Delphi改变主菜单颜色

Question

我正在创建自己的 OnAdvancedDrawItem 来更改 MainMenu 的颜色。它运作良好，但我在底部看到一条烦人的白线。

当鼠标悬停在菜单上时它会消失，但当选择另一个应用程序时它会回来。我怎样才能摆脱它？

这是我的背景着色的基本代码。

unit MenMain;

interface

uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, Menus, ImgList, StdCtrls;

type
  TForm1 = class(TForm)
  MainMenu1: TMainMenu;
  File2: TMenuItem;
  Edit1: TMenuItem;
  Window1: TMenuItem;
  procedure Window1AdvancedDrawItem(Sender: TObject; ACanvas: TCanvas; ARect: TRect; State: TOwnerDrawState);
private

public

end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Window1AdvancedDrawItem(Sender: TObject; ACanvas: TCanvas;  ARect: TRect; State: TOwnerDrawState);
begin
  with TMenuItem(Sender) do
  begin
    with ACanvas do
    begin
      Brush.Color := clMoneyGreen;
      Inc(ARect.Bottom,1);
      FillRect(ARect);
      Font.Color := clBlue;
      DrawText(ACanvas.Handle, PChar(Caption),Length(Caption),ARect,          DT_SINGLELINE or DT_VCENTER);
    end;
  end;
end;

end.

Answer 1

ARect OnAdvancedDrawItem的参数事件处理程序是 rcItem DRAWITEMSTRUCT的已传递给 WM_DRAWITEM信息。 documentation关于矩形有这样的说法:

A rectangle that defines the boundaries of the control to be drawn. This rectangle is in the device context specified by the hDC member. The system automatically clips anything that the owner window draws in the device context for combo boxes, list boxes, and buttons, but does not clip menu items. When drawing menu items, the owner window must not draw outside the boundaries of the rectangle defined by the rcItem member.

因此，尽管设备上下文没有被剪切到矩形，但您有责任不在其外部进行绘制。当您执行 Inc(ARect.Bottom,1); 时就会发生这种情况在填充矩形之前。