ImageHandler.cpp Example File

 #include "ImageHandler.h"
 #include <QImage>
 #include <QPainter>
 #include <QDebug>
 #include <QThread>
 #include <QTime>

 #if QT_VERSION < 0x050000
     #include <QGraphicsObject>
     #include <QStyleOptionGraphicsItem>
 #endif // QT_VERSION < Qt 5.0

 #if defined(QZXING_QML)
     #include <QQuickItem>
     #include <QQuickItemGrabResult>
     #include <QQuickWindow>
 #endif //QZXING_QML

 ImageHandler::ImageHandler(QObject *parent) :
     QObject(parent)
 {
 }

 QImage ImageHandler::extractQImage(QObject *imageObj, int offsetX, int offsetY, int width, int height)
 {
     QImage img;
 #if defined(QZXING_QML)
 #if QT_VERSION >= 0x050000
     QQuickItem *item = qobject_cast<QQuickItem *>(imageObj);

     if (!item || !item->window()->isVisible()) {
         qDebug() << "Item is NULL";
         return QImage();
     }

     QTime timer;
     timer.start();
     QSharedPointer<QQuickItemGrabResult> result = item->grabToImage();
     pendingGrabbersLocker.lockForWrite();
     pendingGrabbers << result.data();
     pendingGrabbersLocker.unlock();

     connect(result.data(), &QQuickItemGrabResult::ready, this, &ImageHandler::imageGrabberReady);
     while (timer.elapsed() < 1000) {
         pendingGrabbersLocker.lockForRead();
         if (!pendingGrabbers.contains(result.data())) {
             pendingGrabbersLocker.unlock();
             break;
         }
         pendingGrabbersLocker.unlock();
         qApp->processEvents();
         QThread::yieldCurrentThread();
     }
     img = result->image();
 #else
     QGraphicsObject *item = qobject_cast<QGraphicsObject*>(imageObj);

     if (!item) {
         qDebug() << "Item is NULL";
         return QImage();
     }

     img = QImage(item->boundingRect().size().toSize(), QImage::Format_RGB32);
     img.fill(QColor(255, 255, 255).rgb());
     QPainter painter(&img);
     QStyleOptionGraphicsItem styleOption;
     item->paint(&painter, &styleOption);
 #endif
 #endif //defined(QZXING_QML)

     if (offsetX < 0)
         offsetX = 0;
     if (offsetY < 0)
         offsetY = 0;
     if (width < 0)
         width = 0;
     if (height < 0)
         height = 0;

     if (offsetX || offsetY || width || height)
         return img.copy(offsetX, offsetY, width, height);
     else
         return img;
 }

 void ImageHandler::save(QObject *imageObj, const QString &path,
                         const int offsetX, const int offsetY,
                         const int width, const int height)
 {
     QImage img = extractQImage(imageObj, offsetX, offsetY, width, height);
     img.save(path);
 }

 #if QT_VERSION >= 0x050000
     void ImageHandler::imageGrabberReady()
     {
         pendingGrabbersLocker.lockForWrite();
         pendingGrabbers.remove(sender());
         pendingGrabbersLocker.unlock();
     }
 #endif