如何在Qt相机取景器上叠加透明图片？树莓派兼容性问题

我尝试在QCameraViewfinder上叠加带有透明效果的图片，以下代码在Windows系统运行正常，但在树莓派4上透明效果失效。我在树莓派4上使用PySide2 5.11.2版本，已尝试过透明PNG和SVG文件。作为替代方案，当我使用paintEvent绘制图形时，取景器无法显示视频，同时附上相关代码和Windows 11、树莓派4的效果对比图。

初始实现代码 #

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_())

使用QPainter的代码（取景器无视频） #

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()    

效果对比 #

• Windows 11效果：
• 树莓派4效果：

内容的提问来源于stack exchange，提问作者ramiwi