animation-composition
The animation-composition
CSS property specifies the composite operation to use when multiple animations affect the same property simultaneously.
Syntax
css
/* Single animation */
animation-composition: replace;
animation-composition: add;
animation-composition: accumulate;
/* Multiple animations */
animation-composition: replace, add;
animation-composition: add, accumulate;
animation-composition: replace, add, accumulate;
/* Global values */
animation-composition: inherit;
animation-composition: initial;
animation-composition: revert;
animation-composition: revert-layer;
animation-composition: unset;
Note: When you specify multiple comma-separated values on an animation-*
property, they will be applied to the animations in the order in which the animation-name
s appear. If the number of animations and compositions differ, the values listed in the animation-composition
property will cycle from the first to the last animation-name
, looping until all the animations have an assigned animation-composition
value. For more information, see Setting multiple animation property values.
Values
replace
-
The effect value overrides the underlying value of the property. This is the default value.
add
-
The effect value builds on the underlying value of the property. This operation produces an additive effect. For animation types where the addition operation is not commutative, the order of the operands is the underlying value followed by the effect value.
accumulate
-
The effect and underlying values are combined. For animation types where the addition operation is not commutative, the order of the operands is the underlying value followed by the effect value.
Description
Each property that is targeted by the @keyframes at-rule is associated with an effect stack. The value of the effect stack is calculated by combining the underlying value of a property in a CSS style rule with the effect value of that property in the keyframe. The animation-composition
property helps to specify how to combine the underlying value with the effect value.
For example, in the CSS below, blur(5px)
is the underlying value, and blur(10px)
is the effect value. The animation-composition
property specifies the operation to perform to produce the final effect value after compositing the effect of the underlying value and the effect value.
css
.icon:hover {
filter: blur(5px);
animation: 3s infinite pulse;
animation-composition: add;
}
@keyframes pulse {
0% {
filter: blur(10px);
}
100% {
filter: blur(20px);
}
}
Consider different values for the animation-composition
property in the above example. The final effect value in each of those cases will be calculated as explained below:
- With
replace
,blur(10px)
will replaceblur(5px)
in the0%
keyframe. This is the default behavior of the property. - With
add
, the composite effect value in the0%
keyframe will beblur(5px) blur(10px)
. - With
accumulate
, the composite effect value in0%
keyframe will beblur(15px)
.
Note: A composite operation can also be specified in a keyframe. In that case, the specified composite operation is used for each property first within that keyframe and then on each property in the next keyframe.
Formal definition
Initial value | replace |
---|---|
Applies to | all elements |
Inherited | no |
Computed value | as specified |
Animation type | Not animatable |
Formal syntax
Examples
Understanding the animation-composition values
The example below shows the effect of different animation-composition
values side-by-side.
HTML
html
<div class="container">
replace
<div id="replace" class="target"></div>
</div>
<div class="container">
add
<div id="add" class="target"></div>
</div>
<div class="container">
accumulate
<div id="accumulate" class="target"></div>
</div>
CSS
Here the underlying value is translateX(50px) rotate(45deg)
.
css
@keyframes slide {
20%,
40% {
transform: translateX(100px);
background: yellow;
}
80%,
100% {
transform: translateX(150px);
background: orange;
}
}
.target {
transform: translateX(30px) rotate(45deg);
animation: slide 5s linear infinite;
}
.target:hover {
animation-play-state: paused;
}
#replace {
animation-composition: replace;
}
#add {
animation-composition: add;
}
#accumulate {
animation-composition: accumulate;
}
Result
- With
replace
, the final effect value for thetransform
property in the0%, 20%
keyframe istranslateX(100px)
(completely replacing the underlying valuetranslateX(30px) rotate(45deg)
). In this case, the element rotates from 45deg to 0deg as it animates from the default value set on the element itself to the non-rotated value set at the 0% mark. This is the default behavior. - With
add
, the final effect value for thetransform
property in the0%, 20%
keyframe istranslateX(30px) rotate(45deg)
followed bytranslateX(100px)
. So the element is moved30px
to the right, rotated45deg
, then translated100px
more along the redirected X axis. - With
accumulate
, the final effect value in the0%, 20%
keyframe istranslateX(130px) rotate(45deg)
. This means that the two X-axis translation values of30px
and100px
are combined or "accumulated".
Specifications
Specification |
---|
CSS Animations Level 2 # animation-composition |
Browser compatibility
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