drafts: css3-animations/Overview.src.html@b80217b81d3b (annotated)

css3-animations/Overview.src.html@b80217b81d3b (annotated)

css3-animations/Overview.src.html

Wed, 15 Feb 2012 18:36:17 +0000

author: L. David Baron <dbaron@dbaron.org>
date: Wed, 15 Feb 2012 18:36:17 +0000
changeset 4531: b80217b81d3b
parent 4528: 55165315dff5
child 4551: 9291fb211b30
permissions: -rw-r--r--

Clarify wording, as discussed in http://lists.w3.org/Archives/Public/www-archive/2012Feb/0018.html .

 <!DOCTYPE html PUBLIC '-//W3C//DTD HTML 4.01//EN'
   'http://www.w3.org/TR/html4/strict.dtd'>
 <html lang="en">
 <head>
   <title>CSS Animations</title>
   <link rel="stylesheet" type="text/css" href="../default.css">
   <link rel="stylesheet" type="text/css" href="http://www.w3.org/StyleSheets/TR/W3C-ED.css">
 </head>
 <body>
 <div class="head">
 <!--logo-->
 <h1>CSS Animations</h1>
 <h2 class="no-num no-toc">[LONGSTATUS] [DATE]</h2>
 <dl>
   <dt>This version:
     <dd><a href="[VERSION]">http://dev.w3.org/csswg/css3-animations/</a>
     <!--http://www.w3.org/TR/[YEAR]/WD-[SHORTNAME]-[CDATE]-->
   <dt>Latest version:
     <dd><a
       href="http://www.w3.org/TR/css3-animations">[LATEST]</a>
   <dt>Editor's draft:
     <dd><a href="http://dev.w3.org/csswg/[SHORTNAME]/">http://dev.w3.org/csswg/[SHORTNAME]/</a>
   <dt>Previous version:
     <dd><a href="http://www.w3.org/TR/2009/WD-css3-animations-20090320/">
       http://www.w3.org/TR/2009/WD-css3-animations-20090320/</a>
   <dt id="editors-list">Editors:
     <dd><a href="mailto:dino@apple.com">Dean Jackson</a> (<a
       href="http://www.apple.com/">Apple Inc</a>)
     <dd><a href="mailto:hyatt@apple.com">David Hyatt</a> (<a
       href="http://www.apple.com/">Apple Inc</a>)
     <dd><a href="mailto:cmarrin@apple.com">Chris Marrin</a> (<a
       href="http://www.apple.com/">Apple Inc</a>)
     <dd><a href="mailto:sylvaing@microsoft.com">Sylvain Galineau</a>
       (<a class=org href="http://www.microsoft.com/">Microsoft</a>)
     <dd class=vcard><a class=fn href="http://dbaron.org/">L. David Baron</a>
       (<a class=org href="http://www.mozilla.org/">Mozilla</a>)
   <dt>Issues list:
     <dd><a href="https://www.w3.org/Bugs/Public/buglist.cgi?query_format=advanced&amp;product=CSS&amp;component=Animations&amp;resolution=---&amp;cmdtype=doit">in Bugzilla</a>
   <dt>Test suite:
     <dd>none yet
 </dl>
 <!--copyright-->
 <hr title="Separator for header">
 </div>
 <h2 class="no-num no-toc" id="abstract">Abstract</h2>
 <p>This CSS module describes a way for authors to animate the values of CSS properties over time, using keyframes.
     The behavior of these keyframe animations can be controlled by specifying their duration, number of repeats,
     and repeating behavior.
 </p>
 <h2 class="no-num no-toc" id="status">Status of this document</h2>
 <!--status-->
 <h2 class="no-num no-toc" id="contents">Table of contents</h2>
 <!--toc-->
 <h2 id="introduction">Introduction</h2>
     <p><em>This section is not normative.</em>
     <p>
         CSS Transitions [[!CSS3-TRANSITIONS]] provide a way to interpolate CSS property values
         when they change as a result of underlying property changes. This provides an easy way to do simple animation,
         but the start and end states of the animation are controlled by the existing property values,
         and transitions provide little control to the author on how the animation progresses.
     </p>
     <p>
         This proposal introduces <em>defined animations</em>, in which the author can
         specify the changes in CSS properties over time as a set of keyframes. Animations are similar to transitions
         in that they change the presentational value of CSS properties over time.
         The principal difference is that while transitions trigger <i>implicitly</i> when property values change, animations
         are <i>explicitly</i> executed when the animation properties are applied. Because of this, animations require explicit
         values for the properties being animated. These values are specified using animation keyframes, described below.
     </p>
     <p>
         Many aspects of the animation can be controlled, including how many times the animation iterates, whether or not
         it alternates between the begin and end values, and whether or not the animation should be running or paused.
         An animation can also delay its start time.
     </p>
     <h2>Animations</h2>
     <p>
       CSS Animations affect computed property values. During the execution of an animation, the
       computed value for a property is controlled by the animation. This overrides the value
       specified in the normal styling system.
     </p>
     <p>
       In the case of multiple animations specifying behavior for the same property, the animation
       defined last will override the previously defined animations.
     </p>
     <p>
       An animation does not affect the computed value before the application of the animation,
       before the animation delay has expired, and after the end of the animation.
     </p>
     <div class="figure">
       <img src="sandwich.png" alt="">
     </div>
     <p class="caption">
       Computation of animated property values
     </p>
     <p>
       The diagram above shows how property values are computed. The intrinsic style is shown at the
       top of the diagram. The computed value is derived from intrinsic style at the times when an
       animation is not running and also when an animation is delayed (see below for specification of
       animation delay). During an animation, the computed style is derived from the animated value.
     </p>
     <p>
       The start time of an animation is the latter of two moments: the time at which the style is
       resolved that specifies the animation, or the time the document's load event is fired.
       Therefore, an animation specified in the document stylesheet will begin at the document load.
       An animation specified on an element by modifying the style after the document has loaded will
       start when the style is resolved. That may be immediately in the case of a pseudo style rule
       such as hover, or may be when the scripting engine returns control to the browser (in the case
       of style applied by script).
     </p>
     <p>
       An animation applies to an element if the element has a value for
       <code class="property">'animation-name'</code> that references a valid
       keyframes rule. Once an animation has started it continues until it ends
       or the <code class="property">'animation-name'</code> is removed. The values
       used for the keyframes and animation properties are snapshotted at the
       time the animation starts. Changing them during the execution of the
       animation has no effect. Note also, that changing the value of
       <code class="property">'animation-name'</code> does not necessarily
       restart an animation (e.g. if a list of animations are applied and
       one is removed from the list, only that animation will stop; The other
       animations will continue). In order to restart an animation, it must be
       removed then reapplied.
     </p>
     <p>
       The end of the animation is defined by the combination of the
       <code class="property">'animation-duration'</code>,
       <code class="property">'animation-iteration-count'</code> and
       <code class="property">'animation-fill-mode'</code> properties.
     </p>
     <div class="example">
       <p style="display:none">
         Example(s):
       </p>
       <pre>
     div {
       animation-name: diagonal-slide;
       animation-duration: 5s;
       animation-iteration-count: 10;
     }
     @keyframes diagonal-slide {
       from {
         left: 0;
         top: 0;
       }
       to {
         left: 100px;
         top: 100px;
       }
     }
     </pre>This will produce an animation that moves an element from (0, 0) to (100px, 100px) over five seconds and repeats itself nine times (for a total of ten iterations).
     </div>
     <h2>Keyframes</h2>
       <p>
         Keyframes are used to specify the values for the animating properties at various points
         during the animation. The keyframes specify the behavior of one cycle of the animation;
         the animation may iterate one or more times.
       </p>
       <p>
         Keyframes are specified using a specialized CSS at-rule. A <code
         class="property">@keyframes</code> rule consists of the keyword
         "@keyframes", followed by an identifier giving a name for the animation
         (which will be referenced using <code class="property">'animation-name'</code>),
         followed by a set of style rules (delimited by curly braces).
       </p>
       <p>
         The <i>keyframe selector</i> for a keyframe style rule consists of a
         comma-separated list of percentage values or the keywords 'from' or
         'to'. The selector is used to specify the percentage along the duration
         of the animation that the keyframe represents. The
         keyframe itself is specified by the block of property values declared on
         the selector. The keyword 'from' is equivalent to the value 0%. The
         keyword 'to' is equivalent to the value 100%. Note that the percentage
         unit specifier must be used on percentage values. Therefore, "0" is an
         invalid keyframe selector.
       </p>
       <p>
         If a 0% or "from" keyframe is not specified, then the user agent
         constructs a 0% keyframe using the computed values of the properties
         being animated. If a 100% or "to" keyframe is not specified, then the user agent
         constructs a 100% keyframe using the computed values of the properties
         being animated.
       </p>
       <p>
         The <i>keyframe declaration</i> for a keyframe rule consists of
         properties and values. Properties that are unable to be
         animated are ignored in these rules, with the exception of <code
         class="property">'animation-timing-function'</code>, the behavior
         of which is described below.
       </p>
       <p class="note">
           NOTE: describe what happens if a property is not present in all keyframes.
       </p>
       <p>
         The @keyframes rule that is used by an animation will be the last one encountered in sorted rules order
         that matches the name of the animation specified by the <code class="property">'animation-name'</code> property.
         <code class="css">@keyframes</code> rules do not cascade;
         therefore an animation will never derive keyframes from more than one <code class="css">@keyframes</code> rule.
       </p>
       <p>
         To determine the set of keyframes, all of the values in the selectors are sorted in increasing order by time.
         If there are any duplicates, then the last keyframe specified inside the <code class="css">@keyframes</code> rule
         will be used to provide the keyframe information for that time. There is no cascading within a
         <code class="css">@keyframes</code> rule if multiple keyframes specify the same keyframe selector values.
       </p>
       <p>
         If property is not specified for a keyframe, or is specified but invalid, the animation of that property proceeds
         as if that keyframe did not exist. Conceptually, it is as if a set of keyframes is constructed for each property
         that is present in any of the keyframes, and an animation is run independently for each property.
       </p>
       <div class="example">
         <p style="display:none">
           Example(s):
         </p>
         <pre>
   @keyframes wobble {
 % {
       left: 100px;
     }
 % {
       left: 150px;
     }
 % {
       left: 75px;
     }
 % {
       left: 100px;
     }
   }
   </pre>Four keyframes are specified for the animation named "wobble". In the first keyframe, shown at the beginning of the animation cycle, the 'left' value of the animation is 100px. By 40% of the animation duration, 'left' value has animated to 150px. At 60% of the animation duration, the 'left' value has animated back to 75px. At the end of the animation cycle, the 'left' value has returned to 100px. The diagram below shows the state of the animation if it were given a duration of 10s.
         <div class="figure">
           <img src="animation1.png" alt="">
         </div>
         <p class="caption">
           Animations states specified by keyframes
         </p>
       </div>
       <p>
         The following is the grammar for the keyframes rule.
       </p>
       <pre>
         keyframes-rule: KEYFRAMES_SYM S+ IDENT S* '{' S* keyframes-blocks '}' S*;
         keyframes-blocks: [ keyframe-selector '{' S* declaration? [ ';' S* declaration? ]* '}' S* ]* ;
         keyframe-selector: [ FROM_SYM | TO_SYM | PERCENTAGE ] S* [ ',' S* [ FROM_SYM | TO_SYM | PERCENTAGE ] S* ]*;
         @{K}{E}{Y}{F}{R}{A}{M}{E}{S}   {return KEYFRAMES_SYM;}
         {F}{R}{O}{M}                   {return FROM_SYM;}
         {T}{O}                         {return TO_SYM;}
       </pre>
       <!-- ======================================================================================================= -->
       <h3>
         Timing functions for keyframes
       </h3>
       <p>
         A keyframe style rule may also declare the timing function that is to be used as the animation moves to the next keyframe.
       </p>
       <div class="example">
         <p style="display:none">
           Example(s):
         </p>
         <pre>
   @keyframes bounce {
     from {
       top: 100px;
       animation-timing-function: ease-out;
     }
 % {
       top: 50px;
       animation-timing-function: ease-in;
     }
 % {
       top: 100px;
       animation-timing-function: ease-out;
     }
 % {
       top: 75px;
       animation-timing-function: ease-in;
     }
     to {
       top: 100px;
     }
   }
   </pre>Five keyframes are specified for the animation named "bounce". Between the first and second keyframe (ie. between 0% and 25%) an "ease-out" timing function is used. Between the second and third keyframe (ie. between 25% and 50%) an "ease-in" timing function is used. And so on. The effect will appear as an element that moves up the page 50px, slowing down as it reaches its highest point then speeding up as it falls back to 100px. The second half of the animation behaves in a similar manner, but only moves the element 25px units up the page. A timing function specified on the "to" or 100% keyframe is ignored
       </div>
       <p>
         See <a href="#animation-timing-function_tag">the <code class="property">'animation-timing-function'</code>
           property</a> for more information.
       </p><!-- ======================================================================================================= -->
       <!-- ======================================================================================================= -->
       <h3>
         The <code class="property">'animation-name'</code> Property
       </h3>
       <p>
         The <code class="property">'animation-name'</code> property defines a
         list of animations that apply. Each name is used to select the keyframe at-rule
         that provides the property values for the animation. If the name does
         not match any keyframe at-rule, there are no properties to be animated
         and the animation will not execute. Furthermore, if the animation name
         is 'none' then there will be no animation. This can be used to override
         any animations coming from the cascade. If animations are attempting to
         modify the same property, then the animation closest to the end of the
         list of names wins.
       </p>
       <p>
         Each animation listed by name should have a corresponding value
         for the other animation properties listed below. In the case where the
         other properties do not have lists of the correct length, their values
         are repeated to form a list with the same number of entries as
         <code class="property">'animation-name'</code>.
       </p>
       <table class="propdef">
         <tbody>
           <tr>
             <td>
               <em>Name:</em>
             </td>
             <td>
               <dfn id="animation-name">animation-name</dfn>
             </td>
           </tr>
           <tr>
             <td>
               <em>Value:</em>
             </td>
             <td>
               none | IDENT [, none | IDENT ]*
             </td>
           </tr>
           <tr>
             <td>
               <em>Initial:</em>
             </td>
             <td>
               none
             </td>
           </tr>
           <tr>
             <td>
               <em>Applies&nbsp;to:</em>
             </td>
             <td>
               all elements, :before and :after pseudo elements
             </td>
           </tr>
           <tr>
             <td>
               <em>Inherited:</em>
             </td>
             <td>
               no
             </td>
           </tr>
           <tr>
             <td>
               <em>Percentages:</em>
             </td>
             <td>
               N/A
             </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>
       <!--
       <p>
         It is possible for elements to have multiple animations running that change the same property or properties. In this case the animations combine in a manner defined by the property. For example, animations on <code class="property">'opacity'</code> will add together and animations on <code class="property">'transform'</code> will have their transformation matrices multiplied.
       </p>
       <div class="example">
         <p style="display:none">
           Example(s):
         </p>
         <pre>
         @keyframes 'border-bloat' {
           from {
             border-width: 0;
           }
           to {
             border-width: 10px;
           }
         }
         @keyframes 'border-diet' {
           from {
             border-width: 4px;
           }
           to {
             border-width: 2px;
           }
         }
         div {
           animation-name: 'border-bloat', 'border-diet';
           animation-duration: 10s, 4s;
         }
       </pre>
       <p>
       The above example has two animations executing on the same property, <code class="property">'border-width'</code>. The animations are additive. That is, the
       resulting value for the property will be the addition of the values from the
       two animations.
       </p>
       <p>
         At time '0s' the element's border will be 4px wide (0px from 'border-bloat' plus 4px from 'border-diet').
         At time '4s' the element's border will be 6px wide (4px from 'border-bloat' plus 2px from 'border-diet').
         At time '10s' the element's border will be 10px wide (10px from 'border-bloat' and no addition from
         'border-diet' as it is no longer executing).
       </p>
     </div>
   -->
       <!-- ======================================================================================================= -->
       <h3>
         The <code class="property">'animation-duration'</code> Property
       </h3>
       <p>
         The <code class="property">'animation-duration'</code> property defines the length of time that an animation takes to complete one cycle.
       </p>
       <table class="propdef">
         <tbody>
           <tr>
             <td>
               <em>Name:</em>
             </td>
             <td>
               <dfn id="animation-duration">animation-duration</dfn>
             </td>
           </tr>
           <tr>
             <td>
               <em>Value:</em>
             </td>
             <td>
               &lt;time&gt; [, &lt;time&gt;]*
             </td>
           </tr>
           <tr>
             <td>
               <em>Initial:</em>
             </td>
             <td>
 s
             </td>
           </tr>
           <tr>
             <td>
               <em>Applies&nbsp;to:</em>
             </td>
             <td>
               all elements, :before and :after pseudo elements
             </td>
           </tr>
           <tr>
             <td>
               <em>Inherited:</em>
             </td>
             <td>
               no
             </td>
           </tr>
           <tr>
             <td>
               <em>Percentages:</em>
             </td>
             <td>
               N/A
             </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>
       <p>
         By default the value is '0s', meaning that the animation cycle is
         immediate. A negative value for <code
         class="property">'animation-duration'</code> is treated as '0s'. In this
         case <code class="property">'animation-fill-mode'</code> still applies,
         so an animation that fills backwards will show the value of the 0%
         keyframe during any delay period, and an animation that fill forwards
         will retain the value specified at the 100% keyframe, even if the
         animation was instantaneous. Also, animation events are still fired.
       </p>
       <!-- ======================================================================================================= -->
       <h3 id="animation-timing-function_tag">
         The <code class="property">'animation-timing-function'</code> Property
       </h3>
       <p>
         The <code class="property">'animation-timing-function'</code> property describes how the animation will progress over one cycle of its duration. See the <code class="property">'transition-timing-function'</code> property [[!CSS3-TRANSITIONS]] for a complete description of timing function calculation.
       </p>
       <table class="propdef">
         <tbody>
           <tr>
             <td>
               <em>Name:</em>
             </td>
             <td>
               <dfn id="animation-timing-function">animation-timing-function</dfn>
             </td>
           </tr>
           <tr>
             <td>
               <em>Value:</em>
             </td>
             <td>
               ease | linear | ease-in | ease-out | ease-in-out | step-start | step-end | steps(&lt;number&gt;[, start | end ]) | cubic-bezier(&lt;number&gt;, &lt;number&gt;, &lt;number&gt;, &lt;number&gt;) [, ease | linear | ease-in | ease-out | ease-in-out | step-start | step-end | steps(&lt;number&gt;[, start | end ]) | cubic-bezier(&lt;number&gt;, &lt;number&gt;, &lt;number&gt;, &lt;number&gt;)]*
             </td>
           </tr>
           <tr>
             <td>
               <em>Initial:</em>
             </td>
             <td>
               ease
             </td>
           </tr>
           <tr>
             <td>
               <em>Applies&nbsp;to:</em>
             </td>
             <td>
               all elements, :before and :after pseudo elements
             </td>
           </tr>
           <tr>
             <td>
               <em>Inherited:</em>
             </td>
             <td>
               no
             </td>
           </tr>
           <tr>
             <td>
               <em>Percentages:</em>
             </td>
             <td>
               N/A
             </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>
       <p>
         For a keyframed animation, the <code class="property">'animation-timing-function'</code> applies
         between keyframes, not over the entire animation. For example, in the case of an ease-in-out timing function, an animation will ease in at the start of the keyframe and ease out at the end of the keyframe. A <code class="property">'animation-timing-function'</code> defined within a keyframe block applies to that keyframe, otherwise the timing function specified for the animation is used.
       </p>
       <!-- ======================================================================================================= -->
       <h3>
         The <code class="property">'animation-iteration-count'</code> Property
       </h3>
       <p>
         The <code class="property">'animation-iteration-count'</code> property defines the number of times
         an animation cycle is played. The default value is one, meaning the animation will play from
         beginning to end once. A value of <code class="css">'infinite'</code> will cause the animation to
         repeat forever. Non-integer numbers will cause the animation to end part-way through a cycle.
         Negative values of <code class="property">'animation-iteration-count'</code> are invalid.
         This property is often used with an <code class="property">'animation-direction'</code> value of
         <code class="css">alternate</code>, which will cause the animation to play in reverse on alternate cycles.
       </p>
       <table class="propdef">
         <tbody>
           <tr>
             <td>
               <em>Name:</em>
             </td>
             <td>
               <dfn id="animation-iteration-count">animation-iteration-count</dfn>
             </td>
           </tr>
           <tr>
             <td>
               <em>Value:</em>
             </td>
             <td>
               infinite | &lt;number&gt; [, infinite | &lt;number&gt;]*
             </td>
           </tr>
           <tr>
             <td>
               <em>Initial:</em>
             </td>
             <td>
 
             </td>
           </tr>
           <tr>
             <td>
               <em>Applies&nbsp;to:</em>
             </td>
             <td>
               all elements, :before and :after pseudo elements
             </td>
           </tr>
           <tr>
             <td>
               <em>Inherited:</em>
             </td>
             <td>
               no
             </td>
           </tr>
           <tr>
             <td>
               <em>Percentages:</em>
             </td>
             <td>
               N/A
             </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>
         The <code class="property">'animation-direction'</code> Property
       </h3>
       <p>
         The <code class="property">'animation-direction'</code> property defines whether or not the animation should play in reverse on alternate cycles. If <code class="css">alternate</code> is specified, the animation cycle iterations that are odd counts are played in the normal direction, and the animation cycle iterations that are even counts are played in a reverse direction. When an animation is played in reverse the timing functions are also reversed. For example, when played in reverse an ease-in animation would appear to be an ease-out animation.
       </p>
       <table class="propdef">
         <tbody>
           <tr>
             <td>
               <em>Name:</em>
             </td>
             <td>
               <dfn id="animation-direction">animation-direction</dfn>
             </td>
           </tr>
           <tr>
             <td>
               <em>Value:</em>
             </td>
             <td>
               normal | alternate [, normal | alternate]*
             </td>
           </tr>
           <tr>
             <td>
               <em>Initial:</em>
             </td>
             <td>
               normal
             </td>
           </tr>
           <tr>
             <td>
               <em>Applies&nbsp;to:</em>
             </td>
             <td>
               all elements, :before and :after pseudo elements
             </td>
           </tr>
           <tr>
             <td>
               <em>Inherited:</em>
             </td>
             <td>
               no
             </td>
           </tr>
           <tr>
             <td>
               <em>Percentages:</em>
             </td>
             <td>
               N/A
             </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>
         The <code class="property">'animation-play-state'</code> Property
       </h3>
       <p>
         The <code class="property">'animation-play-state'</code> property defines whether the animation is running or paused. A running animation can be paused by setting this property to <code class="css">'paused'</code>. To continue running a paused animation this property can be set to <code class="css">'running'</code>. A paused animation will continue to display the current value of the animation in a static state, as if the time of the animation is constant. When a paused animation is resumed, it restarts from the current value, not necessarily from the beginning of the animation.
       </p>
       <table class="propdef">
         <tbody>
           <tr>
             <td>
               <em>Name:</em>
             </td>
             <td>
               <dfn id="animation-play-state">animation-play-state</dfn>
             </td>
           </tr>
           <tr>
             <td>
               <em>Value:</em>
             </td>
             <td>
               running | paused [, running | paused]*
             </td>
           </tr>
           <tr>
             <td>
               <em>Initial:</em>
             </td>
             <td>
               running
             </td>
           </tr>
           <tr>
             <td>
               <em>Applies&nbsp;to:</em>
             </td>
             <td>
               all elements, :before and :after pseudo elements
             </td>
           </tr>
           <tr>
             <td>
               <em>Inherited:</em>
             </td>
             <td>
               no
             </td>
           </tr>
           <tr>
             <td>
               <em>Percentages:</em>
             </td>
             <td>
               N/A
             </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>
         The <code class="property">'animation-delay'</code> Property
       </h3>
       <p>
         The <code class="property">'animation-delay'</code> property defines
         when the animation will start. It allows an animation to begin
         execution some time after it is applied. An <code
         class="property">'animation-delay'</code> value of '0s' means the
         animation will execute as soon as it is applied. Otherwise, the value
         specifies an offset from the moment the animation is applied, and the
         animation will delay execution by that offset.
       </p>
       <p>
         If the value for <code class="property">'animation-delay'</code> is a
         negative time offset then the animation will execute the moment it is
         applied, but will appear to have begun execution at the specified
         offset. That is, the animation will appear to begin part-way through
         its play cycle. In the case where an animation has implied starting
         values and a negative <code class="property">'animation-delay'</code>,
         the starting values are taken from the moment the animation is applied.
       </p>
       <table class="propdef">
         <tbody>
           <tr>
             <td>
               <em>Name:</em>
             </td>
             <td>
               <dfn id="animation-delay">animation-delay</dfn>
             </td>
           </tr>
           <tr>
             <td>
               <em>Value:</em>
             </td>
             <td>
               &lt;time&gt; [, &lt;time&gt;]*
             </td>
           </tr>
           <tr>
             <td>
               <em>Initial:</em>
             </td>
             <td>
 s
             </td>
           </tr>
           <tr>
             <td>
               <em>Applies&nbsp;to:</em>
             </td>
             <td>
               all elements, :before and :after pseudo elements
             </td>
           </tr>
           <tr>
             <td>
               <em>Inherited:</em>
             </td>
             <td>
               no
             </td>
           </tr>
           <tr>
             <td>
               <em>Percentages:</em>
             </td>
             <td>
               N/A
             </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>
         The <code class="property">'animation-fill-mode'</code> Property
       </h3>
       <p>
         The <code class="property">'animation-fill-mode'</code> property defines
         what values are applied by the animation outside the time it is executing.
         By default, an animation will not affect property values between the
         time it is applied (the <code class="property">'animation-name'</code> property is
         set on an element) and the time it begins execution (which is determined by
         the <code class="property">'animation-delay'</code> property). Also, by
         default an animation does not affect property values after the animation
         ends (determined by the <code class="property">'animation-duration'</code> property).
         The value of <code class="property">'animation-fill-mode'</code> can
         override this behavior.
       </p>
       <p>
         If the value for <code class="property">'animation-fill-mode'</code> is
         <code class="css">'backwards'</code>, then the animation will
         apply the property values defined in its 0% or 'from' keyframe as soon
         as the animation is applied, during the period defined by
         <code class="property">'animation-delay'</code>.
       </p>
       <p>
         If the value for <code class="property">'animation-fill-mode'</code>
         is <code class="css">'forwards'</code>, then the animation will
         apply the property values defined in its last executing keyframe after
         the final iteration of the animation, until the animation style is
         removed. The last executing keyframe is the 'to' or '100%' keyframe,
         unless the animation has <code
         class="property">'animation-direction'</code> set to <code
         class="css">'alternate'</code> and both a finite and even
         iteration count, in which case it is the 'from' or '0%' keyframe.
       </p>
       <p>
         If the value for <code class="property">'animation-fill-mode'</code>
         is <code class="css">'both'</code>, then the animation will
         follow the rules for both 'forwards' and 'backwards'. That is, it will
         extend the animation properties in both directions.
       </p>
       <table class="propdef">
         <tbody>
           <tr>
             <td>
               <em>Name:</em>
             </td>
             <td>
               <dfn id="animation-fill-mode">animation-fill-mode</dfn>
             </td>
           </tr>
           <tr>
             <td>
               <em>Value:</em>
             </td>
             <td>
               none | forwards | backwards | both [, none | forwards | backwards | both]*
             </td>
           </tr>
           <tr>
             <td>
               <em>Initial:</em>
             </td>
             <td>
               none
             </td>
           </tr>
           <tr>
             <td>
               <em>Applies&nbsp;to:</em>
             </td>
             <td>
               all elements, :before and :after pseudo elements
             </td>
           </tr>
           <tr>
             <td>
               <em>Inherited:</em>
             </td>
             <td>
               no
             </td>
           </tr>
           <tr>
             <td>
               <em>Percentages:</em>
             </td>
             <td>
               N/A
             </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>
         The <code class="property">'animation'</code> Shorthand Property
       </h3>
       <p>
         The <code class="property">'animation'</code> shorthand property
         combines seven of the animation properties into a single property.
       </p>
       <p>
         Note that order is important in this property. The first value that can be
         parsed as a time is assigned to the animation-duration. The second value that
         can be parsed as a time is assigned to animation-delay.
       </p>
       <p class="issue">
         An alternative proposal is to accept the font shorthand approach of
         using a "/" character between the values of the same type. eg. 2s/4s would
         mean a duration of 2 seconds and a delay of 4 seconds.
       </p>
       <table class="propdef">
         <tbody>
           <tr>
             <td>
               <em>Name:</em>
             </td>
             <td>
               <dfn id="animation">animation</dfn>
             </td>
           </tr>
           <tr>
             <td>
               <em>Value:</em>
             </td>
             <td>
               [&lt;animation-name&gt; ||
               &lt;animation-duration&gt; ||
               &lt;animation-timing-function&gt; ||
               &lt;animation-delay&gt; ||
               &lt;animation-iteration-count&gt; ||
               &lt;animation-direction&gt; ||
               &lt;animation-fill-mode&gt;]
               [, [&lt;animation-name&gt; ||
               &lt;animation-duration&gt; ||
               &lt;animation-timing-function&gt; ||
               &lt;animation-delay&gt; ||
               &lt;animation-iteration-count&gt; ||
               &lt;animation-direction&gt; ||
               &lt;animation-fill-mode&gt;] ]*
             </td>
           </tr>
           <tr>
             <td>
               <em>Initial:</em>
             </td>
             <td>
               see individual properties
             </td>
           </tr>
           <tr>
             <td>
               <em>Applies&nbsp;to:</em>
             </td>
             <td>
               all elements, :before and :after pseudo elements
             </td>
           </tr>
           <tr>
             <td>
               <em>Inherited:</em>
             </td>
             <td>
               no
             </td>
           </tr>
           <tr>
             <td>
               <em>Percentages:</em>
             </td>
             <td>
               N/A
             </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><!-- ======================================================================================================= -->
       <h2>
         Animation Events
       </h2>
       <p>
         Several animation related events are available through the <a
         href="http://www.w3.org/TR/DOM-Level-2-Events/events.html">DOM Event
         system</a>. The start and end of an animation, and the end of each
         iteration of an animation all generate DOM events. An element can have
         multiple properties being animated simultaneously. This can occur either
         with a single <code class="property">animation-name</code> value with
         keyframes containing multiple properties, or with multiple <code
         class="property">animation-name</code> values. For the purposes of
         events, each <code class="property">animation-name</code> specifies a
         single animation. Therefore an event will be generated for each <code
         class="property">animation-name</code> value and not necessarily for
         each property being animated.
       </p>
       <p>
         The time the animation has been running is sent with each event
         generated. This allows the event handler to determine the current
         iteration of a looping animation or the current position of an
         alternating animation. This time does not include any time the animation
         was in the <code>paused</code> play state.
       </p>
       <dl>
         <dt>
           <b>Interface <i><a id="Events-AnimationEvent" name='Events-AnimationEvent'>AnimationEvent</a></i></b>
         </dt>
         <dd>
           <p>
             The <code>AnimationEvent</code> interface provides specific contextual information associated with Animation events.
           </p>
           <dl>
             <dt>
               <br>
               <b>IDL Definition</b>
             </dt>
             <dd>
               <div class='idl-code'>
                 <pre>
   interface AnimationEvent : Event {
     readonly attribute DOMString          animationName;
     readonly attribute float              elapsedTime;
     void               initAnimationEvent(in DOMString typeArg,
                                           in boolean canBubbleArg,
                                           in boolean cancelableArg,
                                           in DOMString animationNameArg,
                                           in float elapsedTimeArg);
   };
   </pre>
               </div>
             </dd>
             <dt>
               <b>Attributes</b>
             </dt>
             <dd>
               <dl>
                 <dt>
                   <code class='attribute-name'><a id="Events-AnimationEvent-animationName" name='Events-AnimationEvent-animationName'>animationName</a></code> of type <code>DOMString</code>, readonly
                 </dt>
                 <dd>
                   The value of the <code class="property">animation-name</code> property of the
                   animation that fired the event.
                 </dd>
               </dl>
               <dl>
                 <dt>
                   <code class='attribute-name'><a id="Events-AnimationEvent-elapsedTime" name='Events-AnimationEvent-elapsedTime'>elapsedTime</a></code> of type <code>float</code>, readonly
                 </dt>
                 <dd>
                   The amount of time the animation has been running, in
                   seconds, when this event fired, excluding any time the
                   animation was paused. For an "animationstart" event, the
                   elapsedTime is zero unless there was a negative value for
                   <code class="property">animation-delay</code>, in which
                   case the event will be fired with an elapsedTime of (-1 *
                   delay).
                 </dd>
               </dl>
             </dd>
             <dt>
               <b>Methods</b>
             </dt>
             <dd>
               <dl>
                 <dt>
                   <code class='method-name'><a id="Events-AnimationEvent-initAnimationEvent" name='Events-AnimtionEvent-initAnimationEvent'>initAnimationEvent</a></code>
                 </dt>
                 <dd>
                   <div class='method'>
                     The <code>initAnimationEvent</code> method is used to initialize the value of an <code>AnimationEvent</code> created through the <a href='http://www.w3.org/TR/DOM-Level-2-Events/events.html#Events-DocumentEvent'><code>DocumentEvent</code></a> interface. This method may only be called before the <code>AnimationEvent</code> has been dispatched via the <code>dispatchEvent</code> method, though it may be called multiple times during that phase if necessary. If called multiple times, the final invocation takes precedence.
                     <div class='parameters'>
                       <b>Parameters</b>
                       <div class='paramtable'>
                         <dl>
                           <dt>
                             <code class='parameter-name'>typeArg</code> of type <code>DOMString</code>
                           </dt>
                           <dd>
                             Specifies the event type.<br>
                           </dd>
                           <dt>
                             <code class='parameter-name'>canBubbleArg</code> of type <code>boolean</code>
                           </dt>
                           <dd>
                             Specifies whether or not the event can bubble.<br>
                           </dd>
                           <dt>
                             <code class='parameter-name'>cancelableArg</code> of type <code>boolean</code>
                           </dt>
                           <dd>
                             Specifies whether or not the event's default action can be prevented.
                           </dd>
                           <dt>
                             <code class='parameter-name'>animationNameArg</code> of type <code>DOMString</code>
                           </dt>
                           <dd>
                             Specifies the <a href='http://www.w3.org/TR/DOM-Level-2-Events/events.html#Events-Event'><code>Event</code></a>'s animation name.<br>
                           </dd>
                           <dt>
                             <code class='parameter-name'>elapsedTimeArg</code> of type <code>float</code>
                           </dt>
                           <dd>
                             Specifies the amount of time, in seconds, the animation has been running at the time of initialization.
                           </dd>
                         </dl>
                       </div>
                     </div><!-- parameters -->
                     <div>
                       <b>No Return Value</b>
                     </div>
                     <div>
                       <b>No Exceptions</b>
                     </div>
                   </div><!-- method -->
                 </dd>
               </dl>
             </dd>
           </dl>
         </dd>
       </dl>
       <p>
         The different types of Animation events that can occur are:
       </p>
       <dl>
         <dt>
           <b>animationstart</b>
         </dt>
         <dd>
           The 'animationstart' event occurs at the start of the animation. If there is an
           <code class="property">animation-delay</code> then this event will fire once the delay period
           has expired. A negative delay will cause the event to fire with an elapsedTime equal to
           the absolute value of the delay.
           <ul>
             <li>Bubbles: Yes
             </li>
             <li>Cancelable: No
             </li>
             <li>Context Info: animationName
             </li>
           </ul>
         </dd>
         <dt>
           <b>animationend</b>
         </dt>
         <dd>
           The 'animationend' event occurs when the animation finishes.
           <ul>
             <li>Bubbles: Yes
             </li>
             <li>Cancelable: No
             </li>
             <li>Context Info: animationName, elapsedTime
             </li>
           </ul>
         </dd>
         <dt>
           <b>animationiteration</b>
         </dt>
         <dd>
           The 'animationiteration' event occurs at the end of each iteration of an animation for which <code>animation-iteration-count</code> is greater than one. This event does not occur for animations with an iteration count of one.
           <ul>
             <li>Bubbles: Yes
             </li>
             <li>Cancelable: No
             </li>
             <li>Context Info: animationName, elapsedTime
             </li>
           </ul>
         </dd>
       </dl>
       <!-- ======================================================================================================= -->
         <h2>
           DOM Interfaces
         </h2>
         <p>
           CSS animation is exposed to the CSSOM through a pair of new interfaces
           describing the keyframes.
         </p>
         <dl>
           <dt>
             <b>Interface <i><a id="DOM-CSSRule" name='DOM-CSSRule'>CSSRule</a></i></b>
           </dt>
           <dd>
             <p>
               The following 2 rule types are added to the <code>CSSRule</code> interface. They provide identification for the new keyframe and keyframes rules.
             </p>
             <dl>
               <dt>
                 <b>IDL Definition</b>
               </dt>
               <dd>
                 <div class='idl-code'>
                   <pre>
     interface CSSRule {
       ...
       const unsigned short KEYFRAMES_RULE = 7;
       const unsigned short KEYFRAME_RULE = 8;
       ...
     };</pre>
                 </div>
               </dd> <!-- IDL -->
             </dl>
           </dd>
           <dt>
             <b>Interface <i><a id="DOM-CSSKeyframeRule" name='DOM-CSSKeyframeRule'>CSSKeyframeRule</a></i></b>
           </dt>
           <dd>
             <p>
               The <code>CSSKeyframeRule</code> interface represents the style rule for a single key.
             </p>
             <dl>
               <dt>
                 <br>
                 <b>IDL Definition</b>
               </dt>
               <dd>
                 <div class='idl-code'>
                   <pre>
     interface CSSKeyframeRule : CSSRule {
         attribute DOMString keyText;
         readonly attribute CSSStyleDeclaration style;
     };
     </pre>
                 </div><br>
               </dd>
               <dt>
                 <b>Attributes</b>
               </dt>
               <dd>
                 <dl>
                   <dt>
                     <code class='attribute-name'><a id="DOM-CSSKeyframeRule-keyText" name='DOM-CSSKeyframeRule-keyText'>keyText</a></code> of type <code>DOMString</code>
                   </dt>
                   <dd>
                     This attribute represents the key as the string representation of a floating point number between 0 and 1. If the value
                     in the CSS style is <code>from</code> this value will be 0, and if the value in the CSS style is <code>to</code> this
                     value will be 1.<br>
                   </dd>
                 </dl>
               </dd>
               <dd>
                 <dl>
                   <dt>
                     <code class='attribute-name'><a id="DOM-CSSKeyframeRule-style" name='DOM-CSSKeyframeRule-style'>style</a></code> of type <code>CSSStyleDeclaration</code>
                   </dt>
                   <dd>
                     This attribute represents the style associated with this keyframe.<br>
                   </dd>
                 </dl>
               </dd>
               <dt>
                 <b>No Methods</b>
               </dt>
             </dl>
           </dd>
         </dl>
         <dl>
           <dt>
             <b>Interface <i><a id="DOM-CSSKeyframesRule" name='DOM-CSSKeyframesRule'>CSSKeyframesRule</a></i></b>
           </dt>
           <dd>
             <p>
               The <code>CSSKeyframesRule</code> interface represents a complete set of keyframes for a single animation.
             </p>
             <dl>
               <dt>
                 <br>
                 <b>IDL Definition</b>
               </dt>
               <dd>
                 <div class='idl-code'>
                   <pre>
     interface CSSKeyframesRule : CSSRule {
         attribute          DOMString   name;
         readonly attribute CSSRuleList cssRules;
         void               appendRule(in DOMString rule);
         void               deleteRule(in DOMString key);
         CSSKeyframeRule    findRule(in DOMString key);
     };
     </pre>
                 </div><br>
               </dd>
               <dt>
                 <b>Attributes</b>
               </dt>
               <dd>
                 <dl>
                   <dt>
                     <code class='attribute-name'><a id="DOM-CSSKeyframesRule-name" name='DOM-CSSKeyframesRule-name'>name</a></code> of type <code>DOMString</code>
                   </dt>
                   <dd>
                     This attribute is the name of the keyframes, used by the <code>animation-name</code> property.<br>
                   </dd>
                 </dl>
               </dd>
               <dd>
                 <dl>
                   <dt>
                     <code class='attribute-name'><a id="DOM-CSSKeyframeRules-cssRules" name='DOM-CSSKeyframeRules-cssRules'>cssRules</a></code> of type <code>CSSRuleList</code>
                   </dt>
                   <dd>
                     This attribute gives access to the keyframes in the list.<br>
                   </dd>
                 </dl>
               </dd>
               <dt>
                 <b>Methods</b>
                 <dd>
                   <dl>
                     <!-- ======================================================================================================= -->
                     <dt>
                       <code class='method-name'><a id="DOM-CSSKeyframesRule-appendRule" name='DOM-CSSKeyframesRule-appendRule'>appendRule</a></code>
                     </dt>
                     <dd>
                       <div class='method'>
                         The <code>appendRule</code> method appends the passed CSSKeyframeRule into the list at the passed key.
                         <div class='parameters'>
                           <b>Parameters</b>
                           <div class='paramtable'>
                             <dl>
                                <dt>
                                 <code class='parameter-name'>rule</code> of type <code>DOMString</code>
                               </dt>
                               <dd>
                                 The rule to be appended, expressed in the same syntax as one entry in the
                                 <code>@keyframes</code> rule.
                               </dd>
                             </dl>
                           </div>
                         </div><!-- parameters -->
                         <div class='return-value'>
                           <b>No Return Value</b>
                         </div>
                         <div>
                           <b>No Exceptions</b>
                         </div>
                       </div><!-- ======================================================================================================= -->
                     </dd>
                     <dt>
                       <code class='method-name'><a id="DOM-CSSKeyframesRule-deleteRule" name='DOM-CSSKeyframesRule-deleteRule'>deleteRule</a></code>
                     </dt>
                     <dd>
                       <div class='method'>
                         The <code>deleteRule</code> method deletes the CSSKeyframeRule with the passed key. If a rule with this key
                         does not exist, the method does nothing.
                         <div class='parameters'>
                           <b>Parameters</b>
                           <div class='paramtable'>
                             <dl>
                               <dt>
                                 <code class='parameter-name'>key</code> of type <code>DOMString</code>
                               </dt>
                               <dd>
                                 The key which describes the rule to be deleted. The key must
                                 resolve to a number between 0 and 1, or the rule is ignored.<br>
                               </dd>
                             </dl>
                           </div>
                         </div><!-- parameters -->
                         <div class='return-value'>
                           <b>No Return Value</b>
                         </div>
                         <div>
                           <b>No Exceptions</b>
                         </div>
                       </div><!-- ======================================================================================================= -->
                     </dd>
                     <dt>
                       <code class='method-name'><a id="DOM-CSSKeyframesRule-findRule" name='DOM-CSSKeyframesRule-findRule'>findRule</a></code>
                     </dt>
                     <dd>
                       <div class='method'>
                         The <code>findRule</code> method returns the rule with a key matching the passed key. If no such rule
                         exists, a null value is returned.
                         <div class='parameters'>
                           <b>Parameters</b>
                           <div class='paramtable'>
                             <dl>
                               <dt>
                                 <code class='parameter-name'>key</code> of type <code>DOMString</code>
                               </dt>
                               <dd>
                                 The key which described the rule to find. The key must
                                 resolve to a number between 0 and 1, or the rule is ignored.<br>
                               </dd>
                             </dl>
                           </div>
                         </div><!-- parameters -->
                         <div class='return-value'>
                           <b>Return Value</b>
                           <div class='returnvalue'>
                             <dl>
                               <dt>
                                 <code>CSSKeyframeRule</code>
                               </dt>
                               <dd>
                                 The found rule.<br>
                               </dd>
                             </dl>
                           </div>
                         </div>
                         <div>
                           <b>No Exceptions</b>
                         </div>
                       </div><!-- ======================================================================================================= -->
                     </dd>
                   </dl><!-- method -->
                 </dd>
               </dt>
             </dl>
           </dd>
         </dl>
 <h2>References</h2>
 <h3 class="no-num">Normative references</h3>
 <!--normative-->
 <h3 class="no-num">Other references</h3>
 <!--informative-->
 <h2 class="no-num">Property index</h2>
 <!-- properties -->
 <h2 class="no-num" id="index">Index</h2>
 <!--index-->
 </body>
 </html>
 <!-- Keep this comment at the end of the file
 Local variables:
 mode: sgml
 sgml-default-doctype-name:"html"
 sgml-minimize-attributes:t
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Mercurial > drafts / annotate

css3-animations/Overview.src.html@b80217b81d3b (annotated)

css3-animations/Overview.src.html