在qt中捕獲攝像頭畫面，在ui界面上添加一個comboBox控件、label標籤和兩個pushButton按鈕，comboBox用於顯示攝像頭的設備，按鈕用於開啓攝像頭和捕獲當前幀的畫面，label用於顯示攝像頭捕獲的畫面。

//需要在.pro文件中加上multimedia multimediawidgets
QT       += core gui multimedia multimediawidgets

//mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QCameraImageCapture>
#include<QCameraInfo>
#include<QCameraViewfinder>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    //獲取當前系統的攝像頭設備列表
    const QList<QCameraInfo> cameras = QCameraInfo::availableCameras();
    for(const QCameraInfo &cameraInfo:cameras){
        qDebug()<<cameraInfo.deviceName().toLocal8Bit().data();
        ui->comboBox->addItem(cameraInfo.deviceName().toUtf8().data());
    }
}

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


void MainWindow::on_pushButton_clicked()
{
    //創建攝像頭對象（把系統中的攝像頭路徑給QCamera對象）
    camera = new QCamera(ui->comboBox->currentText().toUtf8());
    //創建取景器對象，也就是用於顯示攝像頭畫面的控件，並給對象一個父指針
    QCameraViewfinder *viewfinder = new QCameraViewfinder(ui->label);
    //根據label大小設置取景器的大小

    viewfinder->resize(ui->label->size());
    //把取景器顯示在ui中
    viewfinder->show();
    //綁定攝像頭和攝像頭畫面控件
    camera->setViewfinder(viewfinder);




    //打開攝像頭
    camera->start();

    //捕獲圖像需要初始化一個新的QCameraImageCapture對象
    imageCapture = new QCameraImageCapture(camera);
    camera->setCaptureMode(QCamera::CaptureStillImage);
    //綁定信號與槽函數進行保存當前幀數據
    connect(imageCapture,&QCameraImageCapture::imageCaptured,this,&MainWindow::ImageCaptureToShow);

}

void MainWindow::on_pushButton_2_clicked()
{
    imageCapture->capture();
}

void MainWindow::ImageCaptureToShow(int id, const QImage &preview)
{
    qDebug()<<"buhuo";
    preview.save("./1.jpg");
}


//mainwindow.h
#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QCamera>
#include <QCameraImageCapture>
#include <QCameraViewfinder>
#include <QMainWindow>

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_pushButton_clicked();

    void on_pushButton_2_clicked();
    void ImageCaptureToShow(int id,const QImage &preview);

private:
    Ui::MainWindow *ui;
    QCamera *camera;
   // QCameraViewfinder *viewfinder;
    QCameraImageCapture *imageCapture;
};
#endif // MAINWINDOW_H