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51 lines
2.7 KiB
Markdown
51 lines
2.7 KiB
Markdown
# Example (JKQTPlotter): Step Line Plots in Different Styles {#JKQTPlotterSpecialStepLinePlot}
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This project (see `./examples/stepplots/`) simply creates a JKQTPlotter widget (as a new window) and adds a single line-graph (a sine-wave). Data is initialized from two QVector<double> objects.
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The source code of the main application can be found in [`stepplots.cpp`](https://github.com/jkriege2/JKQtPlotter/tree/master/examples/stepplots/stepplots.cpp). For the most part, several datasets of cosine-curves are generated. Then graphs of type `JKQTPSpecialLineHorizontalGraph` are added to the plot:
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```.cpp
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// 3 now we make several plots with different step styles, each one also contains a
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// symbol plot indicating the location of the datapoints themselves
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JKQTPSpecialLineHorizontalGraph* graph;
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//-- JKQTPStepLeft ----------------------------------------------------------------------------------------
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graph=new JKQTPSpecialLineHorizontalGraph(&plot);
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// set data for the graph
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graph->setXColumn(columnX);
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graph->setYColumn(columnY1);
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// set step style
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graph->setSpecialLineType(JKQTPStepLeft);
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graph->setLineWidth(1);
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graph->setFillCurve(true);
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graph->setDrawLine(true);
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graph->setTitle("JKQTPStepLeft, filled");
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// enable symbols
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graph->setDrawSymbols(true);
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graph->setSymbolType(JKQTPGraphSymbols::JKQTPCircle);
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```
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Note that you can configure the step type (left/center/right by `graph->setSpecialLineType(JKQTPStepLeft)`. With `graph->setFillCurve(true)` you can draw the curve filled until the y=0-axis and with `graph->setDrawLine(true)` you can switch the line along the values on and off (e.g. to only have the filled area, but no line). With `graph->setDrawSymbols(true)` you can switch on drawing of symbols at the location of the data points.
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... and all graphs are added to the plot:
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```.cpp
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// add the graphs to the plot, so it is actually displayed
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plot.addGraph(graph);
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```
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In addition to the symbol type and line style, you can also alter the size of the symbols (`graph->setSymbolSize(14)`), the line-width used to draw them (`graph->setSymbolLineWidth(1.5)`) and the line width of the graph line (`graph->setLineWidth(1)`). If you want to switch off the line altogether, use `graph->setDrawLine(false`.
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The result looks like this:
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If you use `` instead of the horizontal variant `` and exchange x- for y-data, you will get a plot like this:
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Also note how the red graph is filled towards the y-axis, not the x-axis.
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