42.8 Keyframes

All of the ConstraintSet attributes outlined so far only apply to the start and end points of the animation. In other words if the rotation property were set to 180° on the end point, the rotation will begin when animation starts and complete when the end point is reached. It is not, therefore, possible to configure the rotation to reach the full 180° at a point 50% of the way through the animation and then rotate back to the original orientation by the end of the animation. Fortunately, this type of effect is available using Keyframes.

Keyframes are used to define intermediate points during the animation at which state changes are to occur. Keyframes could, for example, be declared such that the background color of a view is to have transitioned to blue at a point 50% of the way through the animation, green at the 75% point and then back to the original color by the end of the animation. Keyframes are implemented within the Transition element of the MotionScene...