（3）PySide2 signal 和slot

以你之姓@ 2022-03-15 15:21 200阅读 0赞

# 传统写法 #

import sys
    from PySide2.QtWidgets import QApplication, QPushButton
    from PySide2.QtCore import SIGNAL, QObject
    
    def func():
        print("func has been called!")
    
    app = QApplication(sys.argv)
    button = QPushButton("Call func")
    QObject.connect(button, SIGNAL ('clicked()'), func)
    button.show()                                                                                             
    
    sys.exit(app.exec_())

这种写法很复杂，通过静态函数和两个宏来完成signal 和slot的对接所以一点页不不pythonic，官方不推荐的写法

# 新的写法 #

import sys
    from PySide2.QtWidgets import QApplication, QPushButton
    
    def func():
     print("func has been called!")
    
    app = QApplication(sys.argv)
    button = QPushButton("Call func")
    button.clicked.connect(func)
    button.show()
    sys.exit(app.exec_())

这个句法是官方推荐的。

# 自定义Signal 和Slot #

下面定义Slot 和Signal 是最简单的

import sys
    from PySide2 import QtCore, QtGui
    
    # define a function that will be used as a slot
    def sayHello():
     print 'Hello world!'
    
    app = QtGui.QApplication(sys.argv)
    
    button = QtGui.QPushButton('Say hello!')
    
    # connect the clicked signal to the sayHello slot
    button.clicked.connect(sayHello)
    button.show()
    
    sys.exit(app.exec_())

下面展示了如何用Wrapper来定义Slot，并且Signal和Slot开始处理类型变量了

import sys                                                                  
    from PySide2.QtWidgets import QApplication, QPushButton                     
    from PySide2.QtCore import QObject, Signal, Slot                            
                                                                                
    app = QApplication(sys.argv)                                                
                                                                                
    # define a new slot that receives a string and has 
    # 'saySomeWords' as its name 
    @Slot(str)                                                                  
    def say_some_words(words):                                                  
        print(words)                                                               
                                                                                
    class Communicate(QObject):                                                 
     # create a new signal on the fly and name it 'speak' 
     speak = Signal(str)                                                        
                                                                                
    someone = Communicate()                                                     
    # connect signal and slot 
    someone.speak.connect(say_some_words)                                         
    # emit 'speak' signal 
    someone.speak.emit("Hello everybody!")

下面是重载版本

import sys                                                                  
    from PySide2.QtWidgets import QApplication, QPushButton                     
    from PySide2.QtCore import QObject, Signal, Slot                            
                                                                                
    app = QApplication(sys.argv)                                                
                                                                                
    # define a new slot that receives a C 'int' or a 'str' 
    # and has 'saySomething' as its name 
    @Slot(int)                                                                  
    @Slot(str)                                                                  
    def say_something(stuff):                                                   
        print(stuff)                                                            
                                                                                
    class Communicate(QObject):                                                 
        # create two new signals on the fly: one will handle 
        # int type, the other will handle strings 
        speak_number = Signal(int)                                              
        speak_word = Signal(str)                                                  
                                                                                
    someone = Communicate()                                                     
    # connect signal and slot properly 
    someone.speak_number.connect(say_something)                                 
    someone.speak_word.connect(say_something)                                   
    # emit each 'speak' signal 
    someone.speak_number.emit(10)                                               
    someone.speak_word.emit("Hello everybody!"))

pythinic版本的重载（我也第一次看见）

一个对象发出信号

import sys                                                                  
    from PySide2.QtCore import QObject, Signal                                  
                                                                                
    # Must inherit QObject for signals                                          
    class Communicate(QObject):                                                 
        speak = Signal()                                                        
                  
        def __init__(self):                                                     
            super(Communicate, self).__init__()    
            self.speak.connect(self.say_hello)                             
                                                                                
        def speaking_method(self):                                              
            self.speak.emit()   
    
        def say_hello(self):
            print("Hello")                                                
    
                                                                                
    someone = Communicate()                                                 
    someone.speaking_method()

注意： 类的实例才能发射信号 ，类是不可以发射信号的

# Erroneous: refers to class Communicate, not an instance of the class
    Communicate.speak.connect(say_something)
    # raises exception: AttributeError: 'PySide2.QtCore.Signal' object has no attribute 'connect'