PlaylistPortraitView.java 文件源码

@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
    // logic here derived from http://antoine-merle.com/blog/2013/10/04/making-that-google-plus-profile-screen/
    if (visibleItemCount == 0) return;
    if (firstVisibleItem == 0 && mList.getChildCount() > 0) {
        // parallax
        mHeroContainer.setTranslationY(-mList.getChildAt(0).getTop() / 2);
    }
    // sticky header
    final int top = mListHeader.getTop();
    final int stickyHeight = mStickyHeader.getMeasuredHeight();
    final int headerHeight = mListHeader.getMeasuredHeight();
    final int delta = headerHeight - stickyHeight;
    final int pos = delta + top;
    // reposition header
    mStickyHeader.setTranslationY(Math.max(pos,0));
    if (pos < 0 && !mIsStuck) {
        mIsStuck = true;
        makeSlideAnimator(5000, 10000, (ClipDrawable)mStickyHeader.getBackground()).start();
    } else if (pos > 0 && mIsStuck) {
        mIsStuck = false;
        makeSlideAnimator(10000,5000, (ClipDrawable)mStickyHeader.getBackground()).start();
    }
}