public CollapseAnimationListener(AnimatedExpandableListAdapter adapter, int groupPosition, ExpandableListView listView, GroupInfo info, DummyView dummyView)
{
_adapter = adapter;
_groupPosition = groupPosition;
_listView = listView;
_info = info;
_dummyView = dummyView;
}
public ExpandAnimationListener(AnimatedExpandableListAdapter adapter, int groupPosition, DummyView dummyView)
{
_adapter = adapter;
_groupPosition = groupPosition;
_dummyView = dummyView;
}
/**
* Override {@link #getChildView(int, int, boolean, View, ViewGroup)} instead.
*/
public override View GetChildView(int groupPosition, int childPosition, bool isLastChild, View convertView, ViewGroup parent)
{
GroupInfo info = GetGroupInfo(groupPosition);
if (info.Animating)
{
// If this group is animating, return the a DummyView...
if (convertView is DummyView == false)
{
convertView = new DummyView(parent.Context);
convertView.LayoutParameters = new AbsListView.LayoutParams(AbsListView.LayoutParams.MatchParent, 0);
}
if (childPosition < info.FirstChildPosition)
{
// The reason why we do this is to support the collapse
// this group when the group view is not visible but the
// children of this group are. When notifyDataSetChanged
// is called, the ExpandableListView tries to keep the
// list position the same by saving the first visible item
// and jumping back to that item after the views have been
// refreshed. Now the problem is, if a group has 2 items
// and the first visible item is the 2nd child of the group
// and this group is collapsed, then the dummy view will be
// used for the group. But now the group only has 1 item
// which is the dummy view, thus when the ListView is trying
// to restore the scroll position, it will try to jump to
// the second item of the group. But this group no longer
// has a second item, so it is forced to jump to the next
// group. This will cause a very ugly visual glitch. So
// the way that we counteract this is by creating as many
// dummy views as we need to maintain the scroll position
// of the ListView after notifyDataSetChanged has been
// called.
convertView.LayoutParameters.Height = 0;
return(convertView);
}
ExpandableListView listview = (ExpandableListView)parent;
DummyView dummyView = (DummyView)convertView;
// Clear the views that the dummy view draws
dummyView.ClearViews();
// Set the style of the divider
dummyView.SetDivider(listview.Divider, parent.MeasuredWidth, listview.DividerHeight);
// Make measure specs to measure child views
int measureSpecW = View.MeasureSpec.MakeMeasureSpec(parent.Width, MeasureSpecMode.Exactly);
int measureSpecH = View.MeasureSpec.MakeMeasureSpec(0, MeasureSpecMode.Unspecified);
int totalHeight = 0;
int clipHeight = parent.Height;
int len = GetRealChildrenCount(groupPosition);
for (int i = info.FirstChildPosition; i < len; i++)
{
View childView = GetRealChildView(groupPosition, i, (i == len - 1), null, parent);
AbsListView.LayoutParams p = (AbsListView.LayoutParams)childView.LayoutParameters;
if (p == null)
{
p = (AbsListView.LayoutParams)GenerateDefaultLayoutParams();
childView.LayoutParameters = p;
}
int lpHeight = p.Height;
int childHeightSpec;
if (lpHeight > 0)
{
childHeightSpec = View.MeasureSpec.MakeMeasureSpec(lpHeight, MeasureSpecMode.Exactly);
}
else
{
childHeightSpec = measureSpecH;
}
childView.Measure(measureSpecW, childHeightSpec);
totalHeight += childView.MeasuredHeight;
if (totalHeight < clipHeight)
{
// we only need to draw enough views to fool the user...
dummyView.AddFakeView(childView);
}
else
{
dummyView.AddFakeView(childView);
// if this group has too many views, we don't want to
// calculate the height of everything... just do a light
// approximation and break
int averageHeight = totalHeight / (i + 1);
totalHeight += (len - i - 1) * averageHeight;
break;
}
}
Java.Lang.Object o;
int state = (o = dummyView.Tag) == null ? STATE_IDLE : (Int16)o;
if (info.Expanding && state != STATE_EXPANDING)
{
ExpandAnimation ani = new ExpandAnimation(dummyView, 0, totalHeight, info);
ani.Duration = _parent.GetAnimationDuration();
ani.SetAnimationListener(new ExpandAnimationListener(this, groupPosition, dummyView));
dummyView.StartAnimation(ani);
dummyView.Tag = STATE_EXPANDING;
}
else if (!info.Expanding && state != STATE_COLLAPSING)
{
if (info.DummyHeight == -1)
{
info.DummyHeight = totalHeight;
}
ExpandAnimation ani = new ExpandAnimation(dummyView, info.DummyHeight, 0, info);
ani.Duration = _parent.GetAnimationDuration();
ani.SetAnimationListener(new CollapseAnimationListener(this, groupPosition, listview, info, dummyView));
dummyView.StartAnimation(ani);
dummyView.Tag = STATE_COLLAPSING;
}
return(convertView);
}
else
{
return(GetRealChildView(groupPosition, childPosition, isLastChild, convertView, parent));
}
}