[Qt charts 2.1] Problem with DateTimeAxis

Geoffroy

Hi everybody,

I'm facing to an issue with qt charts 2.1
I need to draw a line series within a 10 seconds interval. I have created a DateTimeAxis with min and max parameters set accordingly to my need. It seems that when the time resolution is too high (interval less than few seconds), points are located at the same x position .. Here is a minimalist code which reproduce the problem :

import QtQuick 2.5
import QtQuick.Window 2.2
import QtCharts 2.1


Window {

    visible: true
    width: 640
    height: 480

    ChartView {
        id: chartView
        anchors.fill: parent
        property bool openGL: true

        ValueAxis {
            id: axisY1
            min: -1.5
            max: 1.5
            tickCount: 5
            minorTickCount: 5
        }

        DateTimeAxis {
            id: axisX
            tickCount: 10
            min: new Date(new Date() - 10000)
            max: new Date()
            format: "mm:ss"
        }

        LineSeries {
            id: lineSeries1
            name: "signal 1"
            axisX: axisX
            axisY: axisY1
            useOpenGL: chartView.openGL
            XYPoint { x: toMsecsSinceEpoch(new Date(new Date() - 10000)); y: -1 }
            XYPoint { x: toMsecsSinceEpoch(new Date()); y: 1 }
        }
    }

    function toMsecsSinceEpoch(date) {
        var msecs = date.getTime();
        return msecs;
    }
}

The visual result is a vertical line located at the left of the chart ..
Any ideas for solve that ?

TrevorEdris

Hello,
I am also having this same issue. It seems as though this problem with the DateTimeAxis only persists when used in QML, as I created a simple example using my same dataset with a strictly c++ approach and the dataset was displayed correctly. When used in QML, the points are all mapped to the same X position, as you have stated.