OpenCV_用鼠标在窗口画方形

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 1 void my_mouse_callback(int event,int x,int y,int flags,void* param);
 2 
 3 CvRect box;
 4 
 5 bool drawing_box=false;
 6 
 7 // a little subroutine to draw a box on to an image
 8 void draw_box(IplImage* img,CvRect rect)
 9 {
10     cvRectangle(img,cvPoint(box.x,box.y),cvPoint(box.x+box.width,box.y+box.height),cvScalar(0xff,0x00));
11 }
12 
13 
14 int main(int argc,char** argv)
15 {  
16     box=cvRect(-1,-1,0,0);
17 
18     IplImage* image =cvCreateImage(cvSize(200,200),IPL_DEPTH_8U,3);
19 
20     cvZero(image);
21 
22     IplImage* temp =cvCloneImage(image);
23 
24     cvNamedWindow("Box example");
25     cvNamedWindow("image");
26     cvSetMouseCallback("Box example",my_mouse_callback,(void*) image);
27 
28     while(1){
29         cvCopyImage(image,temp); 
30     /*    if(drawing_box) draw_box(image,box);
31         cvShowImage("image",image);*/
32         if(drawing_box) draw_box(temp,box);
33         cvShowImage("Box example",temp);
34     
35         if(cvWaitKey(15)==27) break;
36     }
37 
38     cvReleaseImage(&image);
39     cvReleaseImage(&temp);
40     cvDestroyWindow("Box example");
41     cvDestroyWindow("image");
42 
43     return 0;
44 
45     
46 }
47 //event 指定鼠标事件类型
48 //int x y 为事件发生时鼠标位置的x,y坐标值。
49 //第四个参数flags 制定了事件在事件发生时的不同状态
50 void my_mouse_callback(int event,int x,int y,int flags,void* param)
51 {
52     IplImage* image= (IplImage*) param;
53     switch(event)
54     {
55     case CV_EVENT_MOUSEMOVE:
56         {
57             if(drawing_box)
58             {
59                 box.width=x-box.x;
60                 box.height=y-box.y;
61             }
62         }
63         break;
64     case CV_EVENT_LBUTTONDOWN:
65         {
66             drawing_box=true;
67             box=cvRect(x,y,0,0);
68         }
69         break;
70     case CV_EVENT_LBUTTONUP:
71         {
72             drawing_box=false;
73             if(box.width<0)
74             {
75                 box.x=box.x+box.width;
76                 box.width*=-1;
77 
78             }
79             if(box.height<0)
80             {
81                 box.y+=box.height;
82                 box.height*=-1;
83             }
84             draw_box(image,box);
85         }
86         break;
87     }
88 }