Can I safely implement `TFrame.Release`?

[piola]

Dear all,

unfortunately, TFrame doesn't implement the Release method as TForm does. TForm.Release does nothing more than

Code: [Select]

procedure TCustomForm.Release;
begin
  if Application <> nil then
    Application.ReleaseComponent(Self)
  else
    Free;
end;

As TFrame is also a TComponent descendant, I'd like to add the same Release method to my frames.

But I wonder whether I can do this safely because I assume that there's a good reason that TFrame lacks the Release method.

[jamie]

I don't think that is a good idea since that is only time delay free operation, but a Tframe is a child control of a form.

Unless you have your terminologies mixed up with other tools like MFC CframeWnd etc.

if you are referring to a TFORM, then yes it should be ok.

[marcov]

(note that disconnecting frames from forms, and e.g. moving to another is a bad idea.  Some components like Tmenu might hook into some global list to get events. At least it does in delphi)

[piola]

Well, I use frames to display different content on a TPanel. All I want to do is to free the panel if it's not needed anymore. But this situation can also occur if the user clicks the "close" button of the frame. And I cannot free the frame inside one of its event handlers. That's why I'd like to use Release.

[cdbc]

Hi
Use 'PostMessage' from 'LCLIntf' and LM_USER from 'LMessages', then you simply send a message to the ParentForm.Handle, e.g.:

Code: Pascal  [Select][+][-]

1. const
2.   LM_FRAMECLOSE = LM_USER + 5;
3. ...
4. // in ParentForm:
5. ...
6.   public
7.     procedure LMFrameClose(var Message: TLMessage); message LM_FRAMECLOSE;
8. ...
9. implementation
10.  
11. Procedure TForm1.LMFrameClose(var Message: TLMessage);
12. begin
13.   TFrame(Message.WParam).Free; // you can do checks if you like...
14. end;
15.  
16. ////////////////// and in your frame's close button do
17. procedure TMyFrame.btnCloseClick(Sender: TObject);
18. begin
19.   PostMessage(Form1.Handle,LM_FRAMECLOSE,ptrint(Self),-1);
20. end;
21.  

This way you avoid calling free in its own eventhandler...
Untested, just written here... 
Try it and see if it works for you.
Regards Benny

[piola]

Thank you. If it's recommended to prefer it to "Release", I'll do so. 

[Joanna]

Well, I use frames to display different content on a TPanel. All I want to do is to free the panel if it's not needed anymore. But this situation can also occur if the user clicks the "close" button of the frame. And I cannot free the frame inside one of its event handlers. That's why I'd like to use Release.

I have used frames a lot but I’ve never never heard of releasing them.
Why not have the button that closes the frame located in the parent of frame? Or Is there a way to call the event handler of frame’s parent to free it?

[MarkMLl]

I have used frames a lot but I’ve never never heard of releasing them.
Why not have the button that closes the frame located in the parent of frame? Or Is there a way to call the event handler of frame’s parent to free it?

I've used them a lot in the context of notebook tabs, without having given much thought to what is actually happening when a tab/page containing a frame is deleted.

MarkMLl

[Joanna]

I’m not familiar with notebook butI’ve used the frames inside of tcdpagecontrol and the frame is deleted when the page is destroyed. The funny thing is it was mistaking the page being destroyed as a page change event and I had to add extra code to check if the page was csdestroying.

[cdbc]

Hi
I've put together a little project, that shows 2 methods of doing what you're after:
1) method 1 uses 'PostMessage' to communicate
2) method 2 uses 'Application.QueueAsyncCall' to communicate
HTH
Regards Benny

[piola]

Thank you all! 

[egsuh]

Why not free? I made a simple demo projects and works fine.

Code: Pascal  [Select][+][-]

1. unit Unit1;
2.  
3. {$mode objfpc}{$H+}
4.  
5. interface
6.  
7. uses
8.    Classes, SysUtils, Forms, Controls, Graphics, Dialogs, StdCtrls;
9.  
10. type
11.  
12.    { TForm1 }
13.  
14.    TForm1 = class(TForm)
15.       Button1: TButton;
16.       procedure Button1Click(Sender: TObject);
17.       procedure FormCreate(Sender: TObject);
18.    private
19.  
20.    public
21.  
22.    end;
23.  
24. var
25.    Form1: TForm1;
26.  
27. implementation
28.  
29. uses unit2;
30.  
31. {$R *.lfm}
32.  
33. { TForm1 }
34.  
35. procedure TForm1.Button1Click(Sender: TObject);
36. begin
37.    Self.Free;
38. end;
39.  
40. procedure TForm1.FormCreate(Sender: TObject);
41. begin
42.    TFrame1.Create(self).parent := Self;
43. end;
44.  
45. end.
46.  
47. /////////////////////////// Frame unit  ///////////////////////////////
48.  
49. unit Unit2;
50.  
51. {$mode ObjFPC}{$H+}
52.  
53. interface
54.  
55. uses
56.    Classes, SysUtils, Forms, Controls, StdCtrls;
57.  
58. type
59.  
60.    { TFrame1 }
61.  
62.    TFrame1 = class(TFrame)
63.       Button1: TButton;
64.       procedure Button1Click(Sender: TObject);
65.    private
66.  
67.    public
68.  
69.    end;
70.  
71. implementation
72.  
73. {$R *.lfm}
74.  
75. { TFrame1 }
76.  
77. procedure TFrame1.Button1Click(Sender: TObject);
78. begin
79.    Self.Free;
80. end;
81.  
82. end.
83.