opencv cameras into qml using python and pyside2

m.reza

hey everyone!
im trying to code an application which capture 6 different camera devices
so far i managed too use QThread getting cameras live in action, while tying to use 'addImageProvider' there is an error saying

sys:1: RuntimeWarning: Invalid return value in function QQuickImageProvider.requestImage, expected PySide2.QtGui.QImage, got tuple.

python side code is:

class VideoThread(QThread):
    changepixmapsignal = Signal(QImage)

    def __init__(self):
        super(VideoThread, self).__init__()
        self._run_flag = True
    def run(self):
        while self._run_flag:
            #imagine this line captures fram the camera in a while loop
            in_rgb_1=frame_comin_from_camera()
            #---------
            color_frame = in_rgb_1.getFrame()
            h, w, ch = color_frame.shape
            img = QImage(color_frame.data, w, h, ch * w, QImage.Format_RGB888)
            scaled_img = img.scaled(640, 480, Qt.KeepAspectRatio)
            self.changepixmapsignal.emit(scaled_img)
    def stop(self):
        """Sets run flag to False and waits for thread to finish"""
        self._run_flag = False
        self.wait()


class ImageProvider(QQuickImageProvider):
    imageChanged = Signal(QImage)

    def __init__(self):
        super(ImageProvider, self).__init__(QQuickImageProvider.Image)

        self.cam = VideoThread()
        self.cam.start()
        self.cam.changepixmapsignal.connect(self.update_image)
#
    def requestImage(self,id, size, requestedSize):
        print("id: ", id)
        print("requested size: ", requestedSize)
        img = QImage(300, 300, QImage.Format_RGBA8888)
        img.fill(Qt.black)
        img = QImage("qml/pages/image.png")
        return img, img.size()

    def update_image(self, img):
        self.imageChanged.emit(img)

class MainWindow(QObject):
    def __init__(self):

        QObject.__init__(self)
        self.timer = QTimer()
        self.timer.timeout.connect(lambda: self.setTime())
        self.timer.start(1000)

    printTime=Signal(str)

    def setTime(self):
        now = datetime.datetime.now()
        fromatDate=now.strftime('%H:%M:%S %p')
        self.printTime.emit(fromatDate)


    def closeEvent(self, event):
        self.thread.stop()
        event.accept()



if __name__ == "__main__":
    app = QGuiApplication(sys.argv)
    engine = QQmlApplicationEngine()

    main = MainWindow()
    myImageProvider = ImageProvider()
    engine.rootContext().setContextProperty("backend", main)
    engine.rootContext().setContextProperty("myImageProvider", myImageProvider)

    engine.addImageProvider("MyImageProvider", myImageProvider)

    engine.load(os.fspath(Path(__file__).resolve().parent / "qml/main.qml"))
    if not engine.rootObjects():
        sys.exit(-1)
    sys.exit(app.exec_())

and qml side is :

    Item {
    id: fieldProcessingPage

    Rectangle {
        id: pageRectangle
        anchors.fill: parent
        implicitWidth: 800
        implicitHeight: 600

        Rectangle {
            id: contentRectangle
            anchors.fill: parent

            Image {
                id: feedImage
                anchors.fill: parent
                fillMode: Image.PreserveAspectFit
                cache: false
                source: "image://MyImageProvider/img"
                property bool counter: false

                function reloadImage() {
                    counter = !counter
                    source = "image://MyImageProvider/img?id=" + counter
                }
            }
        }
    }

    Connections {
        target: myImageProvider

        function onImageChanged(image) {
            feedImage.reloadImage()
        }
    }
}

SGaist

Hi and welcome to devnet,

Based on the error message, just return img in your requestImage function.

m.reza

thanks @SGaist error is gone, but when i launch the app it closes by itself, no specific error, it just say python crashed

if i comment the thread section and doesnt load cameras it launches, but when cameras are working ui wont stay long and closes rapidly

SGaist

I must say I am not really convinced by your implementation.

For example, in your requestImage function, you create a QImage, paint it black, and then replace it with another one loaded from a file (which may or may not fail).

Added to that, you are using a thread to generate images that in the end will not go to screen.

On a side note, did you consider using QtMultimedia to grab images from these cameras ?

m.reza

@SGaist i should say i wanted too use multimedia class but couldn't find the method for it, multimedia class captures the images or load a video from hard drive or a Url, but i couldn't connect it too these live action cameras,
also these cameras only works with their own pipeline, they called Depthai , its using Opencv technology, so just calling a webcam camera wont help, also i have 6 cameras to connect to application,
any idea for that?

SGaist

How are these camera accessible ?

m.reza

@SGaist only trough opencv, its actually a new tech from opencv, i leave the website below
https://docs.luxonis.com/en/latest/

processors kinda pushed inside the camera like a rasbery pie but there is no access to it, for showing the video i can use call back method or showing frame by frame using a while loop
in a thread
but same problem stays, when i use imageprovider qt crashes
is it possible that i can not use more than one stream of images with imageprovider class?
i read the documentation in cpp, it says image provider finds the available stream of images meaning i can not say this stream is camera one for frame number1 and next stream is camera two for frame number 2 ?

SGaist

Did you saw that there is a Qt example in their sources ?

You might want to first get that one running before adding QML to the mix.

m.reza

@SGaist i did, it runs smooth with one camera, since its using available picture to stream, problem is when we have more than one camera, i cant choose each stream directly to communicate with in Qt.
lets say i have a class in python that each def() does one job with a camera, one for focusing on for taking a picture one for sending too AI model and so on, i need to make 6 different object from this class for 6 different cameras and connect them to buttons in Qml, what i explained is alright, but the only part i can not do is the live stream for each camera separately, there is no function or at least i couldn't find which define separate stream of images for separate windows in qml, there are two method so far which looks for available stream of image not a specific one, one is imageprovider, other is paintclass
this is were i have the main problem