SplineChart Example#

The example shows how to create a simple spline chart.

../_images/examples_splinechart1.png

Running the Example#

To run the example from Qt Creator , open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

Creating Spline Charts#

To create spline charts we need to put our data into QSplineSeries . QSplineSeries automatically calculates spline segment control points that are needed to properly draw the spline.

series = QSplineSeries()
series.setName("spline")

Now let’s add some data points to the series.

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)

The data series has been populated. To display it on a chart we create a QChart object and add the data series to it. We also set the title and the values range on the y-axis, so that our chart’s visibility is better.

chart = QChart()
chart.legend().hide()
chart.addSeries(series)
chart.setTitle("Simple spline chart example")
chart.createDefaultAxes()
chart.axes(Qt.Vertical).first().setRange(0, 10)

Then we create a QChartView object with QChart as a parameter. This way we don’t need to create a QGraphicsView scene ourselves. We also set the Antialiasing on to have the rendered lines look nicer.

chartView = QChartView(chart)
chartView.setRenderHint(QPainter.Antialiasing)

Finally, we set the QChartView as the windows’s central widget.

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

Example project @ code.qt.io