public void configureHeaderView(int position) {
if (mHeaderView == null) {
return;
}
int state = mAdapter.getPinnedHeaderState(position);
switch (state) {
case PinnedHeaderAdapter.PINNED_HEADER_GONE:
{
mHeaderViewVisible = false;
break;
}
case PinnedHeaderAdapter.PINNED_HEADER_VISIBLE:
{
mAdapter.configurePinnedHeader(mHeaderView, position, MAX_ALPHA);
if (mHeaderView.getTop() != 0) {
mHeaderView.layout(0, 0, mHeaderViewWidth, mHeaderViewHeight);
}
mHeaderViewVisible = true;
break;
}
case PinnedHeaderAdapter.PINNED_HEADER_PUSHED_UP:
{
View firstView = getChildAt(0);
if (firstView != null) {
int bottom = firstView.getBottom();
int itemHeight = firstView.getHeight();
int headerHeight = mHeaderView.getHeight();
int y;
int alpha;
if (bottom < headerHeight) {
y = (bottom - headerHeight);
alpha = MAX_ALPHA * (headerHeight + y) / headerHeight;
} else {
y = 0;
alpha = MAX_ALPHA;
}
mAdapter.configurePinnedHeader(mHeaderView, position, alpha);
if (mHeaderView.getTop() != y) {
mHeaderView.layout(0, y, mHeaderViewWidth, mHeaderViewHeight + y);
}
mHeaderViewVisible = true;
}
break;
}
}
}
