Display Image from QCamera in Label - c++

Question

I am writing a program, to display two cameras next to each other. In Qt it is pretty simple with the QCamera. But my Cameras are turned by 90°, so I have to turn the Camera in the porgram too.
The QCamera variable has no command to turn it, so I want to display it in a label, and not in a viewfinder. So I take an Image, turn it and display it in a label.
QImage img;
QPixmap img_;
img = ui->viewfinder->grab().toImage();
img_ = QPixmap::fromImage(img);
img_ = img_.transformed(QTransform().rotate((90)%360));
QImage img2;
QPixmap img2_;
img2 = ui->viewfinder->grab().toImage();
img2_ = QPixmap::fromImage(img2);
img2_ = img2_.transformed(QTransform().rotate((90)%360));
ui->label->setPixmap(img_);
ui->label_2->setPixmap(img2_);
When I start the program there are just two black boxes next to each other.
(In the code there is missing the part where I deklare it, but the camera works fine in the viewfinder so I think there is no problem)

Answer 1

Try this:
img_ = QPixmap::grabWindow(ui->viewfinder->winId(), 0, 0, -1, -1); (for take a snapshot as QPixmap)
or
img = QPixmap::grabWindow(ui->viewfinder->winId(), 0, 0, -1, -1).toImage(); (for take a snapshot as QImage)

Answer 2

You can use the orientation of the camera to correct the image orientation in view finder as described in Qt documentation. Here is the link:
http://doc.qt.io/qt-5/cameraoverview.html
and here is the code found in the documentation:
// Assuming a QImage has been created from the QVideoFrame that needs to be presented
QImage videoFrame;
QCameraInfo cameraInfo(camera); // needed to get the camera sensor position and orientation
// Get the current display orientation
const QScreen *screen = QGuiApplication::primaryScreen();
const int screenAngle = screen->angleBetween(screen->nativeOrientation(), screen->orientation());
int rotation;
if (cameraInfo.position() == QCamera::BackFace) {
rotation = (cameraInfo.orientation() - screenAngle) % 360;
} else {
// Front position, compensate the mirror
rotation = (360 - cameraInfo.orientation() + screenAngle) % 360;
}
// Rotate the frame so it always shows in the correct orientation
videoFrame = videoFrame.transformed(QTransform().rotate(rotation));
It looks like you don't even understand, what you are looking at...
Whats the purpose of pasting stuff like that to forum? Did you read ALL description about this? Its only part of the code that - i see You dont understand, but you try to be smart :)