qt+opencv截屏

可以使用OpenCV库中的函数来实现Qt界面的截屏，具体实现可以参考以下代码：

QScreen *screen = QGuiApplication::primaryScreen();
if (screen) {
QPixmap pixmap = screen->grabWindow(QApplication::desktop()->winId());
cv::Mat mat;
cv::cvtColor(qPixmapToMat(pixmap), mat, cv::COLOR_RGBA2BGR); // 将QPixmap转换为OpenCV的Mat格式
// 接下来可以对mat进行处理，如图像保存、图像处理等
}

其中，qPixmapToMat()函数是将QPixmap转换为OpenCV的Mat格式的函数，可以在网上找到实现该函数的代码。

相关问题

qt opencv回调函数

在使用OpenCV中的Qt库时，可以使用setMouseCallback函数来设置鼠标回调函数。该函数的原型为void setMousecallback(const string& winname, MouseCallback onMouse, void* userdata=0)。其中winname是鼠标所运行回调函数的窗口名称，onMouse是回调函数的内容，原型为void onMouse(int event, int x, int y, int flags, void* userdata)。需要注意的是，函数名可以自己定义，但要保持统一。通常情况下，回调函数的传递参数userdata是不被使用的。 <span class="em">1</span><span class="em">2</span><span class="em">3</span>
#### 引用[.reference_title]
- *1* [Qt+OpenCV联合开发（十九）--鼠标操作与响应](https://blog.csdn.net/hml111666/article/details/122784506)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v93^chatsearchT3_2"}}] [.reference_item style="max-width: 50%"]
- *2* *3* [Qt 5.3 下OpenCV 2.4.11 开发（10）使用鼠标回调函数对视频帧截图](https://blog.csdn.net/Dopamy_BusyMonkey/article/details/47395487)[target="_blank" data-report-click={"spm":"1018.2226.3001.9630","extra":{"utm_source":"vip_chatgpt_common_search_pc_result","utm_medium":"distribute.pc_search_result.none-task-cask-2~all~insert_cask~default-1-null.142^v93^chatsearchT3_2"}}] [.reference_item style="max-width: 50%"]
[ .reference_list ]

qt opencv打开摄像头录取视频 截图 的代码

以下是使用Qt和OpenCV打开摄像头，录取视频和截图的代码：

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <opencv2/opencv.hpp>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private slots:
    void on_pushButton_OpenCamera_clicked();
    void on_pushButton_Record_clicked();
    void on_pushButton_Screenshot_clicked();

private:
    Ui::MainWindow *ui;
    cv::VideoCapture cap;
    cv::VideoWriter writer;
    bool isRecording;
};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QFileDialog>
#include <QMessageBox>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow),
    isRecording(false)
{
    ui->setupUi(this);
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_pushButton_OpenCamera_clicked()
{
    if(!cap.isOpened()){
        cap.open(0);
        if(cap.isOpened()){
            ui->pushButton_OpenCamera->setText("Close Camera");
        }
        else{
            QMessageBox::warning(this, "Error", "Failed to open camera.");
        }
    }
    else{
        cap.release();
        ui->pushButton_OpenCamera->setText("Open Camera");
    }
}

void MainWindow::on_pushButton_Record_clicked()
{
    if(!cap.isOpened()){
        QMessageBox::warning(this, "Error", "Please open camera first.");
        return;
    }

    if(!isRecording){
        QString filename = QFileDialog::getSaveFileName(this, "Save Video", ".", "Videos (*.avi)");
        if(filename.isEmpty()){
            return;
        }
        writer.open(filename.toStdString(), cv::VideoWriter::fourcc('M', 'J', 'P', 'G'), 25.0, cv::Size(cap.get(cv::CAP_PROP_FRAME_WIDTH), cap.get(cv::CAP_PROP_FRAME_HEIGHT)));
        if(!writer.isOpened()){
            QMessageBox::warning(this, "Error", "Failed to save video.");
            return;
        }
        isRecording = true;
        ui->pushButton_Record->setText("Stop Record");
    }
    else{
        writer.release();
        isRecording = false;
        ui->pushButton_Record->setText("Start Record");
    }
}

void MainWindow::on_pushButton_Screenshot_clicked()
{
    if(!cap.isOpened()){
        QMessageBox::warning(this, "Error", "Please open camera first.");
        return;
    }

    cv::Mat frame;
    cap.read(frame);
    if(frame.empty()){
        QMessageBox::warning(this, "Error", "Failed to get frame.");
        return;
    }

    QString filename = QFileDialog::getSaveFileName(this, "Save Screenshot", ".", "Images (*.png *.jpg)");
    if(filename.isEmpty()){
        return;
    }
    cv::imwrite(filename.toStdString(), frame);
}

这个代码利用了Qt的UI设计，包含了三个按钮：打开摄像头，开始/停止录制和截图。打开摄像头使用OpenCV的VideoCapture类，录制视频使用VideoWriter类，截图则是读取一帧图像并使用imwrite函数保存。

希望这个代码对你有所帮助！