在线求解——MDI子窗体的Show

Question

我通过Action控制MainForm窗体(MDIForm)的Show MDI子窗体，但是我不知道怎样处理这个问题，就是当我打开某个子窗体后就不能再次打开这个子窗体，请问应该怎么做？我尝试过遍例Screen.Components，若果Components[i] 为某子窗体，则Action的Enable为False,可是没有效果，该怎么办？求助……

Answer 1

procedure Tfmain.OpenForm(FormClass: TFormClass; var fm; AOwner:TComponent);
var
  i: integer;
  Child:TForm;
begin
  for i := 0 to Screen.FormCount -1 do
      if Screen.Forms[i].ClassType=FormClass then
      begin
        Child:=Screen.Forms[i];
        if Child.WindowState=wsMinimized then
           ShowWindow(Child.handle,SW_SHOWNORMAL)
        else
           ShowWindow(Child.handle,SW_SHOWNA);
        if (not Child.Visible) then Child.Visible:=True;
        Child.BringToFront;
        Child.Setfocus;
        TForm(fm):=Child;
        exit;
      end;
  Child:=TForm(FormClass.NewInstance);
  TForm(fm):=Child;
  Child.Create(AOwner);
end;procedure Tfmain.form2menuClick(Sender: TObject);
begin
   OpenForm(Tform2,form2, self);
end;

Answer 2

//菜单响应
procedure TFormMain.SetActiveClientForm(AFormClass: TFormClass);
var
   bFoundChild : Boolean;
   I : integer;
begin
  Screen.Cursor := crAppStart;
  try
  
  
       bFoundChild := False;
       for I := 0 to MDIChildCount-1 do
       begin
           if(MDIChildren[I].ClassType = AFormClass) then
           begin
                MDIChildren[I].BringToFront;
                bFoundChild := True;
                Break;
           end;
       end;
       if(not bFoundChild) then
                  FActiveClinetForm := AFormClass.Create(Self);
            //AddOrSetActiveFormToMenuMain;
  end;  finally
     Screen.Cursor := crDefault;
     application.ProcessMessages;
  end;
end;
procedure TFormMain.Action1Excute(....
begin
  SetActiveClientForm(TForm1); 
end;
procedure TFormMain.Action2Excute(....
begin
  SetActiveClientForm(TForm1); 
end;

Answer 3

在子窗体释放时设置(close): action:=cafree;
                           子窗体：=nil;即可。