python based tutorial: QML using Python parsing function procedure

This article describes the process using a function QML Python parsing, text sample code described in great detail, has a certain reference value of learning for all of us to learn or work, a friend in need under reference
there are two ways:

A, QML define a signal, Python in connection function;

Function here do not specifically designated as slot function, normal function can be.

QML Python function signal connections of
QML:
first defined in QML a signal, where the signal passed to the function of a string (with parameter signals may also or without):
signal mySignal(string my_string)
then transmits this signal to the click of:

onClicked:{
  root.mySignal("hello world")
}

Python:
Use in QML signal connection function in Python:
engine.rootObjects()[0].mySignal.connect(my_func) # 这里的mySignal是在QML里定义的
complete code:
QML:

import QtQuick 2.12
import QtQuick.Controls 2.12
 
ApplicationWindow {
  id: root
  width: 250
  height: 500
  visible: true
 
  signal mySignal(string my_string)
 
  MouseArea {
    id: mouse_area
    anchors.fill: parent
    onClicked: {
      root.mySignal("hello world")
    }
  }
}

Python：

from PyQt5.QtCore import QObject
from PyQt5.QtGui import QGuiApplication
from PyQt5.QtQml import QQmlApplicationEngine
import sys
class MyWindow(QObject):
  def __init__(self):
    super().__init__()
    self.engine = QQmlApplicationEngine()
    self.engine.load('qml-test.qml')
 
    # root signal
    my_obj = self.engine.rootObjects()[0]
    my_obj.mySignal.connect(self.my_func)
 
  def my_func(self, my_string):
    print(my_string)
if __name__ == '__main__':
  app = QGuiApplication(sys.argv)
  window = MyWindow()
  sys.exit(app.exec())

Two, define a Python class and slot function, use this function in the slot in QML
call Python function in the slot in QML
first need to define a class in Python, write a groove function in class:

class Person(QObject):
  def __init__(self):
    super().__init__()
 
  @pyqtSlot() # 注意是槽函数！
  def begin(self):
    print('begin')

SetContextProperty this class then a set of context attribute values:

person = Person()
engine.rootContext().setContextProperty('person', person)

QML file without any special settings, you can directly call the function.

Complete code:

Python：

from PyQt5.QtGui import QGuiApplication
from PyQt5.QtQml import QQmlApplicationEngine
from PyQt5.QtCore import QObject, pyqtSlot
import sys
class Person(QObject):
  def __init__(self):
    super().__init__()
 
  @pyqtSlot() # 注意是槽函数！
  def begin(self):
    print('begin')
if __name__ == '__main__':
  app = QGuiApplication(sys.argv)
  engine = QQmlApplicationEngine()
 
  person = Person()
  engine.rootContext().setContextProperty('person', person)
 
  engine.load('qml-test.qml')
  sys.exit(app.exec())

QML:

import QtQuick 2.12
import QtQuick.Controls 2.12
 
ApplicationWindow {
  id: root
  width: 250
  height: 500
  visible: true
 
  Button{
      text:qsTr("begin")
      onClicked: {
        person.begin()
      }
  }
}

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