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我刚开始使用 pyqt，我想从按钮更改图标。但我正在从另一个类中删除它，而 pyqt 不喜欢那样。

错误是：QPixmap：在 GUI 线程之外使用像素图是不安全的

我知道我必须使用信号 en 发射。但我不知道我必须如何使用它来更改按钮的图标。

这是我现在的代码：

import sys
import time
from PyQt4 import QtGui, QtCore
from pymodbus.exceptions import ConnectionException
from sqlalchemy.orm import sessionmaker
from sqlalchemy import create_engine
from data.database import Tags, Query_Tags


class Example(QtGui.QMainWindow):

    def __init__(self):
        super(Example, self).__init__()

        self.db_engine = create_engine('mysql://modbususer:modbususer@localhost/modbus')

        self.db_session = sessionmaker(bind=self.db_engine)
        self.db_session = self.db_session()  

        self.status = 0
        self.initUI()

    def initUI(self):               

        self.button = QtGui.QPushButton('Aan', self)
        self.button.clicked.connect(self.run)     
        self.button.move(50,50)


        Uit = QtGui.QPushButton('Uit', self)
        Uit.clicked.connect(self.off)     
        Uit.move(150,50)

        self.setGeometry(300, 300, 500, 150)
        self.setWindowTitle('Quit button')    
        self.show()

        self.worker = WorkThread(self)
        self.worker.start()

    def run(self):

        add_tag = Query_Tags('18', '1')
        self.db_session.add(add_tag)
        self.db_session.commit()


    def off(self):

        add_tag = Query_Tags('18', '0')
        self.db_session.add(add_tag)
        self.db_session.commit()

        self.status = 0

        print self.store

    def change(self):

        print "test"
        #self.button.setIcon(QtGui.QIcon("/home/stijnb/test/icon.png"))
        #self.button.setIconSize(QtCore.QSize(16,16))

    def database(self, store):

        self.store = store

"""
    Thread
"""
class WorkThread(QtCore.QThread):

    def __init__(self, layout):

        QtCore.QThread.__init__(self)

        self.layout = layout

    def __del__(self):
        self.wait()

    def run(self):

        self.database = {}

        while True:

            self.db_engine = create_engine('mysql://modbususer:modbususer@localhost/modbus')

            self.db_session = sessionmaker(bind=self.db_engine)
            self.db_session = self.db_session() 

            for result in self.db_session.query(Tags):

                self.database[int(result.id)] = {'naam': result.name, 'value': result.value}

            self.change_icons()
            time.sleep(1)

        return 

        self.terminate()

    def change_icons(self):

        print self.database[21]['value']

        if self.database[21]['value'] == '1':

            self.layout.button.setIcon(QtGui.QIcon("/home/stijnb/test/aan.png"))
            self.layout.button.setIconSize(QtCore.QSize(16,16))

        else:

            self.layout.button.setIcon(QtGui.QIcon("/home/stijnb/test/uit.png"))
            self.layout.button.setIconSize(QtCore.QSize(16,16))

def main():

    app = QtGui.QApplication(sys.argv)

    ex = Example()

    sys.exit(app.exec_())

if __name__ == '__main__':
    main()
4

1 回答 1

1

您不能从除主 GUI 线程之外的任何其他线程触摸 GUI 元素。这就是 Qt 引入消息传递（信号和插槽）的原因。您可以连接到来自工作线程的信号，该信号将在主线程中捕获，然后在主线程中您可以更改您想要的任何元素。

这是一个非常简单的示例，我在其中演示了该概念。

import sys
from PyQt4 import QtGui, QtCore

class Example(QtGui.QMainWindow):
    def __init__(self):
        super(Example, self).__init__()
        # Create a button and set it as a central widget
        self.button = QtGui.QPushButton('My Button', self)
        self.setCentralWidget(self.button)
        # Start the thread
        self.worker = WorkThread(self)
        self.worker.start()
        # Connect the thread's signal "change_text" to
        # "self.change_thread" function
        self.worker.change_text.connect(self.change_text)

    def change_text(self):
        # Slots are always executed in the GUI thread so it's safe to change
        # anything you want in a slot function. Here we just flip the button
        # text from foo to bar and back. But you can change the image or do
        # whatever you want.
        # Slots can also receive parameters so you can emit from your thread
        # which text should be set
        self.button.setText('bar' if self.button.text() == 'foo' else 'foo')


class WorkThread(QtCore.QThread):
    # Define the signal
    change_text = QtCore.pyqtSignal()

    def __init__(self, layout):
        QtCore.QThread.__init__(self)

    def run(self):
        while True:
            # emit the signal every 3 seconds
            self.sleep(3)
            self.change_text.emit()


app = QtGui.QApplication(sys.argv)
ex = Example()
ex.show()
sys.exit(app.exec_())
于 2013-08-22T15:04:45.960 回答