Question

I need to animate some objects on my GLSurfaceView by changing their properties – size, position, rotation angle etc.
I want to use interpolators to change rate of my animation (accelerate/decelerate) and I also need to know when it ends (onAnimationEnd listener).

android.animation.Animator class is perfect for this job, but unfortunately it requires API 11 and I’m developing for API 7.

Is there any other class that I can use? Maybe third-party, but light and optimized for Android.

Answer 1

Turned out that view.animation.*Interpolator classes can be used on their own to return interpolated values. So properties for animation (in my case – angle) can easily be calculated in GLSurfaceView.Renderer.onDrawFrame:

...
DecelerateInterpolator animationInterpolator = new DecelerateInterpolator();
...
long time = SystemClock.uptimeMillis()-animationStart;
float timeInterpolated = (float) time / (float)(animationEnd-animationStart);
timeInterpolated=animationInterpolator.getInterpolation(timeInterpolated);
angle = animationStartAngle + ((animationEndAngle - animationStartAngle) * timeInterpolated);
....