DragView.java 文件源码

@TargetApi(Build.VERSION_CODES.LOLLIPOP)
private void animateFilterTo(float[] targetFilter) {
    float[] oldFilter = mCurrentFilter == null ? new ColorMatrix().getArray() : mCurrentFilter;
    mCurrentFilter = Arrays.copyOf(oldFilter, oldFilter.length);

    if (mFilterAnimator != null) {
        mFilterAnimator.cancel();
    }
    mFilterAnimator = ValueAnimator.ofObject(new FloatArrayEvaluator(mCurrentFilter),
            oldFilter, targetFilter);
    mFilterAnimator.setDuration(COLOR_CHANGE_DURATION);
    mFilterAnimator.addUpdateListener(new AnimatorUpdateListener() {

        @Override
        public void onAnimationUpdate(ValueAnimator animation) {
            mPaint.setColorFilter(new ColorMatrixColorFilter(mCurrentFilter));
            invalidate();
        }
    });
    mFilterAnimator.start();
}