forms - 如何知道打开了哪个表单以及如何关闭它？

Question

我有一个TAction.OnExecute从我的主窗体触发的事件处理程序 FormPrincipal，它会打开其他窗体。

procedure TFormPrincipal.AbreFormBancoExecute(Sender: TObject);
begin
   Formbanco              := Tformbanco.Create(self);
   Formbanco.Parent       := PanelCorpo;
   Formbanco.Align        := alclient;
   Formbanco.BorderIcons  := [];
   Formbanco.Show;
   Formbanco.BorderStyle  := bsNone;
   Formbanco.SetFocus;
end;

一旦我有几个表格，在触发OnExecute打开另一个表格之前如何知道打开了哪个表格以及如何关闭它？

=========== 终于按我的预期工作了======= 主要形式是form1，我从中调用form2和form3。在 form1 中，我有一个 panel1，它是 form2 和 form3 的父级。见 form1 代码： ... var Form1: TForm1;

implementation
{$R *.dfm}
uses unit2, unit3;

procedure Tform1.CloseActiveForm (Formname : string);
// Free memory allocated to the current form , set it to nil
// I'll have to find a better way to perform FreeanNil without
// use many IFs command
begin
     if Formname  = 'form2' then FreeAndnil(Form2) else
         if Formname = 'form3' then FreeandNil(Form3);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
       CloseActiveForm(Edit1.Text); //Edit1 has the current active form name
       if form2 = nil  then
       begin
              Application.CreateForm(Tform2,Form2);
              Form2.Parent  := Panel1;
              Form2.Align   := alclient;

              Form2.Show;
              Form2.BorderStyle :=  bsnone;
              Form2.SetFocus;
              Form2.OnActivate(Sender); //Method Show blocks Activate event
      end;    
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
       CloseActiveForm(Edit1.Text); //Edit1 has the current active form name
       if form3 = nil  then
        begin
              Application.CreateForm(Tform3,Form3);
              Form3.Parent  := Panel1;
              Form3.Align   := alclient;

              Form3.Show;
              Form3.BorderStyle := bsnone;
              Form3.SetFocus;
              Form3.OnActivate(Sender);  //Method Show blocks Activate event             
        end;
end;

procedure TForm1.FormActivate(Sender: TObject);
begin
   Edit1.Text := Screen.ActiveForm.Name;
end;
end.

2）form2和form3中的代码（认为form3是相同的）

...

var
  Form2: TForm2;

implementation

{$R *.dfm}
uses unit1;

procedure TForm2.Button1Click(Sender: TObject);
begin
       Edit2.Text := Screen.ActiveForm.Name;
end;

procedure TForm2.FormActivate(Sender: TObject);
begin
     setfocus;
     Edit1.Text       := Form2.Name;
     Form1.Edit1.Text := Form2.Name; //set form name 

// the property Screen.ActiveForm.Name if used here, will always presents
// form1 name (main form) because this form2 is set to a parent panel 
// in form1
end;  

end.

Answer 1

如果表单存在，则销毁它并创建它的新实例。

procedure TFormPrincipal.AbreFormBancoExecute(Sender: TObject);

  procedure CreateFormbanco;
    begin
    Formbanco               := TFormbanco.Create(self);
    Formbanco.Parent       := PanelCorpo;
    Formbanco.Align        := alclient;
    Formbanco.BorderIcons  := [];
    Formbanco.BorderStyle  := bsNone;
    Formbanco.Show;
    Formbanco.SetFocus;
    Formbanco.OnDestroy    := FormDestroyEvent;
    end;

begin
if not Assigned(Formbanco) then
  begin
  CreateFormbanco;
  end
else
  begin
  Formbanco.Destroy;
  CreateFormbanco;
  end;

procedure TFormPrincipal.FormDestroyEvent(Sender: TObject);
begin
  Formbanco := nil;
end;

此代码将检查是否Formbanco存在，如果存在，它将销毁它并创建它的新实例，否则它将创建一个新实例。

编辑：创建不同的表单并使用上面的代码，只需将其更改Formbanco为TFormbanco他们尊重的新表单名称。