Animation Value Attributes¶
calcMode¶
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), the calcMode
attribute is ignored and discrete interpolation is used.
| value | description |
|---|---|
'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. Except for animateMotion, 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. For
animateMotion, this is the default calcMode. |
'spline' |
Interpolates from one value in the values list to the next according to a time function defined by a cubic Bézier 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. |
values¶
values = <list>
A semicolon-separated list of one or more values. Vector-valued attributes are supported using the vector syntax of the attributeType domain. Per the SMIL specification, leading and trailing white space, and white space before and after semicolon separators, is allowed and will be ignored.
keyTimes¶
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.
If a list of keyTimes is specified, there must be exactly as many values in the keyTimes list as in the values list.
Each successive time value must be greater than or equal to the preceding time value.
The keyTimes list semantics depends upon the interpolation mode:
- For linear and spline animation, the first time value in the list must be 0, and the last time value in the list must be 1. The key time associated with each value defines when the value is set; values are interpolated between the key times.
- For discrete animation, the first time value in the list must be 0. The time associated with each value defines when the value is set; the animation function uses that value until the next time defined in keyTimes.
If the interpolation mode is 'paced', the keyTimes attribute is ignored.
If there are any errors in the keyTimes specification (bad values, too many or too few values), the document fragment is in error.
If the simple duration is indefinite, any keyTimes specification will be ignored.
keySplines¶
keySplines = <list>
A set of Bézier control points associated with the keyTimes list, defining a cubic Bézier function that controls interval pacing. The attribute value is a semicolon-separated list of control point descriptions. Each control point description is a set of four values: x1 y1 x2 y2, describing the Bézier control points for one time segment. Note: SMIL allows these values to be separated either by commas with optional whitespace, or by whitespace alone. The ‘keyTimes’ values that define the associated segment are the Bézier “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 document fragment is in error.