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一文详解PyQt5中信号(Signal)与槽(Slot)

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信号与槽介绍

信号(Signal)与槽(Slot)是Qt中的核心机制,也是在PyQt编程中对象之间进行通信的机制。PyQt的窗口控件类有很多内置信号,开发者也可以添加自定义信号。信号与槽有如下特点:

内置信号与槽的使用

这里演示了内置clicked信号连接槽函数的使用

import sys
from PyQt5.QtWidgets import QPushButton, QApplication, QWidget, QMessageBox

app = QApplication(sys.argv)
widget = QWidget()

def showMsg():
    QMessageBox.information(widget, "信息提示框", "Ok,弹出测试信息")

btn = QPushButton("测试点击按钮", widget)
btn.clicked.connect(showMsg)

widget.show()
sys.exit(app.exec_())

自定义信号与槽的使用

import sys
from PyQt5.QtCore import QObject, pyqtSignal


# 信号对象
class QTypeSignal(QObject):
    # 定义一个信号
    sendmsg = pyqtSignal(object)

    def __init__(self):
        super(QTypeSignal, self).__init__()
    
    def run(self):
        # 发射信号
        self.sendmsg.emit('Hello PyQt5')

# 槽对象
class QTypeSlot(QObject):
    def __init__(self):
        super(QTypeSlot, self).__init__()

    # 槽对象中的槽函数
    def get(self, msg):
        print("QSlot get msg => " + msg)

if __name__ == "__main__":
    send = QTypeSignal()
    slot = QTypeSlot()

    # 1
    print("---把信号绑定到槽函数上---")
    send.sendmsg.connect(slot.get)
    send.run()

    # 2 
    print('---把信号与槽函数断开---')
    send.sendmsg.disconnect(slot.get)
    send.run()

自定义信号和内置槽函数

import sys
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
from PyQt5.QtCore import Qt

class WinForm (QWidget):
    # 自定义信号,不带参数
    button_clicked_signal = pyqtSignal()

    def __init__(self, parent=None):
        super(WinForm, self).__init__(parent)
        self.setWindowTitle("自定义信号和内置槽函数示例")
        self.resize(330, 50)
        btn = QPushButton("关闭", self)

        # 连接信号与槽函数
        btn.clicked.connect(self.btn_clicked)
        
        # 接收信号,连接到槽函数
        self.button_clicked_signal.connect(self.close)

    def btn_clicked(self):
        # 发送自定义信号,无参数
        self.button_clicked_signal.emit()

if __name__ == "__main__":
    app = QApplication(sys.argv)
    win = WinForm()
    win.show()
    sys.exit(app.exec_())

自定义信号和自定义槽函数

import sys
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *

class WinForm(QWidget):
    # 自定义信号,无参数
    button_clicked_signal = pyqtSignal()
    def __init__(self, parent= None):
        super(WinForm, self).__init__(parent)
        self.setWindowTitle("自定义信号和槽函数示例")
        self.resize(350, 50)

        btn = QPushButton("关闭", self)
        btn.clicked.connect(self.btn_clicked)
        self.button_clicked_signal.connect(self.btn_close)
    
    def btn_clicked(self):
        self.button_clicked_signal.emit()

    def btn_close(self):
        self.close()

if __name__ == "__main__":
    app = QApplication(sys.argv)
    win = WinForm()
    win.show()
    sys.exit(app.exec_())    

自定义有参信号

import sys
from PyQt5.QtCore import pyqtSignal, QObject

class CustSignal(QObject):
    # 声明无参数的信号
    signal1 = pyqtSignal()

    # 声明带一个int类型参数的信号
    signal2 = pyqtSignal(int)

    # 声明带一个int和一个str类型参数的信号
    signal3 = pyqtSignal(int, str)

    # 声明带一个列表类型参数的信号
    signal4 = pyqtSignal(list)

    # 声明带一个字典类型参数的信号
    signal5 = pyqtSignal(dict)

    # 声明一个多重载版本的信号,包括带int和str类型参数的信号和带str类型参数的信号
    signal6 = pyqtSignal([int,str], [str])

    def __init__(self, parent=None):
        super(CustSignal, self).__init__(parent)
        
        # 将信号连接到指定的槽函数
        self.signal1.connect(self.signalCall1)
        self.signal2.connect(self.signalCall2)
        self.signal3.connect(self.signalCall4)
        self.signal4.connect(self.signalCall4)
        self.signal5.connect(self.signalCall5)
        self.signal6[int, str].connect(self.signalCall6)
        self.signal6[str].connect(self.signalCall6OverLoad)

        # 发射信号
        self.signal1.emit()
        self.signal2.emit(100)
        self.signal3.emit(200, 'hello')
        self.signal4.emit([1,2,3,4,5,6])
        self.signal5.emit({"name":"xiaowang", "age":"25"})
        self.signal6[int, str].emit(300, 'hello world')
        self.signal6[str].emit('hello pyqt')

    def signalCall1(self):
        print('signal1 emit')
    
    def signalCall2(self, val):
        print('signal3 emit, value:', val)
    
    def signalCall3(self, val, text):
        print('signal3 emit, value:', val, text)

    def signalCall4(self, val):
        print('signal4 emit, value:', val)
    
    def signalCall5(self, val):
        print('signal5 emit, value:', val)

    def signalCall6(self, val, text):
        print('signal6 emit, value:', val, text)

    def signalCall6OverLoad(self, val):
        print('signal6 overload emit, value:', val)

if __name__ == "__main__":
    custSignal = CustSignal()
  

使用自定义信号参数

对于clicked信号来说他是没有参数的,如果连接的槽函数希望可以接收参数,如果直接连接有参数的槽函数会出错,因为信号发出的参数个数一定要大于槽函数接收的参数个数。这里有两种解决方法:

1.使用lambda

2.使用functools模块中的partial函数

import sys
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *
from functools import partial, partialmethod

class WinForm(QMainWindow):
    def __init__(self, parent=None):
        super(WinForm, self).__init__(parent)
        self.setWindowTitle("有参槽函数接收无参信号的解决方法")

        button1 = QPushButton("Button 1")
        button2 = QPushButton("Button 2")

        # 对于clicked信号来说他是没有参数的,如果连接的槽函数希望可以接收参数,如果直接连接有参数
        # 的槽函数会出错,因为信号发出的参数个数一定要大于槽函数接收的参数个数。这里有两种解决方法:
        # 1.使用lambda
        # 2.使用functools模块中的partial函数
        
        # 使用lambda
        button1.clicked.connect(lambda: self.onButtonClick(1))

        # 使用functools模块中的partial函数
        button2.clicked.connect(partial(self.onButtonClick, 2))

        layout = QHBoxLayout()
        layout.addWidget(button1)
        layout.addWidget(button2)
        mainwidget = QWidget()
        mainwidget.setLayout(layout)
        self.setCentralWidget(mainwidget)


    def onButtonClick(self, n):
        print("Button {0} 被按下了".format(n))
        QMessageBox.information(self, "信息提示框", 'Button {0} clicked'.format(n))

if __name__ == "__main__":
    app = QApplication(sys.argv)
    win = WinForm()
    win.show()
    sys.exit(app.exec_())

装饰器信号与槽

@PyQt5.QtCore.pyqtSlot(参数)

def on_发送者对象名称_发射信号名称(self, 参数):

pass

必须先执行了这行代码:QtCore.QMetaObject.connectSlotsByName(self)

from PyQt5 import QtCore
from PyQt5.QtWidgets import QApplication, QWidget, QHBoxLayout, QPushButton, QMessageBox
import sys

# 装饰器信号与槽
# @PyQt5.QtCore.pyqtSlot(参数)
# def on_发送者对象名称_发射信号名称(self, 参数):
#   pass
# 
# 必须要先执行这行代码:QtCore.QMetaObject.connectSlotsByName(self)

class CustWidget(QWidget):
    def __init__(self, parent=None):
        super(CustWidget, self).__init__(parent)
        self.setWindowTitle("装饰器信号与槽Demo")
        self.resize(350, 50)

        self.okButton = QPushButton("OK", self)

        # 使用setObjectName设置对象名称
        self.okButton.setObjectName("okButton")
        layout = QHBoxLayout()
        layout.addWidget(self.okButton)
        self.setLayout(layout)

        QtCore.QMetaObject.connectSlotsByName(self)


    @QtCore.pyqtSlot()
    def on_okButton_clicked(self):
        print("单击了OK按钮")
        QMessageBox.information(self, "信息提示框", "单击了OK按钮")

if __name__ == "__main__":
    app = QApplication(sys.argv)
    win = CustWidget()
    win.show()
    sys.exit(app.exec_())

信号与槽的断开和连接

import sys
from PyQt5.QtCore import *
from PyQt5.QtWidgets import *


# 信号与槽断开连接

class SignalClass(QObject):
    # 声明无参数的信号
    signal1 = pyqtSignal()

    # 声明带一个int类型参数的信号
    signal2 = pyqtSignal(int)

    def __init__(self, parent=None):
        super(SignalClass, self).__init__(parent)

        # 将信号signal1连接到sig1Call和sig2Call这两个槽函数
        self.signal1.connect(self.sig1Call)
        self.signal1.connect(self.sig2Call)

        # 将signal2连接到signal1
        self.signal2.connect(self.signal1)

        # 发射信号
        self.signal1.emit()
        self.signal2.emit(1)

        # 断开signal1,signal2信号与各槽函数的连接
        self.signal1.disconnect(self.sig1Call)
        self.signal1.disconnect(self.sig2Call)
        self.signal2.disconnect(self.signal1)
        
        # 将信号signal1和signal2连接到同一个槽函数sig1Call
        self.signal1.connect(self.sig1Call)
        self.signal2.connect(self.sig1Call)

        # 再次发射信号
        self.signal1.emit()
        self.signal2.emit(2)

    def sig1Call(self):
        print('signal-1 emit')
    
    def sig2Call(self):
        print('signal-2 emit')

if __name__ == "__main__":
    signal = SignalClass()

多线程中信号与槽的使用

import sys
from PyQt5.QtWidgets import QApplication, QWidget
from PyQt5.QtCore import QThread, pyqtSignal

class Main(QWidget):
    def __init__(self, parent=None):
        super(Main, self).__init__(parent)

        # 创建一个线程实例并设置名称,变量,信号与槽
        self.thread = MyThread()
        self.thread.setIdentity("thread1")
        self.thread.sinOut.connect(self.outText)
        self.thread.setVal(6)
        
    def outText(self, text):
        print(text)

class MyThread(QThread):
    
    sinOut = pyqtSignal(str)

    def __init__(self, parent=None):
        super(MyThread, self).__init__(parent)
        self.identity = None

    def setIdentity(self, text):
        self.identity = text
    
    def setVal(self, val):
        self.times = int(val)
        # 执行线程run方法
        self.start()

    def run(self):
        while self.times > 0 and self.identity:
            # 发射信号
            self.sinOut.emit(self.identity + "==>" + str(self.times))
            self.times -= 1

if __name__ == '__main__':
    app = QApplication(sys.argv)
    main = Main()
    main.show()
    sys.exit(app.exec_())

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