TTreeView custom draw item width

Question

I use the OnCustomDrawItem event to draw a TTreeView like this :

Here is my code :

procedure Tform1.trvArbreCustomDrawItem(Sender: TCustomTreeView; Node: TTreeNode; State: TCustomDrawState; var DefaultDraw: Boolean);
var
  vRect      : TRect;
  vBmp       : TBitmap;
  vBmpRect   : TRect;
  vTreeView  : TTreeView;
  vBarreInfo : TScrollInfo;
  vDeltaX    : Integer;
begin
  DefaultDraw := False;
  vTreeView   := TTreeView(Sender);

  vRect := Node.DisplayRect(False);

  vBmp := TBitmap.Create();

  FillChar(vBarreInfo, SizeOF(vBarreInfo), 0);

  vBarreInfo.cbSize := SizeOf(vBarreInfo);
  vBarreInfo.fMask  := SIF_RANGE or SIF_POS;

  if GetScrollInfo(trvArbre.Handle, SB_HORZ, vBarreInfo) then
  begin
    if vBarreInfo.nMax > vRect.Right  - vRect.Left then
    begin
      vBmp.Width  := vBarreInfo.nMax + 1;
      vBmp.Height := vRect.Bottom - vRect.Top;

      vDeltaX := vBarreInfo.nPos;
    end
    else
    begin
      vBmp.Width  := vRect.Right  - vRect.Left;
      vBmp.Height := vRect.Bottom - vRect.Top;

      vDeltaX := 0;
    end;
  end
  else
  begin
    vBmp.Width  := vRect.Right  - vRect.Left;
    vBmp.Height := vRect.Bottom - vRect.Top;

    vDeltaX := 0;
  end;

  vBmpRect := Rect(0, 0, vBmp.Width, vBmp.Height);

  if cdsSelected in State then
  begin
    vBmp.Canvas.Brush.Color := cMenuDownFond;
    vBmp.Canvas.Pen  .Color := cMenuDownBordure;
  end 
  else if cdsHot in State then
  begin
    vBmp.Canvas.Brush.Color := cMenuSurvolFond;
    vBmp.Canvas.Pen  .Color := cMenuSurvolBordure;
  end    
  else
  begin
    vBmp.Canvas.Brush.Color := clWhite;
    vBmp.Canvas.Pen  .Color := clwhite;
  end;

  vBmp.Canvas.Rectangle(vBmpRect);

  vBmpRect.Left := vBmpRect.Left + 3;

  vBmpRect.Left := vBmpRect.Left + (Node.Level * vTreeView.Indent);

  if Node.StateIndex >= 0 then
  begin
    vTreeView.StateImages.Draw(vBmp.Canvas, vBmpRect.Left, vBmpRect.Top, Node.StateIndex);
  end;

  vBmpRect.Left := vBmpRect.Left + 18;

  vTreeView.Images.Draw(vBmp.Canvas, vBmpRect.Left, vBmpRect.Top, Node.ImageIndex);

  vBmpRect.Left := vBmpRect.Left + 18 + 3;

  vBmp.Canvas.Font := vTreeView.Font;

  DrawText
  (
    vBmp.Canvas.Handle,
    PChar(Node.Text),
    Length(Node.Text),
    vBmpRect,
    DT_SINGLELINE or DT_LEFT or DT_VCENTER or DT_NOPREFIX or DT_END_ELLIPSIS
  );

  BitBlt
  (
    Sender.Canvas.Handle,
    vRect.Left,
    vRect.Top,
    vRect.Right  - vRect.Left,
    vRect.Bottom - vRect.Top,
    vBmp.Canvas.Handle,
    vDeltaX,
    0,
    SRCCOPY
  );

  FreeAndNil(vBmp);
end;

My problem is that the node "My last node wich is not too long" is not too long to justify the presence of the horizontal scrollbar.

When I set DefaultDraw to true I obtain :

It seems that the width of the node is computed with a font I don't use.

I tried to change the font of the canvas, to use Windows API, to use the OnAdvancedCustomDrawItem with no result.

Thanks.

Answer 1

I use Delphi 7. I copied ComCtrls.pas in the folder of my application. I changed procedure TCustomTreeView.CNNotify(var Message: TWMNotify);. Line 8979 from Result := Result or CDRF_SKIPDEFAULT to Result := Result or CDRF_SKIPDEFAULT; and I commented line 8980 else if FCanvasChanged then in order to simulate DefaultDraw=True and FCanvasChanged even if I set DefaultDraw to False in event et don't change font. After a lot of tests, I don't see any caveats.