SVG animation with SMIL

Synchronized Multimedia Integration Language (SMIL) is an extension of SVG allowing to animating SVG elements. SMIL allows you to:

  • animate the numeric attributes of an element (x, y, …)
  • animate transform attributes (translation or rotation)
  • animate color attributes
  • follow a motion path

This is done adding an SVG element like <animate> inside the SVG element to animate. Below are examples for the four different ways.

Animating attributes of an element

The following example animates the cx attribute of a circle. To do so, we add an <animate> element inside the <circle> element. The important attributes for <animate> are:

attributeName

The name of the attribute to animate.

from

The initial value of the attribute.

to

The final value.

dur

The duration of the animation (for example, write '5s' for 5 seconds).

If you want to animate more attributes inside the same element, just add more <animate> elements.

html
<svg width="300" height="100">
  <title>Attribute Animation with SMIL</title>
  <rect x="0" y="0" width="300" height="100" stroke="black" stroke-width="1" />
  <circle cx="0" cy="50" r="15" fill="blue" stroke="black" stroke-width="1">
    <animate
      attributeName="cx"
      from="0"
      to="500"
      dur="5s"
      repeatCount="indefinite" />
  </circle>
</svg>

Animating the transform attributes

The <animateTransform> element let you animate transform attributes. This new element is necessary because we are not animating a simple attribute like x which is just a number. Rotation attributes look like this: rotation(theta, x, y), where theta is the angle in degrees, and x and y are absolute positions. In the example below, we animate the center of the rotation and the angle.

html
<svg width="300" height="100">
  <title>SVG SMIL Animate with transform</title>
  <rect x="0" y="0" width="300" height="100" stroke="black" stroke-width="1" />
  <rect
    x="0"
    y="50"
    width="15"
    height="34"
    fill="blue"
    stroke="black"
    stroke-width="1">
    <animateTransform
      attributeName="transform"
      begin="0s"
      dur="20s"
      type="rotate"
      from="0 60 60"
      to="360 100 60"
      repeatCount="indefinite" />
  </rect>
</svg>

Animation following a path

The <animateMotion> element lets you animate an element position and rotation according to a path. The path is defined the same way as in <path>. You can set the attribute to define whether the object rotates following the tangent of the path.

Example 1: Linear motion

In this example, a blue circle bounces between the left and right edges of a black box, over and over again, indefinitely. The animation here is handled by the <animateMotion> element. In this case, we're establishing a path consisting of a MoveTo command to establish the starting point for the animation, then the Horizontal-line command to move the circle 300 pixels to the right, followed by the Z command, which closes the path, establishing a loop back to the beginning. By setting the value of the repeatCount attribute to indefinite, we indicate that the animation should loop forever, as long as the SVG image exists.

html
<svg xmlns="http://www.w3.org/2000/svg" width="300" height="100">
  <title>SVG SMIL Animate with Path</title>
  <rect x="0" y="0" width="300" height="100" stroke="black" stroke-width="1" />
  <circle cx="0" cy="50" r="15" fill="blue" stroke="black" stroke-width="1">
    <animateMotion path="M 0 0 H 300 Z" dur="3s" repeatCount="indefinite" />
  </circle>
</svg>

View live sample

Example 2: Curved motion

Same example as before with a curved path and following the direction of the path.

html
<svg width="300" height="100">
  <title>SVG SMIL Animate with Path</title>
  <rect x="0" y="0" width="300" height="100" stroke="black" stroke-width="1" />
  <rect
    x="0"
    y="0"
    width="20"
    height="20"
    fill="blue"
    stroke="black"
    stroke-width="1">
    <animateMotion
      path="M 250,80 H 50 Q 30,80 30,50 Q 30,20 50,20 H 250 Q 280,20,280,50 Q 280,80,250,80Z"
      dur="3s"
      repeatCount="indefinite"
      rotate="auto" />
  </rect>
</svg>

See also