在網上找了攝像頭拍照的demo，自己敲了一遍，並加了註釋，僅作為學習記錄。

標頭檔案：

#ifndef TEST_CAPTURE_H
#define TEST_CAPTURE_H

#include <QDialog>
#include <QCamera>
#include <QCameraViewfinder>
#include <QCameraImageCapture>
#include <QLabel>
#include <QPushButton>


namespace Ui {
class test_capture;
}

class test_capture : public QDialog
{
    Q_OBJECT

public:
    test_capture(QWidget *parent = 0);
    ~test_capture();

private:
    QCamera *camera;//系統攝像頭裝置
    QCameraViewfinder *cameraViewFinder;//攝像頭取景器部件
    QCameraImageCapture *cameraImageCapture;//截圖部件

    QPushButton *captureBtn;
    QPushButton *saveBtn;
    QPushButton *exitBtn;
    QLabel *displayLabel;

    void translateLanguage();

private slots:
    void captureBtnResponded();
    void saveBtnResponded();
    void exitBtnResponded();
    void cameraImageCaptured(int id, QImage image);

};

#endif // TEST_CAPTURE_H
 

.cpp檔案：

#include "test_capture.h"
#include "ui_test_capture.h"

#include <QHBoxLayout>
#include <QVBoxLayout>

test_capture::test_capture(QWidget *parent) :
    QDialog(parent)
{
    this->resize(600, 400);

    camera = new QCamera();
    cameraViewFinder = new QCameraViewfinder();
    cameraImageCapture = new QCameraImageCapture(camera);

    captureBtn = new QPushButton();
    saveBtn = new QPushButton();
    exitBtn = new QPushButton();

    displayLabel = new QLabel();
    displayLabel->setFixedSize(160, 120);
    //開啟自動平衡收放圖片，顯示影象大小，自動調節為QLabel的大小。
    displayLabel->setScaledContents(true);
    //部件垂直佈局
    QVBoxLayout *rightLayout = new QVBoxLayout;
    rightLayout->addWidget(displayLabel);
    rightLayout->addStretch();
    rightLayout->addWidget(captureBtn);
    rightLayout->addWidget(saveBtn);
    rightLayout->addWidget(exitBtn);
    //部件水平佈局
    QHBoxLayout *mainLayout = new QHBoxLayout;
    mainLayout->addWidget(cameraViewFinder);
    mainLayout->addLayout(rightLayout);

    connect(captureBtn, SIGNAL(clicked()), this, SLOT(captureBtnResponded()));
    connect(saveBtn, SIGNAL(clicked()), this, SLOT(saveBtnResponded()));
    connect(exitBtn, SIGNAL(clicked()), this, SLOT(exitBtnResponded()));
    connect(cameraImageCapture, SIGNAL(imageCaptured(int,QImage)), this,
            SLOT(cameraImageCaptured(int,QImage)));

    cameraImageCapture->setCaptureDestination(QCameraImageCapture::CaptureToFile);
    camera->setCaptureMode(QCamera::CaptureStillImage);
    camera->setViewfinder(cameraViewFinder);
    camera->start();//啟動攝像頭

    /*QVBoxLayout *layout = new QVBoxLayout;
       layout->addWidget(formWidget);
       setLayout(layout);
    */
    this->setLayout(mainLayout);/*必須執行這句程式碼才顯現出佈局*/
    this->translateLanguage();

}

test_capture::~test_capture()
{

}

void test_capture::translateLanguage()
{
    this->setWindowTitle(tr("testCapture"));
    captureBtn->setText(tr("capture"));
    saveBtn->setText(tr("save"));
    exitBtn->setText(tr("exit"));
}

void test_capture::captureBtnResponded()
{
    cameraImageCapture->capture();
}

void test_capture::saveBtnResponded()
{
    const QPixmap *pixmap = displayLabel->pixmap();
    if(pixmap) {pixmap->save("D:\\a.jpg");}
}

void test_capture::exitBtnResponded()
{
    camera->stop();
    this->close();
}

void test_capture::cameraImageCaptured(int id, QImage image)
{
    displayLabel->setPixmap(QPixmap::fromImage(image));
}
 

來自Qt大神 一去二三裡的部落格： http://blog.sina.com.cn/s/blog_a6fb6cc90101g2mg.html