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。
1 /* 2 In this section, we are going to introduce you to the concepts of adding slider and 3 mouse events for basic interactions. To understand this correctly, we will create a small 4 project, where we paint green circles in the image using the mouse events and blur the 5 image with slider. 6 */ 7 #include <opencv2/core.hpp> 8 #include <opencv2/highgui.hpp> 9 #include <opencv2/imgproc.hpp> 10 using namespace cv; 11 12 // Create a variable to save the position value in track 13 int blurAmount = 15; 14 15 // Trackbar call back function 16 static void onChange(int pos, void* userInput); 17 18 // Mouse callback 19 static void onMouse(int event, int x, int y, int, void* userInput); 20 21 int main(int argc, const char** argv) 22 { 23 // Read images 24 Mat boy = imread("../images/eating.jpg"); 25 26 // Create windows 27 namedWindow("Boy"); 28 29 // Create a trackbar 30 createTrackbar("Boy", "Boy", &blurAmount, 30, onChange, &boy); 31 32 setMouseCallback("Boy", onMouse, &boy); 33 34 // Call to onChange to init 35 onChange(blurAmount, &boy); 36 37 // wait app for a key to exit 38 waitKey(0); 39 40 // Destroy the windows 41 destroyWindow("Boy"); 42 43 return 0; 44 } 45 46 // Trackbar call back function 47 static void onChange(int pos, void* userInput) 48 { 49 if (pos <= 0) return; 50 // Aux variable for result 51 Mat imgBlur; 52 53 // Get the pointer input image 54 Mat* image = (Mat*)userInput; 55 56 // Apply a blur filter 57 blur(*image, imgBlur, Size(pos, pos)); 58 59 // Show the result 60 imshow("Boy", imgBlur); 61 } 62 63 // Mouse callback 64 static void onMouse(int event, int x, int y, int, void* userInput) 65 { 66 if (event != EVENT_LBUTTONDOWN) return; 67 68 // Get the pointer input image 69 Mat *image = (Mat*)userInput; 70 71 // Draw circle 72 circle(*image, Point(x, y), 10, Scalar(0, 255, 0), 3); 73 74 // Call onChange to get blurred image 75 onChange(blurAmount, image); 76 }
程序运行效果如下：
