ControlsScreenView.java 文件源码

@TargetApi(21)
void setupDrawables21() {
    //add state transitions
    AnimatedStateListDrawable drawable = (AnimatedStateListDrawable) play.getDrawable();
    drawable.addTransition(R.id.pause_state, R.id.play_state, (AnimatedVectorDrawable)
            ContextCompat.getDrawable(getContext(), R.drawable.vector_pause_play_black_36dp), false);
    drawable.addTransition(R.id.play_state, R.id.pause_state, (AnimatedVectorDrawable)
            ContextCompat.getDrawable(getContext(), R.drawable.vector_play_pause_black_36dp), false);

    /*
    AnimatedStateListDrawable repeatDrawable = (AnimatedStateListDrawable) repeat.getDrawable();
    repeatDrawable.addTransition(R.id.repeat_off_state, R.id.repeat_on_state, (AnimatedVectorDrawable)
            ContextCompat.getDrawable(getContext(), R.drawable.vector_repeat_off_on_black_36dp), true);
    repeatDrawable.addTransition(R.id.repeat_on_state, R.id.repeat_one_state, (AnimatedVectorDrawable)
            ContextCompat.getDrawable(getContext(), R.drawable.vector_repeat_on_one_black_36dp), true);
    repeatDrawable.addTransition(R.id.repeat_one_state, R.id.repeat_off_state, (AnimatedVectorDrawable)
            ContextCompat.getDrawable(getContext(), R.drawable.vector_repeat_one_off_black_36dp), true);
    repeatDrawable.addTransition(R.id.repeat_off_state, R.id.repeat_one_state, (AnimatedVectorDrawable)
            ContextCompat.getDrawable(getContext(), R.drawable.vector_repeat_off_one_black_36dp), true);
            */
}