鼠标操作［OpenCV 笔记10］-白红宇

鼠标操作［OpenCV 笔记10］

阅读量：6673 次

发布时间：2019-06-25

本文共 3135 字，大约阅读时间需要 10 分钟。

void setMouseCallback(const string& winname, MouseCallback onMouse, void* userdata=0)

winname

窗口名字

onMouse

指定窗口每次鼠标事件发生的时候，被调用的函数指针。函数的原型应为void Foo(int event, int x, int y, int flags, void* param)。

event: 变量EVENT_XXX，例如
- EVNET_MOUSEMOVE: 鼠标移动消息
- EVENT_LBUTTONDOWN: 鼠标左键按下消息

x, y: 鼠标指针在图像坐标系中的坐标值（不是窗口坐标系）

flags: EVENT_FLAG的组合

param: 用户定义的传到SetMouseCallback函数调用的参数

userdata

用户定义的传递到回调函数的参数

示例

用鼠标在画框中华矩形，MouseEvent.cxx:

#include 
     
      #include 
      
       #define WINDOW_NAME "Painting Window"// global function declarationvoid on_MouseHandle( int event, int x, int y, int flags, void* param );void DrawRectangle( cv::Mat& img, cv::Rect box );void ShowHelpText();// global variablescv::Rect g_rectangle;bool g_bDrawingBox = false; // draw or notcv::RNG g_rng(12345);// mainint main( int argc, char** argv ){    // initialize parameters    g_rectangle = cv::Rect( -1, -1, 0, 0 );    cv::Mat srcImage( 600, 800, CV_8UC3 ), tempImage;    srcImage.copyTo( tempImage );        g_rectangle = cv::Rect( -1, -1, 0, 0 );    srcImage = cv::Scalar::all(0);        // create window    cv::namedWindow(WINDOW_NAME);        // set call back function    cvSetMouseCallback(WINDOW_NAME, on_MouseHandle, (void*)&srcImage);        while(1)    {        srcImage.copyTo(tempImage);                // show rectangle while the mouse moves        if (g_bDrawingBox)            DrawRectangle(tempImage, g_rectangle);                cv::imshow(WINDOW_NAME, tempImage);                if (cvWaitKey(10)==27) {            cv::imwrite("result.jpg", tempImage);            break; // Press ECS to exit.        }    }    return 0;}// mouse call back functionvoid on_MouseHandle( int event, int x, int y, int flags, void* param ){    cv::Mat& image = *(cv::Mat*) param;    switch (event) {        case cv::EVENT_MOUSEMOVE:            // if mouse moved and drawing flag is true, update the rectangle size            if (g_bDrawingBox) {                g_rectangle.width = x-g_rectangle.x;                g_rectangle.height = y-g_rectangle.y;            }            break;        case cv::EVENT_LBUTTONDOWN:            // if left button was clicked, prepare to draw rectangle            //  (set the flag as true and mark the start position)            {                g_bDrawingBox = true;                g_rectangle = cv::Rect( x, y, 0, 0 );  // mark the start point            }            break;        case cv::EVENT_LBUTTONUP:        {            g_bDrawingBox = false;            if (g_rectangle.width<0) {                g_rectangle.x += g_rectangle.width;                g_rectangle.width *= -1;            }            if (g_rectangle.height<0) {                g_rectangle.y += g_rectangle.height;                g_rectangle.height *= -1;            }            // draw            DrawRectangle(image, g_rectangle);        }            break;    }}// user defined function to draw rectanglevoid DrawRectangle( cv::Mat& img, cv::Rect box ){    // random color    cv::rectangle(img, box.tl(), box.br(), cv::Scalar(g_rng.uniform(0, 255), g_rng.uniform(0, 255), g_rng.uniform(0, 255)));}

结果图