原创 第4节 利用Labwindows/CVI软件对摄像头的控制

         接着，为这面板上的控件进行编辑。显示面板采用的是CANVAS控件，定义变量命为：CANVAS_DISPLAY，用于后面显示时调用，“开始视频”控件定义函数名：StartCB，“退出视频”控件函数名：stopCB，“保存图像”控件函数名：recordbmp，“录像”控件函数名：recordstream，“停止录像”控件函数名：stopstream，显示模式控件采用的Ring控件，定义函数名：method。最后退出面板控件定义函数QuitCallback。在面板的最左边空白处，添加了三个canvas控件，用于在保存图像时，对新保存的三个图像进行显示。
然后为工程新建一个c源文件或通过自动方式来生成一个c源文件。一般使用自动方式，即在uir文件处，通过“Code->Generate->All code”为此面板自动生成c文件代码。保存c源文件为camera.c。接着为这些函数添加代码：
  (1)为“开始视频”控件函数startCB添加代码如下：
        int Display_width;
        int Display_height;
        int Display_top;
        int Display_left;
        switch (event)
         {
          case EVENT_COMMIT:
          //获得面板句柄，用于在调用摄像头函数时，需要使用的句柄handle
         GetPanelAttribute (panelHandle, ATTR_SYSTEM_WINDOW_HANDLE, &handle);
         //获得屏幕中图像要显示的位置
         GetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_LEFT, &Display_left);
         GetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_TOP, &Display_top);
         GetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_HEIGHT, &Display_height);
         GetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_WIDTH, &Display_width);
        //打开摄像头
        result = capCreateCaptureWindowA("",WS_CHILD | WS_VISIBLE ,Display_left,Display_top,Display_width,Display_height,handle,0);
        //设置摄像头函数
       SendMessage((HWND)result, WM_CAP_SET_CALLBACK_VIDEOSTREAM, 0, 0);
       SendMessage((HWND)result, WM_CAP_SET_CALLBACK_ERROR, 0, 0);
       SendMessage((HWND)result, WM_CAP_SET_CALLBACK_STATUSA, 0, 0);
       SendMessage((HWND)result, WM_CAP_DRIVER_CONNECT, 0, 0);
       SendMessage((HWND)result, WM_CAP_SET_SCALE, 1, 0);
      SendMessage((HWND)result, WM_CAP_SET_PREVIEWRATE, 66, 0);
      SendMessage((HWND)result, WM_CAP_SET_OVERLAY, 1, 0);
      SendMessage((HWND)result, WM_CAP_SET_PREVIEW, 1, 0);
      break;
    }
   return 0;

  (2)为“停止视频”控件函数stopCB添加源代码如下：
     if (result != 0)  //如果有摄像头开启
       {
         //发送一个断开连接命令
         SendMessage((HWND)result, WM_CAP_DRIVER_DISCONNECT, 0, 0);
        }
(3)为“保存图像”控件函数recordbmp添加源代码如下：
    //定义BMP位图ID号
     int bitmapID;
     //定义文件存储路径
     char path[MAX_PATHNAME_LEN];
     //定义静态变量，设置循环次数
     static int i;
     i = 0;
     switch (event)
      {
        case EVENT_COMMIT:
        //保存位图
        if (FileSelectPopup ("", "*.bmp", "*.bmp", "保存", VAL_SAVE_BUTTON, 0, 0, 1, 1, path) > 0)
        {
           SendMessage((HWND)result,WM_CAP_SAVEDIB,0,(LPARAM)path);
           //获得BMP位图ID
           GetBitmapFromFile (path, &bitmapID);
           switch (i)
           {
                //设置三个位图浏览器
                case 0:
                    CanvasDrawBitmap (panelHandle, PANEL_CANVAS_SNAP0, bitmapID, VAL_ENTIRE_OBJECT, VAL_ENTIRE_OBJECT);
                    break;
                  case 1:
                    CanvasDrawBitmap (panelHandle, PANEL_CANVAS_SNAP1, bitmapID, VAL_ENTIRE_OBJECT, VAL_ENTIRE_OBJECT);
                    break;
                  case 2:
                    CanvasDrawBitmap (panelHandle, PANEL_CANVAS_SNAP2, bitmapID, VAL_ENTIRE_OBJECT, VAL_ENTIRE_OBJECT);
                    break;
           }
             //删除BMP位图ID
           DiscardBitmap (bitmapID);
          //循环累加，共三次，三次之后回零
          i++;
          if (i == 3)
             {
               i = 0;
              }
          }
            break;
    }
    return 0;
(4)为“开始录像”控件函数recordstream添加源代码如下：
char path[MAX_PATHNAME_LEN];  
    switch (event)
    {
        case EVENT_COMMIT:
            //保存录像
             if (FileSelectPopup ("", "*.avi", "*.avi", "保存", VAL_SAVE_BUTTON, 0, 0, 1, 1, path) > 0)
                {
    SendMessage((HWND)result,WM_CAP_FILE_SET_CAPTURE_FILEA,0,(LPARAM)path);
                  SendMessage((HWND)result, WM_CAP_SEQUENCE, 0, 0);
                }
            break;
    }
    return 0;
(5)为“停止录像”控件函数stopstream添加源代码如下：
    switch (event)
    {
        case EVENT_COMMIT:
//发送WM_CAP_STOP停止命令
            SendMessage((HWND)result, WM_CAP_STOP, 0, 0);        
           break;
    }
    return 0;
}
(6)为“显示模式”控件添加函数method代码如下：
//获得制式种类
GetCtrlVal (panelHandle, PANEL_RING, &kind);
switch (kind)
   {
     case 0:
        //160*120制式
        SetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_WIDTH, 160);
        SetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_HEIGHT, 120);
     break;
     case 1:
        //1176*144制式
        SetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_WIDTH, 176);
        SetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_HEIGHT, 144);
     break;
     case 2:
        //320*240制式
        SetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_WIDTH, 320);
        SetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_HEIGHT, 240);
     break;
     case 3:
        //352*288制式
        SetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_WIDTH, 352);
        SetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_HEIGHT, 288);
     break;
     case 4:
        //1默认制式
        SetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_WIDTH, 592);
        SetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_HEIGHT, 333);
     break;
    }
//获得屏幕中图像要显示的位置
   GetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_LEFT, &left);
   GetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_TOP, &top);
   GetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_HEIGHT, &height);
   GetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_WIDTH, &width);
   //重新定位
   SetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_TOP, (333-height)/2+55);
   SetCtrlAttribute (panelHandle, PANEL_CANVAS_DISPLAY, ATTR_LEFT, (592-width)/2+53);
   //断开连接
   SendMessage((HWND)result, WM_CAP_DRIVER_DISCONNECT, 0, 0);
   //调用开始按钮事件
   startCB(panel, PANEL_CANVAS_DISPLAY, EVENT_COMMIT, NULL, 0, 0);
三、总结
        采用Labwindows/CVI软件实现了摄像头的视频和录像功能，而且可以选择不同的显示分辨率，设计面板较为简单且美观，控件使用方面快捷！主要使用到得函数来自于动态链接库avicap32.dll中的摄像头开启函数capCreateCaptureWindowA，然后通过windows.h声明的SendMessage函数来发送摄像头的显示相关的命令来设置摄像头。