创建样条曲线图

要创建样条曲线图，我们需要将数据输入QSplineSeries 。QSplineSeries 会自动计算样条线段控制点，这些控制点是正确绘制样条曲线所必需的。

auto series = new QSplineSeries;
series->setName("Spline");

现在，让我们为系列添加一些数据点。

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);

数据系列已填充完毕。要在图表中显示，我们需要创建一个QChart 对象，并将数据序列添加到该对象中。我们还在 Y 轴上设置了标题和数值范围，这样图表的可视性就更好了。

auto chart = new QChart;
chart->legend()->hide();
chart->addSeries(series);
chart->setTitle("Simple Spline Chart");
chart->createDefaultAxes();
chart->axes(Qt::Vertical).first()->setRange(0, 10);

然后，我们创建一个QChartView 对象，并将QChart 作为参数。这样我们就不需要自己创建QGraphicsView 场景了。

createDefaultChartView(chart);

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