The issue was solved Add child model in parent repeater's Compoenet.onCompleted.

Repeater { id: repeater1 model: backend.graphModel Component.onCompleted: { repeater2.model = model.GraphMaximumCount } } Repeater { id: repeater2 }

@StudyQt1 said in Plotting chart using lots of data:

Is there a generic way to decide?

Use a profiler. If you're using GCC you can use https://www.thegeekstuff.com/2012/08/gprof-tutorial/
Easier way which is often enough is simply to put debug output at the beginning and end of your methods/functions with timestamps and then check the output of your application while it is running.

@J-Hilk
Ok that's enough I think.

One more question what will happen to scrolleft().

If I keep on incrementing these, will there be any increase in runtime memory or processor load?

Hello! If I understood correctly, and you want to use the same chart view to represent the data in different forms like bars or line, I don't see any reason why not.
If you take a look at https://doc.qt.io/qt-5/qtcharts-lineandbar-example.html, you can find an example of showing both a bar and line charts in the same chart, at the same time. From there, you can modify to show just one at a time, so in your case switching between the series when the menu action is triggered.

Hereby a solution that works for me. Instead of using a repeater, this codesample works with the ChartView's onCompleted signal handler. In the onCompleted handler first three LineSeries are dynamically created, then an AreaSeries is created.

ChartView { id: chartid anchors.fill: parent antialiasing: true //Valueaxis ValueAxis{ id:xAxis; min: 0; max: 40000; tickCount: 9 } ValueAxis{ id:yAxis; min: -200; max: 1400; tickCount: 17 } //Listmodel only for testing Area- and LineSeries concept ListModel{ id: listModel ListElement { x1: 18000; y1: -100; x2: 18000 ; y2: 400 } ListElement { x1: 25000; y1: -100; x2: 25000 ; y2: 1000 } ListElement { x1: 31000; y1: -100; x2: 31000 ; y2: 1200 } ListElement { x1: 36500; y1: -100; x2: 39700 ; y2: 1250 } } Component.onCompleted: { var count = listModel.count; for(var i = 0;i < count;i ++) { if (i < count - 1) // add LineSeries { var lineTypeSeries = chartid.createSeries(ChartView.SeriesTypeLine, "line" + i, xAxis, yAxis); lineTypeSeries.color = "black"; lineTypeSeries.width = 2; lineTypeSeries.borderWidth = 0; lineTypeSeries.append(listModel.get(i).x1, listModel.get(i).y1); lineTypeSeries.append(listModel.get(i).x2, listModel.get(i).y2); } else { var areaTypeSeries = chartid.createSeries(ChartView.SeriesTypeArea, "area" + i, xAxis, yAxis); areaTypeSeries.pointsVisible = true; areaTypeSeries.color = "lightgrey"; areaTypeSeries.borderColor = "black"; areaTypeSeries.borderWidth = 2; areaTypeSeries.lowerSeries = chartid.createSeries(ChartView.SeriesTypeLine, "lowerSerie"); areaTypeSeries.lowerSeries.width = 0; areaTypeSeries.lowerSeries.borderWidth = 0; areaTypeSeries.lowerSeries.color = areaTypeSeries.borderColor; areaTypeSeries.lowerSeries.capStyle = 0x00; areaTypeSeries.lowerSeries.append(listModel.get(i).x1, listModel.get(i).y1); areaTypeSeries.lowerSeries.append(listModel.get(i).x2, listModel.get(i).y1); areaTypeSeries.upperSeries.append(listModel.get(i).x1, listModel.get(i).y2); areaTypeSeries.upperSeries.append(listModel.get(i).x2, listModel.get(i).y2); } } } }