Synthetic point data. More...

#include <qwt_point_data.h>

Inheritance diagram for QwtSyntheticPointData:

Public Member Functions
virtual QRectF	boundingRect () const
	Calculate the bounding rectangle.
QwtInterval	interval () const
	QwtSyntheticPointData (size_t size, const QwtInterval &=QwtInterval())
QRectF	rectOfInterest () const
virtual QPointF	sample (size_t i) const
void	setInterval (const QwtInterval &)
virtual void	setRectOfInterest (const QRectF &)
void	setSize (size_t size)
virtual size_t	size () const
virtual double	x (uint index) const
virtual double	y (double x) const =0
Private Attributes
QwtInterval	d_interval
QwtInterval	d_intervalOfInterest
QRectF	d_rectOfInterest
size_t	d_size

Detailed Description

Synthetic point data.

QwtSyntheticPointData provides a fixed number of points for an interval. The points are calculated in equidistant steps in x-direction.

If the interval is invalid, the points are calculated for the "rectangle of interest", what normally is the displayed area on the plot canvas. In this mode you get different levels of detail, when zooming in/out.

Example

The following example shows how to implement a sinus curve.

#include <cmath>
#include <qwt_series_data.h>
#include <qwt_plot_curve.h>
#include <qwt_plot.h>
#include <qapplication.h>

class SinusData: public QwtSyntheticPointData
{
public:
    SinusData():
        QwtSyntheticPointData( 100 )
    {
    }

    virtual double y( double x ) const
    {
        return qSin( x );
    }
};

int main(int argc, char **argv)
{
    QApplication a( argc, argv );

    QwtPlot plot;
    plot.setAxisScale( QwtPlot::xBottom, 0.0, 10.0 );
    plot.setAxisScale( QwtPlot::yLeft, -1.0, 1.0 );

    QwtPlotCurve *curve = new QwtPlotCurve( "y = sin(x)" );
    curve->setData( new SinusData() );
    curve->attach( &plot );

    plot.show();
    return a.exec();
}

Definition at line 112 of file qwt_point_data.h.

Constructor & Destructor Documentation

QwtSyntheticPointData::QwtSyntheticPointData	(	size_t	size,
		const QwtInterval &	interval = `QwtInterval()`
	)

Constructor

Parameters:

size	Number of points
interval	Bounding interval for the points

See also:: setInterval(), setSize()

Definition at line 166 of file qwt_point_data.cpp.

Member Function Documentation

QRectF QwtSyntheticPointData::boundingRect ( ) const [virtual]

Calculate the bounding rectangle.

This implementation iterates over all points, what could often be implemented much faster using the characteristics of the series. When there are many points it is recommended to overload and reimplement this method using the characteristics of the series ( if possible ).

Returns:: Bounding rectangle

Implements QwtSeriesData< QPointF >.

Definition at line 251 of file qwt_point_data.cpp.

QwtInterval QwtSyntheticPointData::interval ( ) const

Returns:: Bounding interval

See also:: setInterval(), size()

Definition at line 208 of file qwt_point_data.cpp.

QRectF QwtSyntheticPointData::rectOfInterest ( ) const

Returns:: "rectangle of interest"

See also:: setRectOfInterest()

Definition at line 235 of file qwt_point_data.cpp.

QPointF QwtSyntheticPointData::sample ( size_t index ) const [virtual]

Calculate the point from an index

Parameters:

index Index

Returns:: QPointF(x(index), y(x(index)));

Warning:: For invalid indices ( index < 0 || index >= size() ) (0, 0) is returned.

Implements QwtSeriesData< QPointF >.

Definition at line 271 of file qwt_point_data.cpp.

void QwtSyntheticPointData::setInterval ( const QwtInterval & interval )

Set the bounding interval

Parameters:

interval Interval

See also:: interval(), setSize()

Definition at line 199 of file qwt_point_data.cpp.

void QwtSyntheticPointData::setRectOfInterest ( const QRectF & rect ) [virtual]

Set a the "rectangle of interest"

QwtPlotSeriesItem defines the current area of the plot canvas as "rect of interest" ( QwtPlotSeriesItem::updateScaleDiv() ).

If interval().isValid() == false the x values are calculated in the interval rect.left() -> rect.right().

See also:: rectOfInterest()

Reimplemented from QwtSeriesData< QPointF >.

Definition at line 224 of file qwt_point_data.cpp.

void QwtSyntheticPointData::setSize ( size_t size )

Change the number of points

Parameters:

size	Number of points

See also:: size(), setInterval()

Definition at line 179 of file qwt_point_data.cpp.

size_t QwtSyntheticPointData::size ( ) const [virtual]

Returns:: Number of points

See also:: setSize(), interval()

Implements QwtSeriesData< QPointF >.

Definition at line 188 of file qwt_point_data.cpp.

double QwtSyntheticPointData::x ( uint index ) const [virtual]

Calculate a x-value from an index

x values are calculated by dividing an interval into equidistant steps. If !interval().isValid() the interval is calculated from the "rectangle of interest".

Parameters:

index Index of the requested point