View.java 文件源码

public void run() {
    long now = AnimationUtils.currentAnimationTimeMillis();
    if (now >= fadeStartTime) {

        // the animation fades the scrollbars out by changing
        // the opacity (alpha) from fully opaque to fully
        // transparent
        int nextFrame = (int) now;
        int framesCount = 0;

        Interpolator interpolator = scrollBarInterpolator;

        // Start opaque
        interpolator.setKeyFrame(framesCount++, nextFrame, OPAQUE);

        // End transparent
        nextFrame += scrollBarFadeDuration;
        interpolator.setKeyFrame(framesCount, nextFrame, TRANSPARENT);

        state = FADING;

        // Kick off the fade animation
        host.invalidate(true);
    }
}