Windows 7 Touch SDK - Get Gesture Information

下面的步驟說明如何取得Gestre的資料:

1. Set up a window for receiving gestures
如果要收到WM_GESTURE Message, 先確保程式中沒有呼叫RegisterTouchWindow.如下所示:

BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
    HWND hWnd;

    hInst = hInstance; // Store instance handle in our global variable.

    hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
       CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

    if (!hWnd)
    {
       return FALSE;
    }
         
    ShowWindow(hWnd, nCmdShow);
    UpdateWindow(hWnd);

    return TRUE;  
}


2. Handling Gesture Messages
和處理WM_TOUCH的方式一樣,你可以在WndProc的函數中取得WM_GESTURE Message, 如下所示:

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
int wmId, wmEvent;
PAINTSTRUCT ps;
HDC hdc;

 switch (message){
     case WM_GESTURE:
         /* Insert handler code here to interpret the gesture. */
         DecodeGesture(wParam, lParam);         
         break;
  }
}

3. Interpreting the Gesture Messages

可以利用GetGestureInfo函式將Gesture message(lParam)轉換成GESTUREINFO的資料結構. 其資料結構包含gesture的作用點和類型等, 如下所示:

void DecodeGesture(WPARAM wParam, LPARAM lParam)
{
    // Create a structure to populate and retrieve the extra message info.
    GESTUREINFO gi;  

    gi.cbSize = sizeof(GESTUREINFO);
    ZeroMemory(&gi, sizeof(GESTUREINFO));

    BOOL bResult = GetGestureInfo((HGESTUREINFO)lParam, &gi);

    if (bResult){
        // now interpret the gesture
        switch (gi.dwID){
           case GID_ZOOM:
               // Code for zooming goes here     
               break;
           case GID_PAN:
               // Code for panning goes here
               break;
           case GID_ROTATE:
               // Code for rotation goes here
               break;
           case GID_TWOFINGERTAP:
               // Code for two-finger tap goes here
               break;
           case GID_PRESSANDTAP:
               // Code for roll over goes here
               break;
           default:
               // You have encountered an unknown gesture
               break;
        }
    }else{
        DWORD dwErr = GetLastError();
        if (dwErr > 0){
            //GetDlgItem(IDC_STATIC)->SetWindowTextW(L"Error!");
        }
    }
    CloseGestureInfoHandle((HGESTUREINFO)lParam);
  }

參考資料 : http://msdn.microsoft.com/en-us/library/dd371578(VS.85).aspx