How to indent the focus rectangle in an owner-drawn TListBox (Views: 27)
Problem/Question/Abstract: I have a TListBox with style lbOwnerDrawVariable. I want to draw some text indented 10 pixels from the left (this is no problem). However, I also want it so the highlighting color and focus rectangle are indented as well (so the 10 pixel margin is completely blank, no matter what items are selected). I can't seem to do this ... the focus rectangle always seems to extend all the way to the left. How do I get around this? Answer: The problem is that the control as coded draws the focus rectangle after your owner drawing code has completed. To override that you have to make a new control descending from TListbox (or TCustomlistbox) and give it a handler for the CN_DRAWITEM message. Here you need to duplicate what the TCustomlistbox.CNDrawItem method does: procedure TMyListBox.CNDrawItem(var Message: TWMDrawItem); var State: TOwnerDrawState; begin with Message.DrawItemStruct^ do begin State := TOwnerDrawState(LongRec(itemState).Lo); Canvas.Handle := hDC; Canvas.Font := Font; Canvas.Brush := Brush; if (Integer(itemID) >= 0) and (odSelected in State) then begin Canvas.Brush.Color := clHighlight; Canvas.Font.Color := clHighlightText end; if Integer(itemID) >= 0 then DrawItem(itemID, rcItem, State) else Canvas.FillRect(rcItem); if odFocused in State then begin Inc(rcItem.left, 10); {this is the change} DrawFocusRect(hDC, rcItem); end; Canvas.Handle := 0; end; end; |