为什么pyqt应用程序在按下按钮时退出

Question

我是pyqt的新手，我正在尝试创建一个程序来通过网络摄像头捕获某人的脸部图像。该应用程序中有一个线程正在显示视频源，如果您按下按钮，它将显示您的脸部图像或默认的“找不到脸部”图像 data / NoFace.png 。

问题是它在大约2/3的时间内运行良好，有时在我第一次按下“获取图像”按钮时崩溃。它也不打印stacktrace。它给了我这个： 进程结束，退出代码为-1073741819（0xC0000005）

所以我不确定如何解决它。有人可以帮我解释一下吗？

main.py

class FaceApp(QMainWindow):

    def __init__(self):
        super().__init__()
        self.haar_cascade = cv2.CascadeClassifier(
            'data/haarcascade_frontalface_alt.xml')
        self.videoRunning = None
        self.photoData = SharedData()
        self.initUI()

    def setImage(self, image):
        self.videoFeed.setPixmap(QPixmap.fromImage(image))


    def setFaceImg(self):
        if self.photoData.hasphoto:
            img = self.photoData.get_photo()

            img = cv2.flip(img, 1)
            gray = cv2.cvtColor(img, cv2.COLOR_RGB2GRAY)
            faces = self.haar_cascade.detectMultiScale(gray, scaleFactor=1.1, minNeighbors=5)
            faceimg = None
            if len(faces) == 1:
                x, y, w, h = faces[0]
                faceimg = gray[y:y + h, x:x + w]
                img = img[y:y + h, x:x + w]
                self.photoData.FaceImg = np.copy(cv2.resize(faceimg,(128,128)))
            else:
                img = self.photoData.NoFaceImg

            img = cv2.resize(img, (200, 200))
            img = np.copy(img)
            convert_to_qt_format = QImage(img.data, img.shape[1], img.shape[0], QImage.Format_RGB888)
            p = convert_to_qt_format
            self.__setFaceImg__(p)

    def __setFaceImg__(self, image):
        self.faceImg.setPixmap(QPixmap.fromImage(image))

    def CreateMenu(self):
        self.mainMenu = self.menuBar()
        self.fileMenu = self.mainMenu.addMenu('File')

    def initUI(self):
        self.resize(900, 600)
        qtRectangle = self.frameGeometry()
        self.CreateMenu()
        centerpoint = QDesktopWidget().availableGeometry().center()
        qtRectangle.moveCenter(centerpoint)
        QToolTip.setFont(QFont('SansSerif', 10))

        self.videoFeed = QLabel(self)
        self.videoFeed.move(0, 40)
        self.videoFeed.resize(640, 480)


        self.faceImg = QLabel(self)
        self.faceImg.move(650, 40)
        self.faceImg.resize(200, 200)
        facebt = QPushButton("get image", self)
        facebt.move(700, 500)
        facebt.clicked.connect(self.setFaceImg)


        th = VideoThread(self.photoData)
        th.changePixmap.connect(self.setImage)
        th.start()

        self.show()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = FaceApp()

    sys.exit(app.exec_())

video.py

class SharedData:
    def __init__(self):
        self.hasphoto = False
        self.photo = None
        self.FaceImg = None
        self.NoFaceImg = cv2.imread("data/NoFace.png")

    def set_photo(self, photo):
        self.hasphoto = True
        self.photo = photo

    def get_photo(self):
        return self.photo

class VideoThread(QThread):
    changePixmap = pyqtSignal(QImage)

    def __init__(self, PhotoData, parent=None, camera=0):
        QThread.__init__(self, parent=parent)
        self.isRunning = True
        self.PhotoData = PhotoData
        self.cap = None
        if self.cap is not None:
            self.cap.release()
        self.cap = cv2.VideoCapture(camera)

    def run(self):

        while self.isRunning:
            ret, frame = self.cap.read()
            if ret:
                rgb_image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGB)
                self.PhotoData.set_photo(rgb_image)
                p = QImage(rgb_image.data, rgb_image.shape[1], rgb_image.shape[0], QImage.Format_RGB888)
                #p = convert_to_qt_format.scaled(640, 480, Qt.KeepAspectRatio)
                self.changePixmap.emit(p)

    def __del__(self):
        self.cap.release()