private void clearResults() {
if (adapter != null) {
boolean wasSelection = !selectionStrategy.isEmpty();
boolean wasData = !adapter.isEmpty();
loadingStrategy.clearResults();
selectionStrategy.clear();
adapter.notifyDataSetChanged();
// Tell anyone who cares the data and selection has changed, if they have.
if (wasData && onDataChangedListener != null) {
onDataChangedListener.onDataChanged(PickerFragment.this);
}
if (wasSelection && onSelectionChangedListener != null) {
onSelectionChangedListener.onSelectionChanged(PickerFragment.this);
}
}
}
void updateAdapter(SimpleGraphObjectCursor<T> data) {
if (adapter != null) {
// As we fetch additional results and add them to the table, we do not
// want the items displayed jumping around seemingly at random, frustrating the user's
// attempts at scrolling, etc. Since results may be added anywhere in
// the table, we choose to try to keep the first visible row in a fixed
// position (from the user's perspective). We try to keep it positioned at
// the same offset from the top of the screen so adding new items seems
// smoother, as opposed to having it "snap" to a multiple of row height
// We use the second row, to give context above and below it and avoid
// cases where the first row is only barely visible, thus providing little context.
// The exception is where the very first row is visible, in which case we use that.
View view = listView.getChildAt(1);
int anchorPosition = listView.getFirstVisiblePosition();
if (anchorPosition > 0) {
anchorPosition++;
}
GraphObjectAdapter.SectionAndItem<T> anchorItem = adapter.getSectionAndItem(anchorPosition);
final int top =
(view != null
&& anchorItem.getType() != GraphObjectAdapter.SectionAndItem.Type.ACTIVITY_CIRCLE)
? view.getTop()
: 0;
// Now actually add the results.
boolean dataChanged = adapter.changeCursor(data);
if (view != null && anchorItem != null) {
// Put the item back in the same spot it was.
final int newPositionOfItem =
adapter.getPosition(anchorItem.sectionKey, anchorItem.graphObject);
if (newPositionOfItem != -1) {
listView.setSelectionFromTop(newPositionOfItem, top);
}
}
if (dataChanged && onDataChangedListener != null) {
onDataChangedListener.onDataChanged(PickerFragment.this);
}
}
}