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文章目录
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
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_NAMESPACE class Widget : public QWidget { Q_OBJECT public: 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); } 4.widget.ui
总结
在Qt下使用OpenCV务必要配置好环境，这样才能正常使用OpenCV的函数。可以看到在这个示例中使用的都是一些基本的函数，但是很好的实现了本文标题所写的功能。在本人之前的文章中，也有使用Qt的事件过滤器来实现这个功能，见下文参考博客。
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