QmlPlot::QmlPlot(QDeclarativeItem *parent):
    QGraphicsProxyWidget(parent)
{
    customPlot = new QCustomPlot();
    setWidget(customPlot);
    setVisible(true);
}


void QmlPlot::setup()
{
    // LOADS of stuff to make the Plot.
    update(boundingRect());
}

import QtQuick 1.1
import com.ingima.qmlplot 1.0

Rectangle {
    width: 360
    height: 360

    QmlPlot {
        id: myplot
        anchors.fill: parent
        color: "red"
    }

    MouseArea {
        anchors.fill: parent
        onClicked: {
            myplot.setup();
        }
    }
}