Python 主文件PyQt4中的外部函数

我真的很努力地使这个代码工作。我尝试了Qtimer、proccesEvents，但没有得到我想要的结果。GUI启动，所以有些东西可以工作，但是没有变化，所以方法读取不起作用

我在stackoverflow上搜索了很多以寻求帮助，但找不到。 也许我没有能力

代码如下：

import RPi.GPIO as GPIO
import MFRC522
import signal
import time
from PyQt4 import QtCore, QtGui
from ui_mainwindow import Ui_MainWindow

class MainWindow(QtGui.QWidget):
    def __init__(self, parent=None):
        QtGui.QWidget.__init__(self, parent)

        self.ui = Ui_MainWindow()

        self.ui.setupUi(self)

    def reading(self):
        self.ui.processEvents()
        ### Event Functions ###
        continue_reading = True

        # Hook the SIGINT
        signal.signal(signal.SIGINT, end_read)

        # Create an object of the class MFRC522
        MIFAREReader = MFRC522.MFRC522()

        # This loop keeps checking for chips. If one is near it will get the UID and authenticate
        while continue_reading:
            # Scan for cards    
            (status,TagType) = MIFAREReader.MFRC522_Request(MIFAREReader.PICC_REQIDL)

            # Get the UID of the card
            (status,uid) = MIFAREReader.MFRC522_Anticoll()

            # If we have the UID, continue
            if status == MIFAREReader.MI_OK:

                # This is the default key for authentication
                key = [0xFF,0xFF,0xFF,0xFF,0xFF,0xFF]

                # Select the scanned tag
                MIFAREReader.MFRC522_SelectTag(uid)

                # Authenticate
                status = MIFAREReader.MFRC522_Auth(MIFAREReader.PICC_AUTHENT1A, 8, key, uid)

                # Check if authenticated
                if status == MIFAREReader.MI_OK:

                    MIFAREReader.MFRC522_Read(8)

                    self.ui.label_3.show()
                    self.ui.label_2.show()
                    self.ui.label_4.show()
                    self.ui.groupBox.setStyleSheet(_fromUtf8("background: white;\n"
                    "border-style: solid;\n"
                    "border-width: 1px;\n"
                    "border-radius: 20px;"))

                    time.sleep(5)
                    MIFAREReader.MFRC522_StopCrypto1()
                    self.ui.label_3.hide()
                    self.ui.label_2.hide()
                    self.ui.label_4.hide()
                    self.ui.groupBox.setStyleSheet(_fromUtf8("background: white url(scan.png) no-repeat center;\n"
                    "border-style: solid;\n"
                    "border-width: 1px;\n"
                    "border-radius: 20px;"))
                else:
                    self.ui.groupBox.setStyleSheet(_fromUtf8("background: white url(accsd.png) no-repeat center;\n"
                    "border-style: solid;\n"
                    "border-width: 1px;\n"
                    "border-radius: 20px;"))
                    time.sleep(3)
                    self.ui.groupBox.setStyleSheet(_fromUtf8("background: white url(scan.png) no-repeat center;\n"
                    "border-style: solid;\n"
                    "border-width: 1px;\n"
                    "border-radius: 20px;"))

if __name__ == "__main__":
    import sys
    app = QtGui.QApplication(sys.argv)
    MainWindow = QtGui.QMainWindow()
    ui = Ui_MainWindow()
    ui.setupUi(MainWindow)
    MainWindow.show()
    sys.exit(app.exec_())

---

你从不调用函数reading？那为什么要放进去呢

我不确定您想要实现什么，但您可以尝试：

def __init__(self, parent=None):
    QtGui.QWidget.__init__(self, parent)

    self.ui = Ui_MainWindow()

    self.ui.setupUi(self)

    self.reading() ####################

---

但这只会调用函数一次。何时执行读取？

读取数据的任务被阻塞，因此它不应该在GUI的线程上运行，而应该在另一个线程上运行，另一方面，您不应该从另一个线程更改GUI，而是通过信号传达更改，如下所示：

import MFRC522
# import signal
import time

from PyQt4 import QtCore, QtGui
from ui_mainwindow import Ui_MainWindow
import threading

class MainWindow(QtGui.QMainWindow):
    state1, state2, state3, state4 = range(4)
    stateChanged = QtCore.pyqtSignal(int)

    def __init__(self, parent=None):
        QtGui.QMainWindow.__init__(self, parent)
        self.ui = Ui_MainWindow()
        self.ui.setupUi(self)
        self.stateChanged.connect(self.onChangeState)
        threading.Thread(target=self.reading, daemon=True).start()

    def onChangeState(self, state):
        if state == MainWindow.state1:
            self.ui.label_3.show()
            self.ui.label_2.show()
            self.ui.label_4.show()
            self.ui.groupBox.setStyleSheet(_fromUtf8("background: white;\n"
                    "border-style: solid;\n"
                    "border-width: 1px;\n"
                    "border-radius: 20px;"))
        elif state == MainWindow.state2:
            self.ui.label_3.hide()
            self.ui.label_2.hide()
            self.ui.label_4.hide()
            self.ui.groupBox.setStyleSheet(_fromUtf8("background: white url(scan.png) no-repeat center;\n"
                    "border-style: solid;\n"
                    "border-width: 1px;\n"
                    "border-radius: 20px;"))

        elif state == MainWindow.state3:
            self.ui.groupBox.setStyleSheet(_fromUtf8("background: white url(accsd.png) no-repeat center;\n"
                    "border-style: solid;\n"
                    "border-width: 1px;\n"
                    "border-radius: 20px;"))

        elif state == MainWindow.state4:
            self.ui.groupBox.setStyleSheet(_fromUtf8("background: white url(scan.png) no-repeat center;\n"
                    "border-style: solid;\n"
                    "border-width: 1px;\n"
                    "border-radius: 20px;"))


    def reading(self):
        ### Event Functions ###
        continue_reading = True
        # Hook the SIGINT
        #signal.signal(signal.SIGINT, end_read)
        # Create an object of the class MFRC522
        MIFAREReader = MFRC522.MFRC522()
        # This loop keeps checking for chips. If one is near it will get the UID and authenticate
        while continue_reading:
            # Scan for cards    
            (status,TagType) = MIFAREReader.MFRC522_Request(MIFAREReader.PICC_REQIDL)
            # Get the UID of the card
            (status,uid) = MIFAREReader.MFRC522_Anticoll()

            # If we have the UID, continue
            if status == MIFAREReader.MI_OK:
                # This is the default key for authentication
                key = [0xFF,0xFF,0xFF,0xFF,0xFF,0xFF]
                # Select the scanned tag
                MIFAREReader.MFRC522_SelectTag(uid)
                # Authenticate
                status = MIFAREReader.MFRC522_Auth(MIFAREReader.PICC_AUTHENT1A, 8, key, uid)
                # Check if authenticated
                if status == MIFAREReader.MI_OK:

                    MIFAREReader.MFRC522_Read(8)
                    self.stateChanged.emit(MainWindow.state1)
                    time.sleep(5)
                    MIFAREReader.MFRC522_StopCrypto1()
                    self.stateChanged.emit(MainWindow.state2)

                else:
                    self.stateChanged.emit(MainWindow.state3)
                    time.sleep(3)
                    self.stateChanged.emit(MainWindow.state4)


if __name__ == "__main__":
    import sys
    app = QtGui.QApplication(sys.argv)
    w = MainWindow()
    w.show()
    sys.exit(app.exec_())

---

结论很好，但不起作用。这不是问题。问题是什么？问题是读取方法中的while循环将阻塞gui。您需要将该代码放在一个单独的工作线程中，并将信号发送回gui，以便它可以在必要时执行更新。有几十篇关于这个场景的帖子，所以只要寻找，你就会发现。