Multiple cameras [solved]

dvb0222

I am new at the QtMultimedia 5.x QML interface, but I tried this super simple QCamera demo below and it worked perfectly. It sees the camera and displays the viewfinder for me. This is the basis for an app I am developing.

However my system has two cameras. I am wondering if there is an API for selecting which physical camera to use. I see the availableDevices() method on the C++ object but I have to admin I am not connecting this to any selection mechanism.

I don't need a chooser, I can hard code an index into a list of available cameras for a demo....

Thanks in advance!!
@
import QtQuick 2.0
import QtMultimedia 5.0

Item {
width: 640
height: 360

Camera {
    id: camera

    imageProcessing.whiteBalanceMode: CameraImageProcessing.WhiteBalanceFlash

    exposure {
        exposureCompensation: -1.0
        exposureMode: Camera.ExposurePortrait
    }

    flash.mode: Camera.FlashRedEyeReduction

    imageCapture {
        onImageCaptured: {
            photoPreview.source = preview  // Show the preview in an Image
        }
    }
}

VideoOutput {
    source: camera
    anchors.fill: parent
    focus : visible // to receive focus and capture key events when visible
}

Image {
    id: photoPreview
}

}
@

SGaist

Hi,

availableDevices returns all the camera it can find so you can make a simple loop to create a camera + view finder for each entries returned.

Something like this:
@foreach (const QByteArray &device, QCamera::availableDevices()) {
QCamera *camera = new QCamera(device, this);
QCameraViewfinder *viewFinder = new QCameraViewfinder;
camera->setViewfinder(viewFinder);
// rest of logic to setup widgets or anything else
}
@

You can retrieve the camera name with QCamera::deviceDescription with these two function you can build your selection mechanism.

Hope it helps

PS: please enclose your code with coding tags to make it readable

dvb0222

Thanks, I understood how to do it on the C++ side.

So when I find the camera I am interested in, all I do is export it:

@QCamera *selectedCamera = new QCamera(selectedDevice, this);
QQuickView view;
view.rootContext()->setContextProperty("selectedCamera", selectedCamera);@

and set the QML Camera's mediaObject property to that exported object?

@Camera {
id: myCamera
mediaObject: selectedCamera
}@

Or do I share the &QByteArray returned from availableDevices() as a contextProperty? Either way, if it's that easy I'll be very happy.

SGaist

Sorry, QML is currently outside my competence... You'll have to test or maybe ask on the mailing list (there you'll find Qt developers/maintainers this forum is more user oriented)

dvb0222

Yes this works exactly as expected. put the C++ QCamera object into the root context by name, then you can use that name as the value in the mediaobject: field for the QML Camera and the correct camera will be used. If you do not do this and you have multiple cameras, then the camera at array index 0 of the availableDevices() returned list will be used by default.

SGaist

Great !

I also saw something about it in the "Qt Contributor Summit page":http://qt-project.org/wiki/Qt_Multimedia about QtMultimedia.