Qt 5 and OpenCV 4 Computer Vision Projects

Saving a copy

Let's look back at the showImage method of MainWindow. In that method, we created an instance of QPixmap from the image and then added it to imageScene by calling imageScene->addPixmap. We didn't hold any handler of the image out of that function; hence, now we don't have a convenient way to get the QPixmap instance in the new slot, which we will implement for saveAsAction.

To solve this, we add a new private member field, QGraphicsPixmapItem *currentImage, to MainWindow to hold the return value of imageScene->addPixmap and initialize it with nullptr in the constructor of MainWindow. Then, we find the line of code in the body of MainWindow::showImage:

   imageScene->addPixmap(image);

To save the returned value, we replace this ...