protected override void OnPaint(PaintEventArgs e)
{
if (VirtualListSize == 0) return;
int itemWidth = GetItemWidth();
int itemHeight = GetItemHeight();
int pagesize = (ClientSize.Height % itemHeight) == 0 ?
(ClientSize.Height / itemHeight) : (ClientSize.Height / itemHeight) + 1;
int startIndex = GetTopIndex();
int endIndex = Math.Min(startIndex+pagesize, VirtualListSize);
Rectangle bound = new Rectangle(0, 0, itemWidth, itemHeight);
for (int index = startIndex; index < endIndex; index++)
{
var re = new RetrieveCommandListItemEventArgs(index);
OnRetrieveCommandListItem(re);
re.Item.SetIndex(index);
re.Item.SetBounds(bound);
var de = new DrawCommandListItemEventArgs(e.Graphics,re.Item);
OnDrawItem(de);
bound.Y +=itemHeight;
}
}
private void OnRetrieveCommandListItem(RetrieveCommandListItemEventArgs e)
{
RetrieveCommandListItem.Raise(this, e);
}
public CommandListItem GetItemAt(int x, int y)
{
if (y < 0
|| y >= ClientSize.Height
|| VirtualListSize == 0)
return null;
int startIndex = GetTopIndex();
int itemWidth = GetItemWidth();
int itemHeight = GetItemHeight();
int itemNumber = y / itemHeight;
int itemIndex = startIndex + itemNumber;
if (itemIndex >= VirtualListSize)
return null;
var re = new RetrieveCommandListItemEventArgs(itemIndex);
OnRetrieveCommandListItem(re);
re.Item.SetIndex(itemIndex);
re.Item.SetBounds(new Rectangle(0, itemNumber * itemHeight, itemWidth, itemHeight));
return re.Item;
}
