在Qt应用程序中接收WM_COPYDATA消息

Question

我正在开发一个仅限Windows的Qt应用程序,我需要从Microsoft OneNote插件接收数据.该插件是用C#编写的,可以发送WM_COPYDATA消息.如何在C++ Qt应用程序中收到这些消息？

我需要:

• 能够指定一个窗口注册的"类名",就像它调用RegisterClassEx一样,这样我就可以确保插件将WM_COPYDATA消息发送到正确的窗口.
• 可以访问消息ID以检查它是否为WM_COPYDATA和lParam,其中包含带有实际数据的COPYDATASTRUCT.此信息在WndProc中传递,但我无法找到可以拦截这些消息的钩子.

Answer 1

这可以在Qt内处理:

1. 使用将捕获WM_COPYDATA消息的类扩展QWidget:

       class EventReceiverWindow : public QWidget
   {
       Q_OBJECT
   public:
       EventReceiverWindow();
   
   signals:
       void eventData(const QString & data);
   
   private:
       bool winEvent ( MSG * message, long * result );
   };
   

2. 生成一个GUID以设置为QWidget的windowTitle:

   EventReceiverWindow::EventReceiverWindow()
   {
       setWindowTitle("ProjectName-3F2504E0-4F89-11D3-9A0C-0305E82C3301::EventReceiver");
   }
   

3. 覆盖winEvent以处理WM_COPYDATA结构并在获取时发出信号:

   bool EventReceiverWindow::winEvent ( MSG * message, long * result )
   {
           if( message->message == WM_COPYDATA ) {
               // extract the string from lParam
               COPYDATASTRUCT * data = (COPYDATASTRUCT *) message->lParam;
   
               emit eventData(QString::fromAscii((const char *)data->lpData, data->cbData));
   
               // keep the event from qt
               *result = 0;
               return true;
           }
   
           // give the event to qt
           return false;
   }
   

4. 在另一个类中,您可以使用此类来接收消息字符串:

   EventReceiverWindow * eventWindow = new EventReceiverWindow;
   QObject::connect(eventWindow, SIGNAL(eventData(const QString &)), this, SLOT(handleEventData(const QString &)));
   

   ...

   void OneNoteInterface::handleEventData(const QString &data)
   {
       qDebug() << "message from our secret agent: " << data;
   }
   

5. 在发送消息的程序中,只需通过唯一的窗口标题找到窗口.这是C#中的一个例子:

   private struct COPYDATASTRUCT
   {
       public IntPtr dwData;
       public int cbData;
       [MarshalAs(UnmanagedType.LPStr)]
       public string lpData;
   }
   
   private const int WM_COPYDATA = 0x4A;
   
   [DllImport("user32.dll", EntryPoint = "FindWindow", SetLastError = true)]
   static extern IntPtr FindWindowByCaption(IntPtr ZeroOnly, string lpWindowName);
   
   [DllImport("User32.dll", EntryPoint = "SendMessage")]
   private static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, ref COPYDATASTRUCT lParam);
   
   private void sendMessageTo(IntPtr hWnd, String msg)
   {
       int wParam = 0;
       int result = 0;
   
       if (hWnd != IntPtr.Zero )
       {
           byte[] sarr = System.Text.Encoding.Default.GetBytes(msg);
           int len = sarr.Length;
           COPYDATASTRUCT cds;
           cds.dwData = IntPtr.Zero;
           cds.lpData = msg;
           cds.cbData = len + 1;
           result = SendMessage(hWnd, WM_COPYDATA, wParam, ref cds);
       }
   }
   

   然后你可以:

   IntPtr hwnd = FindWindowByCaption(IntPtr.zero, "ProjectName-3F2504E0-4F89-11D3-9A0C-0305E82C3301::EventReceiver");
   sendMessageTo(hwnd, "omg hai");