Qt下使用OpenCV的鼠标回调函数进行圆形/矩形/多边形的绘制

文章目录

前言
一、设置imshow显示窗口
二、绘制圆形
三、绘制矩形
四、绘制多边形
五、示例完整代码
总结

前言

本文主要讲述了在Qt下使用OpenCV的鼠标回调在OpenCV的namedWindow和imshow函数显示出来的界面上进行一些图形的绘制，并最终将绘制好的图形显示在QLabel上。示例代码见文章内容，大家可以参考学习，如有错误之处，欢迎大家批评指正。

项目效果
请添加图片描述

提示：以下是本篇文章正文内容，下面案例可供参考

一、设置imshow显示窗口

这里对imshow出来的窗口进行了初始化，在namedWindow函数中设置了WINDOW_NORMAL标志，用来允许用户调整窗口大小。

//开始绘制区域
void Widget::startDrawArea(Mat imageMat)
{if(imageMat.empty()){QMessageBox::warning(this,"警告","请先选择显示图像!");return;}//显示绘图窗口QString title = "绘制区域";string strTitle = title.toLocal8Bit().toStdString();namedWindow(strTitle,WINDOW_NORMAL);//设置窗口的初始位置和大小moveWindow(strTitle,690,290);resizeWindow(strTitle,400,400);//设置鼠标回调函数m_drawMat = getDrawAreaMat();setMouseCallback(strTitle,mouseHandler,&imageMat);//显示图像并等待用户操作imshow(strTitle,m_drawMat);waitKey(0);
}

二、绘制圆形

绘制圆形的时候，鼠标左键按下记录当前点位为圆心，按下并移动时记录移动的距离为半径，并作判断确保绘制的圆不会超出图形边界，这里会实时显示绘制的圆形，左键松开时结束圆的绘制。

//绘制圆形
if(m_drawCircleFlag)
{m_drawCircleFlag = false;Point pt = Point(x,y);m_radius = norm(pt - m_center);int radiusMax = std::min(m_center.x,resultMat.cols - m_center.x);radiusMax = std::min(radiusMax,m_center.y);radiusMax = std::min(radiusMax,resultMat.rows - m_center.y);if(m_radius > radiusMax){m_radius = radiusMax;}circle(resultMat, m_center, m_radius, Scalar(0, 0, 255), 1, LINE_AA);m_drawMat = resultMat.clone();imshow(strTitle, m_drawMat);
}

三、绘制矩形

绘制矩形的时候，鼠标左键按下记录当前点位为矩形的起点，按下并移动时记录当前点位为矩形的终点，在移动过程中也会实时显示绘制出来的矩形，左键松开时结束矩形的绘制。

//绘制矩形
if(m_drawRectFlag)
{m_drawRectFlag = false;m_endPoint = Point(x, y);rectangle(resultMat, Rect(m_startPoint,m_endPoint), Scalar(0, 255, 0), 1, LINE_AA);m_drawMat = resultMat.clone();imshow(strTitle, m_drawMat);
}

四、绘制多边形

多边形需要获取各个顶点，所以这里在每次鼠标左键松开时将当前点保存到多边形顶点容器中，并在获取下一个顶点时将其与前一点相连起来，直到鼠标右键按下，将最后一点与第一点相连，结束多边形的绘制。这里每两点之间的连线使用了line函数，在结束绘制时还可以使用polylines函数，下面代码中有编写。

//绘制多边形
m_drawPolygonFlag = false;
if(m_vPolygon.size() > 2)
{//如果已经绘制了多个点,将最后一个点与第一个点连接起来line(resultMat, m_vPolygon[0], m_vPolygon.back(), Scalar(255, 0, 0), 1, LINE_AA);//或者使用polylines绘制//vector<vector<cv::Point>> polygons;//polygons.push_back(m_vPolygon);//polylines(resultMat, polygons, 1, Scalar(255, 0, 0), 1, LINE_AA, 0);imshow(strTitle, resultMat);
}

五、示例完整代码

1.MyTest.pro
在这里我将OpenCV库的头文件和库文件打包到了OpenCV文件夹，并放在项目源程序的目录下，然后在pro文件中包含这个路径，代码如下：

#OpenCV
INCLUDEPATH += $$PWD/OpenCV/Includes
DEPENDPATH += $$PWD/OpenCV/Includes
LIBS += -L$$PWD/OpenCV/Lib/ -lopencv_world455

2.widget.h

#ifndef WIDGET_H
#define WIDGET_H#include <QWidget>
#include <QMessageBox>
#include <QFileDialog>
#include <QDebug>#include "opencv2/opencv.hpp"using namespace cv;
using namespace std;QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACEclass Widget : public QWidget
{Q_OBJECTpublic:Widget(QWidget *parent = nullptr);~Widget();Mat getDrawAreaMat();QPixmap cvMatToPixmap(const Mat imageMat);void startDrawArea(Mat imageMat);private:static void mouseHandler(int event, int x, int y, int flags, void* param);private slots:void on_pb_selectMat_clicked();void on_pb_drawCircle_clicked();void on_pb_drawRect_clicked();void on_pb_drawPolygon_clicked();private:Ui::Widget *ui;Mat m_showMat;   //界面显示图像};
#endif // WIDGET_H

3.widget.cpp

#include "widget.h"
#include "ui_widget.h"//全局变量
Mat m_drawMat;   //绘制的图像bool m_drawCircleFlag = false;    //绘制圆形标志
bool m_drawRectFlag = false;      //绘制矩形标志
bool m_drawPolygonFlag = false;   //绘制多边形标志int m_radius = 0;               //绘制圆的半径
Point m_center = Point();       //绘制圆的圆心
Point m_startPoint = Point();   //绘制矩形的起点
Point m_endPoint = Point();     //绘制矩形的终点
vector<Point> m_vPolygon;       //多边形的顶点容器Widget::Widget(QWidget *parent): QWidget(parent), ui(new Ui::Widget)
{ui->setupUi(this);this->setFixedSize(650,420);
}Widget::~Widget()
{delete ui;
}//显示绘制的区域
Mat Widget::getDrawAreaMat()
{//绘制圆Mat showMat = m_showMat.clone();if((m_radius != 0) && (m_center != Point(0,0))){circle(showMat, m_center, m_radius, Scalar(0, 0, 255), 1, LINE_AA);}//绘制矩形if((m_startPoint != Point(0,0)) && (m_endPoint != Point(0,0))){rectangle(showMat, Rect(m_startPoint,m_endPoint), Scalar(0, 255, 0), 1, LINE_AA);}//绘制多边形int vNum = m_vPolygon.size();for(int i=1;i<vNum;i++){line(showMat, m_vPolygon[i-1], m_vPolygon[i], Scalar(255, 0, 0), 1, LINE_AA);if(i == vNum-1){line(showMat, m_vPolygon[0], m_vPolygon.back(), Scalar(255, 0, 0), 1, LINE_AA);}}return showMat;
}//Mat转QPixmap
QPixmap Widget::cvMatToPixmap(const Mat imageMat)
{QImage showImage;if(imageMat.channels() > 1){showImage = QImage((const unsigned char*)(imageMat.data),imageMat.cols,imageMat.rows,imageMat.step,QImage::Format_RGB888);   //彩色图}else{showImage = QImage((const unsigned char*)(imageMat.data),imageMat.cols,imageMat.rows,imageMat.step,QImage::Format_Indexed8);   //灰度图}//OpenCV使用BGR顺序,而Qt使用RGB顺序,因此需要交换颜色通道return QPixmap::fromImage(showImage.rgbSwapped());
}//开始绘制区域
void Widget::startDrawArea(Mat imageMat)
{if(imageMat.empty()){QMessageBox::warning(this,"警告","请先选择显示图像!");return;}//显示绘图窗口QString title = "绘制区域";string strTitle = title.toLocal8Bit().toStdString();namedWindow(strTitle,WINDOW_NORMAL);//设置窗口的初始位置和大小moveWindow(strTitle,690,290);resizeWindow(strTitle,400,400);//设置鼠标回调函数m_drawMat = getDrawAreaMat();setMouseCallback(strTitle,mouseHandler,&imageMat);//显示图像并等待用户操作imshow(strTitle,m_drawMat);waitKey(0);
}//鼠标回调函数
void Widget::mouseHandler(int event, int x, int y, int flags, void* param)
{QString title = "绘制区域";string strTitle = title.toLocal8Bit().toStdString();Mat resultMat = *(Mat*)param;if(event == EVENT_LBUTTONDOWN)   //鼠标左键按下{//绘制圆,确定圆心if(m_drawCircleFlag){m_center = Point(x,y);}//绘制矩形,确定起点if(m_drawRectFlag){m_startPoint = Point(x,y);}}else if(event == EVENT_MOUSEMOVE && (flags & EVENT_FLAG_LBUTTON))   //左键按下并移动{//实时显示绘制的圆if(m_drawCircleFlag){//计算半径Point pt = Point(x,y);m_radius = norm(pt - m_center);//确保圆不会超出图像边界int radiusMax = std::min(m_center.x,resultMat.cols - m_center.x);radiusMax = std::min(radiusMax,m_center.y);radiusMax = std::min(radiusMax,resultMat.rows - m_center.y);if(m_radius > radiusMax){m_radius = radiusMax;}m_drawMat = resultMat.clone();circle(m_drawMat, m_center, m_radius, Scalar(0, 0, 255), 1, LINE_AA);imshow(strTitle, m_drawMat);}//实时显示绘制的矩形if(m_drawRectFlag){m_endPoint = Point(x, y);m_drawMat = resultMat.clone();rectangle(m_drawMat, Rect(m_startPoint,m_endPoint), Scalar(0, 255, 0), 1, LINE_AA);imshow(strTitle, m_drawMat);}}else if(event == EVENT_LBUTTONUP)   //鼠标左键抬起{//结束绘制圆if(m_drawCircleFlag){m_drawCircleFlag = false;Point pt = Point(x,y);m_radius = norm(pt - m_center);int radiusMax = std::min(m_center.x,resultMat.cols - m_center.x);radiusMax = std::min(radiusMax,m_center.y);radiusMax = std::min(radiusMax,resultMat.rows - m_center.y);if(m_radius > radiusMax){m_radius = radiusMax;}circle(resultMat, m_center, m_radius, Scalar(0, 0, 255), 1, LINE_AA);m_drawMat = resultMat.clone();imshow(strTitle, m_drawMat);}//结束绘制矩形if(m_drawRectFlag){m_drawRectFlag = false;m_endPoint = Point(x, y);rectangle(resultMat, Rect(m_startPoint,m_endPoint), Scalar(0, 255, 0), 1, LINE_AA);m_drawMat = resultMat.clone();imshow(strTitle, m_drawMat);}//绘制多边形的各顶点if(m_drawPolygonFlag){m_vPolygon.push_back(Point(x, y));for(size_t i = 1; i < m_vPolygon.size(); i++){line(resultMat, m_vPolygon[i-1], m_vPolygon[i], Scalar(255, 0, 0), 1, LINE_AA);}imshow(strTitle, resultMat);}}else if(event == EVENT_RBUTTONDOWN)   //鼠标右键按下{//结束绘制多边形m_drawPolygonFlag = false;if(m_vPolygon.size() > 2){//如果已经绘制了多个点,将最后一个点与第一个点连接起来line(resultMat, m_vPolygon[0], m_vPolygon.back(), Scalar(255, 0, 0), 1, LINE_AA);//或者使用polylines绘制//vector<vector<cv::Point>> polygons;//polygons.push_back(m_vPolygon);//polylines(resultMat, polygons, 1, Scalar(255, 0, 0), 1, LINE_AA, 0);imshow(strTitle, resultMat);}}
}//选择图像
void Widget::on_pb_selectMat_clicked()
{QString fileName = QFileDialog::getOpenFileName(this,"选择图像文件","E:/PhotoTest/myPhoto","Image Files(*.png *.jpg *.bmp)");if(!fileName.isEmpty()){m_showMat = imread(fileName.toLocal8Bit().toStdString(),1);//更新界面显示QPixmap showPixmap = cvMatToPixmap(m_showMat);if(!showPixmap.isNull()){ui->lb_showMat->setPixmap(showPixmap.scaled(ui->lb_showMat->size(),Qt::KeepAspectRatio,Qt::SmoothTransformation));   //保持比例}else{QMessageBox::warning(this,"警告","图像文件打开失败!");}}
}//绘制圆形
void Widget::on_pb_drawCircle_clicked()
{setEnabled(false);m_drawCircleFlag = true;m_drawRectFlag = false;m_drawPolygonFlag = false;m_radius = 0;m_center = Point(0,0);startDrawArea(m_showMat.clone());//更新界面显示QPixmap showPixmap = cvMatToPixmap(getDrawAreaMat());if(!showPixmap.isNull()){ui->lb_showMat->setPixmap(showPixmap.scaled(ui->lb_showMat->size(),Qt::KeepAspectRatio,Qt::SmoothTransformation));}setEnabled(true);
}//绘制矩形
void Widget::on_pb_drawRect_clicked()
{//点击后禁用窗口交互setEnabled(false);m_drawCircleFlag = false;m_drawRectFlag = true;m_drawPolygonFlag = false;m_startPoint = Point(0,0);m_endPoint = Point(0,0);startDrawArea(m_showMat.clone());QPixmap showPixmap = cvMatToPixmap(getDrawAreaMat());if(!showPixmap.isNull()){ui->lb_showMat->setPixmap(showPixmap.scaled(ui->lb_showMat->size(),Qt::KeepAspectRatio,Qt::SmoothTransformation));}//绘制结束后开启交互setEnabled(true);
}//绘制多边形
void Widget::on_pb_drawPolygon_clicked()
{setEnabled(false);m_drawCircleFlag = false;m_drawRectFlag = false;m_drawPolygonFlag = true;m_vPolygon.clear();startDrawArea(m_showMat.clone());QPixmap showPixmap = cvMatToPixmap(getDrawAreaMat());if(!showPixmap.isNull()){ui->lb_showMat->setPixmap(showPixmap.scaled(ui->lb_showMat->size(),Qt::KeepAspectRatio,Qt::SmoothTransformation));}setEnabled(true);
}