How to overlay transparent image on qt camera? - qt

Question

Im trying to overlay an image with transparency on QCameraViewfinder. The following code works fine on windows, but ignores the transparency on raspberry pi.
Im using pyside2 version 5.11.2 on RPI4 and tried tranparent PNG and SVG files.
As an alternative, if Im using paintEvent to draw shapes, the viewfinder doesnt show video. My QPainter code is attached too.
from PySide2.QtMultimedia import QCamera, QCameraInfo
from PySide2.QtMultimediaWidgets import QCameraViewfinder
from PySide2 import QtCore, QtGui
from PySide2.QtWidgets import *
from PySide2.QtGui import *
from PySide2.QtCore import *
import sys
class ExampleWindow(QMainWindow):
def __init__(self, windowsize):
super().__init__()
self.windowsize = windowsize
self.initUI()
def initUI(self):
self.setFixedSize(self.windowsize)
widget = QWidget()
self.setCentralWidget(widget)
self.view_finder = QCameraViewfinder()
camerainfo = QCameraInfo.availableCameras()[0]
self.camera = QCamera(camerainfo)
self.camera.setViewfinder(self.view_finder)
self.camera.start()
layout_box = QHBoxLayout(widget)
layout_box.setContentsMargins(0, 0, 0, 0)
layout_box.addWidget(self.view_finder)
pixmap = QPixmap('crosshair3.png')
self.image = QLabel(widget)
self.image.setPixmap(pixmap)
self.image.setFixedSize(pixmap.size())
hw = pixmap.size().width()/2
hh = pixmap.size().height()/2
self.image.move(self.rect().center().x()-hw, self.rect().center().y()-hh)
if __name__ == '__main__':
app = QApplication(sys.argv)
screensize = app.desktop().availableGeometry().size()
ex = ExampleWindow(screensize)
ex.show()
sys.exit(app.exec_())
When using QPainter there is no video on the viewfinder:
class MyQCameraViewfinder(QCameraViewfinder):
def __init__(self, parent=None):
super().__init__(parent)
def paintEvent(self, event):
paint = QtGui.QPainter()
paint.begin(self)
paint.setRenderHint(QtGui.QPainter.Antialiasing)
paint.setPen(QtCore.Qt.black)
paint.setBrush(QtCore.Qt.white)
paint.drawEllipse(QtCore.QRect(17, 22, 50, 50))
paint.end()
on windows 11:
on rpi 4: