Opencv之鼠标事件/窗口交互详解
Opencv之鼠标事件/窗口交互详解
平时在做图像处理demo或者研究测试算法时，经常会用到
imshow和鼠标的交互，比如在显示图像的窗口上画点、线、圆、矩形、多边形等操作，故在此做出用法总结。
1.opencv API及参数介绍
cv::setMouseCallback(const string& windowname, MouseCallback onMouse, void* userdata=0)
{
....
}
// windowname: 要操作的窗口名称
// onMouse: 鼠标事件函数，鼠标事件发生以后，要执行的回调函数。函数原型是
// void onMouse(int event, int x, int y, int flags, void * para)
// userdata: 回调函数的参数
鼠标回调函数介绍：
void onMouse(int event, int x, int y, int flags, void *para)
// int event: 鼠标事件，见后续说明
// x, y 是鼠标在图像坐标系中的坐标
// flags :
// para： 是用户传递到回调函数中的参数
截取感兴趣区域ROI：
cv::selectROIs("MultiTracker", frame, bboxes_, showCrosshair, fromCenter);
// “MultiTracker” : windowsName
// frame: 当前画面；格式为cv::Mat
// bboxes： 要存储的框框格式为：std::vector涉及的相关参数：
// EVENT的参数定义
enum
{
CV_EVENT_MOUSEMOVE =0,//滑动
CV_EVENT_LBUTTONDOWN =1,//左键点击
CV_EVENT_RBUTTONDOWN =2,//右键点击
CV_EVENT_MBUTTONDOWN =3,//中键点击
CV_EVENT_LBUTTONUP =4,//左键放开
CV_EVENT_RBUTTONUP =5,//右键放开
CV_EVENT_MBUTTONUP =6,//中键放开
CV_EVENT_LBUTTONDBLCLK =7,//左键双击
CV_EVENT_RBUTTONDBLCLK =8,//右键双击
CV_EVENT_MBUTTONDBLCLK =9//中键双击
};
enum
{
CV_EVENT_FLAG_LBUTTON =1,//左键拖拽
CV_EVENT_FLAG_RBUTTON =2,//右键拖拽
CV_EVENT_FLAG_MBUTTON =4,//中键拖拽
CV_EVENT_FLAG_CTRLKEY =8,//按CTRL不放
CV_EVENT_FLAG_SHIFTKEY =16,//按SHIFT不放
CV_EVENT_FLAG_ALTKEY =32//按ALT不放
};
或者python-opencv中的参数也相同：
# mouse callback function
def mouse_event(event, x, y, flags, param):
'''
:param event: 点击事件标识
:param x: 坐标x
:param y: 坐标y
:param flags:按键事件标识
:param param: 携带参数
:return:
'''
if flags == cv2.EVENT_FLAG_ALTKEY:
print('摁住Alt')
if flags == cv2.EVENT_FLAG_CTRLKEY:
print('摁住Ctrl')
if flags == cv2.EVENT_FLAG_SHIFTKEY:
print('摁住Shift')
if flags == cv2.EVENT_FLAG_LBUTTON:
print('摁住左键')
if flags == cv2.EVENT_FLAG_MBUTTON:
print('摁住中键')
if flags == cv2.EVENT_FLAG_RBUTTON:
print('摁住右键')
if event == cv2.EVENT_LBUTTONDBLCLK:
print('左键双击')
if event == cv2.EVENT_MBUTTONDBLCLK:
print('中键双击')
if event == cv2.EVENT_RBUTTONDBLCLK:
print('右键双击')
if event == cv2.EVENT_LBUTTONDOWN:
print('左键击下')
if event == cv2.EVENT_LBUTTONUP:
print('左键弹起')
if event == cv2.EVENT_MBUTTONDOWN:
print('中键击下')
if event == cv2.EVENT_MBUTTONUP:
print('中键弹起')
if event == cv2.EVENT_RBUTTONDOWN:
print('右键击下')
if event == cv2.EVENT_RBUTTONUP:
print('右键弹起')
if event == cv2.EVENT_MOUSEWHEEL:
if flags > 0:
print('向前滚动')
else:
print('向后滚动')
if event == cv2.EVENT_MOUSEHWHEEL:
if flags > 0:
print('向左滚动') # 按住Alt
else:
print('向右滚动')
if __name__ == '__main__':
img = np.mat(np.zeros((300, 300, 3), np.uint8)) # 构造一个像素值全为1的图形
cv2.namedWindow('mouse') #命名窗口为mouse
cv2.setMouseCallback('mouse', mouse_event) # 窗口与回调函数绑定
while True:
cv2.imshow('mouse', img)
if cv2.waitKey(1) & 0xFF == ord('q'): # 摁下q退出
break
cv2.destroyAllWindows() #销毁所有窗口
2.一个可以绘制矩形和控制缩放的demo
#include 3.图象中画点
- 对于拼接后的图像显示窗口，依次绘制左右图中的对应点程序
- 右键删除尚未调通
std::vector<cv::Point2f>pointsL; //依次存放左右图中的对应点
std::vector<cv::Point2f>pointsR;
cv::Mat mask;
cv::Point2f p_;
//鼠标回调函数
void on_mouse(int event, int x, int y, int flags, void* param)
{
float cols = mask.cols/2;
int rad = 6;
if (event == cv::EVENT_LBUTTONUP || !(flags & cv::EVENT_FLAG_LBUTTON))
cv::Point2f pt = cv::Point2f(-10, -10);
else if (event == cv::EVENT_LBUTTONDOWN)
{
cv::Point2f pt(x, y);
if (pt.x>=0&&pt.x <= cols)
{
pointsL.push_back(pt);
cv::circle(mask, pt, rad, cv::Scalar(0, 255, 0), 2);
}
else {
pointsR.push_back(pt);
cv::circle(mask, pt, rad, cv::Scalar(0, 0, 255), 2);
}
//cv::circle(mask, pt, 2, cv::Scalar(0, 255, 0), 2);
cv::imshow("image", mask);
}
else if (event == cv::EVENT_RBUTTONDOWN) //按下右键，重画
{
cv::Point2f pt(x, y);
if (pointsL.size()>0)
{
pointsL.pop_back();
}
else if (pointsR.size() > 0)
{
pointsR.pop_back();
}
}
std::cout << "pointsL" << std::endl;
for (int i = 0; i < pointsL.size(); ++i)
{
std::cout << pointsL[i] << std::endl;
}
std::cout << "pointsR" << std::endl;
for (int i = 0; i < pointsR.size(); ++i)
{
std::cout << pointsR[i] << std::endl;
}
}
4.opencv例程分水岭分割中的界面应用
鼠标时间包含绘制直线的交互操作
static void help(char** argv)
{
cout << "\nThis program demonstrates the famous watershed segmentation algorithm in OpenCV: watershed()\n"
"Usage:\n" << argv[0] << " [image_name -- default is fruits.jpg]\n" << endl;
cout << "Hot keys: \n"
"\tESC - quit the program\n"
"\tr - restore the original image\n"
"\tw or SPACE - run watershed segmentation algorithm\n"
"\t\t(before running it, *roughly* mark the areas to segment on the image)\n"
"\t (before that, roughly outline several markers on the image)\n";
}
Mat markerMask, img;
Point prevPt(-1, -1);
static void onMouse(int event, int x, int y, int flags, void*)
{
if (x < 0 || x >= img.cols || y < 0 || y >= img.rows)
return;
if (event == EVENT_LBUTTONUP || !(flags & EVENT_FLAG_LBUTTON))
prevPt = Point(-1, -1);
else if (event == EVENT_LBUTTONDOWN)
prevPt = Point(x, y);
else if (event == EVENT_MOUSEMOVE && (flags & EVENT_FLAG_LBUTTON))
{
Point pt(x, y);
if (prevPt.x < 0)
prevPt = pt;
line(markerMask, prevPt, pt, Scalar(12,234,12), 40, 8, 0);
line(img, prevPt, pt, Scalar(12,234,12), 40, 8, 0);
prevPt = pt;
imshow("image", img);
}
}
int main(int argc, char** argv)
{
cv::CommandLineParser parser(argc, argv, "{help h | | }{ @input | fruits.jpg | }");
if (parser.has("help"))
{
help(argv);
return 0;
}
//string filename = samples::findFile(parser.get("@input"));
Mat img0 = imread("..."), imgGray;
if (img0.empty())
{
cout << "Couldn't open image ";
help(argv);
return 0;
}
help(argv);
//img0 = img0(Rect(1000, 1000, 800, 800));
namedWindow("image", WINDOW_NORMAL);
img0.copyTo(img);
cvtColor(img, markerMask, COLOR_BGR2GRAY);
cvtColor(markerMask, imgGray, COLOR_GRAY2BGR);
markerMask = Scalar::all(0);
imshow("image", img);
setMouseCallback("image", onMouse, 0);
for (;;)
{
char c = (char)waitKey(0);
if (c == 27)
break;
if (c == 'r')
{
markerMask = Scalar::all(0);
img0.copyTo(img);
namedWindow("image", WINDOW_NORMAL);
imshow("image", img);
}
if (c == 'w' || c == ' ')
{
//对绘制完成的图像进行下一步操作
//须在键入相应按键后执行
}
}
return 0;
}