Qt使用QCamera實現(xiàn)切換相機,分辨率和圖像捕獲功能

更新時間：2023年04月04日 14:24:59 作者：Star_ID

這篇文章主要為大家介紹了如何利用Qt中的相機類QCamera，取景器類QCameraViewfinder，圖像捕獲類QCameraImageCapture實現(xiàn)切換相機、分辨率和圖像捕獲功能，需要的可以了解一下

demo中主要涉及的Qt類有：相機類QCamera，取景器類QCameraViewfinder，圖像捕獲類QCameraImageCapture，因此添加模塊multimedia multimediawidgets。

QT += core gui multimedia multimediawidgets

在widget.h中添加相關(guān)類聲明：

class QCamera;
class QCameraViewfinder;
class QCameraImageCapture;
class QCameraInfo;
class QCameraViewfinderSettings;

在類Widget中添加私有變量：

QCamera *camera;                   //相機
QCameraViewfinder *viewfinder;     //取景器
QCameraImageCapture *imageCapture; //圖像捕獲
QList<QCameraInfo> cameras;        //相機列表
QList<QSize> mResSize = {};        //分辨率列表

在widget.cpp中添加頭文件：

#include <QCamera>
#include <QCameraInfo>
#include <QCameraViewfinder>
#include <QCameraImageCapture>
#include <QFileDialog>
#include <QList>
#include <QDebug>

在widget.cpp的構(gòu)造函數(shù)中添加代碼：

先設(shè)置下窗口名稱及大小

setWindowTitle("Camera");
setFixedSize(600,400);

接著獲取所有相機列表并選擇一個相機初始化

cameras = QCameraInfo::availableCameras();   //獲取所有相機的列表
//qDebug() << "this is camera: ";
if (cameras.count() > 0) {
    for(const QCameraInfo &cameraInfo:cameras) {
        qDebug() << cameraInfo.description();
    }
    camera = new QCamera(cameras.at(0));     //初始化實例化一個相機對象
}

實例化取景器類，取景器本質(zhì)是一個窗口類，若不將當(dāng)前窗口設(shè)為父對象，則可以另起一個窗口顯示。將當(dāng)前窗口設(shè)為父對象后，視頻畫面便在當(dāng)前窗口顯示。

//設(shè)置取景器
viewfinder = new QCameraViewfinder(this);
camera->setViewfinder(viewfinder);
viewfinder->resize(600,350);                 //設(shè)置取景器顯示大小
//viewfinder->show();

實例化一個圖像捕獲類，并開啟相機

imageCapture = new QCameraImageCapture(camera);
camera->start();                             //開啟相機

設(shè)置默認攝像頭的分辨率及幀率。注意：幀率一定要與攝像頭匹配，否則不會顯示畫面。

//設(shè)置默認攝像頭參數(shù)
QCameraViewfinderSettings set;
set.setResolution(640, 480);                 //設(shè)置顯示分辨率
set.setMaximumFrameRate(25);                 //設(shè)置幀率
camera->setViewfinderSettings(set);

設(shè)置兩個下拉框部件的初始化

//添加初始化的相機選項
for(const QCameraInfo &cameraInfo:cameras) {
    qDebug() << "CameraInfo:" << cameraInfo;
    ui->cameraSel->addItem(cameraInfo.description());
}
ui->cameraSel->setCurrentIndex(0);

//添加初始化相機的分辨率選項
mResSize = camera->supportedViewfinderResolutions();
//qDebug() << "mResSize = " << mResSize;
for (const QSize &msize:mResSize) {
       qDebug() << msize; //攝像頭支持分辨率打印
       ui->resolutionSel->addItem(QString::number(msize.width(), 10) + "*" + QString::number(msize.height(), 10));
}
ui->resolutionSel->setCurrentIndex(0);

調(diào)整下widget.ui的內(nèi)容，添加兩個下拉框及一個按鈕

編寫信號槽連接

首先是選擇攝影機，先釋放之前的內(nèi)存，再將camera指向新的。選擇新的相機意味著分辨率選項也會變化，因此需要刪除分辨率下拉框中前相機的所有分辨率選項，再添加新相機的所有分辨率選項。

connect(ui->cameraSel, QOverload<int>::of(&QComboBox::activated), [=](int index){
    //qDebug() << "Index" << ui->cameraSel->currentIndex() << ": " << ui->cameraSel->currentText();
    camera->stop();
    delete camera;
    camera = new QCamera(cameras[index]);                //camera指向指定的攝像頭
    camera->setCaptureMode(QCamera::CaptureStillImage);  //設(shè)定捕獲模式
    camera->setViewfinder(viewfinder);                   //設(shè)置取景器
    camera->start();

    //刪除前相機的所有分辨率內(nèi)容
    for (int i = 0; i < mResSize.size(); i++) {
           ui->resolutionSel->removeItem(0);
    }

    //添加新相機的所有分辨率
    mResSize.clear();
    //qDebug() << "now mResSize = " << mResSize;
    mResSize = camera->supportedViewfinderResolutions();
    for (const QSize &msize:mResSize) {
           qDebug() << msize; //攝像頭支持分辨率打印
           ui->resolutionSel->addItem(QString::number(msize.width(), 10) + "*" + QString::number(msize.height(), 10));
    }
    ui->resolutionSel->setCurrentIndex(0);
});

選擇分辨率

connect(ui->resolutionSel, QOverload<int>::of(&QComboBox::activated), [=](int index){
    //qDebug() << "Index" << ui->resolutionSel->currentIndex() << ": " << ui->resolutionSel->currentText();
    //qDebug() << "mResSize:" << mResSize[index];
    //重新設(shè)置攝像頭參數(shù)
    QCameraViewfinderSettings reset;
    reset.setResolution(mResSize[index]);
    camera->setViewfinderSettings(reset);
});

截圖按鈕

connect(ui->screenShot, &QPushButton::clicked, [=](){
    camera->setCaptureMode(QCamera::CaptureStillImage);
    delete imageCapture;
    imageCapture = new QCameraImageCapture(camera);
    QString fileName = QFileDialog::getSaveFileName();
    camera->searchAndLock();
    imageCapture->capture(fileName);
    camera->unlock();
});

最終效果

附完整代碼

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>

QT_BEGIN_NAMESPACE
namespace Ui { class Widget; }
QT_END_NAMESPACE

class QCamera;
class QCameraViewfinder;
class QCameraImageCapture;
class QCameraInfo;
class QCameraViewfinderSettings;

class Widget : public QWidget
{
    Q_OBJECT

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

private:
    Ui::Widget *ui;
    QCamera *camera;                   //相機
    QCameraViewfinder *viewfinder;     //取景器
    QCameraImageCapture *imageCapture; //圖像捕獲
    QList<QCameraInfo> cameras;        //相機列表
    QList<QSize> mResSize = {};        //分辨率列表
    //QCameraViewfinderSettings *set;
};
#endif // WIDGET_H

widget.cpp

#include "widget.h"
#include "ui_widget.h"
#include <QCamera>
#include <QCameraInfo>
#include <QCameraViewfinder>
#include <QCameraImageCapture>
#include <QFileDialog>
#include <QList>
#include <QDebug>

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);
    setWindowTitle("Camera");
    setFixedSize(600,400);

    cameras = QCameraInfo::availableCameras();   //獲取所有相機的列表
    //qDebug() << "this is camera: ";
    if (cameras.count() > 0) {
        for(const QCameraInfo &cameraInfo:cameras) {
            qDebug() << cameraInfo.description();
        }
        camera = new QCamera(cameras.at(0));     //初始化實例化一個相機對象
    }

    //設(shè)置取景器
    viewfinder = new QCameraViewfinder(this);
    camera->setViewfinder(viewfinder);
    viewfinder->resize(600,350);                 //設(shè)置取景器顯示大小
    //viewfinder->show();

    imageCapture = new QCameraImageCapture(camera);
    camera->start();                             //開啟相機

    //設(shè)置默認攝像頭參數(shù)
    QCameraViewfinderSettings set;
    set.setResolution(640, 480);                 //設(shè)置顯示分辨率
    set.setMaximumFrameRate(25);                 //設(shè)置幀率
    camera->setViewfinderSettings(set);

    //添加初始化的相機選項
    for(const QCameraInfo &cameraInfo:cameras) {
        qDebug() << "CameraInfo:" << cameraInfo;
        ui->cameraSel->addItem(cameraInfo.description());
    }
    ui->cameraSel->setCurrentIndex(0);

    //添加初始化相機的分辨率選項
    mResSize = camera->supportedViewfinderResolutions();
    //qDebug() << "mResSize = " << mResSize;
    for (const QSize &msize:mResSize) {
           qDebug() << msize; //攝像頭支持分辨率打印
           ui->resolutionSel->addItem(QString::number(msize.width(), 10) + "*" + QString::number(msize.height(), 10));
    }
    ui->resolutionSel->setCurrentIndex(0);

    //信號槽連接
    connect(ui->cameraSel, QOverload<int>::of(&QComboBox::activated), [=](int index){
        //qDebug() << "Index" << ui->cameraSel->currentIndex() << ": " << ui->cameraSel->currentText();
        camera->stop();
        delete camera;
        camera = new QCamera(cameras[index]);                //camera指向指定的攝像頭
        camera->setCaptureMode(QCamera::CaptureStillImage);  //設(shè)定捕獲模式
        camera->setViewfinder(viewfinder);                   //設(shè)置取景器
        camera->start();

        //刪除前相機的所有分辨率內(nèi)容
        for (int i = 0; i < mResSize.size(); i++) {
               ui->resolutionSel->removeItem(0);
        }

        //添加新相機的所有分辨率
        mResSize.clear();
        //qDebug() << "now mResSize = " << mResSize;
        mResSize = camera->supportedViewfinderResolutions();
        for (const QSize &msize:mResSize) {
               qDebug() << msize; //攝像頭支持分辨率打印
               ui->resolutionSel->addItem(QString::number(msize.width(), 10) + "*" + QString::number(msize.height(), 10));
        }
        ui->resolutionSel->setCurrentIndex(0);
    });

    connect(ui->resolutionSel, QOverload<int>::of(&QComboBox::activated), [=](int index){
        //qDebug() << "Index" << ui->resolutionSel->currentIndex() << ": " << ui->resolutionSel->currentText();
        //qDebug() << "mResSize:" << mResSize[index];
        //重新設(shè)置攝像頭參數(shù)
        QCameraViewfinderSettings reset;
        reset.setResolution(mResSize[index]);
        camera->setViewfinderSettings(reset);
    });

    connect(ui->screenShot, &QPushButton::clicked, [=](){
        camera->setCaptureMode(QCamera::CaptureStillImage);
        delete imageCapture;
        imageCapture = new QCameraImageCapture(camera);
        QString fileName = QFileDialog::getSaveFileName();
        camera->searchAndLock();
        imageCapture->capture(fileName);
        camera->unlock();
    });
}

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

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