尝试将 4x4 键盘与 pyqt5 gui 应用程序一起使用

Question

我正在尝试使用 pad4pi 模块和基于 pyqt5 的 GUI 应用程序编写从 4x4 键盘（机械）输入的代码。

当我尝试单击按钮时，它可以正常工作，但是当我尝试生成某些事件时，我收到错误消息：

QObject::startTimer: Timers can only be used with threads started with QThread

class DigitalClock(QWidget,QThread):
    def __init__(self):
        super().__init__()
        SetupKeyboard.keypad.registerKeyPressHandler(self.printKey)
        self.setWindowTitle("OM SAI RAM")
        self.showFullScreen() 
        #self.setCursor(Qt.BlankCursor)
        button = QPushButton("Click", self) 
        button.clicked.connect(self.change)
        button.move(10,10)    
        button.show()

    def change(self):
        self.newpage = Authentication_page()
        self.close()

    def printKey(self, key):
        if key == 'A':
            self.newpage = Authentication_page()
            self.close()

class Authentication_page(QWidget):
    """
    Class to validate authentication.
    """
    def __init__(self):
        super().__init__()
        self.showFullScreen() 
        self.maindesign()

    def maindesign(self):
        """Method to design main page"""
        ####Label###
        self.admin_header = QLabel("Admin Panel", self)
        self.admin_header.setStyleSheet("font-size:40px")
        self.admin_header.move(130, 10)
        self.admin_header.show() 

当我点击按钮代码工作正常但当我按下机械按钮时，代码冻结并显示错误消息。

Answer 1

registerKeyPressHandler 分配的处理程序在监控键的线程中执行，在您的情况下，printKey 在您尝试创建小部件但被 Qt 禁止的辅助线程中执行。

解决方案是创建一个 QObject 并通过发送按下的键来发出信号（因为信号是线程安全的），然后连接到接收信息的插槽：

from PyQt5.QtCore import pyqtSignal, pyqtSlot, QObject
from PyQt5.QtWidgets import QLabel, QPushButton, QWidget

from pad4pi import rpi_gpio


class KeypadManager(QObject):
    keyPressed = pyqtSignal(object)

    def __init__(self, parent=None):
        super().__init__(parent)
        factory = rpi_gpio.KeypadFactory()
        self._keypad = factory.create_4_by_4_keypad()
        self._keypad.registerKeyPressHandler(self._key_press_handler)

    def _key_press_handler(self, key):
        self.keyPressed.emit(key)


class DigitalClock(QWidget):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.setWindowTitle("OM SAI RAM")
        self._keypad_manager = KeypadManager()
        self._keypad_manager.keyPressed.connect(self.printKey)

        # self.setCursor(Qt.BlankCursor)
        button = QPushButton("Click", self)
        button.clicked.connect(self.show_authentication_page)
        button.move(10, 10)

        self.showFullScreen()

    def show_authentication_page(self):
        self.newpage = Authentication_page()
        self.close()

    @pyqtSlot(object)
    def printKey(self, key):
        if key == "A":
            self.show_authentication_page()


class Authentication_page(QWidget):
    # ...