def start(): global img, pre_pts try: root = tk.Tk() root.withdraw() f_path = filedialog.askopenfilename() if not f_path: messagebox.showinfo('提示', '请选取有效图片') else: img = cv.imread(f_path) pre_pts = -1, -1 cv.namedWindow('picture', cv.WINDOW_NORMAL) cv.resizeWindow('picture', 256, 256) cv.moveWindow('picture', 600, 300) cv.imshow('picture', img) cv.setMouseCallback('picture', draw) cv.waitKey(0) cv.destroyAllWindows() root.destroy() except Exception as e: print("出现错误:", e)上述代码报错时，下列主界面会卡住并退出程序：class Faceshow(QMainWindow, Ui_MainWindow): def __init__(self, parent=None): super(Faceshow, self).__init__(parent) self.setupUi(self) self.main_button.clicked.connect(start) self.main_exit.clicked.connect(self.quit) def quit(self): self.close() if __name__ == '__main__': hxz = QApplication(sys.argv) ui = Faceshow() ui.show() sys.exit((hxz.exec_()))

可能是因为出现了异常，但是异常没有被捕获，导致程序直接退出。你可以在 `start()` 函数中加上异常处理，例如用 `try...except` 块包裹代码，打印出错误信息，然后使程序继续运行。这样就可以避免程序直接退出。修改后的代码如下：

def start():
    global img, pre_pts
    try:
        root = tk.Tk()
        root.withdraw()
        f_path = filedialog.askopenfilename()
        if not f_path:
            messagebox.showinfo('提示', '请选取有效图片')
        else:
            img = cv.imread(f_path)
            pre_pts = -1, -1
            cv.namedWindow('picture', cv.WINDOW_NORMAL)
            cv.resizeWindow('picture', 256, 256)
            cv.moveWindow('picture', 600, 300)
            cv.imshow('picture', img)
            cv.setMouseCallback('picture', draw)
            cv.waitKey(0)
            cv.destroyAllWindows()
        root.destroy()
    except Exception as e:
        print("出现错误:", e)
        traceback.print_exc()

class Faceshow(QMainWindow, Ui_MainWindow):
    def __init__(self, parent=None):
        super(Faceshow, self).__init__(parent)
        self.setupUi(self)
        self.main_button.clicked.connect(start)
        self.main_exit.clicked.connect(self.quit)

    def quit(self):
        self.close()

if __name__ == '__main__':
    hxz = QApplication(sys.argv)
    ui = Faceshow()
    ui.show()
    sys.exit((hxz.exec_()))

这样程序就不会卡住并退出了，而是会在控制台中打印出错误信息，方便你进行调试。