C / C++ / MFC

LRESULT CALLBACK WindowProc (HWND window_handle, UINT message, WPARAM w_param, LPARAM l_param)
{
   LRESULT result (0);

   switch (message)
   {
      case WM_DESTROY:
         PostQuitMessage (0); 
         break;

      case WM_SIZE:
         {
            switch (w_param)
            {
               case SIZE_MAXIMIZED:
               case SIZE_RESTORED:
               {
                   window_width = (float)(LOWORD (l_param));
                   window_height = (float)(HIWORD (l_param));
               }
               break;
            }
         }
         break;

        case WM_INPUT:
        {		
            UINT data_size (0);
            GetRawInputData ((HRAWINPUT)l_param, RID_INPUT,NULL, &data_size, sizeof (RAWINPUTHEADER));
            
            vector<BYTE> data;
            data.resize (data_size);

            if (GetRawInputData ((HRAWINPUT)l_param, RID_INPUT, &data [0], &data_size, sizeof(RAWINPUTHEADER)) != data_size)
            {
                OutputDebugString(TEXT("GetRawInputData does not return correct size !\n")); 
                break;
            }
              
            RAWINPUT* raw = (RAWINPUT*)(&data [0]);
           
            if (raw->header.dwType == RIM_TYPEHID) 
            {
                RID_DEVICE_INFO device_info;
	       UINT info_size = sizeof(RIDI_DEVICEINFO);
	       GetRawInputDeviceInfo ( raw->header.hDevice, RIDI_DEVICEINFO, (LPVOID)&device_info, &info_size);
				   
	       if(device_info.hid.dwVendorId = 0x0457)
	       {
     	           DigitizerData* result = (DigitizerData*)(raw->data.hid.bRawData);
					
                    g_CurUsedSize = result->active_touch_count;	
				
         	           BOOL bGot = FALSE;

		  if(g_CurUsedSize <= 5)
		  {
		      if(g_PreUsedSize <  g_CurUsedSize)
		      {
		        PlaySound(TEXT("C:\\default.wav"),NULL, SND_FILENAME|SND_ASYNC );
	              }
	          }
		  bGot = TRUE;
	       }
	   }

	   if(bGot)
	   {
              g_PreUsedSize =  g_CurUsedSize;
	   }
         }				 
     }
     result = DefWindowProc (window_handle, message, w_param, l_param);
 }
         break;

      default: 
         result = DefWindowProc (window_handle, message, w_param, l_param);
         break;
   }
   return result;
}