Get QtGraphs with XYModelMapper working

Igor23

@GrecKo Thanks! I also found that out. But the lineseries must also have a color different from backround and there must be explicit axes. My working qml file is now:

import QtQuick
import QtGraphs
import graphsexample 1.0

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")
    GraphsView {
        id: graphsView
        antialiasing: true
        anchors.fill: parent
        //legend.visible: false
        ValueAxis {
            id: axisX
            min: 0
            max: 10  // Anpassen an Ihre Daten
            titleText: "X-Achse"
        }

        ValueAxis {
            id: axisY
            min: 0
            max: 10  // Anpassen an Ihre Daten
            titleText: "Y-Achse"
        }
        LineSeries {
            id: lineSeries
            color: "#00ff00"
            joinStyle: Qt.RoundJoin
            XYModelMapper {
                model: Graphsmodel
                series: lineSeries
                xSection: 0
                ySection: 1
            }
            axisX: axisX
            axisY: axisY
        }
    }
}

Also this Connections don't work. It must be Graphsmodel with captal letter in XYModelMapper:

    Connections{
        id: graphsmodel
        target: Graphsmodel
    }

Igor23

@GrecKo I have an additional question, because it is important for my project:
How can I update the axes in the following sense:

ValueAxis {
    id: axisX
    min: Graphsmodel.returnXmin()
    max: Graphsmodel.returnXmax()
    titleText: "X-Achse"
}

Even with fixed starting values this is not working for me.

GrecKo

Try to expose the xMin and xMan as properties with a NOTIFY signal instead to make the min and max binding automatically update. I guess it is currently calling returnXmin/max initially when the model is maybe empty, and then it isn't called again.

Igor23

@GrecKo How do you mean this exactly? Can you give an example code?

Igor23

And I have a second additional question: is there maximum number of points I can draw via Lineseries and XYModelMapper? It seems to me as there is a limit by Qt framework ...

JoeCFD

@Igor23 add the following in your model
Q_PROPERTY( float minX MEMBER m_fMinX NOTIFY minXChanged )
define m_fMinX and signal minXChanged in your model.

Do the same for maxX.

and

ValueAxis {
    id: axisX
    min: Graphsmodel.minX
    max: Graphsmodel.maxX
    titleText: "X-Achse"
}

JoeCFD

@Igor23 It seems there is no limit. But your drawing will get slower if there are too many points. You need some kind of optimization.

SGaist

The LineSeries type has a count property that returns the number of data points in the series so I would venture that the maximum int value is the limit but I wouldn't try to show that many data point anyway because it does not make sense. If anything, I would rather allow the user to zoom in/out of sections of a LineSeries if they need more precise data.

Igor23

@JoeCFD This works for me. Thank you!

Igor23

Sorry, I still have a question: How can I make a logarithmic scale to one axis? I didn't find in the web - only for 3D.

JoeCFD

This post is deleted!

Bob64

@JoeCFD That is Charts - I believe @Igor23 is using the newer Graphs module. From what I remember when I looked into it, logarithmic axis was one of the missing features of Graphs vs Charts.

JoeCFD

@Bob64 You are right. I did not pay attention to it.