Menu messages

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Jon © (2007-11-24 01:50) [0]

Why can I not receive messages for menu"s?
I want to trap and process WM_NC* messages for PMenu.

unit PopupEx; interface uses Windows, KOL, Messages; type PPopupMenuEx = ^TPopupMenuEx; TPopupMenuEx = object(TControl) public destructor Destroy; virtual; end; function NewPopupMenuEx(AParent: PControl; MaxCmdReserve: DWORD; const Template: array of PKOLChar; aOnMenuItem: TOnMenuItem): PPopupMenuEx; implementation function MenuWndProc(Sender: PControl; var Msg: TMsg; var Rslt: Integer): Boolean; begin Result := False; end; function NewPopupMenuEx; begin Result := PPopupMenuEx(NewMenu(AParent,MaxCmdReserve,Template,aOnMenuItem)); // Result.AttachProc(@MenuWndProc); // <------ ERROR!! end; destructor TPopupMenuEx.Destroy; begin inherited; end; end.

If I uncomment the line with AttachProc, a runtime error is generated.

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Vladimir Kladov © (2007-11-24 20:11) [1]

Self is absent. Event must be a method, not a regular procedure, so if you use regular procedure in place of the method of the object, you must add (the first) parameter, which is passed for objects" methods hidden.

A bit strange idea to inherit new successor from the TControl but name it as it would be a menu.

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Jon © (2007-11-24 21:42) [2]

Thanks Vladimir.

> Self is absent.
I did not think that AttachProc needs self. I know that MakeMethod requires it.
Code changed to:
function MenuWndProc(Dummy: Pointer; Sender: PControl; var Msg: TMsg; var Rslt: Integer): Boolean;
but still the same error.

> A bit strange idea to inherit new successor from the TControl
> but name it as it would be a menu.

If I inherit from PMenu then I am unable to use AttachProc.

I can find no other way to receive WM_NC* messages for a menu.

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Vladimir Kladov © (2007-11-24 22:19) [3]

Oh, beg oardon! It is my error, I forget it (far away i used it).

But your error seems in inheriting from incorrect domain. Your TPopupMenuEx is just declared as a successor of TControl, but really it is created calling NewMenu, so TMenu object is created (and even not your TPopupMenuEx). Typecast does not make it a TPopupMenuEx, it just instructs the compiler to think that it is of TPopupMenuEx type derived from TControl, but physically it is still a TMenu object. (Hm, yor destructor also will never be called, too).

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Jon © (2007-11-24 23:17) [4]

It looks like I still have a lot to learn. Thank you for your words of wisdom.
I studied examples but obviously did not understand - I shall look again.
Do you recommend a better way to receive required messages?
I can find no OnMessage event for PMenu.

Menu is not a window in a common sense. It should not receive any messages itself. But the owning window can receive some messages like WM_ENTERMENULOOP, WM_EXITMENULOOP, WM_COMMAND, WM_MENUCOMMAND... All this is defined in MSDN very detailed.

Understood. I solved it using a hook. Your information helped steer me in the right direction. Thank you.

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