plot.cpp
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#include "plot.h"
#include <qwt_plot_curve.h>
#include <qwt_plot_grid.h>
#include <qwt_symbol.h>
#include <qwt_plot_picker.h>
#include <qwt_scale_engine.h>
Plot::Plot( QWidget *parent ):
QwtPlot( parent )
{
setCanvasBackground( Qt::white );
setAxisScale(QwtPlot::yLeft, 0.0, 10.0 );
setTransformation( new QwtNullTransform() );
populate();
QwtPlotPicker *picker = new QwtPlotPicker( canvas() );
picker->setTrackerMode( QwtPlotPicker::AlwaysOn );
}
void Plot::populate()
{
QwtPlotGrid *grid = new QwtPlotGrid();
grid->setMinorPen( Qt::black, 0, Qt::DashLine );
grid->enableXMin( true );
grid->attach( this );
QwtPlotCurve *curve = new QwtPlotCurve();
curve->setTitle("Some Points");
curve->setPen( Qt::blue, 4 ),
curve->setRenderHint( QwtPlotItem::RenderAntialiased, true );
QwtSymbol *symbol = new QwtSymbol( QwtSymbol::Ellipse,
QBrush( Qt::yellow ), QPen( Qt::red, 2 ), QSize( 8, 8 ) );
curve->setSymbol( symbol );
QPolygonF points;
points << QPointF( 10.0, 4.4 )
<< QPointF( 100.0, 3.0 ) << QPointF( 200.0, 4.5 )
<< QPointF( 300.0, 6.8 ) << QPointF( 400.0, 7.9 )
<< QPointF( 500.0, 7.1 ) << QPointF( 600.0, 7.9 )
<< QPointF( 700.0, 7.1 ) << QPointF( 800.0, 5.4 )
<< QPointF( 900.0, 2.8 ) << QPointF( 1000.0, 3.6 );
curve->setSamples( points );
curve->attach( this );
}
void Plot::setTransformation( QwtTransform *transform )
{
QwtLinearScaleEngine *scaleEngine = new QwtLinearScaleEngine();
scaleEngine->setTransformation( transform );
setAxisScaleEngine( QwtPlot::xBottom, scaleEngine );
// we have to reassign the axis settinge, because they are
// invalidated, when the scale engine has changed
QwtScaleDiv scaleDiv =
axisScaleEngine( QwtPlot::xBottom )->divideScale( 10.0, 1000.0, 8, 10 );
QList<double> ticks;
ticks += 10.0;
ticks += scaleDiv.ticks( QwtScaleDiv::MajorTick );
scaleDiv.setTicks( QwtScaleDiv::MajorTick, ticks );
setAxisScaleDiv( QwtPlot::xBottom, scaleDiv );
replot();
}