Auto Axes in QML Lineseries Charts

eswar

Hi

In line series charts, i was append the c++ data to qml. Herewith add coding for your reference. In that i need to auto adjust the X and Y axes minimum and maximum value based on the received data from c++.

ChartView {

    id: chartView

    title: "Real Time Charts"
    anchors.fill: parent
    animationOptions: ChartView.SeriesAnimations
    antialiasing: true
    theme: ChartView.ChartThemeBlueCerulean

    ValueAxis {
        id: axisY2
        min: 0
        max: 100
        minorTickCount: 3
        tickCount: 10

    }

    ValueAxis {
        id: axisX
        min: 0
        max: 50
        minorTickCount: 3
        tickCount: 7
        gridVisible: false
       color: "white"
    }

    LineSeries {
        id: lineSeries1
        name: "signal 1"
        axisX: axisX
        axisY: axisY1

For rate changed, i was append the data to the lineseries...

        onRateChanged:  {

lineSeries1.append(currentIndex,rate)

Question?

Instead of defining X and Y min and max values, i need a solution to adjust min and max values automatically based on the received data.

SamGrant

I did something similar to this, but using JavaScript to read my data...

I have two properties in my main.qml that are my min & max for my axis. I update them via the JavaScript.

In my QML with the charts, I make sure that the min & max parameters point to the properties in my main.qml.

main.qml :

property alias appWin: mainWindow
property double maxWspd: 0.0
property double minWspd: 100.0

JavaScript:

if( appWin.maxWspd < Math.ceil((appWin.wxWspd))+1 ) {
    appWin.maxWspd = Math.ceil((appWin.wxWspd))+1;
}
if( appWin.minWspd > Math.floor((appWin.wxWspd))-1 ) {
    appWin.minWspd = Math.floor((appWin.wxWspd))-1;
}

MyGraphs.qml:

        ValueAxis {
            id: axisYw
            min: appWin.minWspd
            max: appWin.maxWspd
            tickCount: 5
            labelFormat: "%.1f"
            labelsFont:Qt.font({pointSize: 12})
            labelsColor: appWin.baseFontColor
            color: appWin.graphTickColor
        }