CODEWITHSUNDEEP
c++qtchartsqtcharts
JohnnyFromBF
JohnnyFromBF

Reputation: 10191

How to adjust the LineChart example from Qt Charts?

I'm trying to adjust the LineChart example from the Qt Charts library. Here's the code:

#include <QtWidgets/QApplication>
#include <QtWidgets/QMainWindow>
#include <QtCharts/QChartView>
#include <QtCharts/QLineSeries>

QT_CHARTS_USE_NAMESPACE

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QLineSeries *series = new QLineSeries();

    series->append(0, 6);
    series->append(2, 4);
    series->append(3, 8);
    series->append(7, 4);
    series->append(10, 5);
    *series << QPointF(11, 1) << QPointF(13, 3) << QPointF(17, 6) << QPointF(18, 3) << QPointF(20, 2);

    QChart *chart = new QChart();
    chart->legend()->hide();
    chart->addSeries(series);
    chart->createDefaultAxes();
    chart->setTitle("Simple line chart example");

    QChartView *chartView = new QChartView(chart);
    chartView->setRenderHint(QPainter::Antialiasing);

    QMainWindow window;
    window.setCentralWidget(chartView);
    window.resize(400, 300);
    window.show();

    return a.exec();
}

I want to change the chart in a way that I can draw a point at certain x,y pairs in a different color. Now I tried to change the color of the chart line and it works, but it's not the chart line I want to change but the color of the point at x,y. Thus I guess I'll have to add points to the chart first, but apparently the API gives me only the append() method not something like drawPoint(). What do I have to do to get this functionality? Is it available already and I'm just not seeing it?

Upvotes: 2

Views: 6019

Answers (1)

tedris
tedris

Reputation: 41

If all you want to do is add points onto the graph at specific locations, then QScatterSeries would be the best way to do so. As far as I know, if you want each point to be a separate color, they must be contained in a separate series, as the whole series will share the same properties.

QScatterSeries* redSeries = new QScatterSeries;
redSeries->append(0, 6);
redSeries->append(2, 4);
redSeries->setColor(Qt::red);

QScatterSeries* blueSeries = new QScatterSeries;
blueSeries->append(3, 8);
blueSeries->append(7, 4);
blueSeries->append(10, 5);
blueSeries->setColor(Qt::blue);

...

chart->addSeries(redSeries);
chart->addSeries(blueSeries);

Upvotes: 1

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