JKQtPlotter/examples/simpletest_symbols_and_styles/README.md
jkriege2 0e2237e92f - more refactorings to modernize C++
- fixed JKQTPColumnMathImage with modifiers
- improved documentation
- make use of link_prl/create_prl in QMake projects (see http://doc.qt.io/qt-5/qmake-advanced-usage.html)
2019-01-26 18:00:42 +01:00

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# Example (JKQTPlotter): Line Graph with Different Symbols and Line Styles {#JKQTPlotterSymbolsAndStyles}
This project (see `./examples/simpletest_symbols_and_styles/`) 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.
The source code of the main application can be found in [`jkqtplotter_simpletest_symbols_and_styles.cpp`](../simpletest_symbols_and_styles/jkqtplotter_simpletest_symbols_and_styles.cpp). Mainly several graphs are generated in a loop and then different symbol and line styles are applied to the graph (set by `graph->setSymbol()` for the symbol and `graph->setStyle()` for the line style). The colors are set automtically from an internal default palette. The main loop looks like this:
```.cpp
QVector<Qt::PenStyle> pens {Qt::NoPen, Qt::SolidLine, Qt::DashLine, Qt::DotLine, Qt::DashDotLine, Qt::DashDotDotLine };
int ipen=0;
for (int symbolID=0; symbolID<=JKQTPMaxSymbolID; symbolID++) {
// generate some plot data
QVector<double> Y;
for (auto& xx: X) {
Y<<sin(xx)+static_cast<double>(symbolID)*1.5;
}
JKQTPXYLineGraph* graph=new JKQTPXYLineGraph(&plot);
// copy data into datastore and immediately set the yColumn
graph->setXColumn(columnX);
graph->setYColumn(ds->addCopiedColumn(Y, "y"+QString::number(symbolID)));
// set symbol + pen style and color
graph->setSymbol(static_cast<JKQTPGraphSymbols>(symbolID));
graph->setStyle(pens[ipen]);
// set symbol size
graph->setSymbolSize(14);
// set width of symbol lines
graph->setSymbolWidth(1.5);
// set width of graph line
graph->setLineWidth(1);
// graph title is made from symbol+penstyle
graph->setTitle(JKQTPGraphSymbols2NameString(static_cast<JKQTPGraphSymbols>(graph->getSymbol()))+QString(", ")+jkqtp_QPenStyle2String(graph->getStyle()));
// add the graph to the plot, so it is actually displayed
plot.addGraph(graph);
ipen++;
if (ipen>=pens.size()) ipen=0;
}
```
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->setSymbolWidth(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`.
The result looks like this:
![jkqtplotter_simpletest_symbols_and_styles](../../screenshots/jkqtplotter_simpletest_symbols_and_styles.png)