Zoom QCameraViewfinder Video possible?

pauledd

Hi there,

I have a simple app that shows me the live video of a webcam
that looks through my telescope.

I use a QCamera and a QCameraViewfinder object to view the live
video from /dev/video0. The QCameraViewfinder is limited in size with 375x380. The video is set to 640x480. Of cause it gets squashed within the viewfinder dimension. But I am interested in the area around the circle (the red square). Is there any way to zoom into the red square triggered by a push button?
image of the app

I just stumbled upon the QGraphicsVideoItem that has a "setScale" Attribute. Is that the right way? But if yes how do I connect my QCamera to a QGraphicsVideoItem?

EDIT:
Here's some code that I use to build my camera:

        camera = new QCamera("/dev/video0");
	cameraVf = new QCameraViewfinder(frame4);
	camera->setViewfinder(cameraVf);
	cameraVf->setGeometry(5,40,375,380);
	QCameraViewfinderSettings vfsettings;
	vfsettings.setPixelFormat(QVideoFrame::Format_YUV420P);
	vfsettings.setResolution(640,480);
	camera->setViewfinderSettings(vfsettings);
	cameraVf->show();

pauledd

I think I found a solution. I roughly quadrupled the QCameraViewfinder size and repositioned it to the middle.
Its all done with "cameraVf->setGeometry(x,y,x,y);". And I parented the viewfinder to a new QFrame
to have a frame and to have the viewfinder not overlaying the start button.

alt text

mainwindow.cpp

...
        QFrame *frameVideo = new QFrame(frame4);		// extra frame where the video is in
	frameVideo->setGeometry(5,35,375,380);
	
	camera = new QCamera("/dev/video0");
	cameraVf = new QCameraViewfinder(frameVideo);
	camera->setViewfinder(cameraVf);
	cameraVf->setGeometry(0,0,375,380);
	QCameraViewfinderSettings vfsettings;
	vfsettings.setPixelFormat(QVideoFrame::Format_YUV420P);
	vfsettings.setResolution(640,480);
	camera->setViewfinderSettings(vfsettings);
	cameraVf->show();
...

void MainWindow::onZoomClicked(){
	if(cameraVf->width() != 1600)
	{
		cameraVf->setGeometry(-590,-490,1600,1440);  // zoom in
	}
	else
	{
		cameraVf->setGeometry(0,0,375,380);		// zoom out
	}
}