OnMessage (C++)

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The following code handles a custom message that the application sends to itself when a file is ready for reading.


int WM_FILEREADY = WM_USER + 2000;

void __fastcall TForm1::Button1Click(TObject *Sender)
  const wchar_t *Path = L"../overview.rtf";
  PostMessage(Application->Handle, WM_FILEREADY, 0, int(Path));

__fastcall TForm1::TForm1(TComponent* Owner)
  : TForm(Owner)
  Application->OnMessage = AppMessage;

void __fastcall TForm1::AppMessage(tagMSG &Msg, bool &Handled)
  if (Msg.message == WM_FILEREADY)
	Memo1->Lines->LoadFromFile(String((wchar_t *)Msg.lParam));
    Handled = true;

    For all other messages, Handled remains False 
    so that other message handlers can respond.