SwipeRefreshLayout.java 文件源码

private void startScaleUpAnimation(AnimationListener listener) {
    mCircleView.setVisibility(View.VISIBLE);
    if (android.os.Build.VERSION.SDK_INT >= 11) {
        // Pre API 11, alpha is used in place of scale up to show the
        // progress circle appearing.
        // Don't adjust the alpha during appearance otherwise.
        mProgress.setAlpha(MAX_ALPHA);
    }
    mScaleAnimation = new Animation() {
        @Override
        public void applyTransformation(float interpolatedTime, Transformation t) {
            setAnimationProgress(interpolatedTime);
        }
    };
    mScaleAnimation.setDuration(mMediumAnimationDuration);
    if (listener != null) {
        mCircleView.setAnimationListener(listener);
    }
    mCircleView.clearAnimation();
    mCircleView.startAnimation(mScaleAnimation);
}