SVG Tiny 1.2 - 20050413

1 Introduction

Contents

1.1 About SVG

SVG is a language for describing two-dimensional graphics in XML [XML10]. SVG allows for three types of graphic objects: vector graphic shapes (e.g., paths consisting of straight lines and curves), multimedia (such as raster images and video) and text. Graphical objects can be grouped, styled, transformed and composited into previously rendered objects.

SVG drawings can be interactive and dynamic. Animations can be defined and triggered either declaratively (i.e., by embedding SVG animation elements in SVG content) or via scripting.

Sophisticated applications of SVG are possible by use of a supplemental scripting language which accesses the SVG Micro Document Object Model (uDOM), which provides complete access to all elements, attributes and properties. A rich set of event handlers can be assigned to any SVG graphical object. Because of its compatibility and leveraging of other Web standards, features like scripting can be done on XHTML and SVG elements simultaneously within the same Web page.

SVG is a language for rich graphical content. For accessibility reasons, if there is an original source document containing higher-level structure and semantics, it is recommended that the higher-level information be made available somehow, either by making the original source document available, or making an alternative version available in a format which conveys the higher-level information, or by using SVG's facilities to include the higher-level information within the SVG content. For suggested techniques in achieving greater accessibility, see Accessibility.

It is believed that this specification is in conformance with the Web Architecture [AWWW].

1.2 SVG Tiny 1.2

Industry demand, overwhelming support in the SVG working group and requests from the SVG developer community established the need for some form of SVG suited to displaying vector graphics on small devices. Moreover, the mission statement of SVG 1.0 specifically addressed small devices as a target area for vector graphics display. In order to meet these demands the SVG Working Group created a profile specification that was suitable for use on mobile devices as well as on desktops. The SVG Mobile 1.1 specification addressed that requirement and defined two profiles to deal with the variety of mobile devices having different characteristics in terms of CPU speed, memory size, and color support. The SVG Mobile 1.1 specification defined SVG Tiny (SVGT) 1.1, suitable for highly restricted mobile devices; it also defined a second profile, SVG Basic (SVGB) 1.1, targeted for higher level mobile devices. The major difference between SVG Tiny 1.1 and SVG Basic 1.1 was the absence of scripting and styling in SVG 1.1 Tiny, and thus any requirement to maintain a Document Object Model (DOM). This saved a substantial amount of memory in most implementations.

Experience with SVG Tiny 1.1, which was widely adopted in the industry and shipped as standard on a variety of cellphones, indicated that the profile was a little too restrictive in some areas. Features from SVG 1.1 such as gradients and opacity, were seen to have substantial value for creating attractive content, and were shown to be implementable on cellphones. There was also considerable interest in adding audio and video capabilities, building on the SMIL support in SVG Tiny 1.1.

Advances such as DOM Level 3, which introduces namespace support and value normalization, prompted a second look at the use of programming languages and scripting with SVG Tiny. In conjunction with the Java JSR 226 group [JSR226], a lightweight interface called the microDOM, or uDOM, was developed. This could be, but need not be, implemented on top of DOM Level 3. With this advance, lightweight programatic control of SVG (for example, for games or user interfaces) and use with scripting languages, became feasible on the whole range of platforms from cellphones through to desktops. In consequence, there is only a single Mobile profile for SVG 1.2 - SVG Tiny 1.2

This specification defines the features and syntax for Scalable Vector Graphics (SVG) Tiny 1.2, the core specification and baseline profile of SVG 1.2. Other SVG specifications will extend this baseline functionality to create supersets (for example, SVG 1.2 Full). The SVG Tiny 1.2 specification adds to SVG Tiny 1.1 features requested by SVG authors, implementors and users; SVG Tiny 1.2 is a superset of SVG Tiny 1.1.

1.2.1 Modularization

This specification describes a collection of abstract modules that provide specific units of functionality. These modules may be combined with each other and with modules defined in other specifications (such as XHTML) to create SVG subset and extension document types that qualify as members of the SVG family of document types. See Conformance for a description of SVG family documents, and [XHTMLplusMathMLplusSVG] for a profile that combines XHTML, MathML and SVG.

Each major section of the SVG specification produces a module named after that section, e.g. "Text Module" or "Structure Module".

1.2.2 Element and Attribute collections

Modules define a named collection of either elements or attributes. These collections are used as a shorthand when describing the set of attributes allowed on a particular element (eg. the "Style" attibute collection) or the set of elements allowed as children of a particular element (eg. the "Shape" element collection). All collections have names that begin with an uppercase character.

When defining a profile, it is assumed that all the element and attribute collections are defined to be empty. That way, a module can redefine the collection as it is included in the profile, adding elements or attributes to make them available within the profile. Therefore, it is not a mistake to refer to an element or attribute collection from a module that is not included in the profile, it simply means that collection is empty.

1.2.3 Profiling the SVG specification

The modularization of SVG 1.2 allows profiles to be described by listing the SVG modules they allow and possibly a small number of restrictions or extensions on the elements provided by those modules.

The "Tiny" profile of SVG 1.2 is the collection of all the modules listed in this specification.

When applied to conformance, the term "SVG Tiny" refers to the "Tiny" profile of SVG 1.2 defined by this specification. If an implementation does not implement the Tiny profile, it must state either the profile to which it conforms, or that it implements a subset of SVG Tiny.

1.3 Defining an SVG Tiny 1.2 document

SVG Tiny 1.2 is a backwards compatible upgrade to SVG Tiny 1.1 . A few key differences from SVG Tiny 1.1 should be noted:

The namespace for SVG Tiny 1.2 is the same as that of SVG 1.0 and 1.1, http://www.w3.org/2000/svg

Here is an example of an SVG 1.2 file:

Example: 01_01.svg 
<?xml version="1.0"?>
<svg xmlns="http://www.w3.org/2000/svg" 
    version="1.2" baseProfile="tiny"
    viewBox="0 0 30 30">
    <desc>Example SVG file</desc>
        <rect x="10" y="10" width="10" height="10" fill="red"/>
</svg>

Here is an example of defining an entity in the internal DTD subset. Note that in XML, there is no requirement to fetch the external DTD subset and so relying on an external subset reduces interoperability. Also note that the SVG Working Group does not provide a normative DTD for SVG Tiny 1.2 but instead provides a normative RelaxNG schema.

Example: entity.svg 
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.2 Tiny//EN" [
    <!ENTITY Smile "
    <rect x='.5' y='.5' width='29' height='39' fill='black' stroke='red'/>
    <g transform='translate(0, 5)'>
		  <circle cx='15' cy='15' r='10' fill='yellow'/>
		  <circle cx='12' cy='12' r='1.5' fill='black'/>
		  <circle cx='17' cy='12' r='1.5' fill='black'/>
		  <path d='M 10 19 L 15 23 20 19' stroke='black' stroke-width='2'/>
    </g>
    ">
    ]>
<svg xmlns="http://www.w3.org/2000/svg">
   <desc>This example shows an entity from a DOCTYPE declaration being used.</desc>
   &Smile; 
</svg>

1.4 SVG MIME type, file name extension and Macintosh file type

The MIME type for SVG is "image/svg+xml" (see Media Type registration for image/svg+xml).

It is recommended that SVG files have the extension ".svg" (all lowercase) on all platforms. It is recommended that gzip-compressed SVG files have the extension ".svgz" (all lowercase) on all platforms.

It is recommended that SVG files stored on Macintosh HFS file systems be given a file type of "svg" (all lowercase, with a space character as the fourth letter). It is recommended that gzip-compressed SVG files stored on Macintosh HFS file systems be given a file type of "svgz" (all lowercase).

1.5 Compatibility with Other Standards Efforts

SVG Tiny 1.2 leverages and integrates with other W3C specifications and standards efforts. By leveraging and conforming to other standards, SVG becomes more powerful and makes it easier for users to learn how to incorporate SVG into their Web sites.

The following describes some of the ways in which SVG maintains compatibility with, leverages and integrates with other W3C efforts:

In environments which support [DOM3] for other XML grammars (e.g., XHTML [XHTML]) and which also support SVG and the SVG DOM, a single scripting approach can be used simultaneously for both XML documents and SVG graphics, in which case interactive and dynamic effects will be possible on multiple XML namespaces using the same set of scripts.

1.6 Definitions

basic shape
Standard shapes which are predefined in SVG as a convenience for common graphical operations. Specifically: 'rect', 'circle', 'ellipse', 'line', 'polyline', 'polygon'.
canvas
A surface onto which graphics elements are drawn, which can be real physical media such as a display or paper or an abstract surface such as a allocated region of computer memory. See the discussion of the SVG canvas in the chapter on Coordinate Systems, Transformations and Units.
container element
An element which can have graphics elements and other container elements as child elements. Specifically: 'svg', 'g', 'defs', 'a' and 'switch'.
current SVG document fragment
The XML document sub-tree which starts with parent 'svg' element of a given SVG element, with the requirement that all container elements between the outermost 'svg' and this element are all elements in the SVG language.
current transformation matrix (CTM)
Transformation matrices define the mathematical mapping from one coordinate system into another using a 3x3 matrix using the equation [x' y' 1] = [x y 1] * matrix. The current transformation matrix (CTM) defines the mapping from the user coordinate system into the viewport coordinate system. See Coordinate system transformations.
fill
The operation of painting the interior of a shape or the interior of the character glyphs in a text string.
font
A font represents an organized collection of glyphs in which the various glyph representations will share a common look or styling such that, when a string of characters is rendered together, the result is highly legible, conveys a particular artistic style and provides consistent inter-character alignment and spacing.
glyph
A glyph represents a unit of rendered content within a font. Often, there is a one-to-one correspondence between characters to be drawn and corresponding glyphs (e.g., often, the character "A" is rendered using a single glyph), but other times multiple glyphs are used to render a single character (e.g., use of accents) or a single glyph can be used to render multiple characters (e.g., ligatures). Typically, a glyph is defined by one or more shapes such as a path, possibly with additional information such as rendering hints that help a font engine to produce legible text in small sizes.
graphics element
One of the element types that can cause graphics to be drawn onto the target canvas. Specifically: 'path', 'text', 'textArea', 'rect', 'circle', 'ellipse', 'line', 'polyline', 'polygon', 'image', 'use', 'animation' and 'video'.
graphics referencing element
A graphics element which uses a reference to a different document or element as the source of its graphical content. Specifically: 'use', 'image', 'animation' and 'video'.
in error
A value is 'in error' if it is specifically stated as being 'in error' or 'an error' in the prose of this specification. See Error Processing for more detail on handling errors.
IRI Reference
An International Resource Identifier [IRI] which serves as a reference to a resource or (with a fragment identifier) to a secondary resource. See References.
local IRI reference
An International Resource Identifier [IRI] that does not include an <absoluteIRI> or <relativeIRI> and thus represents a reference to an element within the current document. See References.
non-local IRI reference
An International Resource Identifier [IRI] that includes an <absoluteIRI> or <relativeIRI> and thus (usually) represents a reference to a different document or an element within a different document. See References and the 'defs' element.
paint
A paint represents a way of putting color values onto the canvas. A paint might consist of both color values and associated alpha values which control the blending of colors against already existing color values on the canvas. SVG supports two types of built-in paint: color and gradients.
presentation attribute
An XML attribute on an SVG element which specifies a value for a given property for that element. See Styling.
property
A parameter that helps specify how a document should be rendered. A complete list of SVG's properties can be found in Property Index. Properties are assigned to elements in the SVG language by presentation attributes. See Styling.
shape
A graphics element that is defined by some combination of straight lines and curves. Specifically: 'path', 'rect', 'circle', 'ellipse', 'line', 'polyline', 'polygon'.
stroke
The operation of painting the outline of a shape or the outline of character glyphs in a text string.
SVG canvas
The canvas onto which the SVG content is rendered. See the discussion of the SVG canvas in the chapter on Coordinate Systems, Transformations and Units.
SVG document fragment
The XML document sub-tree which starts with an 'svg' element. An SVG document fragment can consist of a stand-alone SVG document, or a fragment of a parent XML document enclosed by an 'svg' element. When an 'svg' element is a descendant of another 'svg' element, there are two SVG document fragments, one for each 'svg' element. (One SVG document fragment is contained within another SVG document fragment.)
SVG viewport
The viewport within the SVG canvas which defines the rectangular region into which SVG content is rendered. See the discussion of the SVG viewport in the chapter on Coordinate Systems, Transformations and Units.
text content element
One of SVG's elements that can define a text string that is to be rendered onto the canvas. SVG Tiny 1.2's text content elements are the following: 'text' and 'tspan'.
transformation
A modification of the current transformation matrix (CTM) by providing a supplemental transformation in the form of a set of simple transformations specifications (such as scaling, rotation or translation) and/or one or more transformation matrices. See Coordinate system transformations.
transformation matrix
Transformation matrices define the mathematical mapping from one coordinate system into another using a 3x3 matrix using the equation [x' y' 1] = [x y 1] * matrix. See current transformation matrix (CTM) and Coordinate system transformations.
unsupported value
An unsupported value is a value that does not conform to this specification, but is not specifically listed as 'in error'. See the Implementation Notes for more detail on processing unsupported values.
user agent
The general definition of a user agent is an application that retrieves and renders Web content, including text, graphics, sounds, video, images, and other content types. A user agent may require additional user agents that handle some types of content. For instance, a browser may run a separate program or plug-in to render sound or video. User agents include graphical desktop browsers, multimedia players, text browsers, voice browsers, and assistive technologies such as screen readers, screen magnifiers, speech synthesizers, onscreen keyboards, and voice input software.



A "user agent" may or may not have the ability to retrieve and render SVG content; however, an "SVG user agent" retrieves and renders SVG content.
user coordinate system
In general, a coordinate system defines locations and distances on the current canvas. The current user coordinate system is the coordinate system that is currently active and which is used to define how coordinates and lengths are located and computed, respectively, on the current canvas. See initial user coordinate system and Coordinate system transformations.
user space
A synonym for user coordinate system.
user units
A coordinate value or length expressed in user units represents a coordinate value or length in the current user coordinate system. Thus, 10 user units represents a length of 10 units in the current user coordinate system.
viewport
A rectangular region within the current canvas onto which graphics elements are to be rendered. See the discussion of the SVG viewport in the chapter on Coordinate Systems, Transformations and Units.
viewport coordinate system
In general, a coordinate system defines locations and distances on the current canvas. The viewport coordinate system is the coordinate system that is active at the start of processing of an 'svg' element, before processing the optional viewBox attribute. In the case of an SVG document fragment that is embedded within a parent document which uses CSS to manage its layout, then the viewport coordinate system will have the same orientation and lengths as in CSS, with the origin at the top-left on the viewport. See The initial viewport and Establishing a new viewport.
viewport space
A synonym for viewport coordinate system.
viewport units
A coordinate value or length expressed in viewport units represents a coordinate value or length in the viewport coordinate system. Thus, 10 viewport units represents a length of 10 units in the viewport coordinate system.
SVG Tiny 1.2 - 20050413