QT：捕获到缓冲区而不保存到文件

Question

在我的项目中，我使用QCameraImageCapture::CaptureToBuffer捕获要缓冲的照片。但这也会将图像保存到文件中。由于我打算连续捕获图像，因此我想防止它将图像保存到文件中。这是我的代码：

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
   ui(new Ui::MainWindow)
{
ui->setupUi(this);
scene = new QGraphicsScene(this);
ui->graphicsView->setScene(scene);
cam = new QCamera;
cam->setCaptureMode(QCamera::CaptureStillImage);

viewfinder = new QCameraViewfinder;
viewfinder->show();
QCameraImageCapture *cap = new QCameraImageCapture(cam);
cap->setCaptureDestination(QCameraImageCapture::CaptureToBuffer);

cam->setViewfinder(viewfinder);


QObject::connect(cap, &QCameraImageCapture::imageCaptured, [=] (int id, QImage img) {
    QByteArray buf;
    QBuffer buffer(&buf);
    buffer.open(QIODevice::WriteOnly);
    img.save(&buffer, "BMP");


});

QObject::connect(cap, &QCameraImageCapture::readyForCaptureChanged, [=] (bool state) {
   if(state == true) {
       cam->searchAndLock();
       cap->capture();
       cam->unlock();
   }
});
cam->start();

}