如何在QML的Chartview的繪圖區域添加文本

Question

如何在QML ChartView類型的繪圖區域內的特定（x，y）位置放置文本？

例如，我想將文本放置在XYPoint {x：-3; Y：20}我不想放在窗口的（x，y）上，我想放在繪圖區域的（x，y）上

我閱讀了文檔，但是找不到任何財產！

//繪制點的ChartView

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
    }
}

Answer 1

好的，您可以使用ChartView.mapToPosition來計算系列中指定點（或系列中的其他點）的全局位置，例如：

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;
    }
}