c++ - Delphi XE - 无法从系统菜单中删除项目

Question

我有以下代码，它正在向系统菜单添加项目。我的问题是 DeleteMenu(SysMenu, cLANGMENU, MF_BYCOMMAND) 没有删除添加到系统菜单的弹出菜单。我不明白的是为什么要为添加的项目(扫描组件)工作，而不是为“程序语言”工作

procedure TForm1.Button1Click(Sender: TObject);
const aBaseItem : string = 'Programm-Sprache';
      cSepSYSTEM_MENU = wm_user + 100;
      cScanCompSystemMenu = wm_user + 101;
      cLANGMENU = wm_user + 102;
      SC_ITEM = $FF00;
var
  MenuItemInfo: TMenuItemInfo;
  PopupMenu: HMENU;
  Result: Boolean;
  SysMenu: HMenu;
  iPos, NumItems : Integer;
  wTemp1, wtemp2 : string;
  Buffer: array[0..79] of Char;
begin
  {Create the popup menu}
  PopupMenu := CreatePopupMenu;
  {Insert an item into it}
  for iPos := 5 downto 0 do
  begin
    FillChar(MenuItemInfo, SizeOf(MenuItemInfo), iPos);
      with MenuItemInfo do
      begin
        cbSize := SizeOf(MenuItemInfo);
        fMask := MIIM_TYPE or MIIM_ID;
        fType := MFT_STRING;
        wID := SC_ITEM + iPos;
        dwTypeData := PChar(inttostr(iPos));
        cch := Length(dwTypeData) * 2 + 2; //4; {'Item' is 4 chars}
      end;
    Result := InsertMenuItem(PopupMenu, 0, True, MenuItemInfo);
    Assert(Result, 'InsertMenuItem failed');
  end;

  SysMenu := GetSystemMenu(Handle, False);
  //why this isn't working???
  if not DeleteMenu(SysMenu, cLANGMENU, MF_BYCOMMAND) then
   begin
     ShowMessage('System Error Message: '+ SysErrorMessage(GetLastError)) ;
     //error message is - operation completed succesfully
   end;

  {Insert the popup into the system menu}
  FillChar(MenuItemInfo, SizeOf(MenuItemInfo), 0);
  with MenuItemInfo do
  begin
    cbSize := SizeOf(MenuItemInfo);
    fMask := MIIM_SUBMENU or MIIM_TYPE or MIIM_ID;
    fType := MFT_STRING;
    hSubMenu := PopupMenu;
    wId := cLANGMENU;
    dwTypeData :=  PChar('Test');//Before editing the question it was Program Language
    cch := Length(dwTypeData) * 2 + 2; //7; {'SubMenu' is 7 chars}
  end;

  Assert(SysMenu <> 0);
  Result := InsertMenuItem(SysMenu, GetMenuItemCount(SysMenu), True, MenuItemInfo);
  Assert(Result, 'InsertMenuItem failed');


      SysMenu := GetSystemMenu(Handle, False);
  //delete menu if exists - this is working
  DeleteMenu(SysMenu,cSepSYSTEM_MENU,MF_SEPARATOR);
  DeleteMenu(SysMenu,cScanCompSystemMenu,MFT_STRING);
  //add new ones
  InsertMenu(SysMenu, Word(-1), MF_SEPARATOR, cSepSYSTEM_MENU, '');
  FillChar(MenuItemInfo, SizeOf(TMenuItemInfo), #0);
  with MenuItemInfo do
   begin
   cbSize := SizeOf(TMenuItemInfo);
    fMask := MIIM_TYPE or MIIM_ID or MIIM_STATE;
    fType := MFT_STRING;
    wId := cScanCompSystemMenu;
    dwTypeData := PChar('Scan components');
    cch := Length('Scan components');
   end;
  Result := InsertMenuItem(SysMenu, GetMenuItemCount(SysMenu), True, MenuItemInfo);
  Assert(Result, 'InsertMenuItem failed');
end;

LE: 这段代码运行了几次，所以我需要删除每次添加的项目。LE2:即使这段代码是用 Delphi(Object Pascal) 编写的，它也会从 Windows 调用 WinApi 函数。也许有人对此进行了大量工作并且是 C/C++ 程序员可以提供帮助。

Answer 1

The documentation表示需要设置miim_ID标志才能使用wID。没有它，操作系统会忽略该字段，因此您创建的菜单项不会获得您指定的 ID 值。因此，您进一步尝试通过该 ID 引用该项目将失败。

您在添加“扫描组件”项时设置了该标志，但在“测试”项中省略了它。

您可以通过调用 GetSystemMenu(Handle, True) 让自己更轻松。这将在您每次调用时重置菜单，因此您不必撤消任何先前的自定义设置。