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35 lines
1.5 KiB
Markdown
35 lines
1.5 KiB
Markdown
# Example (JKQTPlotter): Plotting Bezier Curves {#JKQTPlotterGeometricBezier}
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This project shows the capabilities of JKQTPlotter to also draw arrows as geometric elements, using JKQTPGeoBezierCurve.
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The source code of the main application can be found in [`geo_bezier.cpp`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/geo_bezier/geo_bezier.cpp). First a plot is generated. Then several types of bezier curves are added to the plot and their control points shown.
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Here is an example for drawing a cubic bézier curve:
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```.cpp
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JKQTPGeoBezierCurve* bezCubic=new JKQTPGeoBezierCurve(&plot);
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bezCubic->setCubic(QPointF(0.25,0.25), QPointF(0.8,2.5), QPointF(3.25,0.2), QPointF(3.75,2.75));
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bezCubic->setLineColor(QColor("maroon"));
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bezCubic->setHeadDecoratorSizeFactor(JKQTPArrow);
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bezCubic->setTailDecoratorSizeFactor(JKQTPArrow);
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plot.addGraph(bezCubic);
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```
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Finally we also add symbols for each control point and a poly-line connecting them:
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```.cpp
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JKQTPGeoPolyLines* l2;
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plot.addGraph(l2=new JKQTPGeoPolyLines(&plot, bezCubic->getPoints()));
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l2->setLineColor(QColor("darkgrey"));
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l2->setLineWidth(1);
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JKQTPXYScatterGraph* scatCubic=new JKQTPXYScatterGraph(&plot);
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scatCubic->setXYColumns(plot.getDatastore()->addCopiedPoints(bezCubic->getPoints()));
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scatCubic->setSymbolColor(QColor("blue"));
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scatCubic->setSymbolType(JKQTPCircle);
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plot.addGraph(scatCubic);
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```
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Here is the resulting plot:
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