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# 19 Animation

### Contents

## 19.1 Introduction

Because the Web is a dynamic medium, SVG supports the ability to change vector graphics over time. SVG content can be animated in the following ways:

- Using SVG's Animation Elements. SVG document fragments can describe time-based modifications to the document's elements. Using the various animation elements, you can do motion paths, fade-in/fade-out effects and objects that grow, shrink, spin or change color.
- Using the SVG DOM. The SVG DOM conforms to key aspects of the "Document Object Model (DOM) level 1" [DOM1] and "Document Object Model (DOM) level 2" [DOM2] specifications. Every attribute and style sheet setting is accessible to scripting, and SVG offers a set of additional DOM interfaces to support efficient animation via scripting. As a result, virtually any kind of animation can be achieved. The timer facilities in scripting languages such as ECMAScript can be used to start up and control the animations. (See example below.)
- SVG has been designed to allow future versions of SMIL [SMIL1] to use animated or static SVG content as media components.
- In the future, it is expected that future versions of SMIL will be modularized and that components of it could be used in conjunction with SVG and other XML grammars to achieve animation effects.

## 19.2 Animation elements

### 19.2.1 Relationship to SMIL Animation

SVG's animation elements were developed in collaboration with the W3C Synchronized Multimedia (SYMM) Working Group, developers of the Synchronized Multimedia Integration Language (SMIL) 1.0 Specification [SMIL1].

The SYMM working group, in collaboration with the SVG working group, has authored the SMIL Animation specification [SMILANIM], which represents a general-purpose XML animation feature set. SVG incorporates the animation features defined in the SMIL Animation specification and provides some SVG-specific extensions.

SVG supports the following four animation elements which are defined in the SMIL Animation specification:

| 'animate' |  | allows scalar attributes and properties to be assigned different values over time
| 'set' |  | a convenient shorthand for 'animate', which is useful for assigning animation values to non-numeric attributes and properties, such as the 'visibility' property
| 'animateMotion' |  | moves an element along a motion path
| 'animateColor' |  | modifies the color value of particular attributes or properties over time

Additionally, SVG includes the following compatible extensions to SMIL Animation:

| 'animateTransform' |  | modifies one of SVG's transformation attributes over time, such as the transform attribute
| path attribute |  | SVG allows the any feature from SVG's path data syntax to be specified in a path attribute to the 'animateMotion' element. (SMIL Animation only allows a subset of SVG's path data syntax within a path attribute.)
| keyPoints attribute |  | SVG adds a keyPoints attribute to the 'animateMotion' to provide precise control of the velocity of motion path animations
| rotate attribute |  | SVG adds a rotate attribute to the 'animateMotion' to control whether an object is automatically rotated so that its X-axis points in the same direction (or opposite direction) as the directional tangent vector of the motion path

SMIL Animation requires that the host language define how identify the elements which are to be animated. For compatibility with other aspects of the language, SVG uses URI references via an xlink:href attribute to identify the elements which are to be targets of the animations.

SMIL Animation requires that the host language define the meaning for document begin and the document end. Since an 'svg' is sometimes the root of the XML document tree and other times can be a component of a parent XML grammar, SVG defines an effective begin and effective end for an SVG document fragment. The effective begin of an SVG document fragment is the exact time at which the 'svg' element's onload event is triggered. The effective end of an SVG document fragment is the point at which the document fragment has been released and is no longer being processed by the user agent.

The term presentation time indicates the effective position in time relative to the effective begin of a document fragment. Presentation time behaves like the timecode shown on a counter of a tape-deck that advances at the speed of the presentation. It reflects that the presentation can be stopped, and that its speed can be decreased or increased either by user actions, or by the animation engine itself.

SVG defines more constrained error processing that is defined in the SMIL Animation [SMILANIM] specification. SMIL Animation defines error processing behavior where the document continues to run in certain error situations, whereas all animations within an SVG document fragment will stop in the event of any error within the document (see Error processing).

The SMIL Animation specification was jointly developed by the SYMM and SVG working groups. SVG is a host language in terms of SMIL Animation and therefore introduces additional constraints and features as permitted by that specification. Except as specifically noted, all animation elements and attributes described for SVG conform to the SMIL Animation [SMILANIM] specification.

### 19.2.2 Animation elements example

Example anim01 below demonstrates each of SVG's five animation elements.

    <?xml version="1.0" standalone="no"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20000303 Stylable//EN"
      "http://www.w3.org/TR/2000/03/WD-SVG-20000303/DTD/svg-20000303-stylable.dtd">
    <svg width="8cm" height="3cm"  viewBox="0 0 800 300">
      <desc>Example anim01 - demonstrate animation elements</desc>

      <!-- The following illustrates the use of the 'animate' element
            to animate a rectangles x, y, and width attributes so that
            the rectangle grows to ultimately fill the viewport. -->
      <rect id="RectElement" x="300" y="100" width="300" height="100"
            style="fill:rgb(255,255,0)" >
        <animate attributeName="x" attributeType="XML"
                 begin="0s" dur="9s" fill="freeze" from="300" to="0" />
        <animate attributeName="y" attributeType="XML"
                 begin="0s" dur="9s" fill="freeze" from="100" to="0" />
        <animate attributeName="width" attributeType="XML"
                 begin="0s" dur="9s" fill="freeze" from="300" to="800" />
        <animate attributeName="height" attributeType="XML"
                 begin="0s" dur="9s" fill="freeze" from="100" to="300" />
      </rect>

      <!-- Set up a new user coordinate system so that
            the text string's origin is at (0,0), allowing
            rotation and scale relative to the new origin -->
      <g transform="translate(100,100)" >
        <!-- The following illustrates the use of the 'set', 'animateMotion',
             'animateColor' and 'animateTransform' elements. The 'text' element
             below starts off hidden (i.e., invisible). At 3 seconds, it:
               * becomes visible
               * continuously moves diagonally across the viewport
               * changes color from blue to dark red
               * rotates from -30 to zero degrees
               * scales by a factor of three. -->
        <text id="TextElement" x="0" y="0"
              style="font-family:Verdana; font-size:35.27; visibility:hidden" >
          It's alive!
          <set attributeName="visibility" attributeType="CSS" to="visible"
               begin="3s" dur="6s" fill="freeze" />
          <animateMotion path="M 0 0 L 100 100"
               begin="3s" dur="6s" fill="freeze" />
          <animateColor attributeName="fill" attributeType="CSS"
               from="rgb(0,0,255)" to="rgb(128,0,0)"
               begin="3s" dur="6s" fill="freeze" />
          <animateTransform attributeName="transform" attributeType="XML"
               type="rotate" from="-30" to="0"
               begin="3s" dur="6s" fill="freeze" />
          <animateTransform attributeName="transform" attributeType="XML"
               type="scale" from="1" to="3"
               begin="3s" dur="6s" fill="freeze" />
        </text>
      </g>
    </svg>

Example anim01
At zero seconds |  | At three seconds
At six seconds |  | At nine seconds

View this example as SVG (SVG-enabled browsers only)

The sections below describe the various animation attributes and elements.

### 19.2.3 Attributes to identify the target of an animation

The following attributes are common to all animation elements and identify the target element and the attribute or property whose value changes over time.

    <!ENTITY % animTargetAttrs
     "%xlinkRefAttrs;
      xlink:href %URI; #IMPLIED
      attributeName  CDATA  #REQUIRED
      attributeType  CDATA  #IMPLIED" >

Attribute definitions:

xlink:href = "<uri>"
  A URI reference to the element which is the target of this animation and which therefore will be modified over time.
  The target element must be part of the current SVG document fragment.
  <uri> must point to exactly one target element which is capable of being the target of the given animation. If <uri> points to multiple target elements or the given target element is not capable of being a target of the given animation or the given target element is not part of the current SVG document fragment, then the document is in error (see Error processing).
  If the xlink:href attribute is not provided, then the target element will be the immediate parent element of the current animation element.
  Refer to the descriptions of the individual animation elements for any restrictions on what types of elements can be targets of particular types of animations.
  For more information, see [SMILANIM-TARGET].
attributeName = <attributeName>
  Specifies the name of the target attribute. An XMLNS prefix may be used to indicate the XML namespace for the attribute. The prefix will be interpreted in the scope of the target element.
  For more information, see [SMILANIM-TARGET].
attributeType = "CSS | XML | auto"
  Specifies the namespace in which the target attribute and its associated values are defined. The attribute value is one of the following:
  "XML"
    This specifies that the value of "attributeName" is the name of an XML attribute on the target element. The attribute must be defined as animatable in this specification.
  "CSS"
    This specifies that the value of "attributeName" is the name of a CSS property defined as animatable in this specification.
  "auto"
    This specifies that the user agent will automatically check to determine if there is an animatable SVG property whose name matches the value of attributeName; if not, the user agent will check to determine if there is an animatable XML attribute on the target element whose name matches the value of attributeName.
  The default value is "auto".
  For more information, see [SMILANIM-TARGET].

Attributes defined elsewhere:
  %xlinkRefAttrs;.

### 19.2.4 Attributes to control the timing of the animation

The following attributes are common to all animation elements and control the timing of the animation, including what causes the animation to start and end, whether the animation runs repeatedly, and whether to retain the end state the animation once the animation ends.

    <!ENTITY % animTimingAttrs
     "begin CDATA #IMPLIED
      dur CDATA #IMPLIED
      restart (always | never | whenNotActive) 'always'
      repeatCount CDATA #IMPLIED
      repeatDur CDATA #IMPLIED
      end CDATA #IMPLIED
      fill (remove | freeze) 'remove'" >

Attribute definitions:

begin
  Defines when the element begins (i.e. become active).
  The attribute value can be one of the following types of values:
  clock-value
    Specifies the presentation time at which the animation begins. The begin is thus defined relative to the document begin.
  syncbase-value : ( id-ref "." ) ( "begin" | "end" ) ( "+"clock-value )?
    Describes a syncbase and an offset from that syncbase. The element begin is defined relative to the begin `B` or active end `AE` of another animation.
  event-value : ( id-ref "." )? ( event-ref ) ( "+"clock-value )?
    Describes an event and an optional offset that determine the element begin. The animation begin is defined relative to the time that the event is raised. The list of event-symbols available for a given event-base element is the list of event attributes available for the given element as defined by the SVG DTD, with the one difference that the leading 'on' is removed from the event name (i.e., the animation event name is 'click', not 'onclick'). (See Event handling for a discussion of the various event attributes that can be used as Event-symbols.) Details of event-based timing are described in [SMILANIM-UNIFY].
  "indefinite"
    The begin of the animation will be determined by a "beginElement()" method call or a hyperlink targeted to the animation element.
    The SMIL Animation DOM methods are described in DOM interfaces.
    Hyperlink-based timing is described in [SMILANIM-LINKS].
  For more information, see [SMILANIM-ATTR-BEGIN].
dur
  Specifies the simple duration.
  The attribute value can be one of the following types of values:
  clock-value
    Specifies the length of the simple duration in presentation time.
  "indefinite"
    Specifies the simple duration `d` as indefinite.
  For more information, see [SMILANIM-ATTR-DUR].
end
  Defines the active end `AE` of the animation (i.e. the end of the active duration).
  The attribute value can be one of the following types of values:
  clock-value
    Specifies the presentation time of the active end. The active end is thus defined relative to the document begin.
  syncbase-value : ( id-ref ) ( ".begin" | ".end" )? ( "+"clock-value )?
    Describes a syncbase and an offset from that syncbase. The active end is defined relative to the begin `B` or active end `AE` of another animation.
  event-value : ( id-ref "." )? ( event-ref ) ( "+"clock-value )?
    Describes an event and an optional offset that determine the active end. The active end is defined relative to the time that the event is raised. The event must be raised after the animation begins, and before the active duration otherwise ends (e.g. as defined by `repeatDur`). The list of event-symbols available for a given event-base element is the list of event attributes available for the given element as defined by the SVG DTD. (See Event handling for a discussion of the various event attributes that can be used as Event-symbols.) Details of event-based timing are described in [SMILANIM-UNIFY].
  "indefinite"
    The active end of the animation will be determined by an "endElement()" method call. The SMIL Animation DOM methods are described in the specification of DOM Interface ElementTimeControl section.
  For more information, see [SMILANIM-ATTR-END].
restart
  always
    The animation can be restarted at any time.
    This is the default value.
  never
    The animation cannot be restarted for the remainder of the document duration.
  whenNotActive
    The animation can only be restarted when it is not active (i.e. after the active end). Attempts to restart the animation during its active duration are ignored.
  For more information, see [SMILANIM-ATTR-RESTART].
repeatCount
  Specifies the number of iterations of the animation function. It can have the following attribute values:
  numeric value
    This is a (base 10) "floating point" numeric value that specifies the number of iterations. It can include partial iterations expressed as fraction values. A fractional value describes a portion of the simple duration `d`. Values must be greater than 0. `
    `
  "indefinite"
    The animation is defined to repeat indefinitely (i.e. until the document ends).
  For more information, see [SMILANIM-ATTR-REPEATCOUNT].
repeatDur
  Specifies the total duration for repeat. It can have the following attribute values:
  clock-value
    Specifies the duration in presentation time to repeat the animation function `f(t)`.
  "indefinite"
    The animation is defined to repeat indefinitely (i.e. until the document ends).
  For more information, see [SMILANIM-ATTR-REPEATDUR].
fill
  This attribute can have the following values:
  freeze
    The animation effect F(t) is defined to freeze the effect value at the last value of the active duration. The animation effect is "frozen" for the remainder of the document duration (or until the animation is restarted - see [SMILANIM-RESTART]).
  remove
    The animation effect is removed (no longer applied) when the active duration of the animation is over. After the active end `AE` of the animation, the animation no longer affects the target (unless the animation is restarted - see [SMILANIM-RESTART]).
    This is the default value.
  For more information, see [SMILANIM-ATTR-FILL].

If both `repeatCount` or `repeatDur` are specified (and the simple duration is not indefinite), the active duration is defined as the minimum of the specified repeatDur, and the simple duration multiplied by repeatCount. For the purposes of this comparison, a defined value is considered to be "less than" a value of "indefinite". If the simple duration is indefinite, and both `repeatCount` or `repeatDur` are specified, the `repeatCount` will be ignored, and the `repeatDur` will be used (refer to the examples below describing `repeatDur` and an indefinite simple duration). These rules are included in [SMILANIM-D].

##### Timing Attribute Values

In the syntax specifications that follow, allowed white space is indicated as "S", defined as follows (taken from the [XML] definition for "S"):

    S ::= (#x20 | #x9 | #xD | #xA)+

###### Clock values

Clock values have the following syntax:

    Clock-val         ::= Full-clock-val | Partial-clock-val
                          | Timecount-val
    Full-clock-val    ::= Hours ":" Minutes ":" Seconds ("." Fraction)?
    Partial-clock-val ::= Minutes ":" Seconds ("." Fraction)?
    Timecount-val     ::= Timecount ("." Fraction)? (Metric)?
    Metric            ::= "h" | "min" | "s" | "ms"
    Hours             ::= DIGIT+; any positive number
    Minutes           ::= 2DIGIT; range from 00 to 59
    Seconds           ::= 2DIGIT; range from 00 to 59
    Fraction      ::= DIGIT+
    Timecount         ::= DIGIT+
    2DIGIT        ::= DIGIT DIGIT
    DIGIT         ::= [0-9]

For Timecount values, the default metric suffix is "s" (for seconds). No embedded white space is allowed in clock values, although leading and trailing white space characters will be ignored.

Clock values describe presentation time.

The following are examples of legal clock values:

- Full clock values: `
  02:30:03` = 2 hours, 30 minutes and 3 seconds
  `50:00:10.25` = 50 hours, 10 seconds and 250 milliseconds
- Partial clock value: `
  02:33` = 2 minutes and 33 seconds
  `00:10.5` = 10.5 seconds = 10 seconds and 500 milliseconds
- Timecount values:
  `3.2h` = 3.2 hours = 3 hours and 12 minutes
  `45min` = 45 minutes
  `30s` = 30 seconds
  `5ms` = 5 milliseconds
  `12.467` = 12 seconds and 467 milliseconds

Fractional values are just (base 10) floating point definitions of seconds. Thus:

`00.5s = 500 milliseconds
00:00.005 = 5 milliseconds`

###### Syncbase values

A syncbase value has the following syntax:

`Syncbase-value ::= ( Syncbase-element "." Time-symbol )
( S "+" S Clock-value )?
Syncbase-element ::= Id-value
Time-symbol ::= "begin" | "end"`

A syncbase value starts with a Syncbase-element term defining the value of an "id" attribute of an animation element referred to as the syncbase element. This element must be another animation element contained in the host document.

The syncbase element is qualified with one of the following time symbols:

begin
  Specifies the begin time of the syncbase element.
end
  Specifies the Active End `AE` of the syncbase element.

The time symbol can be followed by a clock value. The clock value specifies a presentation time offset from the time (i.e. the begin or end) specified by the syncbase and time symbol. If the clock value is omitted, it defaults to "0".

No embedded white space is allowed between a syncbase element and a time-symbol. White space will be ignored before and after a "+" for a clock value. Leading and trailing white space characters (i.e. before and after the entire syncbase value) will be ignored.

Examples:

`begin="x.end+45s"` : Begin 45 seconds after "x" ends
`begin=" x.begin "` : Begin when "x" begins
`end="x.begin + 1m"` : End 1 minute after "x" begins

###### Event values

An event value has the following syntax:

`Event-value ::= ( Eventbase-element "." )? Event-symbol
( S "+" S Clock-value )?
Eventbase-element ::= Id-value`

An Event value starts with an Eventbase-element term that specifies the event-base element. The event-base element is the element on which the event is observed. Given DOM event bubbling, the event-base element may be either the element that raised the event, or it may be an ancestor element on which the bubbled event can be observed. Refer to DOM-Level2-Events [DOM2-EVENTS] for details.
The "Id-value" is the value of an attribute declared to be an "id" in the host language, for the event-base element. This element must be another animation element contained in the host document.
If the Eventbase-element term is missing, the event-base element defaults to the target element of the animation.

If the id value term is missing, the event-base element is defined to be the target element of the animation.

The event value must specify an Event-symbol. This term specifies the name of the event that is raised on the Event-base element. . The list of event-symbols available for a given event-base element is the list of event attributes available for the given element as defined by the SVG DTD. (See Event handling for a discussion of the various event attributes that can be used as Event-symbols.)

The last term specifies an optional clock-value that is a presentation time offset from the event. If this term is omitted, the offset is 0.

No embedded white space is allowed between an eventbase element and an event-symbol. White space will be ignored before and after a "+" for a clock value. Leading and trailing white space (i.e. before and after the entire eventbase value) is not allowed.

Note that it is not considered an error to specify an event that cannot be raised on the Event-base element (such as click for audio or other non-visual elements). Similarly, if the host language allows dynamically created events (as supported by DOM-Level2-Events [DOM2-EVENTS]), and it is not possible to specify all Event-symbol names, unrecognized names may not be considered errors. Host language specifications must include a description of legal event names, and/or allow any name to be used.

Examples:

`begin=" x.onload "` : Begin when "onload" is observed on "x"
`begin="x.onfocus+3s"` : Begin 3 seconds after an "onfocus" event on "x"

The defaults for the event and target element syntax make it easy to define simple interactive behavior. The following example sets the `rect` element color to be red for 5 seconds, when the user clicks on the element.

`<rect ...>
<set begin="onclick" dur="5s" to="red"
attributeName="fill" attributeType="CSS" />
...
</rect>`

### 19.2.5 Attributes that define animation values over time

The following attributes are common to elements 'animate', 'animateMotion', 'animateColor' and 'animateTransform'. These attributes define the values that are assigned to the target attribute or property over time. The attributes below provide control over the relative timing of keyframes and the interpolation method between discrete values.

    <!ENTITY % animValueAttrs
     "calcMode (discrete | linear | evenPace | spline) 'linear'
      values CDATA #IMPLIED
      from CDATA #IMPLIED
      to CDATA #IMPLIED
      by CDATA #IMPLIED
      keyTimes CDATA #IMPLIED
      keySplines CDATA #IMPLIED" >

Attribute definitions:

The animation is described either as a list of values, or in a simplified form that describes the from, to and by values.

from = "<value>"
  Specifies the starting value of the animation.
to = "<value>"
  Specifies the ending value of the animation.
by = "<value>"
  Specifies a relative offset value for the animation.
values = "<list>"
  A semicolon-separated list of one or more values. Vector-valued attributes are supported using the vector syntax of the `attributeType` domain.

The animation values specified in the animation element must be legal values for the specified attribute. Leading and trailing white space, and white space before and after semi-colon separators, will be ignored.

All values specified must be legal values for the specified attribute (as defined in the associated namespace). If any values are not legal, the animation will have no effect.

If a list of values is used, the animation will apply the values in order over the course of the animation. If a list of values is specified, any from, to and by attribute values are ignored.

The simpler syntax provides for several variants. Note that `from` is optional, but that one of `by` or `to` must be used (unless of course a list of `values` is provided). It is not legal to specify both `by` and `to` attributes - if both are specified, only the `to` attribute will be used (the `by` will be ignored). The combinations of attributes yield the following classes of animation:

from-to animation
  Specifying a `from` value and a `to` value defines a simple animation, equivalent to a `values` list with 2 values. The animation function is defined to start with the `from` value, and to finish with the `to` value.
from-by animation
  Specifying a `from` value and a `by` value defines a simple animation in which the animation function is defined to start with the `from` value, and to change this over the course of the simple duration `d` by a delta specified with the `by` attribute. This can only be used with attributes that support addition (e.g. most numeric attributes).
by animation
  Specifying only a by value defines a simple animation in which the animation function is defined to offset the underlying value for the attribute, using a delta that varies over the course of the simple duration `d`, starting from a delta of 0 and ending with the delta specified with the `by` attribute. This can only be used with attributes that support addition.
to animation
  This describes an animation in which the animation function is defined to start with the underlying value for the attribute, and finish with the value specified with the `to` attribute. Using this form, an author can describe an animation that will start with whatever value the attribute has originally, and will end up at the desired `to` value.

For more information on these attributes, see [SMILANIM-ATTR-VALUES].

The last two forms "by animation" and "to animation" have additional semantic constraints when combined with other animations. The details of this are described in [SMILANIM-FROMTOBY-ADD].

Examples

The following example using the `values` syntax animates the width of a 'rect' over the course of 10 seconds from a width of 40 to a width of 100 and back to 40.

    <rect ...>
       <animate attributeName="width" values="40;100;40" dur="10s"/>
    </rect>

The following "from-to animation" example animates the width of a 'rect' over the course of 10 seconds from a width of 50 to a width of 100.

    <rect ...>
       <animate attributeName="width" from="50" to="100" dur="10s"/>
    </rect>

The following "from-by animation" example animates the width of a 'rect' over the course of 10 seconds from a width of 50 to a width of 75.

    <rect ...>
       <animate attributeName="width" from="50" by="25" dur="10s"/>
    </rect>

The following "by animation" example animates the width of a 'rect' over the course of 10 seconds from the original width of 40 to a width of 70.

    <rect width="40"...>
       <animate attributeName="width" by="30" dur="10s"/>
    </rect>

The following "to animation" example animates the width of a 'rect' over the course of 10 seconds from the original width of 40 to a width of 100.

    <rect width="40"...>
       <animate attributeName="width" to="100" dur="10s"/>
    </rect>

By default, a simple linear interpolation is performed over the values, evenly spaced over the duration of the animation. Additional attributes can be used for finer control over the interpolation and timing of the values. The `calcMode` attribute defines the basic method of applying values to the attribute. The `keyTimes` attribute provides additional control over the timing of the animation function, associating a time with each value in the `values` list. Finally, the `keySplines` attribute provides a means of controlling the pacing of interpolation between the values in the `values` list.

`calcMode` = "discrete | linear | paced | spline"
  Specifies the interpolation mode for the animation. This can take any of the following values. The default mode is "linear", however if the attribute does not support linear interpolation (e.g. for strings), this attribute is ignored and discrete interpolation is always used.
  `"discrete"`
    This specifies that the animation function will jump from one value to the next without any interpolation.
  `"linear"`
    Simple linear interpolation between values is used to calculate the animation function. This is the default `calcMode`.
  `"paced"`
    Defines interpolation to produce an even pace of change across the animation. This is only supported for values that define a linear numeric range, and for which some notion of "distance" between points can be calculated (e.g. position, width, height, etc.). If "`paced`" is specified, any `keyTimes` or `keySplines` will be ignored.
  `"spline"`
    Interpolates from one value in the `values` list to the next according to a time function defined by a cubic Bezier spline. The points of the spline are defined in the `keyTimes` attribute, and the control points for each interval are defined in the `keySplines` attribute.
`keyTimes` = "<list>"
  A semicolon-separated list of time values used to control the pacing of the animation. Each time in the list corresponds to a value in the `values` attribute list, and defines when the value is used in the animation function. Each time value in the `keyTimes` list is specified as a floating point value between 0 and 1 (inclusive), representing a proportional offset into the simple duration of the animation element.
  Each successive time value must be greater than or equal to the preceding time value.
  The first time value in the list must be 0, and the last time value in the list must be 1.
  If a list of `keyTimes` is specified, there must be exactly as many values in the `keyTimes` list as in the `values` list.
  If there are any errors in the `keyTimes` specification (bad values, too many or too few values), the animation will have no effect.
  If the simple duration is indefinite, any `keyTimes` specification will be ignored.
`keySplines` = "<list>"
  A set of Bezier control points associated with the `keyTimes` list, defining a cubic Bezier function that controls interval pacing. The attribute value is a semi-colon separated list of control point descriptions. Each control point description is a set of four values: `x1 y1 x2 y2`, describing the Bezier control points for one time segment. The `keyTimes` values that define the associated segment are the Bezier "anchor points", and the `keySplines` values are the control points.
  Thus, there must be one fewer sets of control points than there are `keyTimes`.
  The values must all be in the range 0 to 1.
  This attribute is ignored unless the `calcMode` is set to "spline".
  If there are any errors in the `keySplines` specification (bad values, too many or too few values), the animation will have no effect.

If the `keyTimes` attribute is not specified, the values in the `values` attribute are assumed to be equally spaced through the animation duration, according to the calcMode:

- For discrete animation, the duration is divided into equal time periods, one per value. The animation function takes on the values in order, one value for each time period.
- For linear and spline animation, the duration is divided into `n-1` even periods, and the animation function is a linear interpolation between the values at the associated times. Note that a linear animation will be a nicely closed loop if the first value is repeated as the last.

Note that for the shorthand forms to animation and from-to animation, there are only 1 and 2 values respectively. Thus a discrete to animation will simply set the "to" value for the simple duration. A discrete from-to animation will set the "from" value for the first half of the simple duration and the "to" value for the second half of the simple duration.

Note that if the `calcMode` is set to "paced", the `keyTimes` attribute is ignored, and the values in the `values` attribute are spaced to produce a constant rate of change as the target attribute value is interpolated.

If the argument values for `keyTimes` or `interSpline` are not legal (including too few or too many values for either attribute), the animation will have no effect.

In the `calcMode`, `keyTimes` and `keySplines` attribute values, leading and trailing white space and white space before and after semi-colon separators will be ignored.

##### Examples

This example describes a somewhat unusual usage: "from-to animation" with discrete animation. The 'text' element supports the font-style property, which takes a string, and so implies a `calcMode` of discrete. The animation will set the font-style to "normal" for 5 seconds (half the simple duration) and then set the font-style to "italic" for 5 seconds.

    <text style="font-style:normal"...>
      <animate attributeName="font-style"
          from="normal" to="italic" dur="10s"/>
    </text>

This example illustrates the use of `keyTimes`:

    <animate attributeName="x" dur="10s" values="0; 50; 100"
         keyTimes="0; .8; 1" calcMode="linear"/>

The `keyTimes` values causes the "x" attribute to have a value of "0" at the start of the animation, "50" after 8 seconds (at 80% into the simple duration) and "100" at the end of the animation. The value will change more slowly in the first half of the animation, and more quickly in the second half.

Extending this example to use `keySplines`:

    <animate attributeName="x" dur="10s" values="0; 50; 100"
         keyTimes="0; .8; 1" calcMode="spline"
         keySplines=".5 0 .5 1; 0 0 1 1" />

The `keyTimes` still causes the "x" attribute to have a value of "0" at the start of the animation, "50" after 8 seconds and "100" at the end of the animation. However, the `keySplines` values define a curve for pacing the interpolation between values. In the example above, the spline causes an ease-in and ease-out effect between time 0 and 8 seconds (i.e. between `keyTimes` 0 and .8, and `values` "0" and "50"), but a strict linear interpolation between 8 seconds and the end (i.e. between `keyTimes` .8 and 1, and `values` "50" and "100"). See the figure below for an illustration of the curves that these `keySplines` values define.

For some attributes, the pace of change might not be easily discernable by viewers. However for animations like motion, the ability to make the speed of the motion change gradually, and not in abrupt steps can be important. The `keySplines` attribute provides this control.

The following figure illustrates the interpretation of the `keySplines` attribute. Each diagram illustrates the effect of `keySplines` settings for a single interval (i.e. between the associated pairs of values in the `keyTimes` and `values` lists.). The horizontal axis can be thought of as the input value for the unit progress of interpolation within the interval - i.e. the pace with which interpolation proceeds along the given interval. The vertical axis is the resulting value for the unit progress, yielded by the `keySplines` function.

Examples of keySplines
| keySplines="0 0 1 1" (the default) |  | keySplines=".5 0 .5 1"
| keySplines="0 .75 .25 1" |  | keySplines="1 0 .25 .25"

To illustrate the calculations, consider the simple example:

    <animate dur="4s" values="10; 20" keyTimes="0; 1"
         calcMode="spline" keySplines={as in table} />

Using the keySplines values for each of the four cases above, the approximate interpolated values as the animation proceeds are:

keySplines values | Initial value | After 1s | After 2s | After 3s | Final value
0 0 1 1 | 10.0 | 12.5 | 15.0 | 17.5 | 20.0
.5 0 .5 1 | 10.0 | 11.0 | 15.0 | 19.0 | 20.0
0 .75 .25 1 | 10.0 | 18.0 | 19.3 | 19.8 | 20.0
1 0 .25 .25 | 10.0 | 10.1 | 10.6 | 16.9 | 20.0

For a formal definition of Bezier spline calculation, see [FOLEY-VANDAM].

### 19.2.6 Combining animations

At a particular moment in time, an attribute can be animated by several animations, i.e. animations can overlap in time. The effect of this depends on whether the animations combined are additive or non-additive. An additive animation function will take the initial value of the attribute as defined by the animations that are already running, and use it as its begin value. A non-additive animation will replace the initial value with a new begin value

When there are multiple animations defined for a given attribute with complete durations that overlap at any moment, the two either add together or one overrides the other. The active animations are prioritized according to their begin. The animation first activated (i.e. begun by scheduled timing or by an event) has lowest priority and the most recently begun animation has highest priority. Higher priority animations that are not additive will override all earlier animations, and simply set the attribute value. Animations that are additive apply (i.e. add to) to the result of the earlier-activated animations. When two animations have the same begin, the first in lexical order has lower priority.

For more information, see [SMILANIM-ADD] and [SMILANIM-ACCUM].

### 19.2.7 Attributes that control whether animations are additive

The following attributes are common to elements 'animate', 'animateMotion', 'animateColor' and 'animateTransform'.

It is frequently useful to define animation as an offset or delta to an attribute's value, rather than as absolute values. A simple "grow" animation can increase the width of an object by 10 pixels:

    <rect width="20px" ...>
      <animate attributeName="width" from="0px" to="10px" dur="10s"
               additive="sum"/>
    </rect>

The width begins at 20 pixels, and increases to 30 pixels over the course of 10 seconds. If the animation were declared to be not additive, the same from and to values would make the width go from 0 to 10 pixels over 10 seconds.

When there are multiple animations defined for a given attribute that are active at a given moment, the two either add together or one overrules the other. The active animations are prioritized according to the activation time of each. The animation first activated (i.e. begun by scheduled timing or by an event) has lowest priority and the most recently begun animation has highest priority. Higher priority animations that are not additive will overrule all earlier animations, and set the attribute value. Animations that are additive apply (i.e. add to) to the result of the earlier-activated animations. When two animations start at the same point in time, the first in lexical order is applied first.

It is frequently useful for repeated animations to build upon the previous results, accumulating with each interation. The following example causes the rectangle to continue to grow with each repeat of the animation:

    <rect width="20px" ...>
      <animate attributeName="width" from="0px" to="10px" dur="10s"
               additive="sum" accumulate="sum" repeatCount="5"/>
    </rect>

At the end of the first repetition, the rectangle has a width of 30 pixels. At the end of the second repetition, the rectangle has a width of 40 pixels. At the end of the fifth repetition, the rectangle has a width of 80 pixels.

    <!ENTITY % animAdditionAttrs
     "additive       (replace | sum) 'replace'
      accumulate     (none | sum) 'none'" >

Attribute definitions:

additive = "replace | sum"
  Controls whether or not the animation is additive.
  If `"sum"`, the animation will add to the underlying value of the attribute and other lower priority animations.
  If `"replace"`, the animation will override the underlying value of the attribute and other lower priority animations. This is the default, however the behavior is also affected by the animation value attributes `by` and `to`, as described in [SMILANIM-FROMTOBY-ADD].
accumulate = "none | sum"
  Controls whether or not the animation is cumulative.
  If `"sum"`, each repeat iteration after the first builds upon the last value of the previous iteration.
  If `"none"`, repeat iterations are not cumulative. This is the default.
  This attribute is ignored if the target attribute value does not support addition, or if the animation element does not repeat.
  Cumulative animation is not defined for "to animation". This attribute will be ignored if the animation function is specified with only the `to` attribute.

### 19.2.8 Inheritance

SVG allows both attributes and properties to be animated. If a given attribute or property is inheritable by descendants, then animations on a parent element such as a 'g' element has the effect of propagating the attribute or property animation values to descendant elements as the animation proceeds; thus, descendant elements can inherit animated attributes and properties from their ancestors.

### 19.2.9 The 'animate' element

The 'animate' element is used to animate a single attribute or property over time. For example, to make a rectangle repeatedly fade away over 5 seconds, you can specify:

    <rect>
      <animate attributeType="text/css" attributeName="opacity"
             from="1" to="0" dur="5s" repeatCount="indefinite" />
    </rect>

    <!ENTITY % animateExt "" >
    <!ELEMENT animate (%descTitle;%animateExt;) >
    <!ATTLIST animate
      %stdAttrs;
      %testAttrs;
      externalResourcesRequired %Boolean; #IMPLIED
      %animTargetAttrs;
      %animTimingAttrs;
      %animValueAttrs;
      %animAdditionAttrs; >

Attributes defined elsewhere:
  %stdAttrs;, %testAttrs;, %animTargetAttrs;, %animTimingAttrs;, %animValueAttrs;, %animAdditionAttrs;.

For a list of attributes and properties that can be animated using the 'animate' element, see Elements, attributes and properties that can be animated.

### 19.2.10 The 'set' element

The 'set' element provides a simple means of just setting the value of an attribute for a specified duration. It supports all attribute types, including those that cannot reasonably be interpolated, such as string and boolean values. The 'set' element is non-additive. The effect of repeatCount and repeatDur attributes are just to extend the defined duration. In addition, using fill="freeze" will have the same effect as an indefinite duration.

    <!ENTITY % setExt "" >
    <!ELEMENT set (%descTitle;%setExt;) >
    <!ATTLIST set
      %stdAttrs;
      %testAttrs;
      externalResourcesRequired %Boolean; #IMPLIED
      %animTargetAttrs;
      %animTimingAttrs;
      to CDATA #IMPLIED >

Attribute definitions:

to = "<value>"
  Specifies the value for the attribute during the duration of the 'set' element. The <value> must be appropriate to the target attribute or property.

Attributes defined elsewhere:
  %stdAttrs;, %testAttrs;, %animTargetAttrs;, %animTimingAttrs;.

For a list of attributes and properties that can be animated using the 'set' element, see Elements, attributes and properties that can be animated.

### 19.2.11 The 'animateMotion' element

The 'animateMotion' element causes a referenced element to move along a motion path.

    <!ENTITY % animateMotionExt "" >
    <!ELEMENT animateMotion (%descTitle;%animateMotionExt;) >
    <!ATTLIST animateMotion
      %stdAttrs;
      %testAttrs;
      externalResourcesRequired %Boolean; #IMPLIED
      %xlinkRefAttrs;
      xlink:href %URI; #IMPLIED
      %animTimingAttrs;
      %animValueAttrs;
      %animAdditionAttrs;
      path CDATA #IMPLIED
      rotate CDATA #IMPLIED
      origin CDATA #IMPLIED >

For 'animateMotion', the specified values for from, by, to and values consists of x, y coordinate pairs, with a comma separating the x coordinate from the y coordinate. For example, from="33,15" specifies an x coordinate value of 33 and a y coordinate value of 15.

If provided, the values attribute must consists of a list of x, y coordinate pairs, where commas separate the x coordinate from the y coordinate and semicolons separate the various coordinate pairs, such as values="10,20;30,20;30,40" or values="10mm,20mm;30mm,20mm;30mm,40mm". Each coordinate represents a length. Attributes from, by, to and values specify a shape on the current canvas which represents the motion path.

For more flexibility in controlling the motion path, the path attribute provides the ability to specify a motion path using any of SVG's path data commands. If a path is specified, it will override the motion path provided by the values or from/to/by attributes. (Note that a path can only contain values in user space, whereas from, by, to and values can specify coordinates in user space or using CSS unit identifiers. For more information on CSS units, see Processing rules for CSS units and percentages.)

The various (x,y) points of the shape provide a supplemental transformation matrix onto the CTM for the referenced object which causes a translation along the X and Y axis of the current user coordinate system by the (x,y) values of the shape computed over time. Thus, the referenced object is translated over time by the offset of the motion path relative to the origin of the current user coordinate system.

The default calculation mode (calcMode) for animateMotion is "paced". This will produce constant velocity motion along the specified path. Note that while animateMotion elements can be additive, it is important to observe that the addition of two or more "paced" (constant velocity) animations might not result in a combined motion animation with constant velocity.

When a path is combined with "linear" or "spline" calcMode settings, and if attribute keyPoints is not provided, the number of values is defined to be the number of points defined by the path, unless there are "move to" commands within the path. A "move to" command within the path (i.e. other than at the beginning of the path description) does not count as an additional point for the purpose of keyTimes and keySplines, and does not define an additional "segment" for the purposes of timing or interpolation. When a path is combined with a "paced" calcMode setting, all "move to" commands are considered to have 0 length (i.e. they always happen instantaneously), and is not considered in computing the pacing.

For more flexibility in controlling the velocity along the motion path, the keyPoints attribute provides the ability to specify the progress along the motion path for each of the keyTimes specified values. If specified, keyPoints causes keyTimes to apply to the values in keyPoints rather than the points specified in the values attribute array or the points on the path attribute.

The override rules for 'animateMotion are as follows. Regarding the definition of the motion path, the path attribute overrides values, which overrides from/by/to. Regarding determining the points which correspond to the keyTimes attributes, the keyPoints attribute overrides path, which overrides values, which overrides from/by/to.

Attribute definitions:

path = "<path-data>"
  The motion path, expressed in the same format and interpreted the same way as the d= attribute on the 'path' element. The effect of a motion path animation is to add a supplemental transformation matrix onto the CTM for the referenced object which causes a translation along the X and Y axis of the current user coordinate system by the computed X and Y values computed over time.
keyPoints = "<list-of-numbers>"
  keyPoints takes a semicolon-separated list of floating point values between 0 and 1 and indicates how far along the motion path the object shall move at the moment in time specified by corresponding keyTimes value. Distance calculations use the user agent's distance along the path algorithm. Each progress value in the list corresponds to a value in the `keyTimes` attribute list.
  If a list of `keyPoints` is specified, there must be exactly as many values in the `keyPoints` list as in the `keyTimes` list.
  If there are any errors in the `keyPoints` specification (bad values, too many or too few values), the animation will have no effect.
rotate = "<angle> | auto | auto-reverse"
  auto indicates that the object is rotated over time by the angle of the direction (i.e., directional tangent vector) of the motion path. auto-reverse indicates that the object is rotated over time by the angle of the direction (i.e., directional tangent vector) of the motion path plus 180 degrees. An actual angle value can also be given, which represents an angle relative to X-axis of current user coordinate system. The rotate attribute adds a supplemental transformation matrix onto the CTM to apply a rotation transformation about the origin of the current user coordinate system. The rotation transformation is applied after the supplemental translation transformation that is computed due to the path attribute. The default value is 0.
origin = "default"
  The origin attribute is defined in the SMIL Animation specification [SMILANIM-ATTR-ORIGIN]. It has no effect in SVG.

Attributes defined elsewhere:
  %stdAttrs;, %testAttrs;, %animTargetAttrs;, %animTimingAttrs;, %animValueAttrs;, %animAdditionAttrs;.

At any time t within a motion path animation of effective duration dur, the computed coordinate (x,y) along the motion path is determined by finding the point (x,y) which is t/dur distance along the motion path using the user agent's distance along the path algorithm.

The following example demonstrates the supplemental transformation matrices that are computed during a motion path animation.

Example animMotion01 shows a triangle moving along a motion path.

    <?xml version="1.0" standalone="no"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20000303 Stylable//EN"
      "http://www.w3.org/TR/2000/03/WD-SVG-20000303/DTD/svg-20000303-stylable.dtd">
    <svg width="5cm" height="3cm"  viewBox="0 0 500 300">
      <desc>Example animMotion01 - demonstrate motion animation computations</desc>

      <!-- Draw the outline of the motion path in blue, along
              with three small circles at the start, middle and end. -->
      <path d="M100,250 C 100,50 400,50 400,250"
            style="fill:none; stroke:blue; stroke-width:7.06" />
      <circle cx="100" cy="250" r="17.64" style="fill:blue" />
      <circle cx="250" cy="100" r="17.64" style="fill:blue" />
      <circle cx="400" cy="250" r="17.64" style="fill:blue" />

      <!-- Here is a triangle which will be moved about the motion path.
           It is defined with an upright orientation with the base of
           the triangle centered horizontally just above the origin. -->
      <path d="M-25,12.5 L25,12.5 L 0,87.5 z"
            style="fill:yellow; stroke:red; stroke-width:7.06" >

        <!-- Define the motion path animation -->
        <animateMotion dur="6s" repeatCount="indefinite"
                       path="M100,250 C 100,50 400,50 400,250" rotate="auto" />
      </path>
    </svg>

Example animMotion01
At zero seconds |  | At three seconds |  | At six seconds

View this example as SVG (SVG-enabled browsers only)

The following table shows the supplemental transformation matrices that are applied to achieve the effect of the motion path animation.

| After 0s | After 3s | After 6s
Supplemental transform due to movement along motion path | translate(100,250) | translate(250,100) | translate(400,250)
Supplemental transform due to rotate="auto" | rotate(-90) | rotate(0) | rotate(90)

For a list of elements that can be animated using the 'animateMotion' element, see Elements, attributes and properties that can be animated.

### 19.2.12 The 'animateColor' element

The 'animateColor' element specifies a color transformation over time.

    <!ENTITY % animateColorExt "" >
    <!ELEMENT animateColor (%descTitle;%animateColorExt;) >
    <!ATTLIST animateColor
      %stdAttrs;
      %testAttrs;
      externalResourcesRequired %Boolean; #IMPLIED
      %animTargetAttrs;
      %animTimingAttrs;
      %animValueAttrs;
      %animAdditionAttrs; >

Attributes defined elsewhere:
  %stdAttrs;, %testAttrs;, %animTargetAttrs;, %animTimingAttrs;, %animValueAttrs;, %animAdditionAttrs;.

The from, by and to attributes take color values, where each color value is expressed using the same syntax that is available for the target attribute or property.

The values attribute for the 'animateColor' element consists of a semicolon-separated list of color values, where each individual color value is expressed using the same syntax that is available for the target attribute or property.

Out of range color values can be provided, but user agent processing will be implementation dependent. User agents should clamp color values to allow color range values as late as possible, but note that system differences might preclude consistent behavior across different systems.

The 'color-interpolation' property applies to color interpolations that result from 'animateColor' animations.

For a list of attributes and properties that can be animated using the 'animateColor' element, see Elements, attributes and properties that can be animated.

### 19.2.13 The 'animateTransform' element

The 'animateTransform' element animates a transformation attribute on a target element, thereby allowing animations to control translation, scaling, rotation and/or skewing.

    <!ENTITY % animateTransformExt "" >
    <!ELEMENT animateTransform (%descTitle;%animateTransformExt;) >
    <!ATTLIST animateTransform
      %stdAttrs;
      %testAttrs;
      externalResourcesRequired %Boolean; #IMPLIED
      %animTargetAttrs;
      %animTimingAttrs;
      %animValueAttrs;
      %animAdditionAttrs;
      type (translate | scale | rotate | skewX | skewY) "translate" >

Attribute definitions:

type = "translate | scale | rotate | skewX | skewY"
  Indicates the type of transformation which is to have its values change over time.

Attributes defined elsewhere:
  %stdAttrs;, %testAttrs;, %animTargetAttrs;, %animTimingAttrs;, %animValueAttrs;, %animAdditionAttrs;.

The from, by and to attributes take a value expressed using the same syntax that is available for the given transformation type:

- For a type="translate", each individual value is expressed as <tx> [,<ty>].
- For a type="scale", each individual value is expressed as <sx> [,<sy>].
- For a type="rotate", each individual value is expressed as <rotate-angle>.
- For a type="skewX" and type="skewY", each individual value is expressed as <skew-angle>.

(See The transform attribute.)

The values attribute for the 'animateTransform' element consists of a semicolon-separated list of values, where each individual value is expressed as described above for from, by and to.

If calcMode has the value paced, then a total "distance" for each component of the transformation is calculated (e.g., for a translate operation, a total distance is calculated for both tx and ty) consisting of the sum of the absolute values of the differences between each pair of values, and the animation runs to produce a constant distance movement for each individual component.

When an animation is active, the effect of non-additive 'animateTransform' (i.e., additive="replace") is to replace the given attribute's value with the transformation defined by the 'animateTransform'. The effect of additive (i.e., additive="sum") is to post-multiply the transformation matrix corresponding to the transformation defined by this 'animateTransform'. To illustrate:

    <circle ...>
      <animateTransform type="rotate" from="0" to="90" dur="5s"/>
      <animateTransform type="scale" from="1" to="2" dur="5s"/>
    </circle>

In the code snippet above, at time 5 seconds, the visual result of above animation would be equivalent to the following static circle:

    <circle transform="rotate(90); scale(2)" ... />

For a list of attributes and properties that can be animated using the 'animateTransform' element, see Elements, attributes and properties that can be animated.

### 19.2.14 Elements, attributes and properties that can be animated

The following lists all of the elements which can be animated by an 'animateMotion' element:

- 'svg' ('animateMotion' has no effect on outermost 'svg' elements)
- 'g'
- 'path'
- 'rect'
- 'circle'
- 'ellipse'
- 'line'
- 'polyline'
- 'polygon'
- 'text'
- 'use'
- 'image'
- 'clipPath'
- 'mask'
- 'switch'

Each attribute or property within this specification indicates whether or not it can be animated by SVG's animation elements. Animatable attributes and properties are designated as follows:
Animatable: yes.
whereas attributes and properties that cannot be animated are designated:
Animatable: no.

SVG has a defined set of basic data types for its various supported attributes and properties. For those attributes and properties that can be animated, the following table indicates which animation elements can be used to animate each of the basic data types.

Basic data type | Additive? | 'animate' | 'set' | 'animate Color' | 'animate Transform' | Notes
--- | --- | --- | --- | --- | --- | ---
<angle> | yes | yes | yes | no | no |
<color> | yes | yes | yes | yes | no | Only RGB color values are additive.
<coordinate> | yes | yes | yes | no | no |
<frequency> | no | no | no | no | no |
<integer> | yes | yes | yes | no | no |
<length> | yes | yes | yes | no | no |
<list of xxx> | no | yes | yes | no | no |
<number> | yes | yes | yes | no | no |
<paint> | yes | yes | yes | yes | no | Only RGB color values are additive.
<percentage> | yes | yes | yes | no | no |
<time> | no | no | no | no | no |
<transform-list> | yes | no | no | no | yes |
<uri> | yes | yes | yes | no | no |
All other animatable attributes and properties | no | yes | yes | no | no |

Any deviation from the above table or other special note about the animation capabilities of a particular attribute or property is included in section of the specification where the given attribute or property is defined.

## 19.3 Animation using the SVG DOM

The following example shows a simple animation:

    <?xml version="1.0" standalone="no"?>
    <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20000303 Stylable//EN"
      "http://www.w3.org/TR/2000/03/WD-SVG-20000303/DTD/svg-20000303-stylable.dtd">
    <svg width="4in" height="3in"
         viewBox="0 0 400 300"
         onload="StartAnimation()" >

      <defs>
        <script type="text/ecmascript"><![CDATA[
          var timer_increment = 50.
          var max_time = 10000
          var text_element
          StartAnimation() {
            text_element = document.getElementById("TextElement");
            ShowAndGrowElement(0);
          }
          ShowAndGrowElement(timevalue) {
            timevalue = timevalue + timer_increment
            if (timevalue > max_time)
              timevalue = timevalue - floor(timevalue/max_time) * max_time

            // Scale the text string gradually until it is 20 times larger
            scalefactor = (timevalue * 20.) / max_time
            text_element.SetAttribute("transform", "scale(" + scalefactor + ")")

            // Make the string more opaque
            opacityfactor = timevalue / max_time
            text_element.getStyle().setProperty("opacity", "opacity:" + opacityfactor, "")

            // Call ShowAndGrowElement again <timer_increment> milliseconds later.
            setTimeout("ShowAndGrowElement(" + timer_increment + ")")
          }
        ]]></script>
      </defs>

      <g transform="translate(50,300)" style="fill:red; font-size:10">
        <text id="TextElement">SVG</text>
      </g>
    </svg>

Download this example

The above SVG file contains a single graphics element, a text string that says "SVG". The animation loops continuously. The text string starts out small and transparent and grows to be large and opaque. Here is an explanation of how this example works:

- The 'svg' element's `width` and `height` attributes indicate that the viewport is a rectangle of size 4inches by 3inches. The `viewBox` attribute indicates that the initial coordinate system has (0,0) at its top left and (400,300) at its bottom right. (Thus, 1 inch equals 100 user units.) The `onload="StartAnimation()"` attribute indicates that when the document has been fully loaded and processed, then invoke ECMAScript function StartAnimation().
- The 'script' element defines the ECMAScript which makes the animation happen. The `StartAnimation()` function is only called once to give a value to global variable `text_element` and to make the initial call to `ShowAndGrowElement()`. `ShowAndGrowElement()` is called every 50 milliseconds and resets the `transform` and `style` attributes on the text element to new values each time it is called. At the end of `ShowAndGrowElement`, the function tells the ECMAScript engine to call itself again after 50 more milliseconds.
- The 'g' element shifts the coordinate system so that the origin is shifted toward the lower-left of the viewing area. It also defines the fill color and font-size to use when drawing the text string.
- The 'text' element contains the text string and is the element whose attributes get changed during the animation.

If scripts are modifying the same attributes or properties that are being animated by SVG's animation elements, the scripts modify the base value for the animation. If a base value is modified while an animation element is animating the corresponding attribute or property, the animations are required to adjust dynamically to the new base value.

If a script is modifying a property on the override style sheet at the same time that an animation element is animating that property, the result is implementation-dependent; thus, it is recommended that this be avoided.

## 19.4 DOM interfaces

The following interfaces are defined below: ElementTimeControl, SVGAnimationElement, SVGAnimateElement, SVGSetElement, SVGAnimateMotionElement, SVGAnimateTransformElement, TimeEvent.

### Interface ElementTimeControl

The ElementTimeControl interface, defined in the SMIL Animation specification [SMILANIM-DOM-METHODS], defines common methods for elements which define animation behaviors compatible with SMIL Animation.

Calling `beginElement()` causes the animation to begin in the same way that an animation with event-based begin timing begins. The effective begin time is the current presentation time at the time of the DOM method call. Note that `beginElement()` is subject to the `restart` attribute in the same manner that event-based begin timing is. If an animation is specified to disallow restarting at a given point, `beginElement()` methods calls must fail.

Calling `beginElementAt(seconds)` has the same behavior as `beginElement()`, except that the animation starts midway into the animation (i.e., a given number of `seconds` offset from the normal start of the animation.) If the offset value goes beyond the simple duration or the simple duration is undefined, (e.g., the end time is indefinite), then the animation does not start.

Calling `endElement()` causes an animation to end the active duration. Depending upon the value of the `fill` attribute, the animation effect may no longer be applied, or it may be frozen at the current effect. If an animation is not currently active (i.e. if it has not yet begun or if it is frozen), the `endElement()` method will fail.

IDL Definition

      interface ElementTimeControl {
        boolean beginElement (  )
                        raises( DOMException );
        boolean beginElementAt ( in float offset )
                        raises( DOMException );
        boolean endElement (  )
                        raises( DOMException );
        boolean endElementAt ( in float offset )
                        raises( DOMException );
      };

Methods
  beginElement

    Causes this element to begin the local timeline (subject to sync constraints).

    No Parameters
    Return value

      boolean |  | `true` if the method call was successful and the element was begun. `false` if the method call failed. Possible reasons for failure include: The element is already active and can't be restart when it is active. (the `restart` attribute is set to `"whenNotActive"`) The element is active or has been active and can't be restart. (the `restart` attribute is set to `"never"`).

    Exceptions

      DOMException |  | SYNTAX_ERR: The element was not defined with the appropriate syntax to allow `beginElement` calls.

  beginElementAt

    Causes this element to begin the local timeline (subject to sync constraints), at the passed offset from the current time when the method is called. If the offset is >= 0, the semantics are equivalent to an event-base begin with the specified offset. If the offset is < 0, the semantics are equivalent to beginElement(), but the element active duration is evaluated as though the element had begun at the passed (negative) offset from the current time when the method is called.

    Parameters

      in float offset |  | The offset in seconds at which to begin the element.

    Return value

      boolean |  | `true` if the method call was successful and the element was begun. `false` if the method call failed. Possible reasons for failure include: The element is already active and can't be restart when it is active. (the `restart` attribute is set to `"whenNotActive"`) The element is active or has been active and can't be restart. (the `restart` attribute is set to `"never"`).

    Exceptions

      DOMException |  | SYNTAX_ERR: The element was not defined with the appropriate syntax to allow `beginElementAt` calls.

  endElement
    Causes this element to end the local timeline (subject to sync constraints).
    No Parameters
    Return value

      boolean |  | `true` if the method call was successful and the element was ended. `false` if method call failed. Possible reasons for failure include: The element doesn't support the `endElement` method. (the `end` attribute is not set to `"indefinite"`) The element is not active.

    Exceptions

      DOMException |  | SYNTAX_ERR: The element was not defined with the appropriate syntax to allow `endElement` calls.

  endElementAt

    Causes this element to end the local timeline (subject to sync constraints) at the specified offset from the current time when the method is called.

    Parameters

      in float offset |  | The offset in seconds at which to end the element. Must be >= 0.

    Return value

      boolean |  | `true` if the method call was successful and the element was begun. `false` if the method call failed. Possible reasons for failure include: The element is not active.

    Exceptions

      DOMException |  | SYNTAX_ERR: The element was not defined with the appropriate syntax to allow `endElementAt` calls.

### Interface SVGAnimationElement

The SVGAnimationElement interface is the base interface for all of the animation element interfaces: SVGAnimateElement, SVGSetElement, SVGAnimateMotionElement and SVGAnimateTransformElement.

Unlike other SVG DOM interfaces, the SVG DOM does not specify convenience DOM properties corresponding to the various language attributes on SVG's animation elements. Specification of these convenience properties in a way that will be compatible with future versions of SMIL Animation is expected in a future version of SVG. The current method for accessing and modifying the attributes on the animation elements is to use the standard `getAttribute`, `setAttribute`, `getAttributeNS` and `setAttributeNS` defined in DOM2.

IDL Definition

      interface SVGAnimationElement : SVGElement, SVGTests, ElementTimeControl {
        readonly attribute SVGElement targetElement;

        float getStartTime (  );
        float getCurrentTime (  );
        float getSimpleDuration (  )
                        raises( DOMException );
      };

Attributes
  readonly SVGElement targetElement
    The element which is being animated.
Methods
  getStartTime

    Returns the start time in seconds for this animation.

    No Parameters
    Return value

      float |  | The start time in seconds for this animation relative to the start time of the time container.

    No Exceptions
  getCurrentTime

    Returns the current time in seconds relative to time zero for the given time container.

    No Parameters
    Return value

      float |  | The current time in seconds relative to time zero for the given time container.

    No Exceptions
  getSimpleDuration

    Returns the number of seconds for the simple duration for this animation. If the simple duration is undefined (e.g., the end time is indefinite), then an exception is raised.

    No Parameters
    Return value

      float |  | The number of seconds for the simple duration for this animation.

    Exceptions

      DOMException |  | NOT_SUPPORTED_ERR: The simple duration is not determined on the given element.

### Interface SVGAnimateElement

The SVGAnimateElement interface corresponds to the 'animate' element.

Object-oriented access to the attributes of the 'animate' element via the SVG DOM is not available.

IDL Definition

      interface SVGAnimateElement : SVGAnimationElement;

### Interface SVGSetElement

The SVGSetElement interface corresponds to the 'set' element.

Object-oriented access to the attributes of the 'set' element via the SVG DOM is not available.

IDL Definition

      interface SVGSetElement : SVGAnimationElement;

### Interface SVGAnimateMotionElement

The SVGAnimateMotionElement interface corresponds to the 'animateMotion' element.

Object-oriented access to the attributes of the 'animateMotion' element via the SVG DOM is not available.

IDL Definition

      interface SVGAnimateMotionElement : SVGAnimationElement;

### Interface SVGAnimateTransformElement

The SVGAnimateTransformElement interface corresponds to the 'animateTransform' element.

Object-oriented access to the attributes of the 'animateTransform' element via the SVG DOM is not available.

IDL Definition

      interface SVGAnimateTransformElement : SVGAnimationElement;

### Interface TimeEvent

The TimeEvent interface, defined in the SMIL Animation specification [SMILANIM-DOM-METHODS], defines events that occur due to animation state changes.

The available event types for animation events are:

begin
  This event is raised when the element local timeline begins to play. It will be raised each time the element begins the active duration (i.e. when it restarts, but not when it repeats). It may be raised both in the course of normal (i.e. scheduled or interactive) timeline play, as well as in the case that the element was begun with the beginElement() or beginElementAt() methods. Note that if an element is restarted while it is currently playing, the element will raise an end event and another begin event, as the element restarts.
  - Bubbles: No
  - Cancelable: No
  - Context Info: None
end
  This event is raised at the active end of the element. Note that this event is not raised at the simple end of each repeat. This event may be raised both in the course of normal (i.e. scheduled or interactive) timeline play, as well as in the case that the element was ended with the endElement() or endElementAt() methods. Note that if an element is restarted while it is currently playing, the element will raise an end event and another begin event, as the element restarts.
  - Bubbles: No
  - Cancelable: No
  - Context Info: None
repeat
  This event is raised when an element local timeline repeats. It will be raised each time the element repeats, after the first iteration.
  The event provides a numerical indication of which repeat iteration is beginning. The value is a 0-based integer, but the repeat event is not raised for the first iteration and so the observed values of the detail attribute will be >= 1.
  - Bubbles: No
  - Cancelable: No
  - Context Info: detail (current iteration)

IDL Definition

      interface TimeEvent : events::Event {
        readonly attribute views::AbstractView view;
        readonly attribute long                detail;

        void initTimeEvent ( in DOMString typeArg, in views::AbstractView viewArg, in long detailArg );
      };

Attributes
  readonly views::AbstractView view
    Identifies the AbstractView [DOM2-VIEWS] from which the event was generated.
  readonly long detail
    Specifies some detail information about the Event, depending on the type of the event. For this event type, indicates the repeat number for the animation.
Methods
  initTimeEvent
    Initiatizes the value of a TimeEvent created through the DocumentEvent interface. This method may only be called before the TimeEvent has been dispatched via the dispatchEvent method, though it may be called multiple times during that phase if necessary. If called multiple times, the final invocation takes precedence.
    Parameters

      in DOMString typeArg |  | Specifies the event type.
      in views::AbstractView viewArg |  | Specifies the Event's AbstractView.
      in long detailArg |  | Specifies the Event's detail.

    No Return Value
    No Exceptions

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