xmlns:v="http://PLACEHODER/versioned-content"
xmlns:v1="http://PLACEHODER/Circle/v1" xmlns:v2="http://PLACEHO-
DER/Circle/v2" xmlns:v3="http://PLACEHODER/Circle/v3" >
<v:Compatibility.Rules> <v:Ignorable NamespaceUri="
http://PLACEHODER/Circle/v2" /> <v:Ignorable NamespaceUri="
http://PLACEHODER/Circle/v3" > <v:CarryAlong
Attributes="Luminance" /> </v:Ignorable>
</v:Compatibility.Rules> <Canvas> <Circle
Center="0,0" Radius="20" Color="Blue" v2:Opacity="0.5"
v3:Luminance="13" /> <Circle Center="25,0" Radius="20"
Color="Black" v2:Opacity="0.5" v3:Luminance="13" /> <Circle
Center="50,0" Radius="20" Color="Red" v2:Opacity="0.5"
v3:Luminance="13" /> <Circle Center="13,20" Radius="20"
Color="Yellow" v2:Opacity="0.5" v3:Luminance="13" /> <Circle
Center="38,20" Radius="20" Color="Green" v2:Opacity="0.5"
v3:Luminance="13" /> </Canvas> </FixedPanel>
[0226] Using <MustUnderstand>
[0227] The following example demonstrates the use of the
<MustUnderstand> element.
33 <FixedPanel xmlns="http://PLACEHOLDER/fixed-- content"
xmlns:v="http://PLACEHODER/versioned-content"
xmlns:v1="http://PLACEHODER/Circle/v1" xmlns:v2="http://PLACEHOD-
ER/Circle/v2" xmlns:v3="http://PLACEHODER/Circle/v3" >
<v:Compatibility.Rules> <v:Ignorable
NamespaceUri="http://PLACEHODER/Circle/v2" /> <v:Ignorable
NamespaceUri="http://PLACEHODER/Circle/v3" > <v:CarryAlong
Attributes="Luminance" /> </v:Ignorable>
</v:Compatibility.Rules> <Canvas>
<v:Compatibility.Rules> <v:MustUnderstand
NamespaceUri="http://PLACEHODER/ Circle/v3" />
</v:Compatbility.Rules> <Circle Center="0,0" Radius="20"
Color="Blue" v2:Opacity="0.5" v3:Luminance="13" /> <Circle
Center="25,0" Radius="20" Color="Black" v2:Opacity="0.5"
v3:Luminance="13" /> <Circle Center="50,0" Radius="20"
Color="Red" v2:Opacity="0.5" v3:Luminance="13" /> <Circle
Center="13,20" Radius="20" Color="Yellow" v2:Opacity="0.5"
v3:Luminance="13" /> <Circle Center="38,20" Radius="20"
Color="Green" v2:Opacity="0.5" v3:Luminance="13" />
</Canvas> </FixedPanel>
[0228] Use of the <MustUnderstand> element causes the
references to v3:Luminance to be in error, even though it was
declared to Ignorable in the root element. This technique is useful
if combined with alternate content that uses, for example, the
Luminance property of Canvas added in Version 2 instead (see
below). Outside the scope of the Canvas element, Circle's Luminance
property is ignorable again.
34 <FixedPanel xmlns="http://PLACEHOLDER/fixed-- content"
xmlns:v="http://PLACEHODER/versioned-content"
xmlns:v1="http://PLACEHODER/Circle/v1" xmlns:v2="http://PLACEHOD-
ER/Circle/v2" xmlns:v3="http://PLACEHODER/Circle/v3" >
<v:Compatibility.Rules> <v:Ignorable
NamespaceUri="http://PLACEHODER/Circle/v2" /> <v:Ignorable
NamespaceUri="http://PLACEHODER/Circle/v3" > <v:CarryAlong
Attributes="Luminance" /> </v:Ignorable>
</v:Compatibility.Rules> <Canvas>
<v:Compatibility.Rules> <v:MustUnderstand
NamespaceUri="http://PLACEHODER/ Circle/v3" />
</v:Compatbility.Rules> <v:AlternateContent>
<v:Prefer> <Circle Center="0,0" Radius="20" Color="Blue"
v2:Opacity="0.5" v3:Luminance="13" /> <Circle Center="25,0"
Radius="20" Color="Black" v2:Opacity="0.5" v3:Luminance="13" />
<Circle Center="50,0" Radius="20" Color="Red" v2:Opacity="0.5"
v3:Luminance="13" /> <Circle Center="13,20" Radius="20"
Color="Yellow" v2:Opacity="0.5" v3:Luminance="13" /> <Circle
Center="38,20" Radius="20" Color="Green" v2:Opacity="0.5"
v3:Luminance="13" /> </v:Prefer> <v:Fallback>
<Canvas Luminance="13"> <Circle Center="0,0" Radius="20"
Color="Blue" v2:Opacity="0.5" /> <Circle Center="25,0"
Radius="20" Color="Black" v2:Opacity="0.5" /> <Circle
Center="50,0" Radius="20" Color="Red" v2:Opacity="0.5" />
<Circle Center="13,20" Radius="20" Color="Yellow"
v2:Opacity="0.5" /> <Circle Center="38,20" Radius="20"
Color="Green" v2:Opacity="0.5" /> </Canvas>
</v:Fallback> </v:AlternateContent> </Canvas>
</FixedPanel>
[0229] Using <AlternateContent>
[0230] If any element or attribute is declared as
<MustUnderstand> but is not understood in the <Prefer>
block of an <AlternateContent> block, the <Prefer>
block is skipped in its entirety and the <Fallback> block is
processed as normal (that is, any MustUnderstand items encountered
are reported as errors).
35 <v:AlternateContent> <v:Prefer> <Path
xmlns:m="http://schemas.example.com/2008/metallic-finishes"
m:Finish="GoldLeaf" ..... /> </v:Prefer>
<v:Fallback> <Path Fill="Gold" ..... />
</v:Fallback> </v:AlternateContent>
[0231] The Reach Package Format
[0232] In the discussion that follows, a description of a specific
file format is provided. Separate primary sub-headings in this
section include "Introduction to the Reach Package Format", "The
Reach Package Structure", "Fixed Payload Parts", "FixedPage Markup
Basics", "Fixed-Payload Elements and Properties" and "FixedPage
Markup". Each primary sub-heading has one or more related
sub-headings.
[0233] Introduction to the Reach Package Format
[0234] Having described an exemplary framework above, the
description that follows is one of a specific format that is
provided utilizing the tools described above. It is to be
appreciated and understood that the following description
constitutes but one exemplary format and is not intended to limit
application of the claimed subject matter.
[0235] In accordance with this embodiment, a single package may
contain multiple payloads, each acting as a different
representation of a document. A payload is a collection of parts,
including an identifiable "root" part and all the parts required
for valid processing of that root part. For instance, a payload
could be a fixed representation of a document, a reflowable
representation, or any arbitrary representation.
[0236] The description that follows defines a particular
representation called the fixed payload. A fixed payload has a root
part that contains a FixedPanel markup which, in turn, references
FixedPage parts. Together, these describe a precise rendering of a
multi-page document.
[0237] A package which holds at least one fixed payload, and
follows other rules described below, is known referred to as a
reach package. Readers and writers of reach packages can implement
their own parsers and rendering engines, based on the specification
of the reach package format.
[0238] Features of Reach Packages
[0239] In accordance with the described embodiment, reach packages
address the requirements that information workers have for
distributing, archiving, and rendering documents. Using known
rendering rules, reach packages can be unambiguously and exactly
reproduced or printed from the format in which they are saved,
without tying client devices or applications to specific operating
systems or service libraries. Additionally, because the reach
payload is expressed in a neutral, application-independent way, the
document can typically be viewed and printed without the
application used to create the package. To provide this ability,
the notion of a fixed payload is introduced and contained in a
reach package.
[0240] In accordance with the described embodiment, a fixed payload
has a fixed number of pages and page breaks are always the same.
The layout of all the elements on a page in a fixed payload is
predetermined. Each page has a fixed size and orientation. As such,
no layout calculations have to be performed on the consuming side
and content can simply be rendered. This applies not just to
graphics, but to text as well, which is represented in the fixed
payload with precise typographic placement. The content of a page
(text, graphics, images) is described using a powerful but simple
set of visual primitives.
[0241] Reach packages support a variety of mechanisms for
organizing pages. A group of pages are "glued" together one after
another into a "FixedPanel." This group of pages is roughly
equivalent to a traditional multi-page document. A FixedPanel can
then further participate in composition--the process of building
sequences and selections to assemble a "compound" document.
[0242] In the illustrated and described embodiment, reach packages
support a specific kind of sequence called a FixedPanel sequence
that can be used, for example, to glue together a set of
FixedPanels into a single, larger "document." Imagine, for example,
gluing together two documents that came from different sources: a
two-page cover memo (a FixedPanel) and a twenty-page report (a
FixedPanel).
[0243] Reach packages support a number of specific selectors that
can be used when building document packages containing alternate
representations of the "same" content. In particular, reach
packages allow selection based on language, color capability, and
page size. Thus, one could have, for example, a bi-lingual document
that uses a selector to pick between the English representation and
the French representation of the document.
[0244] In addition to these simple uses of selector and sequence
for composition in a reach package, it is important to note that
selectors and sequences can also refer to further selectors and
sequences thus allowing for powerful aggregate hierarchies to be
built. The exact rules for what can and cannot be done, in
accordance with this embodiment, are specified below in the section
entitled "The Reach Package Structure".
[0245] Additionally, a reach package can contain additional
payloads that are not fixed payloads, but instead are richer and
perhaps editable representations of the document. This allows a
package to contain a rich, editable document that works well in an
editor application as well as a representation that is visually
accurate and can be viewed without the editing application.
[0246] Finally, in accordance with this embodiment, reach packages
support what is known as a print ticket. The print ticket provides
settings that should be used when the package is printed. These
print tickets can be attached in a variety of ways to achieve
substantial flexibility. For example, a print ticket can be
"attached" to an entire package and its settings will affect the
whole package. Print tickets can be further attached at lower
levels in the structure (e.g., to individual pages) and these print
tickets will provide override settings to be used when printing the
part to which they are attached.
[0247] The Reach Package Structure
[0248] As described above, a reach package supports a set of
features including "fixed" pages, FixedPanels, composition, print
tickets, and the like. These features are represented in a package
using the core components of the package model: parts and
relationships. In this section and its related sub-sections, a
complete definition of a "reach package" is provided, including
descriptions of how all these parts and relationships must be
assembled, related, etc.
[0249] Reach Package Structure Overview
[0250] FIG. 10 illustrates an exemplary reach package and, in this
embodiment, each of the valid types of parts that can make up or be
found in a package. The table provided just below lists each valid
part type and provides a description of each:
36 FixedPage Each FixedPage part represents the content of a page
application/xml+FixedPage-PLACEHOLDER FixedPanel Each FixedPanel
glues together a set of FixedPages in
application/xml+FixedPanel-PLACEHOLDER order Font Fonts can be
embedded in a package to ensure reliable reproduction of the
document's glyphs. Image Image parts can be included image/jpeg
image/png Composition Parts Selectors and sequences can be used to
build a application/xml+Selector+[XXX] "composition" block,
introducing higher-level organization
Application/xml+Sequence+[XXX] to the package. Descriptive Metadata
Descriptive metadata (e.g., title, keywords) can be
application/xml+SimpleTypeProperties-PLACEHOLDER included for the
document. Print Ticket A print ticket can be included to provide
settings to be application/xml+PRINTTICKET-PLACEHOLDER used when
printing the package.
[0251] Because a reach package is designed to be a "view and print
anywhere" document, readers and writers of reach packages must
share common, unambiguously-defined expectations of what
constitutes a "valid" reach package. To provide a definition of a
"valid" reach package, a few concepts are first defined below.
[0252] Reach Composition Parts
[0253] A reach package must contain at least one FixedPanel that is
"discoverable" by traversing the composition block from the
starting part of the package. In accordance with the described
embodiment, the discovery process follows the following
algorithm:
[0254] Recursively traverse the graph of composition parts starting
at the package starting part.
[0255] When performing this traversal, only traverse into
composition parts that are reach composition parts (described
below).
[0256] Locate all of the terminal nodes (those without outgoing
arcs) at the edge of the graph.
[0257] These terminal nodes refer (via their <item> elements)
to a set of parts called the reach payload roots.
[0258] Fixed Payload
[0259] A fixed payload is a payload whose root part is a FixedPanel
part. For example, each of the fixed payloads in FIG. 10 has as its
root part an associated FixedPanel part. The payload includes the
full closure of all of the parts required for valid processing of
the FixedPanel. These include:
[0260] The FixedPanel itself;
[0261] All FixedPages referenced from within the FixedPanel;
[0262] All image parts referenced (directly, or indirectly through
a selector) by any of the FixedPages in the payload;
[0263] All reach selectors (as described below) referenced directly
or indirectly from image brushes used within any of the FixedPages
within the payload;
[0264] All font parts referenced by any of the FixedPages in the
payload;
[0265] All descriptive metadata parts attached to any part in the
fixed payload; and
[0266] Any print tickets attached to any part in the fixed
payload.
[0267] Validity Rules for Reach Package
[0268] With the above definitions in place, conformance rules that
describe a "valid" reach package in accordance with the described
embodiment are now described:
[0269] A reach package must have a starting part defined using the
standard mechanism of a package relationship as described
above;
[0270] The starting part of a reach package must be either a
selector or a sequence;
[0271] A reach package must have at least one reach payload root
that is a FixedPanel;
[0272] PrintTicket parts may be attached to any of the composition
parts, FixedPanel parts or any of the FixedPage parts identified in
the FixedPanel(s). In the present example, this is done via the
http://PLACEHOLDER/HasPrintTicketRel relationship;
[0273] PrintTickets may be attached to any or all of these
parts;
[0274] Any given part must have no more than one PrintTicket
attached;
[0275] A Descriptive Metadata part may be attached to any part in
the package;
[0276] Every Font object in the FixedPayload must meet the font
format rules defined in section "Font Parts".
[0277] References to images from within any FixedPage in the fixed
payload may point to a selector which may make a selection
(potentially recursively through other selectors) to find the
actual image part to be rendered;
[0278] Every Image object used in the fixed payload must meet the
font format rules defined in section "Image Parts";
[0279] For any font, image or selector part referenced from a
FixedPage (directly, or indirectly through selector), there must be
a "required part" relationship (relationship
name=http://mmcf-fixed-RequiredResource-- PLACEHOLDER) from the
referencing FixedPage to the referenced part.
[0280] Reach Composition Parts
[0281] While a reach package may contain many types of composition
part, only a well-defined set of types of composition parts have
well-defined behavior according to this document. These composition
parts with well-defined behavior are called reach composition
parts. Parts other than these are not relevant when determining
validity of a reach package.
[0282] The following types of composition parts are defined as
reach composition parts:
37 Language Selector Chooses between representations
application/xml+selector+language based on their natural language
Color Selector Chooses between representations
application/xml+selector+color based on whether they are
monochromatic or color Page Size Selector Chooses between
representations application/xml+selector+pagesize based on their
page size Content Type Selector Chooses between representations
application/xml+selector+contenttype based on whether their content
types can be understood by the system Fixed Sequence Combines
children that are fixed application/xml+sequence- +fixed content
into a sequence
[0283] Reach Selectors
[0284] Those selector composition parts defined as reach
composition parts are called reach selectors. As noted above, a
language selector picks between representations based on their
natural language, such as English or French. To discover this
language, the selector inspects each of its items. Only those that
are XML are considered. For those, the root element of each one is
inspected to determine its language. If the xml:lang attribute is
not present, the part is ignored. The selector then considers each
of these parts in turn, selecting the first one whose language
matches the system's default language.
[0285] A color selector chooses between representations based on
whether they are monochromatic or color. The page size selector
chooses between representations based on their page size. A content
type selector chooses between representations based on whether
their content types can be understood by the system.
[0286] Reach Sequences
[0287] Those sequence composition parts defined as reach
composition parts are called reach sequences. A fixed sequence
combines children that are fixed content into a sequence.
[0288] Fixed Payloads Parts
[0289] The fixed payload can contain the following kinds of parts:
a FixedPanel part, a FixedPage part, Image parts, Font parts, Print
Ticket parts, and Descriptive Metadata parts, each of which is
discussed below under its own sub-heading.
[0290] The FixedPanel Part
[0291] The document structure of the Fixed-Payload identifies
FixedPages as part of a spine, as shown below. The relationships
between the spine part and the page parts are defined within the
relationships stream for the spine. The FixedPanel part is of
content type application/xml+PLACEHO- LDER.
[0292] The spine of the Fixed-Payload content is specified in
markup by including a <FixedPanel> element within a
<Document> element. In the example below, the
<FixedPanel> element specifies the sources of the pages that
are held in the spine.
38 <!-- SPINE --> <Document $XMLNSFIXED$ >
<FixedPanel> <PageContent Source="p1.xml" />
<PageContent Source="p2.xml" /> </FixedPanel>
</Document>
[0293] The <Document> Element
[0294] The <Document> element has no attributes and must have
only one child: <FixedPanel>.
[0295] The <FixedPanel> Element
[0296] The <FixedPanel> element is the document spine,
logically binding an ordered sequence of pages together into a
single multi-page document. Pages always specify their own width
and height, but a <FixedPanel> element may also optionally
specify a height and width. This information can be used for a
variety of purposes including, for example, selecting between
alternate representations based on page size. If a
<FixedPanel> element specifies a height and width, it will
usually be aligned with the width and height of the pages within
the <FixedPanel>, but these dimensions do not specify the
height and width of individual pages.
[0297] The following table summarizes FixedPanel attributes in
accordance with the described embodiment.
39 <FixedPanel> Attribute Description PageHeight Typical
height of pages contained in the <FixedPanel>. Optional
PageWidth Typical width of pages contained in the
<FixedPanel>. Optional
[0298] The <PageContent> element is the only allowable child
element of the <FixedPanel> element. The <PageContent>
elements are in sequential markup order matching the page order of
the document.
[0299] The <PageContent> Element
[0300] Each <PageContent> element refers to the source of the
content for a single page. To determine the number of pages in the
document, one would count the number of <PageContent>
children contained within the <FixedPanel>.
[0301] The <PageContent> element has no allowable children,
and has a single required attribute, Source, which refers to the
FixedPage part for the contents of a page.
[0302] As with the <FixedPanel> element, the
<PageContent> element may optionally include a PageHeight and
PageWidth attribute, here reflecting the size of the single page.
The required page size is specified in the FixedPage part; the
optional size on <PageContent> is advisory only. The
<PageContent> size attributes allow applications such as
document viewers to make visual layout estimates for a document
quickly, without loading and parsing all of the individual
FixedPage parts.
[0303] The table provided just below summarizes <PageContent>
attributes and provides a description of the attributes.
40 <PageContent> Attribute Description Source A URI string
that refers to the page content, held in a distinct part within the
package. The content is identified as a part within the package.
Required. PageHeight Optional PageWidth Optional
[0304] The URI string of the page content must reference the part
location of the content relative to the package.
[0305] The FixedPage Part
[0306] Each <PageContent> element in the <FixedPanel>
references by name (URI) a FixedPage part. Each FixedPage part
contains FixedPage markup describing the rendering of a single page
of content. The FixedPage part is of Content Type
application/xml+PLACEHOLDER-FixedPa- ge.
[0307] Describing FixedPages in Markup
[0308] Below is an example of how the markup of the source content
might look for the page referenced in the sample spine markup above
(<PageContent Source="p1.xml"/>).
41 // /content/p1.xml <FixedPage PageHeight="1056"
PageWidth="816"> <Glyphs OriginX = "96" OriginY = "96"
UnicodeString = "This is Page 1!" FontUri = "../Fonts/Times.TTF"
FontRenderingEmsize = "16" /> </FixedPage>
[0309] The table below summarizes FixedPage properties and provides
a description of the properties.
42 FixedPage Property Description PageHeight Required PageWidth
Required
[0310] Reading Order in FixedPage Markup
[0311] In one embodiment, the markup order of the Glyphs child
elements contained within a FixedPage must be the same as the
desired reading order of the text content of the page. This reading
order may be used both for interactive selection/copy of sequential
text from a FixedPage in a viewer, and for enabling access to
sequential text by accessibility technology. It is the
responsibility of the application generating the FixedPage markup
to ensure this correspondence between markup order and reading
order.
[0312] Image Parts
[0313] Supported Formats
[0314] In accordance with the described embodiment, image parts
used by FixedPages in a reach package can be in a fixed number of
formats, e.g., PNG or JPEG, although other formats can be used.
[0315] Font Parts
[0316] In accordance with the described embodiment, reach packages
support a limited number of font formats. In the illustrated and
described embodiment, the supported font format include the
TrueType format and the OpenType format.
[0317] As will be appreciated by the skilled artisan, the OpenType
font format is an extension of the TrueType font format, adding
support for PostScript font data and complex typographical layout.
An OpenType font file contains data, in table format, that
comprises either a TrueType outline font or a PostScript outline
font.
[0318] In accordance with the described embodiment, the following
font formats are not supported in reach packages: Adobe type 1,
Bitmap font, Font with hidden attribute (use system Flag to decide
whether to enumerate it or not), Vector fonts, and EUDC font (whose
font family name is EUDC).
[0319] Subsetting Fonts
[0320] Fixed payloads represent all text using the Glyphs element
described in detail below. Since, in this embodiment, the format is
fixed, it is possible to subset fonts to contain only the glyphs
required by FixedPayloads. Therefore, fonts in reach packages may
be subsetted based on glyph usage. Though a subsetted font will not
contain all the glyphs in the original font, the subsetted font
must be a valid OpenType font file.
[0321] Print Ticket Parts
[0322] Print ticket parts provide settings that can be used when
the package is printed. These print tickets can be attached in a
variety of ways to achieve substantial flexibility. For example, a
print ticket can be "attached" to an entire package and its
settings will affect the whole package. Print tickets can be
further attached at lower levels in the structure (e.g., to
individual pages) and these print tickets will provide override
settings to be used when printing the part to which they are
attached.
[0323] Descriptive Metadata
[0324] As noted above, descriptive metadata parts provide writers
or producers of packages with a way in which to store values of
properties that enable readers of the packages to reliably discover
the values. These properties are typically used to record
additional information about the package as a whole, as well as
individual parts within the container.
[0325] FixedPage Markup Basics
[0326] This section describes some basic information associated
with the FixedPage markup and includes the following sections:
"Fixed Payload and Other Markup Standards", "FixedPage Markup
Model", "Resources and Resource References", and "FixedPage Drawing
Model".
[0327] Fixed Payload and Other Markup Standards
[0328] The FixedPanel and FixedPage markup for the Fixed Payload in
a reach package is a subset from Windows.RTM. Longhorn's Avalon
XAML markup. That is, while the Fixed Payload markup stands alone
as an independent XML markup format (as documented in this
document), it loads in the same way as in Longhorn systems, and
renders a WYSIWYG reproduction of the original multi-page
document.
[0329] As some background on XAML markup, consider the following.
XAML markup is a mechanism that allows a user to specify a
hierarchy of objects and the programming logic behind the objects
as an XML-based markup language. This I provides the ability for an
object model to be described in XML. This allows extensible
classes, such as classes in the Common Language Runtime (CLR) of
the .NET Framework by Microsoft Corporation, to be accessed in XML.
The XAML mechanism provides a direct mapping of XML tags to CLR
objects and the ability to represent related code in the markup. It
is to be appreciated and understood that various implementations
need not specifically utilize a CLR-based implementation of XAML.
Rather, a CLR-based implementation constitutes but one way in which
XAML can be employed in the context of the embodiments described in
this document.
[0330] More specifically, consider the following in connection with
FIG. 11 which illustrates an exemplary mapping of CLR concepts
(left side components) to XML (right side components). Namespaces
are found in the xmlns declaration using a CLR concept called
reflection. Classes map directly to XML tags. Properties and events
map directly to attributes. Using this hierarchy, a user can
specify a hierarchy tree of any CLR objects in XML markup files.
Xaml files are xml files with a .xaml extension and a mediatype of
application/xaml+xml. Xaml files have one root tag that typically
specifies a namespace using the xmlns attribute. The namespace may
be specified in other types of tags.
[0331] Continuing, tags in a xaml file generally map to CLR
objects. Tags can be elements, compound properties, definitions or
resources. Elements are CLR objects that are generally instantiated
during runtime and form a hierarchy of objects. Compound property
tags are used to set a property in a parent tag. Definition tags
are used to add code into a page and define resources. The resource
tag provides the ability to reuse a tree of objects merely by
specifying the tree as a resource. Definition tags may also be
defined within another tag as an xmlns attribute.
[0332] Once a document is suitably described in markup (typically
by a writer), the markup can be parsed and processed (typically by
a reader). A suitably configured parser determines from the root
tag which CLR assemblies and namespaces should be searched to find
a tag. In many instances, the parser looks for and will find a
namespace definition file in a URL specified by the xmlns
attribute. The namespace definition file provides the name of
assemblies and their install path and a list of CLR namespaces.
When the parser encounters a tag, the parser determines which CLR
class the tag refers to using the xmlns of the tag and the xmlns
definition file for that xmlns. The parser searches in the order
that the assemblies and namespaces are specified in the definition
file. When it finds a match, the parser instantiates an object of
the class.
[0333] Thus, the mechanism described just above, and more fully in
the application incorporated by reference above, allows object
models to be represented in an XML-based file using markup tags.
This ability to represent object models as markup tags can be used
to create vector graphic drawings, fixed-format documents,
adaptive-flow documents, and application UIs asynchronously or
synchronously.
[0334] In the illustrated and described embodiment, the Fixed
Payload markup is a very minimal, nearly completely parsimonious
subset of Avalon XAML rendering primitives. It represents visually
anything that can be represented in Avalon, with full fidelity. The
Fixed Payload markup is a subset of Avalon XAML elements and
properties--plus additional conventions, canonical forms, or
restrictions in usage compared to Avalon XAML.
[0335] The radically-minimal Fixed Payload markup set defined
reduces the cost associated with implementation and testing of
reach package readers, such as printer RIPs or interactive viewer
applications--as well as reducing the complexity and memory
footprint of the associated parser. The parsimonious markup set
also minimizes the opportunities for subsetting, errors, or
inconsistencies among reach package writers and readers, making the
format and its ecosystem inherently more robust.
[0336] In addition to the minimal Fixed Payload markup, the reach
package will specify markup for additional semantic information to
support viewers or presentations of reach package documents with
features such as hyperlinks, section/outline structure and
navigation, text selection, and document accessibility.
[0337] Finally, using the versioning and extensibility mechanisms
described above, it is possible to supplement the minimal Fixed
Payload markup with a richer set of elements for specific target
consuming applications, viewers, or devices.
[0338] FixedPage Markup Model
[0339] In the illustrated and described embodiment, a FixedPage
part is expressed in an XML-based markup language, based on
XML-Elements, XML-Attributes, and XML-Namespaces. Three
XML-Namespaces are defined in this document for inclusion in
FixedPage markup. One such namespace references the Version-control
elements and attributes defined elsewhere in this specification.
The principle namespace used for elements and attributes in the
FixedPage markup is "http://schemas.microsoft.com/MMCF--
PLACEHOLDER-FixedPage". And finally, FixedPage markup introduces a
concept of "Resources" which requires a third namespace, described
below.
[0340] Although FixedPage markup is expressed using XML-Elements
and XML-Attributes, its specification is based upon a higher-level
abstract model of "Contents" and "Properties". The FixedPage
elements are all expressed as XML-elements. Only a handful of
FixedPage elements can hold "Contents", expressed as child
XML-elements. But a property-value may be expressed using an
XML-Attribute or using a child XML-element.
[0341] FixedPage Markup also depends upon the twin concepts of a
Resource-Dictionary and Resource-Reference. The combination of a
Resource-Dictionary and multiple Resource-References allows for a
single property-value to be shared by multiple properties of
multiple FixedPage-markup elements.
[0342] Properties in FixedPage Markup
[0343] In the illustrated and described embodiment, there are three
forms of markup which can be used to specify the value of a
FixedPage-markup property.
[0344] If the property is specified using a resource-reference,
then the property name is used as an XML-attribute name, and a
special syntax for the attribute-value indicates the presence of a
resource reference. The syntax for expressing resource-references
is described in the section entitled "Resources and
Resource-References".
[0345] Any property-value that is not specified as a
resource-reference may be expressed in XML using a nested child
XML-element identifying the property whose value is being set. This
"Compound-Property Syntax" is described below.
[0346] Finally, some non-resource-reference property-values can be
expressed as simple-text strings. Although all such property-values
may be expressed using Compound-Property Syntax, they may also be
expressed using simple XML-attribute syntax
[0347] For any given element, any property may be set no more than
once, regardless of the syntax used for specifying a value.
[0348] Simple Attribute Syntax
[0349] For a property value expressible as a simple string,
XML-attribute-syntax may be used to specify a property-value. For
example, given the FixedPage-markup element called
"SolidColorBrush," with the property called "Color", the following
syntax can be used to specify a property value:
43 <!-- Simple Attribute Syntax --> <SolidColorBrush
Color="#FF0000" />
[0350] Compound-Property Syntax
[0351] Some property values cannot be expressed as a simple string,
e.g. an XML-element is used to describe the property value. Such a
property value cannot be expressed using simple attribute syntax.
But they can be expressed using compound-property syntax.
[0352] In compound-property syntax, a child XML-Element is used,
but the XML-Element name is derived from a combination of the
parent-element name and the property name, separated by dot. Given
the FixedPage-markup element <Path>, which has a property
"Fill" which may be set to a <SolidColorBrush>, the following
markup can be used to set the "Fill" property of the <Path>
element:
44 <!-- Compound-Property Syntax --> <Path>
<Path.Fill> <SolidColorBrush Color="#FF0000" />
</Path.Fill> ... </Path>
[0353] Compound-Property Syntax may be used even in cases where
Simple-Attribute Syntax would suffice to express a property-value.
So, the example of the previous section:
45 <!-- Simple Attribute Syntax --> <SolidColorBrush
Color="#FF0000" />
[0354] Can be expressed instead in Compound-Property Syntax:
46 <!-- Compound-Property Syntax --> <SolidColorBrush>
<SolidColorBrush.Color>#FF0000<-
;/SolidColorBrush.Color> </SolidColorBrush>
[0355] When specifying property-value using Compound-Property
Syntax, the child XML-elements representing "Properties" must
appear before child XML-elements representing "Contents". The order
of individual Compound-Property child XML-elements is not
important, only that they appear together before any "Contents" of
the parent-element.
[0356] For example, when using both Clip and RenderTransform
properties of the <Canvas> element (described below), both
must appear before any <Path> and <Glyphs> Contents of
the <Canvas>:
47 <Canvas> <!-- First, the property-related child
elements --> <Canvas.RenderTransfo- rm>
<MatrixTransform Matrix="1,0,0,1,0,0">
</Canvas.RenderTransform> <Canvas.Clip>
<PathGeometry> ... </PathGeometry> </Canvas.Clip>
<!-- Then, the "Contents" --> <Path ...> ...
</Path> <Glyphs ...> ... </Glyphs>
</Canvas>
[0357] Resources and Resource References
[0358] Resource Dictionaries can be used to hold shareable property
values, each called a resource. Any property value which is itself
a FixedPage-markup element may be held in a Resource Dictionary.
Each resource in a Resource Dictionary carries a name. The
resource's name can be used to reference the resource from a
property's XML-attribute.
[0359] In the illustrated and described embodiment, the
<Canvas> and <FixedPage> elements can carry a Resource
Dictionary. A Resource Dictionary is expressed in markup as a
property of the <Canvas> and <FixedPage> elements in a
property called "Resources". However, individual resource-values
are embedded directly within the <FixedPage.Resources> or
<Canvas.Resources> XML-element. Syntactically, the markup for
<Canvas.Resources> and <FixedPage.Resource> resembles
that for markup elements with "Contents".
[0360] In accordance with this embodiment, <Canvas.Resources>
or <FixedPage.Resources> must precede any
compound-property-syntax property values of the <Canvas> or
<FixedPage>. They similarly must precede any "Contents" of
the <Canvas> or <FixedPage>.
[0361] Defining Fixed-Payload Resource Dictionaries
[0362] Any <FixedPage> or <Canvas> can carry a Resource
Dictionary, expressed using the <Canvas.Resources>
XML-element. Each element within a single resource dictionary is
given a unique name, identified by using an XML-attribute
associated with the element. To distinguish this "Name" attribute
from those attributes corresponding to properties, the Name
attribute is taken from a namespace other than that of the
FixedFormat elements. The URI for that XML-namespace is
"http://schemas.microsoft.com/PLACEHOLDER-for-resources". In the
example below, two geometries are defined: one for a rectangle and
the other for a circle.
48 <Canvas xmlns:def="http://schemas.microsoft.com/PLACE-
HOLDER-for- resources"> <Canvas.Resources>
<PathGeometry def:Name="Rectangle"> <PathFigure> ...
</PathFigure> </PathGeometry> <PathGeometry
def:Name="Circle"> <PathFigure> ... </PathFigure>
</PathGeometry> </Canvas.Resources> </Canvas>
[0363] Referencing Resources
[0364] To set a property value to one of the resources defined
above, use an XML-attribute value which encloses the resource name
in { }. For example, "{Rectangle}" will denote the geometry to be
used. In the markup sample below, the rectangular region defined by
the geometry objects in the dictionary will be filled by the
SolidColorBrush.
49 <Canvas> <Canvas.Resources> <PathGeometry
def:Name="Rectangle"> ... </PathGeometry>
</Canvas.Resources> <Path> <Path.Data>
<PathGeometry PathGeometry="{Rectangle}" />
</Path.Data> <Path.Fill> <SolidColorBrush
Color="#FF0000" /> </Path.Fill> </Path>
</Canvas>
[0365] In accordance with this embodiment, a resource reference
must not occur within the definition of a resource in a Resource
Dictionary.
[0366] Scoping Rules for Resolving Resource References
[0367] Although a single Name may not be used twice in the same
Resource Dictionary, the same name may be used in two different
Resource Dictionaries within a single FixedPage part. Furthermore,
the Resource Dictionary of an inner <Canvas> may re-use a
Name defined in the Resource Dictionary of some outer
<Canvas> or <FixedPage>.
[0368] When a resource-reference is used to set a property of an
element, various Resource Dictionaries are searched for a resource
of the given name. If the element bearing the property is a
<Canvas>, then the Resource Dictionary (if present) of that
<Canvas> is searched for a resource of the desired name. If
the element is not a <Canvas> then search begins with the
nearest containing <Canvas> or <FixedPage>. If the
desired name is not defined in the initially searched Resource
Dictionary, then the next-nearest containing <Canvas> or
<FixedPage> is consulted. An error occurs if the search
continued to the root <FixedPage> element, and a resource of
the desired name is not found in a Resource Dictionary associated
with that <FixedPage>.
[0369] The example below demonstrates these rules.
50 <FixedPage xmlns:def="http://schemas.microsoft.com/PL-
ACEHOLDER- for-resources" PageHeight="1056" PageWidth="816">
<FixedPage.Resources> <Fill
def:Name="FavoriteColorFill"> <SolidColorBrush
Color="#808080" /> </Fill> </FixedPage.Resources>
<Canvas> <Canvas.Resources> <Fill
def:Name="FavoriteColorFil- l"> <SolidColorBrush
Color="#000000" /> </Fill> </Canvas.Resources>
<!-- The following Path will be filed with color #000000 -->
<Path Fill="{FavoriteColorFill}"> <Path.Data> ...
</Path.Data> </Path> <Canvas> <!-- The
following Path will be filed with color #000000 --> <Path
Fill="{FavoriteColorFill}"> <Path.Data> ...
</Path.Data> </Path> </Canvas> </Canvas>
<-- The following path will be filled with color #808080 -->
<Path Fill="{FavoriteColorFill}"> <Path.Data> ...
</Path.Data> </Path> </FixedPage>
[0370] FixedPage Drawing Model
[0371] The FixedPage (or a nested Canvas child) element is the
element on which other elements are rendered. The arrangement of
content is controlled by properties specified for the FixedPage (or
Canvas), the properties specified for elements on the FixedPage (or
Canvas), and by compositional rules defined for the Fixed-Payload
namespace.
[0372] Using Canvas to Position Elements
[0373] In fixed markup, all elements are positioned relative to the
current origin (0,0) of the coordinate system. The current origin
can be moved by applying the RenderTransform attribute to each
element of the FixedPage or Canvas that contains an element.
[0374] The following example illustrates positioning of elements
through RenderTransform.
51 <Canvas> <Canvas.Resources> <PathGeometry
def:Name="StarFish"> <!-- Various PathFigures in here -->
... </PathGeometry> <PathGeometry
def:Name="LogoShape">- ; <!-- Various PathFigures in here
--> ... </PathGeometry> </Canvas.Resources> <!--
Draw a green StarFish and a red LogoShape shifted by 100 to the
right and 50 down --> <Canvas>
<Canvas.RenderTransform> <MatrixTransform
Matrix="1,0,0,1,100,50"/> </Canvas.RenderTransform>
<Path Fill="#00FF00" Data="{StarFish}"/> <Path
Fill="#FF0000" Data="{LogoShape}"/> </Canvas> <!-- Draw
a green StarFish and a red LogoShape shifted by 200 to the right
and 250 down --> <Canvas> <Canvas.RenderTransform>
<MatrixTransform Matrix="1,0,0,1,200,250"/>
</Canvas.RenderTransform> <Path Fill="#00FF00"
Data="{StarFish}"/> <Path Fill="#FF0000"
Data="{LogoShape}"/> </Canvas> </Canvas>
[0375] Coordinate Systems and Units
[0376] In accordance with the illustrated and described embodiment,
the coordinate system is initially set up so that one unit in that
coordinate system is equal to {fraction (1/96)}.sup.th of an inch,
expressed as a floating point value, the origin (0,0) of the
coordinate system is the left top corner of the FixedPage
element.
[0377] A RenderTransform attribute can be specified on any child
element to apply an affine transform to the current coordinate
system.
[0378] Page Dimensions
[0379] The page dimensions are specified by the "PageWidth" and
"PageHeight" parameters on the FixedPage element.
[0380] Composition Rules
[0381] FixedPages use the painter's model with alpha channel. In
accordance with the described embodiment, composition must occur
according to these rules, and in the following order:
[0382] The FixedPage (or any nested Canvas) is thought of as a
unbounded surface to which child elements are drawn in the order
they appear in the markup. The alpha channel of this surface is
initialized to "0.0" (all transparent). In practice the ideal
unbounded surface can be thought of as a bitmap buffer large enough
to hold all marks produced by rendering all the child elements.
[0383] The contents of the surface are transformed using the affine
transform specified by the RenderTransform property of the
FixedPage (or Canvas).
[0384] All child elements are rendered onto the surface, clipped by
the Clip property (which is also transformed using the
RenderTransform property) of the FixedPage (or Canvas). The
FixedPage additionally clips to the rectangle specified by
(0,0,PageWidth,PageHeight). If a child element has an Opacity
property or OpacityMask property, it is applied to the child
element before it is rendered onto the surface.
[0385] Finally, the contents of the FixedPage (or Canvas) are
rendered onto its containing element. In the case of FixedPage, the
containing element is the physical imaging surface.
[0386] Rendering occurs according to these rules:
[0387] The only elements that produce marks on a surface are
"Glyphs" and "Path".
[0388] All other rendering effects can be achieved by positioning
"Glyphs" and "Path" elements onto a "Canvas", and applying their
various valid attributes.
[0389] Fixed-Payload Elements and Properties
[0390] The Fixed Payload, in accordance with the illustrated and
described embodiment, includes a small set of XML elements used in
markup to represent pages and their contents. The markup in a
FixedPanel part brings the pages of a document together to a
common, easily-indexed root, using <Document>,
<FixedPanel>, and <PageContent> elements. Each
FixedPage part represents a page's contents in a <FixedPage>
element with only <Path> and <Glyphs> elements (which
together do all of the drawing), and the <Canvas> element to
group them.
[0391] The Fixed-Payload markup's element hierarchy is summarized
in following sections entitled "Top-level elements", "Geometry for
Path, Clip", "Brushes used to fill a Path, Glyphs, or OpacityMask",
"Resource dictionaries for FixedPage or Canvas", "Opacity masks for
alpha transparency", "Clipping paths" and "Transforms".
52 Top-level elements <Document> [exactly one per FixedPanel
part] Attributes: [none] Child Elements: <FixedPanel>
[exactly one] <FixedPanel> Attributes: PageHeight [optional]
PageWidth [optional] Child Elements: <PageContent> [1-N of
these child elements] <PageContent> Attributes: Source
[required] PageHeight [optional] PageWidth [optional] Child
Elements: [none] <FixedPage> Properties expressed via simple
XML attributes directly: PageHeight [required (here or as child
element)] PageWidth [required (here or as child element)] Resource
dictionary itself expressed as an XML child element:
<FixedPage.Resources> Properties expressed via XML child
elements <FixedPage.PageHeight> [required (here or as
attribute)] <FixedPage.PageWidth> [required (here or as
attribute)] Content via XML child Elements: <Canvas>
<Path> <Glyphs> <Canvas> Properties expressed via
simple XML attributes directly: Opacity Properties expressed via
resource dictionary reference: Clip RenderTransform OpacityMask
Resource dictionary itself expressed as an XML child element:
<Canvas.Resources> Properties expressed via XML child
elements <Canvas.Opacity> <Canvas.Clip>
<Canvas.RenderTransform> <Canvas.OpacityMask> Content
via XML child Elements: <Canvas> <Path> <Glyphs>
<Path> Properties expressed via simple XML attributes
directly: Opacity Properties expressed via resource dictionary
reference: Clip RenderTransform OpacityMask Fill Properties
expressed via XML child elements <Path.Opacity>
<Path.Clip> <Path.RenderTransform>
<Path.OpacityMask> <Path.Fill> <Path.Data>
<Glyphs> Properties expressed via simple XML attributes
directly: Opacity BidiLevel FontFaceIndex FontHintingEmSize
FontRenderingEmSize FontUri Indices OriginX OriginY Sideways
StyleSimulations UnicodeString Properties expressed via resource
dictionary reference: Clip RenderTransform OpacityMask Fill
Properties expressed via XML child elements <Glyphs.Clip>
<Glyphs.RenderTransform> <Glyphs.OpacityMask>
<Glyphs.Fill> <Glyphs.Opacity> <Glyphs.BidiLevel>
<Glyphs.FontFaceIndex> <Glyphs.FontHintingEmSize>
<Glyphs.FontRenderingEmSize> <Glyphs.FontUri>
<Glyphs.Indices> <Glyphs.OriginX>
<Glyphs.OriginY> <Glyphs.Sideways>
<Glyphs.StyleSimulations> <Glyphs.UnicodeString>
[0392]
53 Geometry for Path, Clip <Path.Data> Attributes: [none]
Property value expressed as a single XML child element: [Path.Data
has exactly one total of these children] <GeometryCollection>
<PathGeometry> <GeometryCollection> Attributes:
CombineMode Child Elements: [1-N children]
<GeometryCollection> <PathGeometry>
<PathGeometry> Attributes: FillRule Child Elements: [1-N
children] <PathFigure> <PathFigure> Attributes: [None]
Child Elements: [StartSegment comes first, CloseSegment last, 1-N
of Poly* in between.] <StartSegment> <PolyLineSegment>
<PolyBezierSegment> <CloseSegment> <StartSegment>
Properties expressed via simple XML attributes directly: Point
Properties expressed via XML child elements
<StartSegment.Point> <PolyLineSegment> Properties
expressed via simple XML attributes directly: Points Properties
expressed via XML child elements <PolyLineSegment.Points>
<PolyBezierSegment> Properties expressed via simple XML
attributes directly: Points Properties expressed via XML child
elements <PolyBezierSegment.Points> Brushes used to fill a
Path, Glyphs, or OpacityMask <Path.Fill> Attributes: [none]
Property value expressed as a single XML child element: [Path.Fill
has exactly one of these children] <SolidColorBrush>
<ImageBrush> <DrawingBrush> <LinearGradientBrush>
<RadialGradientBrush> <Glyphs.Fill> Attributes: [none]
Property value expressed as a single XML child element:
[Glyphs.Fill has exactly one of these children]
<SolidColorBrush> <ImageBrush> <DrawingBrush>
<LinearGradientBrush> <RadialGradientBrush>
<SolidColorBrush> Properties expressed via simple XML
attributes directly: Opacity Color Properties expressed via XML
child elements <SolidColorBrush.Opacity>
<SolidColorBrush.Color> <ImageBrush> Properties
expressed via simple XML attributes directly: Opacity
HorizontalAlignment VerticalAlignment ViewBox ViewPort Stretch
TileMode ContentUnits ViewportUnits ImageSource Properties
expressed via resource dictionary reference: Transform Properties
expressed via XML child elements <ImageBrush.Opacity>
<ImageBrush.Transform> <ImageBrush.HorizontalAlignment>
<ImageBrush.VerticalAli- gnment> <ImageBrush.ViewBox>
<ImageBrush.ViewPort> <ImageBrush.Stretch>
<ImageBrush.TileMode> <ImageBrush.ContentUnits>
<ImageBrush.ViewportUnits> <ImageBrush.ImageSource>
<DrawingBrush> Properties expressed via simple XML attributes
directly: Opacity HorizontalAlignment VerticalAlignment ViewBox
ViewPort Stretch TileMode ContentUnits ViewportUnits Properties
expressed via resource dictionary reference: Transform Drawing
Properties expressed via XML child elements
<DrawingBrush.Opacity> <DrawingBrush.Transform>
<DrawingBrush.HorizontalAlignment>
<DrawingBrush.VerticalAlignment>
<DrawingBrush.ViewBox&g- t; <DrawingBrush.ViewPort>
<DrawingBrush.Stretch&- gt; <DrawingBrush.TileMode>
<DrawingBrush.Content- Units>
<DrawingBrush.ViewportUnits> <DrawingBrush.Drawing>
<DrawingBrush.Drawing> Content via XML child Elements:
<Canvas> <Path> <Glyphs>
<LinearGradientBrush> Properties expressed via simple XML
attributes directly: Opacity MappingMode SpreadMethod StartPoint
EndPoint Properties expressed via resource dictionary reference:
Transform GradientStops Properties expressed via XML child elements
<LinearGradientBrush.Opacity&- gt;
<LinearGradientBrush.Transform>
<LinearGradientBrush.MappingMode> <LinearGradientBrush.S-
preadMethod> <LinearGradientBrush.StartPoint>
<LinearGradientBrush.EndPoint> <LinearGradientBrush.Grad-
ientStops> <RadialGradientBrush> Properties expressed via
simple XML attributes directly: Opacity Center Focus RadiusX
RadiusY Properties expressed via resource dictionary reference:
Transform GradientStops Properties expressed via XML child elements
<RadialGradientBrush.Opacity> <RadialGradientBrush.Trans-
form> <RadialGradientBrush.Center>
<RadialGradientBrush.Focus> <RadialGradientBrush.RadiusX-
> <RadialGradientBrush.RadiusY>
<RadialGradientBrush.GradientStops> <GradientStops>
Content via XML child Elements: <GradientStop> [1-N of these
children] <GradientStop> Properties expressed via simple XML
attributes directly: Color Offset Properties expressed via XML
child elements <GradientStop.Color>
<GradientStop.Offset>
[0393]
54 Resource dictionaries for FixedPage or Canvas
<FixedPage.Resources> <Canvas.Resources>
[0394] These elements are discussed above in the section that
discusses Resource Dictionaries.
55 Opacity masks for alpha transparency <Canvas.OpacityMask>
Attributes: [none] Property value expressed as a single XML child
element: [Canvas.OpacityMask has exactly one of these children]
<SolidColorBrush> <ImageBrush> <DrawingBrush>
<LinearGradientBrush> <RadialGradientBrush>
<Path.OpacityMask> Attributes: [none] Property value
expressed as a single XML child element: [Path.OpacityMask has
exactly one of these children] <SolidColorBrush>
<ImageBrush> <DrawingBrush> <LinearGradientBrush>
<RadialGradientBrush> <Glyphs.OpacityMask> Attributes:
[none] Property value expressed as a single XML child element:
[Glyphs.OpacityMask has exactly one of these children]
<SolidColorBrush> <ImageBrush> <DrawingBrush>
<LinearGradientBrush> <RadialGradientBrush> Clipping
paths <Canvas.Clip> Attributes: [none] Property value
expressed as a single XML child element: [Canvas.Clip has exactly
one of these children] <GeometryCollection>
<PathGeometry> <Path.Clip> Attributes: [none] Property
value expressed as a single XML child element: [Path.Clip has
exactly one of these children] <GeometryCollection>
<PathGeometry> <Glyphs.Clip> Attributes: [none]
Property value expressed as a single XML child element:
[Glyphs.Clip has exactly one of these children]
<GeometryCollection> <PathGeometry>
[0395] Transforms
56 <Canvas.RenderTransform> Property value expressed as a
single XML child element: <MatrixTransform> [required]
<Path.RenderTransform> Property value expressed as a single
XML child element: <MatrixTransform> [required]
<Glyphs.RenderTransform&g- t; Property value expressed as a
single XML child element: <MatrixTransform> [required]
<MatrixTransform> Properties expressed via simple XML
attributes directly: Matrix Properties expressed via XML child
elements <MatrixTransform.Matrix>
<ImageBrush.Transform> Properties expressed via simple XML
attributes directly: MatrixTransform Properties expressed via XML
child elements <ImageBrush.Transform.MatrixTransform>
<DrawingBrush.Transform> Properties expressed via simple XML
attributes directly: MatrixTransform Properties expressed via XML
child elements <DrawingBrush.Transform.M- atrixTransform>
<LinearGradientBrush.Transform> Properties expressed via
simple XML attributes directly: MatrixTransform Properties
expressed via XML child elements
<LinearGradientBrush.Transform.MatrixTransform>
<RadialGradientBrush.Transform> Properties expressed via
simple XML attributes directly: MatrixTransform Properties
expressed via XML child elements
<RadialGradientBrush.Transform.MatrixTransform>
[0396] FixedPage Markup
[0397] Each FixedPage part represents a page's contents in XML
markup rooted in a <FixedPage> element. This FixedPage markup
provides WYSIWYG fidelity of a document between writers and
readers, with only a small set of elements and properties:
<Path> and <Glyphs> elements (which together do all of
the drawing), and the <Canvas> element to group them.
[0398] Common Element Properties
[0399] Before discussing attributes specific to each element in
FixedPage markup, consider the attributes common to the drawing and
grouping elements: Opacity, Clip, RenderTransform, and OpacityMask.
Not only are these the only properties common to the top-level
elements, they are also the only properties that "accumulate" their
results from parent to child element, as described in the
Composition Rules section above. The accumulation is a result of
the application of the Composition Rules. The table that follows
provides a summary description of these common attributes, followed
by a more thorough discussion of each of the attributes.
57 Elements Description Attribute Opacity Canvas, Path, Glyphs,
Defines uniform transparency and of the element SolidColorBrush,
ImageBrush, DrawingBrush, LinearGradientBrush, RadialGradientBrush
Child Element Clip Canvas, Path, Glyphs Clip restricts the region
to which a brush can be applied on the canvas. RenderTransform
Canvas, Path, Glyphs RenderTransform establishes a new coordinate
frame for the children of the element. Only MatrixTransform
supported OpacityMask Canvas, Path, Glyphs Specifies a rectangular
mask of alpha values that is applied in the same fashion as the
Opacity attribute, but allow different alpha value on a
pixel-by-pixel basis
[0400] Opacity Attribute
[0401] Opacity is used to transparently blend the two elements when
rendering (Alpha Blending). The Opacity attribute ranges from 0
(fully transparent) to 1 (fully opaque). Values outside of this
inclusive range are clamped to this range during markup parsing.
So, effectively, [-.infin. . . . 0] is transparent and [1 . . .
.infin.] is opaque.
[0402] The Opacity Attribute is applied through the following
computations (assuming non-premultiplied source and destination
colors, both specified as scRGB):
[0403] O.sub.E: Opacity attribute of element or alpha value at
corresponding position in OpacityMask
[0404] A.sub.S: Alpha value present in source surface
[0405] R.sub.S: Red value present in source surface
[0406] G.sub.S: Green value present in source surface
[0407] B.sub.S: Blue value present in source surface
[0408] A.sub.D: Alpha value already present in destination
surface
[0409] R.sub.D: Red value already present in destination
surface
[0410] G.sub.D: Green value already present in destination
surface
[0411] B.sub.D: Blue value already present in destination
surface
[0412] A*: Resulting Alpha value for destination surface
[0413] R*: Resulting Red value for destination surface
[0414] G*: Resulting Green value for destination surface
[0415] B*: Resulting Blue value for destination surface
[0416] All values designated with a T subscript are temporary
values (e.g. R.sub.T1).
[0417] Step 1: Multiply Source Alpha Value with Opacity Value
A.sub.S=A.sub.S*O.sub.E
[0418] Step 2: Premultiply Source Alpha
A.sub.T1=A.sub.S
R.sub.T1=R.sub.S*A.sub.S
G.sub.T1=G.sub.S*A.sub.S
B.sub.T1=B.sub.S*A.sub.S
[0419] Step 3: Premultiply Destination Alpha
A.sub.T2=A.sub.D
R.sub.T2=R.sub.D*A.sub.D
G.sub.T2=G.sub.D*A.sub.D
B.sub.T2=B.sub.D*A.sub.D
[0420] Step 3: Blend
A.sub.T2=(1-A.sub.T1)*A.sub.T2+A.sub.T1
R.sub.T2=(1-A.sub.T1)*R.sub.T2+R.sub.T1
G.sub.T2=(1-A.sub.T1)*G.sub.T2+G.sub.T1
B.sub.T2=(1-A.sub.T1)*B.sub.T2+B.sub.T1
[0421] Step 4: Reverse Pre-multiplication
If A.sub.T2=0, set all A*R*G*B* to 0.
[0422] Else:
A*=A.sub.T2
R*=R.sub.T2/A.sub.T2
G*=G.sub.T2/A.sub.T2
B*=B.sub.T2/A.sub.T2
[0423] Clip Property
[0424] The Clip property is specified as one of the geometric
elements <GeometryCollection> or <PathGeometry> (see
Path.Data for details).
[0425] The Clip property is applied in the following way:
[0426] All rendered contents that fall inside the geometric element
described by the Clip child element are visible.
[0427] All rendered contents that fall outside the geometric
element described by the Clip child element are not visible.
[0428] RenderTransform Child Element
[0429] MatrixTransform is the only transformation attribute
available to elements. It expresses an affine transformation. The
syntax follows:
58 <X.RenderTransform> <MatrixTransform
Matrix="1,0,0,1,0,0"/> </X.RenderTransform> X represents
the element to which the transform is applied.
[0430] The six numbers specified in the Matrix attribute are m00,
m01, m10, m11, dx, dy.
[0431] The full matrix looks like:
59 m00 m01 0 m10 m11 0 dx dy 1
[0432] A given coordinate X,Y is transformed with a RenderTransform
to yield the resulting coordinate X',Y' by applying these
computations:
X'=X*m00+Y*m10+dx
Y'=X*m01+Y*m11+dy
[0433] OpacityMask Child Element The OpacityMask specifies a Brush,
but in contrast to a Fill Brush, only the alpha channel (see
Opacity attribute above) of the brush is used as an additional
parameter for rendering the element. Each alpha value for each
pixel of the element is then additionally multiplied with the alpha
value at the corresponding position in the OpacityMask Brush.
[0434] The <Canvas> Element
[0435] The <Canvas> element is used to group elements
together. Typically, FixedPage elements are grouped together in a
<Canvas> when they share a composed common attribute (i.e.,
Opacity, Clip, RenderTransforrn, or OpacityMask). By grouping these
elements together on a Canvas, common attributes can often be
applied to the canvas instead of to the individual elements.
[0436] Attributes and Child Elements of <Canvas>
[0437] The <Canvas> element has only the common attributes
described earlier: Opacity, Clip, RenderTransform, and OpacityMask.
They are used with the <Canvas> element as described in the
table below:
60 Effect on Canvas Attribute Opacity Defines uniform transparency
of the canvas Child Element Clip Clip describes the region to which
a brush can be applied by the Canvas' child elements.
RenderTransform RenderTransform establishes a new coordinate frame
for the children elements of the canvas, such as another canvas.
Only MatrixTransform supported OpacityMask Specifies a rectangular
mask of alpha values that is applied in the same fashion as the
Opacity attribute, but allow different alpha value on a
pixel-by-pixel basis
[0438] The following markup example illustrates the use of
<Canvas>.
61 <Canvas> <Path Fill="#0000FF"> <Path.Data>
<PathGeometry> <PathFigure> <StartSegment
Point="0,0"/> <PolylineSegment Points="100,0 100,100 0,100
0,0"/> <CloseSegment/> </PathFigure>
</PathGeometry> </Path.Data> </Path>
</Canvas>
[0439] With respect to the reading order in Canvas markup, consider
the following. As with FixedPage, the markup order of the Glyphs
child elements contained within a Canvas must be the same as the
desired reading order of the text content. This reading order may
be used both for interactive selection/copy of sequential text from
a FixedPage in a viewer, and for enabling access to sequential text
by accessibility technology. It is the responsibility of the
application generating the FixedPage markup to ensure this
correspondence between markup order and reading order.
[0440] Child Glyphs elements contained within nested Canvas
elements are ordered in-line between sibling Glyphs elements
occurring before and after the Canvas.
[0441] Example:
62 <FixedPage> <Glyphs . . . UnicodeString="Now is the
time for " /> <Canvas> <Glyphs . . . UnicodeString="all
good men and women " /> <Glyphs . . . UnicodeString="to come
to the aid " /> </Canvas> <Glyphs . . .
UnicodeString="of the party." /> </FixedPage>
[0442] The <Path> Element
[0443] The Path Element is an XML-based element that describes a
geometric region. The geometric region is a shape which may be
filled, or used as a clipping path. Common geometry types, such as
rectangle and ellipse, can be represented using Path geometries. A
path is described by specifying the required Geometry.Data child
element and the rendering attributes, such as Fill or Opacity.
[0444] Properties and Child Elements of <Path>
[0445] The following properties are applicable to <Path>
elements as described below:
63 Effect on Path Properties Opacity Defines uniform transparency
of the filled path. Child Element Clip Clip describes the region to
which a brush can be applied by the path's geometry.
RenderTransform RenderTransform establishes a new coordinate frame
for the children elements of the path, such as the geometry defined
by Path.Data. Only MatrixTransform supported OpacityMask Specifies
a rectangular mask of alpha values that is applied in the same
fashion as the Opacity attribute, but allows different alpha value
for different areas of the surface Data Describes the path's
geometry. Fill Describes the brush used to paint the path's
geometry.
[0446] To describe how to paint a region described by the geometry
of the <Path.Data> child element, use the Fill property. To
restrict the region on which <Path.Data> shapes can be drawn,
use the Clip property.
[0447] Using <Path> to Describe Geometries
[0448] A path's geometry is specified as a series of nested child
elements of <Path.Data>, as shown below. The geometry may be
represented with either a <GeometryCollection> containing a
set of <PathGeometry> child elements, or a single
<PathGeometry> child element containing
<PathFigures>.
64 <Path> <Path.Data> <GeometryCollection>
<PathGeometry> <PathFigure> ... </PathFigure>
</PathGeometry> </GeometryCollection>
</Path.Data> <Path>
[0449] The same <GeometryCollection> or <PathGeometry>
elements define the geometry for a clipping path used in the Clip
property of Canvas, Path, or Glyphs.
[0450] The following table introduces the hierarchy of child
elements defining Path geometries.
65 Geometry Elements Description GeometryCollection A set of
PathGeometry elements rendered using Boolean CombineMode
operations. PathGeometry A set of PathFigure elements that are each
filled using the same FillRule option. PathFigure A set of one or
more segment elements StartSegment, PolyLineSegment
PolyBezierSegment CloseSegment
[0451] GeometryCollection
[0452] A GeometryCollection is a set of geometric objects that are
combined together for rendering according to Boolean CombineMode
options. The GeometryCollection element is the mechanism in
FixedPage markup for building visual combinations of geometric
shapes.
66 Attributes Effect on GeometryCollection CombineMode Specifies
different modes for combining geometries.
[0453] The CombineMode attribute specifies the Boolean operation
used to combine the set of geometric shapes in a
GeometryCollection. Depending on the mode, different regions will
be included or excluded.
67 CombineMode Options Description Complement Specifies that the
existing region is replaced by the result of the existing region
being removed from the new region. Said differently, the existing
region is excluded from the new region. Exclude Specifies that the
existing region is replaced by the result of the new region being
removed from the existing region. Said differently, the new region
is excluded from the existing region. Intersect Two regions are
combined by taking their intersection. Union Two regions are
combined by taking the union of both. Xor Two regions are combined
by taking only the areas enclosed by one or the other region, but
not both.
[0454] CombineModes are handled as follows:
[0455] Not Commutative Complement and Exclude are not commutative
and therefore are defined between the first geometry in the
GeometryCollection and each individual remaining geometries. For
example, for the set {g1, g2, g3} a CombineMode of Exclude would be
applied as ((g1 exclude g2) and (g1 exclude g3)).
[0456] Commutative Boolean operations Union, Xor, Intersect are
commutative and therefore apply order-independent to the
geometries.
[0457] PathGeometry
[0458] A PathGeometry element contains a set of PathFigure
elements. The union of the PathFigures defines the interior of the
PathGeometry.
68 Attributes Effect on GeometryCollection FillRule Specifies
alternate algorithms for filling paths that describe an enclosed
area.
[0459] With respect to the FillRule attribute, consider the
following. The filled area of PathGeometry is defined by taking all
of the contained PathFigure that have their Filled attribute set to
true and applying the FillRule to determine the enclosed area.
FillRule options specify how the intersecting areas of Figure
elements contained in a Geometry are combined to form the resulting
area of the Geometry.
[0460] In accordance with the described embodiment, EvenOdd Fill
and NonZero Fill algorithms are provided.
[0461] The EvenOdd Fill algorithm determines the "insideness" of a
point on the canvas by drawing a ray from that point to infinity in
any direction and then examining the places where a segment of the
shape crosses the ray. Starting with a count of zero, add one each
time a Segment crosses the ray from left to right and subtract one
each time a path segment crosses the ray from right to left. After
counting the crossings, if the result is zero then the point is
outside the path. Otherwise, it is inside.
[0462] The NonZero Fill algorithm determines the "insideness" of a
point on the canvas by drawing a ray from that point to infinity in
any direction and counting the number of path Segments from the
given shape that the ray crosses. If this number is odd, the point
is inside; if even, the point is outside.
[0463] PathFigure
[0464] A PathFigure element is composed of a set of one or more
line or curve segments. The segment elements define the shape of
the PathFigure. The PathFigure must always define a closed
shape.
69 Attributes Effect on PathFigure FillRule Specifies alternate
algorithms for filling paths that describe an enclosed area.
[0465] A figure requires a starting point, after which each line or
curve segment continues from the last point added. The first
segment in the PathFigure set must be a StartSegment, and
CloseSegment must be the last segment. StartSegment has a Point
attribute. CloseSegment has no attributes.
70 StartSegment Attribute Description Point The location of the
line segment (starting point).
[0466] Fixed-Payload Markup for Path.Data Geometries
[0467] The following provides the markup for drawing and filling a
Path on a Canvas. In the specific example below, a rectangular Path
is drawn on a Canvas and filled with a solid green brush.
71 <Canvas> <Path Fill="#0000FF"> <Path.Data>
<PathGeometry> <PathFigure> <StartSegment
Point="0,0"/> <PolylineSegment Points="100,0 100,100 0,100
0,0"/> <CloseSegment/> </PathFigure>
</PathGeometry> </Path.Data> </Path>
</Canvas>
[0468] The following markup describes drawing a cubic Bzier curve.
That is, in addition to the PolyLineSegment, Fixed-Payload markup
includes the PolyBezierSegment for drawing cubic Bzier curves.
72 <Canvas> <Path Fill="#0000FF"> <Path.Data>
<PathGeometry> <PathFigure> <StartSegment
Point="0,0"/> <Polybeziersegment Points="100,0 100,100 0,100
0,0"/> <CloseSegment/> </PathFigure>
</PathGeometry> </Path.Data> </Path>
</Canvas>
[0469] Brushes
[0470] A brush is used to paint the interior of geometric shapes
defined by the <Path> element, and to fill the character
bitmaps rendered with a <Glyphs> element. A brush is also
used in defining the alpha-transparency mask in
<Canvas.OpacityMask>, <Path.OpacityMask>, and
<Glyphs.OpacityMask>. The FixedPage markup includes the
following brushes:
73 Brush Type Description SolidColorBrush Fills defined geometric
regions with a solid color. ImageBrush Fills a region with an
image. DrawingBrush Fills a region with a vector drawing.
LinearGradientBrush Fills a region with a linear gradient.
RadialGradientBrush Fills a region with a radial gradient.
[0471] Attributes vary across brushes, although all brushes have an
Opacity attribute. The ImageBrush and DrawingBrush share tiling
capabilities. The two gradient-fill brushes have attributes in
common as well.
[0472] The use of a brush child element in markup is shown
below:
74 <Path> <Path.Fill> <SolidColorBrush
Color="#00FFFF"/> </Path.Fill> ... </Path>
[0473] Common Properties for Brushes
[0474] In accordance with the described embodiment, the following
properties are applicable to all brushes, except for the simple
brush SolidColorBrush, which has fewer optional child elements.
75 Attribute Brush Type Description Opacity All brushes Child
Element Brush Type Description Transform All brushes Describes a
MatrixTransform except for applied to the brush's coordinate
SolidColorBrush space.
[0475] Common Attributes for DrawingBrush and ImageBrush
76 HorizontalAlignment DrawingBrush, ImageBrush Center, Left, or
Right VerticalAlignment DrawingBrush, ImageBrush Center, Bottom, or
Top ViewBox DrawingBrush, ImageBrush ViewPort DrawingBrush,
ImageBrush Stretch DrawingBrush, ImageBrush None, Fill, Uniform, or
UniformToFill TileMode DrawingBrush, ImageBrush None, Tile, FlipY,
FLipX, or FlipXY ContentUnits DrawingBrush, ImageBrush Absolute or
RelativeToBoundingBox ViewportUnits DrawingBrush, ImageBrush
Absolute or RelativeToBoundingBox
[0476] The Horizontal Alignment attribute specifies how the brush
is aligned horizontally within the area it fills out. The Vertical
Alignment attribute specifies how the brush is aligned vertically
within the area it fills out. The ViewBox attribute has a default
value of (0,0,0,0), interpreted as unset. When unset, no adjustment
is made and the Stretch attribute is ignored. The viewbox specifies
a new coordinate system for the contents, i.e. redefines the extent
and origin of the viewport. The Stretch attribute helps to specify
how those contents map into the viewport. The value of the viewBox
attribute is a list of four "unitless" numbers <min-x>,
<min-y>, <width> and <height>, separated by
whitespace and/or a comma, and is of type Rect. The Viewbox rect
specifies the rectangle in user space that maps to the bounding
box. It works the same as inserting a scaleX and scaleY. The
Stretch attribute (in case the option is other than none) provides
additional control for preserving the aspect ratio of the graphics.
An additional transformation is applied to all descendants of the
given element to achieve the specified effect. If there is a
transform on the Brush, it is applied "above" the mapping to
ViewBox.
[0477] The Stretch attribute has the following modes: None, Fill,
Uniform, UniformToFill.
77 Stretch Attribute Option Description None Default. Preserve
original size. Fill Aspect ratio is not preserved and the content
is scaled to fill the bounds established. Uniform Scale size
uniformly until the image fits the bounds established.
UniformToFill Scale size uniformly to fill the bounds established
and clip as necessary.
[0478] Simple Brushes and their Attributes
[0479] The Path.Brush and Canvas.Brush child elements include the
following: SolidColorBrush, ImageBrush, and DrawingBrush.
[0480] SolidColorBrush fills defined geometric regions with a solid
color. If there is an alpha component of the color, it is combined
in a multiplicative way with the corresponding opacity attribute in
the Brush.
78 Attributes Effect Color Specifies color for filled elements
[0481] The following example illustrates how color attributes are
expressed for the SolidColorBrush.
79 <Path> <Path.Fill> <SolidColorBrush
Color="#00FFFF"/> </Path.Fill> ... </Path>
[0482] ImageBrush can be used to fill a space with an image. The
markup for ImageBrush allows a URI to be specified. If all other
attributes are set to their default values, the image will be
stretched to fill the bounding box of the region.
80 Attributes Effect ImageSource Specifies URI of image
resource.
[0483] The ImageSource attribute must reference either one of the
supported Reach Image Formats or a selector which leads to an image
of one of these types.
[0484] DrawingBrush can be used to fill a space with a vector
drawing. DrawingBrush has a Drawing Child Element, whose use in
markup is shown below.
81 <Path> <Path.Fill> <DrawingBrush>
<DrawingBrush.Drawing> <Drawing> <Path ... />
<Glyphs ... /> </Drawing> </DrawingBrush.Drawing>
</DrawingBrush> </Path.Fill> </Path>
[0485] Gradient Brushes and their Attributes
[0486] Gradients are drawn by specifying a set of gradient stops as
XML Child Elements of the gradient brushes. These gradient stops
specify the colors along some sort of progression. There are two
types of gradient brushes supported in this framework: linear and
radial.
[0487] The gradient is by drawn by doing interpolations between the
gradient stops in the specified color space. LinearGradientBrush
and GradientBrush share the following common attributes:
82 Attribute Description SpreadMethod This property describes how
the brush should fill the content area outside of the primary,
initial gradient area. Default value is Pad. MappingMode This
property determines whether the parameters describing the gradient
are interpreted relative to the object bounding box. Default value
is relative-to- bounding-box. Child element Description
GradientStops Holds an ordered sequence of GradientStop
elements
[0488] With respect to the SpreadMethod attribute, consider the
following. SpreadMethod options specify how the space is filled.
The default value is Pad.
83 SpreadMethod Attribute Options Effect on Gradient Pad The first
color and the last color are used to fill the remaining space at
the beginning and end, respectively. Reflect The gradient stops are
replayed in reverse order repeatedly to fill the space. Repeat The
gradient stops are repeated in order until the space is filled.
[0489] MappingMode Attribute
[0490] With respect to the LinearGradientBrush, consider the
following. The LinearGradientBrush specifies a linear gradient
brush along a vector.
84 Attribute Description EndPoint End point of the linear gradient.
The LinearGradientBrush interpolates the colors from the StartPoint
to the EndPoint, where StartPoint represents offset 0, and the
EndPoint represents offset 1. Default is 1, 1. StartPoint Start
point of the linear gradient.
[0491] The following markup example shows the use of the
LinearGradientBrush. A page with a rectangular path is filled with
a linear gradient:
85 <FixedPanel> <FixedPage> <Path>
<Path.Fill> <LinearGradientBrush StartPoint="0,0"
Endpoint="1,0"> <LinearGradientBrush.GradientStops>
<GradientStopCollection> <GradientStop Color="#FF0000"
Offset="0"/> <GradientStop Color="#0000FF" Offset="1"/>
</GradientStopCollection> </LinearGradientBrush.Gra-
dientStops> </LinearGradientBrush> </Path.Fill>
<Path.Data> <PathGeometry> <PathFigure>
<StartSegment Point="0,0"/> <PolyLineSegment Points="100,0
100,100 0,100"/> <CloseSegment/> </PathFigure>
</PathGeometry> </Path.Data> </Path>
</FixedPage> </FixedPanel>
[0492] This example shows a page with a rectangular path that is
filled with a linear gradient. The Path also has a clip property in
the shape of an octagon which clips it.
86 <FixedPanel> <FixedPage> <Path>
<Path.Clip> <PathGeometry> <PathFigure>
<StartSegment Point="25,0"/> <PolyLineSegment Points="75,0
100,25 100,75 75,100 25,100 0,75 0,25"/> <CloseSegment/>
</PathFigure> </PathGeometry> </Path.Clip>
<Path.Fill> <LinearGradientBrush StartPoint="0,0"
EndPoint="1,0"> <LinearGradientBrush.GradientStops>
<GradientStopCollection> <GradientStop Color="#FF0000"
Offset="0"/> <GradientStop Color="#0000FF" Offset="1"/>
</GradientStopCollection> </LinearGradientBrush.Gra-
dientStops> </LinearGradientBrush> </Path.Fill>
<Path.Data> <PathGeometry> <PathFigure>
<StartSegment Point="0,0"/> <PolyLineSegment Points="100,0
100,100 0,100"/> <CloseSegment/> </PathFigure>
</PathGeometry> </Path.Data> </Path>
</FixedPage> </FixedPanel>
[0493] The RadialGradient is similar in programming model to the
linear gradient. However, whereas the linear gradient has a start
and end point to define the gradient vector, the radial gradient
has a circle along with a focal point to define the gradient
behavior. The circle defines the end point of the gradient--in
other words, a gradient stop at 1.0 defines the color at the
circle's circumference. The focal point defines center of the
gradient. A gradient stop at 0.0 defines the color at the focal
point.
87 Attribute Description Center Center point of this radial
gradient. The RadialGradientBrush interpolates the colors from the
Focus to the circumference of the ellipse. The circumference is
determined by the Center and the radii. Default is 0.5, 0.5 Focus
Focus of the radial gradient. RadiusX Radius in the X dimension of
the ellipse which defines the radial gradient. Default is 0.5
RadiusY Radius in the Y dimension of the ellipse which defines the
radial gradient. Default is 0.5 FillGradient Pad, Reflect,
Repeat
[0494] Alpha and Transparency
[0495] In accordance with the illustrated and described embodiment,
each pixel of each element carries an alpha value ranging from 0.0
(completely transparent) to 1.0 (fully opaque). The alpha value is
used when blending elements to achieve the visual effect of
transparency.
[0496] Each element can have an Opacity attribute with which the
alpha value of each pixel of the element will be multiplied
uniformly.
[0497] Additionally, the OpacityMask allow the specification of
per-pixel opacity which will control how rendered content will be
blended into its destination. The opacity specified by OpacityMask
is combined multiplicatively with any opacity which may already
happen to be present in the alpha channel of the contents. The
per-pixel Opacity specified by the OpacityMask is determined by
looking at the alpha channel of each pixel in the mask--the color
data is ignored.
[0498] The type of OpacityMask is Brush. This allows the
specification of how the Brush's content is mapped to the extent of
the content in a variety of different ways. Just as when used to
fill geometry, the Brushes default to filling the entire content
space, stretching or replicating its content as appropriate. This
means that an ImageBrush will stretch its ImageSource to completely
cover the contents, a GradientBrush will extend from edge to
edge.
[0499] The required computations for alpha blending are described
in the earlier section "Opacity Attribute".
[0500] The following example illustrates how an OpacityMask is used
to create a "fade effect" on a Glyphs element. The OpacityMask in
the example is a linear gradient that fades from opaque black to
transparent black.
88 // /content/p1.xml <FixedPage PageHeight="1056"
PageWidth="816"> <Glyphs OriginX = "96" OriginY = "96"
UnicodeString = "This is Page 1!" FontUri = "../Fonts/Times.TTF"
FontRenderingEmSize = "16" > <Glyphs.OpacityMask>
<LinearGradientBrush StartPoint="0,0" EndPoint="1,0">
<LinearGradientBrush.Gr- adientStops>
<GradientStopCollection> <GradientStop Color="#FF000000"
Offset="0"/> <GradientStop Color="#00000000" Offset="1"/>
</GradientStopCollection> </LinearGradientBrush.Grad-
ientStops> </LinearGradientBrush>
</Glyphs.OpacityMask> </Glyphs> </FixedPage>
[0501] Images in Reach Documents
[0502] On FixedPages, images fill enclosed regions. To place an
image on a FixedPage, a region must first be specified on the page.
The region is defined by the geometry of a Path element.
[0503] The Fill property of the Path element specifies the fill
contents for the described region. Images are one type of fill,
drawn into a region by the ImageBrush. All brushes have default
behavior that will fill an entire region by either stretching or
repeating (tiling) the brush content as appropriate. In the case of
ImageBrush, the content specified by the ImageSource property will
be stretched to completely cover the region.
[0504] The markup below demonstrates how to place an image onto a
Canvas.
89 <Canvas> <Path> <Path.Data>
<GeometryCollection> ... </GeometryCollection>
</Path.Data> <Path.Fill> <ImageBrush
ImageSource="/images/dog.jpg" /> </Path.Fill>
</Path> </Canvas>
[0505] Since many images are rectangular, including a rectangular
Path element in the Resource Dictionary may be useful in
simplifying the markup. The Path can then be positioned using a
RenderTransform attribute (see above).
90 <Canvas> <Canvas.Resources> <PathGeometry
def:Name="Rectangle"> <PathFigure> <StartSegment
Point="0,0"/> <PolylineSegment Points="100,0 100,100
0,100"/> <CloseSegment/> </PathFigure>
</PathGeometry> </Canvas.Resources> <Canvas>
<Canvas.RenderTransform> <MatrixTransform
Matrix="1,0,0,1,100,100"/> </Canvas.RenderTransform>
<Path Data="{Rectangle}"> <Path.Fill> <ImageBrush
ImageSource="/images/dog.jpg" /> </Path.Fill>
</Path> </Canvas> </Canvas>
[0506] Color
[0507] Colors can be specified in illustrated and described markup
using scRGB or sRGB notation. The scRGB specification is known as
"IEC 61966-2-2 scRGB" and can be obtained from www.iec.ch
[0508] The ARGB parameters are described in the table below.
91 Name Description R The red scRGB component of the current color
G The green scRGB component of the current color B The blue scRGB
component of the current color A The alpha scRGB component of the
current color
[0509] Color Mapping
[0510] Currently, consideration is being given to the tagging of
colored elements with metadata specifying color context. Such
metadata could contain an ICC color profile, or other color
definition data.
[0511] The <Glyphs> Element
[0512] Text is represented in Fixed Payloads using a Glyphs
element. The element is designed to meet requirements for printing
and reach documents.
[0513] Glyphs elements may have combinations of the following
properties.
92 Markup representation Property Purpose (Glyphs element) Origin
Origin of first glyph in run. The glyph Specified by is placed so
that the leading edge of its OriginX and advance vector and it's
baseline OriginY intersect this point. properties
FontRenderingEmSize Font size in drawing surface units Measured in
(default 96ths of an inch) Length units. FontHintingEmSize Size to
hint for in points. Fonts may Measured in include hinting to
produce subtle doubles differences at different sizes, such as
representing thicker stems and more open bowls in points size of
the smaller sizes, to produce results that font look more like the
same style than pure scaling can. This is not the same as hinting
for device pixel resolution, which is handled automatically. To
date (March 2003) no known fonts include size hinting. Default
value - 12 pts. GlyphIndices Array of 16 bit glyph numbers that
Part of Indices represent this run. property. See below for
representation AdvanceWidths Array of advance widths, one for each
Part of Indices glyph in GlyphIndices. The nominal property. See
origin of the nth glyph in the run (n > 0) below for is the
nominal origin of the n - 1th glyph representation. plus the n -
1th advance width added along the runs advance vector. Base glyphs
generally have a non-zero advance width, combining glyphs generally
have a zero advance width. GlyphOffsets Array of glyph offsets.
Added to the Part of Indices nominal glyph origin calculated above
property. See to generate the final origin for the below for glyph.
representation. Base glyphs generally have a glyph offset of (0,
0), combining glyphs generally have an offset that places them
correctly on top of the nearest preceding base glyph. GlyphTypeface
The physical font from which all FontUri, glyphs in this run are
drawn. FontFaceIndex and StyleSimulations properties UnicodeString
Optional* yes Array of characters represented by this glyph run.
*Note that for GlyphRun's generated from Win32 printer drivers,
text that was originally printed by Win32
ExtTextOut(ETO_GLYPHINDEX) calls is passed to the driver with glyph
indices and without Unicode codepoints. In this case, the generated
Glyphs markup, and thus the constructed GlyphRun object will omit
the codepoints. With no codepoints, functionality such as cut and
past or search in a fixed format viewer are unavailable, however
text display remains possible. ClusterMap One entry per character
in Part of Indices UnicodeString. property. See Each value gives
the offset of the first below for glyph in GlyphIndices that
represents representation. the corresponding character in
UnicodeString. Where multiple characters map to a single glyph, or
where a single character maps to multiple glyphs, or where multiple
characters map to multiple glyphs indivisibly, the character or
character(s) and glyph or glyph(s) are called a cluster. All
entries in the ClusterMap for a multi-character cluster map to the
offset in the GlyphIndices array of the first glyph of the cluster.
Sideways The glyphs are laid out on their side. yes By default,
glyphs are rendered as they would be in horizontal text, with the
origin corresponding to the Western baseline origin. With the
sideways flag set, the glyph is turned on it's side, with the
origin being the top center of the unturned glyph. BidiLevel The
Unicode algorithm bidi nesting yes level. Numerically even values
imply left-to-right layout, numerically odd values imply
right-to-left layout. Right-to-left layout places the run origin at
the right side of the first glyph, with positive values in the
advance vector placing subsequent glyphs to the left of the
previous glyph. Brush The foreground brush used to draw Picked up
from glyphs the Shape Fill property. Language Language of the run,
usually comes Specified by from the xml: lang property of markup.
xml: lang property
[0514] Overview of Text Markup
[0515] Glyph Metrics
[0516] Each glyph defines metrics that specify how it aligns with
other glyphs. Exemplary metrics in accordance with one embodiment
are shown in FIG. 12.
[0517] Advance Widths and Combining Marks
[0518] In general, glyphs within a font are either base glyphs or
combining marks that may be attached to base glyphs. Base glyphs
usually have an advance width that is non-zero, and a 0,0 offset
vector. Combining marks usually have a zero advance width. The
offset vector may be used to adjust the position of a combining
mark and so may have a non 0,0 value for combining marks.
[0519] Each glyph in the glyph run has three values controlling its
position. The values indicate origin, advance width, and glyph
offset, each of which is described below:
[0520] Origin: Each glyph is assumed to be given a nominal origin,
for the first glyph in the run this is the origin of the run.
[0521] Advance Width: The advance width for each glyph provides the
origin of the next glyph relative to this glyphs origin. The
advance vector is always drawn in the direction of the run
progression.
[0522] Glyph Offset (Base or Mark): The glyph offset vector adjusts
this glyphs position relative to its nominal origin.
[0523] Characters, Glyphs, and the Cluster Map
[0524] Cluster maps contain one entry per Unicode codepoint. The
value in the entry is the offset of the first glyph in the
GlyphIndices array that represents this codepoint. Alternately,
where the codepoint is part of a group of codepoints representing
an indivisible character cluster, the first glyph in the
GlyphIndices array represents the offset of the first glyph that
represents that cluster.
[0525] Cluster Mappings
[0526] The cluster map can represent codepoint-to-glyph mappings
that are one-to-one, many-to-one, one-to-many, or many-to-many.
One-to-one mappings are when each codepoint is represented by
exactly one glyph, the cluster map entries in FIG. 13 are 0, 1, 2,
. . . .
[0527] Many-to-one mappings are when two or more codepoints map to
a single glyph. The entries for those codepoints specify the offset
of that glyph in the glpyh index buffer. In the example of FIG. 14,
the `f` and `i` characters have been replaced by a ligature, as is
common typesetting practice in many serif fonts.
[0528] With respect to one-to-many mappings, consider the following
in connection with FIG. 15. `Sara Am` contains a part that sits on
top of the previous base character (the ring), and a part that sits
to the right of the base character (the hook). When Thai text is
micro-justified, the hook is spaced apart from the base character,
while the ring remains on top of the base character, therefore many
fonts encode the ring and the hook as separate glyphs. When one
codepoint maps to two or more glyphs, the value in the ClusterMap
for that codepoint references the first glyph in the GlyphIndeces
array that represents that codepoint.
[0529] With respect to many-to-many mappings, consider the
following in connection with FIG. 16. In some fonts an indivisible
group of codepoints for a character cluster maps to more than one
glyph. For example, this is common in fonts supporting Indic
scripts. When an indivisible group of codepoints maps to one or
more glyphs, the value in the ClusterMap for each of the codepoints
reference the first glyph in the GlyphIndeces array that represents
that codepoint.
[0530] The following example shows the Unicode and glyph
representations of the Tamil word . The first two codepoints
combine to generate three glyphs.
[0531] Specifying Clusters
[0532] Cluster specifications precede the glyph specification for
the first glyph of a non 1:1 cluster (mappings are more complex
than one-character-to-one-glyph).
[0533] Each cluster specification has the following form:
93 (ClusterCodepointCount [:ClusterGlyphCount]) Cluster Default
specification part Type Purpose value ClusterCodepointCount
positive Number of 16 bit Unicode 1 integer codepoints combining to
form this cluster ClusterGlyphCount positive Number of 16 bit glyph
1 integer indices combining to form this cluster
[0534] <Glyphs> Markup
[0535] The Glyphs element specifies a font as a URI, a face index
and a set of other attributes described above. For example:
94 <Glyphs FontUri = "file://c:/windows/fonts/t- imes.ttf"
FontFaceIndex = "0" <!-- Default 0 ==> FontRenderingEmSize =
"20" <!-- No default --> FontHintingEmSize = "12" <!--
Default 12 --> StyleSimulations = "BoldSimulation" <!--
Default None --> Sideways = "false" <!-- Default false -->
BidiLevel = "0" <!-- Default 0 --> Unicode = " ... " <!--
Unicode rep --> Indices = " ... " <!-- See below -->
remaining attributes ... />
[0536] Each glyph specification has the following form:
[0537]
[GlyphIndex][,[Advance][,[uOffset][,[vOffset][,[Flags]]]]].
[0538] Each part of the glyph specification is optional:
95 Glyph specification part Purpose Default value GlyphIndex Index
of glyph in the rendering physical font As defined by the fonts
character map table for the corresponding Unicode codepoint in the
inner text. Advance Placement for next glyph relative to origin of
this glyph. As defined by Measured in direction of advance as
defined by the the fonts HMTX sideways and BidiLevel attributes. or
VMTX font Measured in 100ths of the font em size. metric tables.
Advance must be calculated such that rounding errors do not
accumulate. See note below on how to achieve this requirement.
uOffset, vOffset Offset relative to glyph origin to move this
glyph. 0, 0 Usually used to attach marks to base characters.
Measured in 100ths of the font em size. Flags Distinguishes base
glyphs and combining marks 0 (base glyph)
[0539] With respect to calculating advance without rounding error
accumulation consider the following. Each advance value must be
calculated as the exact unrounded origin of the subsequent glyph
minus the sum of the calculated (i.e. rounded) advance widths of
the preceding glyphs. In this way each glyph is positioned to
within 0.5% of an em of its exact position.
96 <Canvas xmlns="http://schemas.microsoft.com/2005/x- aml/">
<Glyphs FontUri = "file://c:/windows/fonts/- times.ttf"
FontFaceIndex = "0" FontRenderingEmSize = "20" FontHintingEmSize =
"12" StyleSimulations = "ItalicSimulation" Sideways = "false"
BidiLevel = "0" OriginX = "75" OriginY = "75" Fill = "#00FF00"
UnicodeString = "inner text ..." /> <!-- `Hello Windows`
without kerning --> <Glyphs OriginX = "200" OriginY = "50"
UnicodeString = "Hello, Windows!" FontUri =
"file://C:/Windows/Fonts/Times.TTF" Fill = "#00FF00"
FontRenderingEmSize = "20" /> <!-- `Hello Windows` with
kerning --> <Glyphs OriginX = "200" OriginY = "150"
UnicodeString = "Hello, Windows!" Indices = ";;;;;;;,89" FontUri =
"file://C:/Windows/Fonts/Times.TTF" Fill = "#00FF00"
FontRenderingEmSize = "20" /> <!-- `Open file` without `fi`
ligature --> <Glyphs OriginX = "200" OriginY = "250"
UnicodeString = "Open file" FontUri =
"file://C:/Windows/Fonts/Times.TTF" Fill = "#00FF00"
FontRenderingEmSize = "20" /> <!-- `Open file` with `fi`
ligature --> <Glyphs Originx = "200" OriginY = "350"
UnicodeString = "Open file" Indices = ";;;;;(2:1)191" FontUri =
"file://C:/Windows/Fonts/Times.TTF" Fill = "#00FF00"
FontRenderingEmsize = "20" /> <!-- ` B TyMaHe` using
pre-composed `e` --> <Glyphs OriginX = "200" OriginY = "450"
xml:lang = "ru-RU" UnicodeString = " B TyMaHe" FontUri =
"file://C:/Windows/Fonts/- Times.TTF" Fill = "#00FF00"
FontRenderingEmsize = "20" /> <!-- ` B TyMaHe` using
composition of `e` and diaeresis --> <Glyphs OriginX = "200"
OriginY = "500" xml:lang = "ru-RU" UnicodeString = " B TyMaHe"
Indices = "(1:2)72;142,0,-45" FontUri =
"C:.backslash./Windows.backslash./Fonts.backslash./Times.TTF" Fill
= "#00FF00" FontRenderingEmSize = "20" /> <!-- ` B TyMaHe`
Forced rendering right-to-left showing combining mark in logical
order --> <Glyphs OriginX = "200" OriginY = "550" BidiLevel =
"1" xml:lang = "ru-RU" UnicodeString = " B TyMaHe" Indices =
"(1:2)72;142,0,-45" FontUri = "file://C:/Windows/Font- s/Times.TTF"
Fill = "#00FF00" FontRenderingEmSize = "20" />
</Canvas>
[0540] Optimizing the Size of Glyphs Markup
[0541] Markup details, such as glyph indices and advance widths,
can be omitted from the markup if a targeted client can regenerate
them reliably. The following options allow dramatic optimization of
commonly used simple scripts.
[0542] Optimizing Markup of Glyph Indices
[0543] Glyph indices may be omitted from markup where there is a
one-to-one mapping between the positions of characters in the
Unicode string and the positions of glyphs in the glyph string, and
the glyph index is the value in the CMAP (character mapping) table
of the font, and the Unicode character has unambiguous
semantics.
[0544] Glyph indices should be provided in the markup where the
mapping of characters to glyphs:
[0545] is not one-to-one, such as where two or more codepoints form
a single glyph (ligature), or
[0546] one codepoint generates multiple glyphs, or
[0547] where any other form of glyph substitution has happened,
such as through application of an OpenType feature.
[0548] Glyph indices should be provided in markup where a rendering
engine might substitute a different glyph than that in the CMAP
(character mapping) table in the font. Glyph indices should be
provided where the desired glyph representation is not that in the
CMAP table of the font.
[0549] Optimizing Markup of Glyph Positions
[0550] Glyph advance width may be omitted from the markup where the
advance width required is exactly that for the glyph in the HMTX
(horizontal metrics) or VMTX (vertical metrics) tables of the
font.
[0551] Glyph vertical offset may be omitted from the markup where
it is zero. This is almost always true for base characters, and
commonly true for combining marks in simpler scripts. However, this
is often false for combining marks in more complex scripts such as
Arabic and Indic.
[0552] Optimizing Markup of Glyph Flags
[0553] Glyph flags may be omitted for base glyphs with normal
justification priority.
[0554] Conclusion
[0555] The above-described modular content framework and document
format methods and systems provide a set of building blocks for
composing, packaging, distributing, and rendering document-centered
content. These building blocks define a platform-independent
framework for document formats that enable software and hardware
systems to generate, exchange, and display documents reliably and
consistently. The illustrated and described reach package format
provides a format for storing paginated or pre-paginated documents
in a manner in which contents of a reach package can be displayed
or printed with full fidelity among devices and applications in a
wide range of environments and across a wide range of scenarios.
Although the invention has been described in language specific to
structural features and/or methodological steps, it is to be
understood that the invention defined in the appended claims is not
necessarily limited to the specific features or steps described.
Rather, the specific features and steps are disclosed as preferred
forms of implementing the claimed invention.
* * * * *
References