VirtualStringTree aligned text and gridlines

Question

I have a virtualstringtree (Gridlines enabled) with X headers and x roots. I would like to add children (at least 1) to the roots that have only 1 text which is in the middle and goes through all the headers (independent). So no matter if I resize the headers, etc. the text is always aligned to the actual client size of the VirtualStringTree.

Is this possible? If so, how?

Answer 1

This sounds like cell merging. This is discussed here, for example, where the solution is to include toAutoSpanColumns in TreeOptions.AutoOptions.

If you want center-aligned text, override OnDrawText accordingly. Something like:

procedure TForm1.VirtualStringTree1DrawText(Sender: TBaseVirtualTree;
  TargetCanvas: TCanvas; Node: PVirtualNode; Column: TColumnIndex;
  const Text: WideString; const CellRect: TRect; var DefaultDraw: Boolean);
var
  r: TRect;
begin
  r := CellRect;
  Windows.DrawTextW(TargetCanvas.Handle, PWideChar(Text), Length(Text), r, DT_CENTER or DT_VCENTER);
  DefaultDraw := False;
end;