opencv学习之路（5）、鼠标和滑动条操作

一、鼠标事件

#include<opencv2/opencv.hpp>
#include<iostream>
using namespace cv;
using namespace std;

Mat img(500,500,CV_8UC3,Scalar(255,255,255));//定义成全局变量

void OnMouse(int event,int x,int y,int flags,void* param){
    if(event==CV_EVENT_LBUTTONDOWN){//如果鼠标左键按下
        cout<<"mouse down"<<endl;//控制台输出
        circle(img,Point(x,y),80,Scalar(255,255,0),2,8);//在全局变量img上画圆
    }
}

void main(){
    namedWindow("mouse",CV_WINDOW_AUTOSIZE);
    setMouseCallback("mouse",OnMouse,0);
    while(1){
        imshow("mouse",img);
        if(27==waitKey(10))//每隔10毫秒检测是否按下esc键
            break;
    }
}

另外一种方法，不必将img图像设置为全局变量，只需传入其地址即可。

#include<opencv2/opencv.hpp>
#include<iostream>
using namespace cv;
using namespace std;

Point pt;
void OnMouse(int event,int x,int y,int flags,void* param){
    Mat img=*(Mat*)param;//将param强制转换为Mat指针，*(Mat*)=Mat，就如*（int*）=int一样
    switch(event){
        case CV_EVENT_LBUTTONDOWN://鼠标左键按下时
            pt.x=x;
            pt.y=y;
            break;
        case CV_EVENT_LBUTTONUP://鼠标左键抬起时
            rectangle(img,pt,Point(x,y),Scalar(0,255,0),2,8);
            break;
        default:
            break;
    }
}

void main(){
    Mat img(500,500,CV_8UC3,Scalar(255,255,255));
    namedWindow("mouse",CV_WINDOW_AUTOSIZE);
    setMouseCallback("mouse",OnMouse,&img);//传入img的地址，这样就不必将img设置成全局变量了

    while(1){
        imshow("mouse",img);
        if(27==waitKey(10))//每隔10毫秒检测是否按下esc键
            break;
    }
}

二、滑动条操作

#include<opencv2/opencv.hpp>
#include<iostream>
using namespace cv;
using namespace std;

Mat dst;
int value=20;

void onChange(int,void* param){
    Mat src=*(Mat*)param;
    threshold(src,dst,value,255,THRESH_BINARY);//二值化
    //Canny(src,dst,value,255);//canny边缘检测
    imshow("TrackBar",dst);
}

void main(){
    Mat src=imread("1.jpg",0);//读入灰度图
    namedWindow("TrackBar",CV_WINDOW_AUTOSIZE);
    createTrackbar("Threshold","TrackBar",&value,255,onChange,&src);

    threshold(src,dst,value,255,THRESH_BINARY);
    //Canny(src,dst,value,255);
    imshow("TrackBar",dst);//　　21/22/23这三行代码如果去掉的话，在未调整滑动条的情况下，不会有画面显示

    waitKey(0);
}