(C++ VCL) Make your own user messages

To generate a unique messsage number use the function RegisterWindowMessage.

Below is an example to trap all windows messages and to generate and send your own user message.

Unit1.cpp

include <vcl.h>

pragma hdrstop


include "Unit1.h"

//---------------------------------------------------------------------------
pragma package(smart_init)

pragma resource "*.dfm"

TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
  : TForm(Owner), WM_DO_STUFF(RegisterWindowMessage("BILDERBIKKEL_DO_STUFF"))
{
  doHandle = true;
  Application->OnMessage = ApplicationEvents1->OnMessage;
}
//---------------------------------------------------------------------------
void __fastcall TForm1::ApplicationEvents1Message(tagMSG &Msg,
      bool &Handled)
{
  if (Msg.message==0 || doHandle==false) return;
  String output = IntToStr(Msg.message) + '\t' + IntToStr(Msg.lParam) + '\t' + IntToStr(Msg.wParam);
  if (Msg.message==this->WM_DO_STUFF)
  {
    Handled = true;
    output = "*****\t" + output;
  }
  RichEdit1->Lines->Add(output);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *)
{
  PostMessage(0,this->WM_DO_STUFF,69,69);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button2Click(TObject *)
{
  doHandle = !doHandle;
}
//---------------------------------------------------------------------------

Unit1.h

//---------------------------------------------------------------------------
ifndef Unit1H

define Unit1H

//---------------------------------------------------------------------------
include <Classes.hpp>

include <Controls.hpp>

include <StdCtrls.hpp>

include <Forms.hpp>

include <AppEvnts.hpp>

include <ComCtrls.hpp>

include <ExtCtrls.hpp>

//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published:	// IDE-managed Components
  TApplicationEvents *ApplicationEvents1;
  TRichEdit *RichEdit1;
  TPanel *Panel1;
  TButton *Button1;
  TButton *Button2;
  void __fastcall ApplicationEvents1Message(tagMSG &Msg, bool &Handled);
  void __fastcall Button1Click(TObject *Sender);
  void __fastcall Button2Click(TObject *Sender);
private:	// User declarations
  bool doHandle;
public:		// User declarations
  const UINT WM_DO_STUFF;
  __fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
endif

(C++ VCL) Make your own user messages

Unit1.cpp

Unit1.h

Code links

Links