How to Custom Paint the Tree List Background

• Jul 26, 2024

The following example demonstrates how to handle the tree list’s OnCustomDrawBackgroundCell event, used to manually paint the tree list background:

//...
var
  ABitmap: TBitmap;
//...
procedure <Form>.FormCreate(Sender: TObject);
begin
  ABitmap := TBitmap.Create;
  ABitmap.LoadFromFile('E:\EARTH16.BMP');
end;
//...
procedure <Form>.<TreeList>CustomDrawBackgroundCell(Sender: TcxCustomTreeList; ACanvas: TcxCanvas; AViewInfo: TcxTreeListCustomCellViewInfo; var ADone: Boolean);
begin
  // paint the background rectangle with the specified bitmap
  ACanvas.FillRect(AViewInfo.BoundsRect, ABitmap);
  // suppress the default painting
  ADone := True;
end;