animate-elem-87-t.svg

The test consists of two circles: an orange circle on the left, which serves as a reference, and a blue circle on the right, whose transform attribute is animated. Animation of the circles begins at t=1s and lasts for 3s.

The transform animation that applies to the blue circle is of type "scale", and specifies by="1". Since the animation is considered to be equivalent to one that specifies from="0" to="1", when the animation begins the circle will be scaled down to a point, and then will be scaled up until it reaches its original size at t=4s.

The test is passed if the blue circle on the right is always the same size as the orange circle on the left. The test runs from t=0s until t=4s.

This tests that the underlying value of a scale transformation is 0. Since SMIL defines a by animation as being equivalent to an additive values animation where the first value is zero and the second value is the by value, such an animation would begin by post-multiplying a scale(0) transformation to the element's underlying transform list.