public void setAdapter(StickyListHeadersAdapter adapter) {
if (adapter == null) {
if (mAdapter instanceof SectionIndexerAdapterWrapper) {
((SectionIndexerAdapterWrapper) mAdapter).mSectionIndexerDelegate = null;
}
if (mAdapter != null) {
mAdapter.mDelegate = null;
}
mList.setAdapter(null);
clearHeader();
return;
}
if (mAdapter != null) {
mAdapter.unregisterDataSetObserver(mDataSetObserver);
}
if (adapter instanceof SectionIndexer) {
mAdapter = new SectionIndexerAdapterWrapper(getContext(), adapter);
} else {
mAdapter = new AdapterWrapper(getContext(), adapter);
}
mDataSetObserver = new AdapterWrapperDataSetObserver();
mAdapter.registerDataSetObserver(mDataSetObserver);
if (mOnHeaderClickListener != null) {
mAdapter.setOnHeaderClickListener(new AdapterWrapperHeaderClickHandler());
} else {
mAdapter.setOnHeaderClickListener(null);
}
mAdapter.setDivider(mDivider, mDividerHeight);
mList.setAdapter(mAdapter);
clearHeader();
}
private void updateOrClearHeader(int firstVisiblePosition) {
final int adapterCount = mAdapter == null ? 0 : mAdapter.getCount();
if (adapterCount == 0 || !mAreHeadersSticky) {
return;
}
final int headerViewCount = mList.getHeaderViewsCount();
int headerPosition = firstVisiblePosition - headerViewCount;
if (mList.getChildCount() > 0) {
View firstItem = mList.getChildAt(0);
if (firstItem.getBottom() < stickyHeaderTop()) {
headerPosition++;
}
}
// It is not a mistake to call getFirstVisiblePosition() here.
// Most of the time getFixedFirstVisibleItem() should be called
// but that does not work great together with getChildAt()
final boolean doesListHaveChildren = mList.getChildCount() != 0;
final boolean isFirstViewBelowTop =
doesListHaveChildren
&& mList.getFirstVisiblePosition() == 0
&& mList.getChildAt(0).getTop() >= stickyHeaderTop();
final boolean isHeaderPositionOutsideAdapterRange =
headerPosition > adapterCount - 1 || headerPosition < 0;
if (!doesListHaveChildren || isHeaderPositionOutsideAdapterRange || isFirstViewBelowTop) {
clearHeader();
return;
}
updateHeader(headerPosition);
}
public void setAreHeadersSticky(boolean areHeadersSticky) {
mAreHeadersSticky = areHeadersSticky;
if (!areHeadersSticky) {
clearHeader();
} else {
updateOrClearHeader(mList.getFixedFirstVisibleItem());
}
// invalidating the list will trigger dispatchDraw()
mList.invalidate();
}