QML and Qt for Python interaction

app = QGuiApplication(sys.argv)
view = QQuickView()
view.setResizeMode(QQuickView.SizeRootObjectToView)

current_path = os.path.abspath(os.path.dirname(__file__))
qml_file = os.path.join(current_path, 'app.qml')
view.setSource(QUrl.fromLocalFile(qmlFile))
if view.status() == QQuickView.Error:
    sys.exit(-1)

view.show()
res = app.exec_()
del view
sys.exit(res)

import QtQuick 2.0
Text {
    text : 'Hello, world!'
}

class PieChart (QQuickPaintedItem):
    def __init__(self, parent = None):
        QQuickPaintedItem.__init__(self, parent)
        self.color = QColor()
    def paint(self, painter):
        pen = QPen(self.color, 2)
        painter.setPen(pen);
        painter.setRenderHints(QPainter.Antialiasing, True);
        # From drawPie(const QRect &rect, int startAngle, int spanAngle)
        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()
    colorChanged = Signal()
    color = Property(QColor, getColor, setColor, notify=colorChanged)

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

import Charts 1.0
import QtQuick 2.0
Item {
    width: 300; height: 200
    PieChart {
        id: chartA
        width: 100; height: 100
        color: "red"
        anchors.centerIn:parent
    }
    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"
    }
}