TTreeView - Collapse and Expand Images not Alligned

问题

Does anyone know how I can align the collapse/expand images with the center of my icon? Using a white theme they are correct, but in the dark theme, the arrows seem to be bottom-aligned:

回答1:

If you're using VCL Style Utils components, then modify UxTheme_TreeView in Vcl.Styles.UxTheme.pas

  case iPartId of
    TVP_GLYPH:
      begin
        LColor := StyleServices.GetSystemColor(clWindowText);
        LRect := pRect;
        LRect.Top := LRect.Top + 1; // <---- here's the change
        //LRect.Top := LRect.Top + 5;
        LRect.Left := LRect.Left + 5;

        if (iStateId = GLPS_OPENED) or (iStateId = HGLPS_OPENED) then
          DrawStyleArrow(hdc, TScrollDirection.sdDown, LRect.Location, 3, LColor)
        else
          DrawStyleArrow(hdc, TScrollDirection.sdRight, LRect.Location, 3, LColor);

        exit(S_OK);
      end;

Also set the tree view property ShowLines := false;

来源：https://stackoverflow.com/questions/61753622/ttreeview-collapse-and-expand-images-not-alligned