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<!DOCTYPE html public '-//W3C//DTD HTML 4.01//EN' 'http://www.w3.org/TR/html4/strict.dtd'>
<html lang="en">
<head profile="http://www.w3.org/2006/03/hcard">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>CSS Transforms</title>
<link rel="stylesheet" type="text/css" href="default.css" />
<link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-[STATUS].css" />
<link id="st" href="alternate-spec-style.css" rel="alternate stylesheet"
type="text/css" disabled title="additional spec styles">
<script type="text/javascript" src="style-toggle.js"></script>
<style type="text/css">
/* Alternate stylesheet fonts are here because in some browsers (Opera 11.5) */
/* The fonts are not applied if only loaded from the alternate stylesheet */
@import url(http://fonts.googleapis.com/css?family=Droid+Serif:700,400,400italic,700italic);
@import url(http://fonts.googleapis.com/css?family=Droid+Sans+Mono);
.singleImgExample {
display: block;
margin: auto;
}
.example-table {
table-layout: fixed;
width: 100%;
}
.example-table tr td img {
width: 90%;
}
a.toggle {
position: fixed;
top: 0.5em;
right: 0.5em;
font-size: smaller;
color: gray;
opacity: 0.2;
}
a.toggle:hover {
opacity: 1;
color: #46A4E9;
}
div.issue-marker {
position: absolute;
width: 20ex;
margin-left: -26ex;
padding-right: 0.5em;
font-weight: normal;
font-size: 11px;
text-align: right;
background-color: white;
font-size: 90%;
padding-top: 0px;
padding-bottom: 0px;
}
div.issue-marker a {
color: red;
}
div.issue-marker .desc {
font-size: 80%;
line-height: 1.4em;
}
div.issue-marker .desc strong {
font-weight: bold;
font-size: 120%;
color: red;
}
</style>
</head>
<body>
<div id="div-head" class="head">
<!--logo-->
<h1>CSS transforms</h1>
<h2 class="no-num no-toc">[LONGSTATUS] [DATE]</h2>
<dl>
<dt>This version:
<dd>
<a href="[VERSION]">http://dev.w3.org/csswg/css3-2d-transforms/</a>
<!--http://www.w3.org/TR/[YEAR]/WD-[SHORTNAME]-[CDATE]-->
<dt>Latest version:
<dd><a
href="http://www.w3.org/TR/css3-2d-transforms">[LATEST]</a>
<dt>Previous version:
<dd><a href="http://www.w3.org/TR/2009/WD-css3-2d-transforms-20090320/">
http://www.w3.org/TR/2009/WD-css3-2d-transforms-20090320/</a>
<dt id="editors-list">Editors:
<dd>Simon Fraser (<a href="http://www.apple.com/">Apple Inc</a>) <simon.fraser @apple.com>
<dd>Dean Jackson (<a href="http://www.apple.com/">Apple Inc</a>) <dino @apple.com>
<dd>David Hyatt (<a href="http://www.apple.com/">Apple Inc</a>) <hyatt @apple.com>
<dd>Chris Marrin (<a href="http://www.apple.com/">Apple Inc</a>) <cmarrin @apple.com>
<dd>Edward O'Connor (<a href="http://www.apple.com/">Apple Inc</a>) <eoconnor @apple.com>
</dl>
<!--copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id="abstract">Abstract</h2>
<strong>THIS IS A WORK IN PROGRESS AND NOT READY FOR REVIEW.</strong>
<p>CSS transforms allows elements styled with CSS to be transformed
in two-dimensional or three=dimensional space. This specification is the convergence of the
<a href="http://www.w3.org/TR/css3-2d-transforms/">CSS 2D transforms</a>,
<a href="http://www.w3.org/TR/css3-3d-transforms/">CSS 3D transforms</a>
and <a href="http://www.w3.org/TR/2009/WD-SVG-Transforms-20090320/">SVG transforms</a>
specifications.</p>
<h2 class="no-num no-toc" id="status">Status of this document</h2>
<!--status-->
<p>
The <a href="ChangeLog">list of changes made to this specification</a> is
available.
</p>
<h2 class="no-num no-toc" id="contents">Table of contents</h2>
<!--toc-->
<h2>Introduction</h2>
<p><em>This section is not normative.</em>
<p>
The CSS <a href="http://www.w3.org/TR/REC-CSS2/visuren.html">visual
formatting model</a> describes a coordinate system within which each
element is positioned. Positions and sizes in this coordinate space can
be thought of as being expressed in pixels, starting in the upper left
corner of the parent with positive values proceeding to the right and
down.
</p>
<p>
This coordinate space can be modified with the <span
class="prop-name">'transform'</span> property. Using transform, elements
can be translated, rotated and scaled in two dimensional space.
The coordinate space
behaves as described in the <a
href="http://www.w3.org/TR/SVG/coords.html#EstablishingANewUserSpace">coordinate
system transformations</a> section of the SVG 1.1 specification. This is
a coordinate system with two axes: the X axis increases horizontally to
the right; the Y axis increases vertically downwards.
</p>
<p>
Transforms apply to block-level and atomic inline-level
elements, but do not apply to elements which may be split into
multiple inline-level boxes.
</p>
<p>
Specifying a value other than 'none' for the <span class="prop-name">'transform'</span>
property establishes a new <em>local coordinate system</em> at the element that it is
applied to. Transformations are cumulative. That is, elements establish their local
coordinate system within the coordinate system of their parent. From the perspective of the
user, an element effectively accumulates all the <span class="prop-name">'transform'</span>
properties of its ancestors as well as any local transform applied to it. The accumulation
of these transforms defines a <em>current transformation matrix (CTM)</em> for the element.
</p>
<p>
The transform property does not affect the flow of the content
surrounding the transformed element. However, the value of the overflow
area takes into account transformed elements. This behavior is similar
to what happens when elements are translated via relative positioning.
Therefore, if the value of the <span class="prop-name">'overflow'</span>
property is <span class="prop-value">'scroll'</span> or <span
class="prop-value">'auto'</span>, scrollbars will appear as needed to
see content that is transformed outside the visible area.
</p>
<p>
Any value other than 'none' for the transform results in the creation of
both a stacking context and a containing block. The object acts as a
containing block for fixed positioned descendants.
</p>
<div class="todo">
Need to go into more detail here about why fixed positioned objects
should do this, i.e., that it's much harder to implement otherwise.
</div>
<div class="issue">
There are two roles for transformations in layout: (1) transformations
that adjust the position of the affected content without changing the
normal layout of that content (much like relative positioning) and (2)
transformation of the content prior to layout that affects the layout
of that content. See <a
href="http://lists.w3.org/Archives/Public/www-style/2007Oct/0209">http://lists.w3.org/Archives/Public/www-style/2007Oct/0209</a>
for examples of both cases. The "transform" property (as defined in
this document) is equally useful for both roles. This document is
focused on satisfying the first role. There is, however, an
architectural question that arises because there needs to be a way to
distinguish which role an author of a stylesheet wants. The key
question is which is the default behavior/role for the "transform"
property and how is the other behavior/role indicated by a stylesheet
author. If you have an opinion on this topic,
please send feedback.
</div>
<div class="issue">
What do fixed backgrounds do in transforms? They should probably ignore
the transform completely, since - even transformed - the object should
be acting as "porthole" through which the fixed background can be viewed
in its original form.
</div><!-- ======================================================================================================= -->
<h2 id="transform-property">
The <span class="prop-name">'transform'</span> Property
</h2>
<p>
A two-dimensional transformation is applied to the coordinate system an element
renders in through the <span
class="prop-name">'transform'</span> property. This property contains a
list of <a href="#transform-functions">transform functions</a>. The
final transformation value for a coordinate system is obtained by converting
each function in the list to its corresponding matrix (either defined in
this specification or by reference to the SVG specification), then multiplying
the matrices.
</p>
<table class="propdef">
<tbody>
<tr>
<td>
<em>Name:</em>
</td>
<td>
<dfn id="effects">transform</dfn>
</td>
</tr>
<tr>
<td>
<em>Value:</em>
</td>
<td>
none | <transform-function> [ <transform-function> ]*
</td>
</tr>
<tr>
<td>
<em>Initial:</em>
</td>
<td>
none
</td>
</tr>
<tr>
<td>
<em>Applies to:</em>
</td>
<td>
block-level and atomic inline-level elements
</td>
</tr>
<tr>
<td>
<em>Inherited:</em>
</td>
<td>
no
</td>
</tr>
<tr>
<td>
<em>Percentages:</em>
</td>
<td>
refer to the size of the element's border box
</td>
</tr>
<tr>
<td>
<em>Media:</em>
</td>
<td>
visual
</td>
</tr>
<tr>
<td>
<em>Computed value:</em>
</td>
<td>
Same as specified value.
</td>
</tr>
</tbody>
</table><!-- ======================================================================================================= -->
<h3 id="svg-transform">The SVG transform attribute</h3>
<p>The <a href="http://www.w3.org/TR/2011/REC-SVG11-20110816/">SVG 1.1 specification</a> did not
specify the 'transform' attribute as a <a href="http://www.w3.org/TR/2011/REC-SVG11-20110816/styling.html#UsingPresentationAttributes">presentation attribute</a>.
In order to improve the integration of
SVG and HTML, this specification makes the SVG 'transform' attribute a
'presentation attribute' and makes the 'transform' property one that applies to SVG elements.</p>
<h4 id="transform-attribute-specificity">SVG transform attribute specificity</h4>
<p>Since the SVG attribute becomes a presentation attribute, its participation to the CSS
cascade is determined by the specificity of presentation attributes, as
<a href="http://www.w3.org/TR/2011/REC-SVG11-20110816/styling.html#UsingPresentationAttributes">explained</a>
in the SVG specification.</p>
<h4 id="transform-attribute-dom">SVG transform attribute DOM</h4>
<p>The SVG specification <a href="http://www.w3.org/TR/2011/REC-SVG11-20110816/coords.html#InterfaceSVGAnimatedTransformList">defines</a> a DOM interface to access the animated and base value of
the SVG transform attribute. To ensure backwards compatibility, this API should still be
supported by user agents. The <code>baseVal</code> should be the value of the 'transform' attribute,
as set on the element, and the <code>animVal</code> should be the property's computed value which account
for CSS animation, if any is underway.</p>
<div class="issue">
<ul>
<li>Should we also make gradientTransform and patternTransform presentation attributes?
Proposal: they
are the 'presentation attributes' for <gradient> and >pattern< respectively,
for the 'transform' property (i.e., there is no 'gradientTransform' property. Instead, the
'gradientTransform' is a presentation attribute that provides a value for the
'transform' property that applies to the <gradient> element.)</li>
<li>Is this proposal working for SMIL animation of the transform property?</li>
</ul>
</div>
<h2 id="transform-origin-property">
The <span class="prop-name">'transform-origin'</span> Property
</h2>
<p>
The <span class="prop-name">'transform-origin'</span> property
establishes the origin of transformation for a coordinate system. This property
is applied by first translating the element's coordinate system by the negated value of the
property, then applying the local transform, then translating by the
property value. This effectively moves the desired transformation origin
of the element to (0,0) in the local coordinate system, then applies
the local transform, then moves the element back to its original
position.
</p>
<p>If only one value is specified, the second value is assumed to be
'center'. If two values are given and at least one value is not a keyword,
then the first value represents the horizontal position (or offset) and
the second represents the vertical position (or
offset). <var><percentage></var> and <var><length></var>
values here represent an offset of the transform origin from the top left corner
of the element's border box.
</p>
<p>If three or four values are given, then
each <var><percentage></var> or<var><length></var>
represents an offset and must be preceded by a keyword,
which specifies from which edge the offset is given. For example,
''transform-origin: bottom 10px right 20px'' represents a
''10px'' vertical offset up from the bottom edge and a
''20px'' horizontal offset leftward from the right edge. If
three values are given, the missing offset is assumed to be zero.
</p>
<p>Positive values represent an offset <em>inward</em> from the edge of
the border box. Negative values represent an offset
<em>outward</em> from the edge of the border box.
</p>
<table class="propdef">
<tbody>
<tr>
<td>
<em>Name:</em>
</td>
<td>
<dfn id="transform-origin">transform-origin</dfn>
</td>
</tr>
<tr>
<td>
<em>Value:</em>
</td>
<td>
[ top | bottom ] |<br>
[ <percentage> | <length> | left | center | right ] [ <percentage> | <length> | top | center | bottom ]? |<br>
[ center | [ left | right ] [ <percentage> | <length> ]? ] && [ center | [ top | bottom ] [ <percentage> | <length> ]? ]<br>
</td>
</tr>
<tr>
<td>
<em>Initial:</em>
</td>
<td>
50% 50%
</td>
</tr>
<tr>
<td>
<em>Applies to:</em>
</td>
<td>
block-level and atomic inline-level elements
</td>
</tr>
<tr>
<td>
<em>Inherited:</em>
</td>
<td>
no
</td>
</tr>
<tr>
<td>
<em>Percentages:</em>
</td>
<td>
refer to the size of the element's border box
</td>
</tr>
<tr>
<td>
<em>Media:</em>
</td>
<td>
visual
</td>
</tr>
<tr>
<td>
<em>Computed value:</em>
</td>
<td>
For <length> the absolute value, otherwise a percentage
</td>
</tr>
</tbody>
</table>
<h3 id="svg-transform-origin">The 'transform-origin' property for SVG elements</h3>
<p>To keep the 'transform' property compatible with existing SVG content that assumed a top/left
coordinate system origin, the user agent stylesheet must contain the following:</p>
<pre class="css">
svg | * {
transform-origin: top left;
}
</pre>
<!-- ======================================================================================================= -->
<h2 id="transform-functions">
The Transformation Functions
</h2>
<p>
The value of the <span class="prop-name">transform</span> property is a
list of <transform-functions> applied in the order provided. The
individual transform functions are separated by whitespace. The
set of allowed transform functions is given below. In this list the
type <translation-value> is defined as a <length> or
<percentage> value, and the <angle> type is defined by <a
href="http://www.w3.org/TR/css3-values/">CSS Values and Units.</a>
</p>
<dl>
<dt>
<span class="prop-value">matrix(<number>, <number>, <number>, <number>, <number>, <number>)</span>
</dt>
<dd>
specifies a 2D transformation in the form of a <a href="http://www.w3.org/TR/SVG/coords.html#TransformMatrixDefined">transformation matrix</a> of six values. <span class="prop-value">matrix(a,b,c,d,e,f)</span> is equivalent to applying the transformation matrix <strong>[a b c d e f]</strong>.
</dd>
<dt>
<span class="prop-value">translate(<translation-value>[, <translation-value>])</span>
</dt>
<dd>
specifies a <a href="http://www.w3.org/TR/SVG/coords.html#TranslationDefined">2D translation</a> by the vector [tx, ty], where tx is the first translation-value parameter and ty is the optional second translation-value parameter. If <em><ty></em> is not provided, ty has zero as a value.
</dd>
<dt>
<span class="prop-value">translateX(<translation-value>)</span>
</dt>
<dd>
specifies a <a href="http://www.w3.org/TR/SVG/coords.html#TranslationDefined">translation</a> by the given amount in the X direction.
</dd>
<dt>
<span class="prop-value">translateY(<translation-value>)</span>
</dt>
<dd>
specifies a <a href="http://www.w3.org/TR/SVG/coords.html#TranslationDefined">translation</a> by the given amount in the Y direction.
</dd>
<dt>
<span class="prop-value">scale(<number>[, <number>])</span>
</dt>
<dd>
specifies a <a href="http://www.w3.org/TR/SVG/coords.html#ScalingDefined">2D scale</a> operation by the [sx,sy] scaling vector described by the 2 parameters. If the second parameter is not provided, it is takes a value equal to the first. For example, scale(1, 1) would leave an element unchanged, while scale(2, 2) would cause it to appear twice as long in both the X
and Y axes, or four times its typical geometric size.
</dd>
<dt>
<span class="prop-value">scaleX(<number>)</span>
</dt>
<dd>
specifies a scale operation using the [sx,1] scaling vector, where sx is given as the parameter.
</dd>
<dt>
<span class="prop-value">scaleY(<number>)</span>
</dt>
<dd>
specifies a scale operation using the [1,sy] scaling vector, where sy is given as the parameter.
</dd>
<dt>
<span class="prop-value">rotate(<angle>)</span>
</dt>
<dd>
specifies a <a href="http://www.w3.org/TR/SVG/coords.html#RotationDefined">2D rotation</a> by the angle specified in the parameter about the origin of the element, as defined by the <em>transform-origin</em> property. For example, rotate(90deg) would cause elements to appear
rotated one-quarter of a turn in the clockwise direction.
</dd>
<dt>
<span class="prop-value">skewX(<angle>)</span>
</dt>
<dd>
specifies a <a href="http://www.w3.org/TR/SVG/coords.html#SkewXDefined">skew transformation along the X axis</a> by the given angle.
</dd>
<dt>
<span class="prop-value">skewY(<angle>)</span>
</dt>
<dd>
specifies a <a href="http://www.w3.org/TR/SVG/coords.html#SkewYDefined">skew transformation along the Y axis</a> by the given angle.
</dd>
</dl>
<h2 id="transform-values">
Transform Values and Lists
</h2>
<p>
The <translation-value> values are defined as [<percentage> | <length>]. All other value types are described <a href="http://www.w3.org/TR/REC-CSS2/syndata.html#values">as CSS types</a>. If a list of transforms is provided, then the net effect is as if each transform had been specified separately in the order provided. For example,
</p>
<pre>
<div style="transform:translate(-10px,-20px) scale(2) rotate(45deg) translate(5px,10px)"/>
</pre>
<p>
is functionally equivalent to:
</p>
<pre>
<div style="transform:translate(-10px,-20px)">
<div style="transform:scale(2)">
<div style="transform:rotate(45deg)">
<div style="transform:translate(5px,10px)">
</div>
</div>
</div>
</div>
</pre>
<p>
That is, in the absence of other styling that affects position and dimensions, a nested set of transforms is equivalent to a single list of transform functions, applied from the outside in. The resulting transform is the matrix multiplication of the list of transforms.
</p>
<div class="example">
<pre>
div {
transform: translate(100px, 100px);
}
</pre>Move the element by 100 pixels in both the X and Y directions.
<div class="figure">
<img src="transform1.png" alt="The 100px translation in X and Y">
</div>
</div>
<div class="example">
<pre>
div {
height: 100px; width: 100px;
transform: translate(80px, 80px) scale(1.5, 1.5) rotate(45deg);
}
</pre>Move the element by 80 pixels in both the X and Y directions, then scale the element by 150%, then rotate it 45 degrees clockwise about the Z axis. Note that the scale and rotate operate about the center of the element, since the element has the default transform-origin of 50% 50%.
<div class="figure">
<img src="compound_transform.png" alt="The transform specified above">
</div>
</div>
<!-- ======================================================================================================= -->
<h2 id="animation">
Transitions and animations between transform values
</h2>
<p>
When animating or transitioning the value of a transform property
the rules described below are applied. The 'from' transform is
the transform at the start of the transition or current keyframe. The
'end' transform is the transform at the end of the transition or
current keyframe.
</p>
<ul>
<li>
If the 'from' and 'to' transforms are both single functions
of the same type:
<ul>
<li>
For translate, translateX, translateY, scale,
scaleX, scaleY, rotate, skew, skewX and skewY functions:
<ul>
<li>
the individual components of the function are
interpolated numerically.
</li>
</ul>
</li>
<li>
For matrix:
<ul>
<li>
the matrix is
decomposed using <a
href="http://tog.acm.org/GraphicsGems/gemsii/unmatrix.c">the
method described by unmatrix</a> into separate translation,
scale, rotation and skew matrices, then each
decomposed matrix is interpolated numerically, and finally
combined in order to produce a resulting 3x2 matrix.
</li>
</ul>
</li>
</ul>
</li>
<li>
If both the 'from' and 'to' transforms are "none":
<ul>
<li>
There is no interpolation necessary
</li>
</ul>
</li>
<li>
If one of the 'from' or 'to' transforms is "none":
<ul>
<li>
The 'none' is replaced by an equivalent identity function list for
the corresponding transform function list.
<p>
For example, if the 'from' transform is "scale(2)" and the 'to'
transform is "none" then the value "scale(1)" will be used as the
'to' value, and animation will proceed using the rule above.
Similarly, if the 'from' transform is "none" and the 'to' transform
is "scale(2) rotate(50deg)" then the animation will execute as
if the 'from' value is "scale(1) rotate(0)".
</p>
<p>
The identity functions are translate(0),
translateX(0), translateY(0), scale(1), scaleX(1), scaleY(1), rotate(0),
skewX(0), skewY(0) and matrix(1, 0, 0, 1, 0, 0).
</p>
</li>
</ul>
</li>
<li>
If both the 'from' and 'to' transforms have the same number of
transform functions and corresponding functions in each transform
list are of the same type:
<ul>
<li>
Each transform function is animated with its corresponding
destination function in isolation using the rules described above.
The individual values are then applied as a list to produce
resulting transform value.
</li>
</ul>
</li>
<li>
Otherwise:
<ul>
<li>
The transform function lists are each converted into the
equivalent matrix value and animation proceeds using the rule
for a single function above.
</li>
</ul>
</li>
</ul>
<p>
In some cases, an animation might cause a transformation matrix to
be singular or non-invertible. For example, an animation in which
scale moves from 1 to -1. At the time when the matrix is in such
a state, the transformed element is not rendered.
</p>
<h2 id="matrix-decomposition">
Matrix decomposition for animation
</h2>
<p>
When interpolating between 2 matrices, each is decomposed into the
corresponding translation, rotation, scale and skew
values. Not all matrices can be accurately described by these values.
Those that can't are decomposed into the most accurate representation
possible, using the technique below. This technique is taken from The
"unmatrix" method in "Graphics Gems II, edited by Jim Arvo", simplified
for the 2D case.
</p>
<h3 id="unmatrix">Unmatrix</h3>
<pre>
Input: a, b, c, d ; 2x2 matrix (rotate, scale, shear) components
tx, ty ; translation components
Output: translate ; a 2 component vector
rotate ; an angle
scale ; a 2 component vector
skew ; skew factor
Returns false if the matrix cannot be decomposed, true if it can
Supporting functions (point is a 2 component vector):
float length(point) returns the length of the passed vector
point normalize(point) normalizes the length of the passed point to 1
float dot(point, point) returns the dot product of the passed points
float atan2(float y, float x) returns the principal value of the arc tangent of
y/x, using the signs of both arguments to determine
the quadrant of the return value
Decomposition also makes use of the following function:
point combine(point a, point b, float ascl, float bscl)
result[0] = (ascl * a[0]) + (bscl * b[0])
result[1] = (ascl * a[1]) + (bscl * b[1])
return result
// Make sure the matrix is invertible
if ((a * d - b * c) == 0)
return false
// Take care of translation
translate[0] = tx
translate[1] = matrix[3][1]
// Put the components into a 2x2 matrix 'mat'
mat[0][0] = a
mat[0][1] = b
mat[1][0] = c
mat[1][1] = d
// Compute X scale factor and normalize first row.
scale[0] = length(row[0])
row[0] = normalize(row[0])
// Compute shear factor and make 2nd row orthogonal to 1st.
skew = dot(row[0], row[1])
row[1] = combine(row[1], row[0], 1.0, -skew)
// Now, compute Y scale and normalize 2nd row.
scale[1] = length(row[1])
row[1] = normalize(row[1])
skew /= scale[1];
// Now, get the rotation out
rotate = atan2(mat[0][1], mat[0][0])
return true;</pre>
<h3>Animating the components</h3>
<p>
Once decomposed, each component of each returned value of the source matrix is linearly interpolated
with the corresponding component of the destination matrix. For instance, the translate[0] and
translate[1] values are interpolated numerically, and the result is used to set the
translation of the animating element.
</p>
<h3>Recomposing the matrix</h3>
<p><em>This section is not normative.</em></p>
<p>
After interpolation the resulting values are used to position the element. One way to use these values
is to recompose them into a 3x2 matrix. This can be done using the Transformation Functions of the
<em>transform</em> property. The following JavaScript example produces a string for this purpose. The
values passed in are the output of the Unmatrix function above:
</p>
<pre>
function compose(translate, rotate, scale, skew, elementID)
{
var s = " translate(" + translate[0] + ", " + translate[1] + ")";
s += " rotate(" + rotate + ")";
s += " skewX(" + skew + ")";
s += " scale(" + scale[0] + ", " + scale[1] + ")";
document.getElementById(elementID).style.transform = s;
}</pre>
<h2 id="dom-interfaces">
DOM Interfaces
</h2>
<p>
This section describes the interfaces and functionality added to the DOM
to support runtime access to the functionality described above.
</p>
<h3 id="cssmatrix-interface">
CSSMatrix
</h3>
<div class="issue issue-marker">
<p class="desc">We actually describe a 3x2 matrix here, similar to <a href="http://www.w3.org/TR/SVG/coords.html#InterfaceSVGMatrix">SVGMatrix</a>.
</p></div>
<dl>
<dt>
<b>Interface <i><a id="DOM-CSSMatrix" name='DOM-CSSMatrix'>CSSMatrix</a></i></b>
</dt>
<dd>
<p>
The <code>CSSMatrix</code> interface represents a 3x2 homogeneous matrix.
</p>
<dl>
<dt>
<b>IDL Definition</b>
</dt>
<dd>
<div class='idl-code'>
<pre>
interface CSSMatrix {
attribute float a;
attribute float b;
attribute float c;
attribute float d;
attribute float e;
attribute float f;
void setMatrixValue(in DOMString string) raises(DOMException);
CSSMatrix multiply(in CSSMatrix secondMatrix);
CSSMatrix inverse() raises(DOMException);
CSSMatrix translate(in float x, in float y);
CSSMatrix scale(in float scaleX, in float scaleY);
CSSMatrix skewX(in float angle);
CSSMatrix skewY(in float angle);
CSSMatrix rotate(in float angle);
};</pre>
</div><br>
</dd> <!-- IDL -->
<dt>
<b>Attributes</b>
</dt>
<dd>
<dl>
<dt>
<code class='attribute-name'><a id="DOM-CSSMatrix-matrix" name='DOM-CSSMatrix-matrix'>a-f</a></code> of type <code>float</code>
</dt>
<dd>
Each of these attributes represents one of the values in the 3x2 matrix.<br>
</dd>
</dl>
</dd> <!-- Attributes -->
<dt>
<b>Methods</b>
</dt>
<dd>
<dl>
<!-- ===================================================== -->
<dt>
<code class='method-name'><a id="DOM-CSSMatrix-setMatrixValue" name='DOM-CSSMatrix-setMatrixValue'>setMatrixValue</a></code>
</dt>
<dd>
<div class='method'>
The <code>setMatrixValue</code> method replaces the existing matrix with one computed from parsing the passed string
as though it had been assigned to the transform property in a CSS style rule.
<div class='parameters'>
<b>Parameters</b>
<div class='paramtable'>
<dl>
<dt>
<code class='parameter-name'>string</code> of type <code>DOMString</code>
</dt>
<dd>
The string to parse.<br>
</dd>
</dl>
</div>
</div><!-- parameters -->
<div class='return-value'>
<b>No Return Value</b>
</div>
<div>
<b>Exceptions</b>
<div class='returnvalue'>
<dl>
<dt>
<code>DOMException SYNTAX_ERR</code>
</dt>
<dd>
Thrown when the provided string can not be
parsed into a CSSMatrix.
</dd>
</dl>
</div>
</div>
</div>
</dd> <!-- setMatrixValue -->
<!-- ===================================================== -->
<dt>
<code class='method-name'><a id="DOM-CSSMatrix-multiply" name='DOM-CSSMatrix-multiply'>multiply</a></code>
</dt>
<dd>
<div class='method'>
The <code>multiply</code> method returns a new CSSMatrix which is the result of this matrix multiplied by the passed matrix, with the passed matrix to the right. This matrix is not modified.
<div class='parameters'>
<b>Parameters</b>
<div class='paramtable'>
<dl>
<dt>
<code class='parameter-name'>secondMatrix</code> of type <code>CSSMatrix</code>
</dt>
<dd>
The matrix to multiply.<br>
</dd>
</dl>
</div>
</div><!-- parameters -->
<div class='return-value'>
<b>Return Value</b>
<div class='returnvalue'>
<dl>
<dt>
<code>CSSMatrix</code>
</dt>
<dd>
The result matrix.<br>
</dd>
</dl>
</div>
</div>
<div>
<b>No Exceptions</b>
</div>
</div>
</dd> <!-- multiply() -->
<!-- ===================================================== -->
<dt>
<code class='method-name'><a id="DOM-CSSMatrix-inverse" name='DOM-CSSMatrix-inverse'>inverse</a></code>
</dt>
<dd>
<div class='method'>
The <code>inverse</code> method returns a new matrix which is the inverse of this matrix. This matrix is not modified.
<div class='parameters'>
<b>No Parameters</b>
</div><!-- parameters -->
<div class='return-value'>
<b>Return Value</b>
<div class='returnvalue'>
<dl>
<dt>
<code>CSSMatrix</code>
</dt>
<dd>
The inverted matrix.<br>
</dd>
</dl>
</div>
</div>
<div>
<b>Exceptions</b>
<div class='returnvalue'>
<dl>
<dt>
<code>DOMException NOT_SUPPORTED_ERR</code>
</dt>
<dd>
Thrown when the CSSMatrix can not be
inverted.
</dd>
</dl>
</div>
</div>
</div><!-- ======================================================================================================= -->
</dd> <!-- inverse() -->
<!-- ===================================================== -->
<dt>
<code class='method-name'><a id="DOM-CSSMatrix-translate" name='DOM-CSSMatrix-translate'>translate</a></code>
</dt>
<dd>
<div class='method'>
The <code>translate</code> method returns a new matrix which is this matrix multiplied by a translation matrix containing the passed values. This matrix is not modified.
<div class='parameters'>
<b>Parameters</b>
<div class='paramtable'>
<dl>
<dt>
<code class='parameter-name'>x</code> of type <code>float</code>
</dt>
<dd>
The X component of the translation value.<br>
</dd>
<dt>
<code class='parameter-name'>y</code> of type <code>float</code>
</dt>
<dd>
The Y component of the translation value.<br>
</dd>
</dl>
</div>
</div><!-- parameters -->