How to add text in plotting area of chartview in q

问题:

How do I place text at specific (x,y) locations within the plotting area of a QML ChartView type?

For example, I would like to place text at the location XYPoint{x: -3; Y: 20} I don't want to place at window's(x,y), i want to put at plotting area's (x,y)

I read documentation,but i don't find any property !!!!!!

//ChartView for plotting points

ChartView{
    id:chrt
    anchors.fill: parent
    height: parent.height
    width: parent.width
    legend.visible: false
    backgroundColor: "black"


    //X- axis
    ValueAxis{
        id: x_axis
        min: -5
        max: 0
        tickCount: 6
    }

    //Right Y axis
    ValueAxis{
        id:right_y_axis
        min:0
        max:40
        tickCount: 5
    }

    //Left Y axis
    ValueAxis{
        id:left_y_axis
        min:0
        max:40
        tickCount: 5
    }

    //Line series for wave 1
    LineSeries{
        id:l1
        axisY: left_y_axis
        axisX:x_axis
        color: "yellow"
        width: 1
    }

    //Line series for wave 2
    LineSeries{
        id:l2
        axisYRight: right_y_axis
        style: Qt.DashLine
        color: "yellow"
        width: 0.6
    }
}

回答1:

Ok, you can use ChartView.mapToPosition to calculate the global position of the specified point from a series (or some another point inside the series), for example:

ChartView{
    id:chart
    anchors.fill: parent
    backgroundColor: "black"

    LineSeries{
        id: series
        XYPoint { x: 10; y: 5  }
        XYPoint { x: 10; y: 1 }
        XYPoint { x: 15; y: 5 }
        XYPoint { x: 20; y: 10 }
        XYPoint { x: 25; y: 5 }
        XYPoint { x: 30; y: 20 }
        XYPoint { x: 40; y: 10 }
    }

    Text {
        id: txt
        text: "Hello"
        color: "white"
    }

    onWidthChanged: updatePointPosition();
    onHeightChanged: updatePointPosition();

    function updatePointPosition()
    {
        var p = chart.mapToPosition(series.at(3), series);
        txt.x = p.x;
        txt.y = p.y;
    }
}