Customize qtChart

steph27

Hi,

I would like to customize my QtChart to have the 3 colors (green, yellow, red) on the range slider at the background of the chart (instead of the shades) :

How can I do that in QML ?

Regards
Stéphane

steph27

Ok I found it :

I call this function each time the QSliderRange change :

void Controller::updateBackground(QQuickItem* item){
    if(item){
        if(QGraphicsScene *scene = item->findChild<QGraphicsScene *>()){
            for(QGraphicsItem *it : scene->items()){
                if(QtCharts::QChart *chart = dynamic_cast<QtCharts::QChart *>(it)){
                    // Customize plot area background
                    QImage background(item->width(), item->height(), QImage::Format_ARGB32);
                    if (background.isNull())
                        continue;
                    background.fill(QColor(Qt::white));
                    QPainter painter(&background);

                    int margin = (item->height()-chart->plotArea().height()) /2;
                    int hRed = (10- _pData->threshHigh)/10 * chart->plotArea().height();
                    int hGreen = _pData->threshLow/10 * chart->plotArea().height();
                    int hYellow = chart->plotArea().height() - hRed - hGreen;

                    // Red zone
                    painter.fillRect(0, 0, item->width(), margin + hRed, QBrush(QColor(255,50,50,128)));
                    // Yellow zone
                    painter.fillRect(0,margin+hRed, item->width(), hYellow, QBrush(QColor(235,220,50,128)));
                    // Green zone
                    painter.fillRect(0,margin+hRed+hYellow, item->width(), margin+hGreen, QBrush(QColor(100,150,100,128)));

                    chart->setPlotAreaBackgroundBrush(background);
                    chart->setPlotAreaBackgroundVisible(true);
                }
            }
        }
    }
}

By passing the ChartView as parameter :

sThresh.first.onValueChanged:     controller.updateBackground(chart)
sThresh.second.onValueChanged:    controller.updateBackground(chart)