如何在AdvancedCustomDrawItem期间绘制TTreeView的样式选择矩形？

我是做定制的TTreeView使用从头开始绘制OnAdvancedCustomDrawItem事件，我想知道如何在我的所有者绘制项目的背景中正确渲染这些选择和热矩形？它们是 Vista/7 风格的，所以我不能简单地用纯色填充背景。

我尝试在以下位置绘制我的物品cdPostPaint舞台，但如果我离开DefaultDraw := True atcdPrePaint阶段绘制选择背景，发生完整的默认绘制，包括项目的文本。

procedure TForm1.TreeView1AdvancedCustomDrawItem(Sender: TCustomTreeView;
  Node: TTreeNode; State: TCustomDrawState; Stage: TCustomDrawStage; var PaintImages,
  DefaultDraw: Boolean);
begin
  case Stage of
    cdPreErase:
    begin
      DefaultDraw := True;
    end;

    cdPostErase:
    begin
      DefaultDraw := True;
    end;

    cdPrePaint:
    begin
      // I thought this will paint only the selected/hot backgrounds, 
      // however this will paint whole item, including text.
      DefaultDraw := True;
    end;

    cdPostPaint:
    begin
      DefaultDraw := False;

      // painting my owner-draw text
      // .........
    end;
  end;

  PaintImages := False;
end;

这是我的解决方案（经过测试）。

注意 TreeView 必须有HotTrack := True正常绘制热门项目。

当主题未启用时，还必须有额外的绘图。

uses
  UxTheme,
  Themes;

const
  TreeExpanderSpacing = 6;

procedure TForm1.DrawExpander(ACanvas: TCanvas; ATextRect: TRect; AExpanded: Boolean;
  AHot: Boolean);
var
  ExpanderRect: TRect;
  Graphics: IGPGraphics;
  Points: array of TGPPoint;
  Brush: IGPBrush;
  Pen: IGPPen;
  ThemeData: HTHEME;
  ElementPart: Integer;
  ElementState: Integer;
  ExpanderSize: TSize;
  UnthemedColor: TColor;
begin
  if ThemeServices.ThemesEnabled then
  begin
    if AHot then
      ElementPart := TVP_HOTGLYPH
    else
      ElementPart := TVP_GLYPH;

    if AExpanded then
      ElementState := GLPS_OPENED
    else
      ElementState := GLPS_CLOSED;

    ThemeData := OpenThemeData(TreeView1.Handle, VSCLASS_TREEVIEW);
    GetThemePartSize(ThemeData, ACanvas.Handle, ElementPart, ElementState, nil,
      TS_TRUE, ExpanderSize);
    ExpanderRect.Left := ATextRect.Left - TreeExpanderSpacing - ExpanderSize.cx;
    ExpanderRect.Right := ExpanderRect.Left + ExpanderSize.cx;
    ExpanderRect.Top := ATextRect.Top + (ATextRect.Bottom - ATextRect.Top - ExpanderSize.cy) div 2;
    ExpanderRect.Bottom := ExpanderRect.Top + ExpanderSize.cy;
    DrawThemeBackground(ThemeData, ACanvas.Handle, ElementPart, ElementState, ExpanderRect, nil);
    CloseThemeData(ThemeData);
  end
  else
  begin

    // Drawing expander without themes enabled

    Graphics := TGPGraphics.Create(ACanvas.Handle);
    Graphics.SmoothingMode := SmoothingModeHighQuality;

    ExpanderRect := ATextRect;
    ExpanderRect.Right := ATextRect.Left - TDPIAware.GetScaledSize(TreeExpanderSpacing96dpi);
    ExpanderRect.Left := ATextRect.Left - TDPIAware.GetScaledSize(TreeExpanderSpacing96dpi) -
      TDPIAware.GetScaledSize(Max(TreeExpanderCollapsedWidth96dpi, TreeExpanderExpandedWidth96dpi));

    if ASelected then
      UnthemedColor := ColorToRGB(clHighlightText)
    else
      if AExpanded then
        UnthemedColor := clBlack
      else
        UnthemedColor := clGray;

    SetLength(Points, 3);
    if AExpanded then
    begin
      Points[0] := TGPPoint.Create(ExpanderRect.Right, ExpanderRect.Top +
        (ExpanderRect.Bottom - ExpanderRect.Top - TreeExpanderExpandedHeight96dpi) div 2);
      Points[1] := TGPPoint.Create(ExpanderRect.Right, ExpanderRect.Top +
        (ExpanderRect.Bottom - ExpanderRect.Top + TreeExpanderExpandedHeight96dpi) div 2);
      Points[2] := TGPPoint.Create(ExpanderRect.Right - TreeExpanderExpandedWidth96dpi,
        ExpanderRect.Top + (ExpanderRect.Bottom - ExpanderRect.Top +
        TreeExpanderExpandedHeight96dpi) div 2);
      Brush := TGPSolidBrush.Create(TGPColor.CreateFromColorRef(UnthemedColor));
      Graphics.FillPolygon(Brush, Points);
    end
    else
    begin
      Points[0] := TGPPoint.Create(ExpanderRect.Right - TreeExpanderCollapsedWidth96dpi,
        ExpanderRect.Top + (ExpanderRect.Bottom - ExpanderRect.Top -
        TreeExpanderCollapsedHeight96dpi) div 2);
      Points[1] := TGPPoint.Create(ExpanderRect.Right,
        ExpanderRect.Top + (ExpanderRect.Bottom - ExpanderRect.Top) div 2);
      Points[2] := TGPPoint.Create(ExpanderRect.Right - TreeExpanderCollapsedWidth96dpi,
        ExpanderRect.Top + (ExpanderRect.Bottom - ExpanderRect.Top +
        TreeExpanderCollapsedHeight96dpi) div 2);
      Pen := TGPPen.Create(TGPColor.CreateFromColorRef(UnthemedColor));
      Graphics.DrawPolygon(Pen, Points);
    end;
  end;
end;

procedure TForm1.TreeView1AdvancedCustomDrawItem(Sender: TCustomTreeView;
  Node: TTreeNode; State: TCustomDrawState; Stage: TCustomDrawStage; var PaintImages,
  DefaultDraw: Boolean);
var
  NodeRect: TRect;
  NodeTextRect: TRect;
  Text: string;
  ThemeData: HTHEME;
  TreeItemState: Integer;
begin
  if Stage = cdPrePaint then
  begin
    NodeRect := Node.DisplayRect(False);
    NodeTextRect := Node.DisplayRect(True);

    // Drawing background
    if (cdsSelected in State) and Sender.Focused then
      TreeItemState := TREIS_SELECTED
    else
      if (cdsSelected in State) and (cdsHot in State) then
        TreeItemState := TREIS_HOTSELECTED
      else
        if cdsSelected in State then
          TreeItemState := TREIS_SELECTEDNOTFOCUS
        else
          if cdsHot in State then
            TreeItemState := TREIS_HOT
          else
            TreeItemState := TREEITEMStateFiller0;

    if TreeItemState <> TREEITEMStateFiller0 then
    begin
      ThemeData := OpenThemeData(Sender.Handle, VSCLASS_TREEVIEW);
      DrawThemeBackground(ThemeData, Sender.Canvas.Handle, TVP_TREEITEM, TreeItemState,
        NodeRect, nil);
      CloseThemeData(ThemeData);
    end;

    // Drawing expander
    if Node.HasChildren then
      DrawExpander(Sender.Canvas, NodeTextRect, Node.Expanded, cdsHot in State);

    // Drawing main text
    SetBkMode(Sender.Canvas.Handle, TRANSPARENT);
    SetTextColor(Sender.Canvas.Handle, clBlue);

    Text := Node.Text;
    Sender.Canvas.TextRect(NodeTextRect, Text,
      [tfVerticalCenter, tfSingleLine, tfEndEllipsis, tfLeft]);

    // Some extended drawing...

  end;

  PaintImages := False;
  DefaultDraw := False;
end;