OpenCV3添加滑动条和鼠标事件到图形界面

鼠标事件和滑动条控制在计算机视觉和OpenCV中非常有用，使用这些控件，用户可以直接与图形界面交互，改变输入图像或者变量的属性值。

 /*
     In this section, we are going to introduce you to the concepts of adding slider and
 mouse events for basic interactions. To understand this correctly, we will create a small
 project, where we paint green circles in the image using the mouse events and blur the
 image with slider.
 */
 #include <opencv2/core.hpp>
 #include <opencv2/highgui.hpp>
 #include <opencv2/imgproc.hpp>
 using namespace cv;

 // Create a variable to save the position value in track
 int blurAmount = ;

 // Trackbar call back function
 static void onChange(int pos, void* userInput);

 // Mouse callback
 static void onMouse(int event, int x, int y, int, void* userInput);

 int main(int argc, const char** argv)
 {
     // Read images
     Mat boy = imread("../images/eating.jpg");

     // Create windows
     namedWindow("Boy");

     // Create a trackbar
     createTrackbar("Boy", "Boy", &blurAmount, , onChange, &boy);

     setMouseCallback("Boy", onMouse, &boy);

     // Call to onChange to init
     onChange(blurAmount, &boy);

     // wait app for a key to exit
     waitKey();

     // Destroy the windows
     destroyWindow("Boy");

     return ;
 }

 // Trackbar call back function
 static void onChange(int pos, void* userInput)
 {
     if (pos <= ) return;
     // Aux variable for result
     Mat imgBlur;

     // Get the pointer input image
     Mat* image = (Mat*)userInput;

     // Apply a blur filter
     blur(*image, imgBlur, Size(pos, pos));

     // Show the result
     imshow("Boy", imgBlur);
 }

 // Mouse callback
 static void onMouse(int event, int x, int y, int, void* userInput)
 {
     if (event != EVENT_LBUTTONDOWN) return;

     // Get the pointer input image
     Mat *image = (Mat*)userInput;

     // Draw circle
     circle(*image, Point(x, y), , Scalar(, , ), );

     // Call onChange to get blurred image
     onChange(blurAmount, image);
 }

程序运行效果如下：