带有命名参数的信号

Posted 2023-02-16

【中文标题】带有命名参数的信号

【英文标题】：Signal with named parameter

【发布时间】：2018-07-29 15:36:09

【问题描述】：

我正在尝试使用 PySide2 复制以下示例。

https://evileg.com/en/post/242/

但由于 PySide2 不支持向 QML 发出，我不知道如何使用 PySide2 来做到这一点？

这是我的代码

ma​​in.py

from PySide2.QtGui import QGuiApplication
from PySide2.QtQml import QQmlApplicationEngine
from PySide2.QtCore import QObject, Signal, Slot, Property


class Calculator(QObject):
    def __init__(self):
        QObject.__init__(self)

    sumResult = Signal(int)
    subResult = Signal(int)

    @Slot(int, int)
    def sum(self, arg1, arg2):
        self.sumResult.emit(arg1 + arg2)

    @Slot(int, int)
    def sub(self, arg1, arg2):
        self.subResult.emit(arg1 - arg2)


if __name__ == "__main__":
    import sys

    app = QGuiApplication(sys.argv)
    engine = QQmlApplicationEngine()
    calculator = Calculator()
    engine.rootContext().setContextProperty("calculator", calculator)
    engine.load("/code/QML/calc.qml")

    engine.quit.connect(app.quit)
    sys.exit(app.exec_())

【参考方案1】：

你不能这样复制，如果你想实现项目你可以让槽返回值：

ma​​in.py

from PySide2 import QtCore, QtGui, QtQml


class Calculator(QtCore.QObject):
    # Slot for summing two numbers
    @QtCore.Slot(int, int, result=int)
    def sum(self, arg1, arg2):
        return arg1 + arg2

    # Slot for subtraction of two numbers
    @QtCore.Slot(int, int, result=int)
    def sub(self, arg1, arg2):
        return arg1 - arg2


if __name__ == "__main__":
    import os
    import sys

    # Create an instance of the application
    app = QtGui.QGuiApplication(sys.argv)
    # Create QML engine
    engine = QtQml.QQmlApplicationEngine()
    # Create a calculator object
    calculator = Calculator()
    # And register it in the context of QML
    engine.rootContext().setContextProperty("calculator", calculator)
    # Load the qml file into the engine
    file = os.path.join(os.path.dirname(os.path.realpath(__file__)), "main.qml")
    engine.load(file)

    engine.quit.connect(app.quit)
    sys.exit(app.exec_())

ma​​in.qml

import QtQuick 2.5
import QtQuick.Controls 1.4
import QtQuick.Layouts 1.2
 
ApplicationWindow 
    visible: true
    width: 640
    height: 240
    title: qsTr("PyQt5 love QML")
    color: "whitesmoke"
 
    GridLayout 
        anchors.top: parent.top
        anchors.left: parent.left
        anchors.right: parent.right
        anchors.margins: 9
 
        columns: 4
        rows: 4
        rowSpacing: 10
        columnSpacing: 10
 
        Text 
            text: qsTr("First number")
        
 
        // Input field of the first number
        TextField 
            id: firstNumber
        
 
        Text 
            text: qsTr("Second number")
        
 
        // Input field of the second number
        TextField 
            id: secondNumber
        
 
        Button 
            height: 40
            Layout.fillWidth: true
            text: qsTr("Sum numbers")
 
            Layout.columnSpan: 2
 
            onClicked: 
                // Invoke the calculator slot to sum the numbers
                sumResult.text = calculator.sum(firstNumber.text, secondNumber.text)
            
        
 
        Text 
            text: qsTr("Result")
        
 
        // Here we see the result of sum
        Text 
            id: sumResult
        
 
        Button 
            height: 40
            Layout.fillWidth: true
            text: qsTr("Subtraction numbers")
 
            Layout.columnSpan: 2
 
            onClicked: 
                // Invoke the calculator slot to subtract the numbers
                subResult.text = calculator.sub(firstNumber.text, secondNumber.text)
            
        
 
        Text 
            text: qsTr("Result")
        
 
        // Here we see the result of subtraction
        Text 
            id: subResult
        
    

注意：对于 PyQt5，将 Slot 更改为 pyqtSlot。

【讨论】：

出现以下错误。任何的想法 ？什么坏了。 QQmlApplicationEngine 无法加载组件文件：//E:/​​code/QML/calc.qml:1 无法为模块“QtQuick”加载插件：无法加载库 C:\Python27\lib\site-packages\PySide2\qml\ QtQuick.2\qtquick2plugin.dll: 找不到指定的程序。

@Ruchit .dll 似乎与您的操作系统不兼容，您是如何安装 pyside2 的？

将C:\Python27\Lib\site-packages\PySide2 添加到PATH 变量后工作正常。

如果你想一遍又一遍地从 python 调用函数中更改 progressBar 值以获得结果是非常糟糕的方法。我会对如何使用 PySide2 中的信号来做这件事很感兴趣