How to achieve show/hide Qt Charts series by clicking legendmarker in Qt Quick

ynakane

Hi.

I want to achieve below example in Qt Quick Project.
https://doc.qt.io/qt-6/qtcharts-legendmarkers-example.html

This example uses the QChartView class, but I'm using the QML ChartView Type.
I don't know how to detect the LegendMarker's Clicked signal from ChartView QML.
It seems that the LegendMarker cannot be accessed from the QML Legend Type.

Thank you in advance.

Robbie Ashby

Hi ynakane,

I was trying to achieve the same thing and was unable to do it using the QML Legend Type. However, I am relatively new to Qt Quick (coming from a widgets background) so may not have been doing things correctly.

The method I found that did work was creating a custom QML legend. I based this off the tutorial example:

https://doc.qt.io/qt-6/qtcharts-qmlcustomlegend-example.html

Change the purpose of the onSelected signal to instead change the series visibility. I also changed the signal so it passed the index instead of the series name. Then in you main QML code connect to the signal like this:

        CustomLegend
        {
            id: customLegend
            width: parent.width
            height: 50
            anchors.top: chartView.bottom
            anchors.horizontalCenter: parent.horizontalCenter
            onSelected:
            {
                chartView.series(seriesIndex).visible = !chartView.series(seriesIndex).visible
            }
        }

I don't know if this is the best method to use but it worked well for me.