app.qml

//![0]
import Charts 1.0
import QtQuick 2.0

Item {
    width: 300; height: 200

    Row {
        anchors.centerIn: parent
        spacing: 20

        PieChart {
            id: chartA
            width: 100; height: 100
            color: "red"
        }

        PieChart {
            id: chartB
            width: 100; height: 100
            color: chartA.color
        }
    }

    MouseArea {
        anchors.fill: parent
        onClicked: { chartA.color = "blue" }
    }

    Text {
        anchors {
            bottom: parent.bottom;
            horizontalCenter: parent.horizontalCenter;
            bottomMargin: 20
        }
        text: "Click anywhere to change the chart color"
    }
}
//![0]

bindings.py

"""PySide6 port of the qml/tutorials/extending-qml/chapter3-bindings example from Qt v5.x"""

import os
import sys

from PySide6.QtCore import Property, Signal, Slot, QUrl, Qt
from PySide6.QtGui import QGuiApplication, QPen, QPainter, QColor
from PySide6.QtQml import qmlRegisterType
from PySide6.QtQuick import QQuickPaintedItem, QQuickView

class PieChart (QQuickPaintedItem):
    def __init__(self, parent = None):
        QQuickPaintedItem.__init__(self, parent)
        self._name = u''
        self._color = QColor()

    def paint(self, painter):
        pen = QPen(self._color, 2)
        painter.setPen(pen)
        painter.setRenderHints(QPainter.Antialiasing, True)
        painter.drawPie(self.boundingRect().adjusted(1,1,-1,-1), 90 * 16, 290 * 16)

    def getColor(self):
        return self._color

    def setColor(self, value):
        if value != self._color:
            self._color = value
            self.update()
            self.colorChanged.emit()

    def getName(self):
        return self._name

    def setName(self, value):
        self._name = value

    colorChanged = Signal()
    color = Property(QColor, getColor, setColor, notify=colorChanged)
    name = Property(str, getName, setName)
    chartCleared = Signal()

    @Slot() # This should be something like @Invokable
    def clearChart(self):
        self.setColor(Qt.transparent)
        self.update()
        self.chartCleared.emit()

if __name__ == '__main__':
    app = QGuiApplication(sys.argv)

    qmlRegisterType(PieChart, 'Charts', 1, 0, 'PieChart')

    view = QQuickView()
    view.setResizeMode(QQuickView.SizeRootObjectToView)
    qmlFile = os.path.join(os.path.dirname(__file__), 'app.qml')
    view.setSource(QUrl.fromLocalFile(os.path.abspath(qmlFile)))
    if view.status() == QQuickView.Error:
        sys.exit(-1)
    view.show()
    res = app.exec_()
    # Deleting the view before it goes out of scope is required to make sure all child QML instances
    # are destroyed in the correct order.
    del view
    sys.exit(res)