QwtSyntheticPointData Class Reference

Synthetic point data. More...

#include <qwt_series_data.h>

Inheritance diagram for QwtSyntheticPointData:

Inheritance graph
[legend]

List of all members.

Public Member Functions

 QwtSyntheticPointData (size_t size, const QwtDoubleInterval &=QwtDoubleInterval())
void setSize (size_t size)
size_t size () const
void setInterval (const QwtDoubleInterval &)
QwtDoubleInterval interval () const
virtual QwtDoubleRect boundingRect () const
virtual QwtDoublePoint sample (size_t i) const
virtual double y (double x) const =0
virtual double x (uint index) const
virtual void setRectOfInterest (const QwtDoubleRect &)
QwtDoubleRect rectOfInterest () const


Detailed Description

Synthetic point data.

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

If the interval is invalid, the points are calculated for the "rect of interest", what normally is the displayed area on the plot canvas. In this mode you get different level of details, 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 QwtSeriesData<QwtDoublePoint> *copy() const
    {
        return new SinusData();
    }
    virtual double y(double x) const
    {
        return std::sin(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(SinusData());
    curve->attach(&plot);

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

Constructor & Destructor Documentation

QwtSyntheticPointData::QwtSyntheticPointData ( size_t  size,
const QwtDoubleInterval interval = QwtDoubleInterval() 
)

Constructor

Parameters:
size Number of points
interval Bounding interval for the points
See also:
setInterval(), setSize()


Member Function Documentation

QwtDoubleRect QwtSyntheticPointData::boundingRect (  )  const [virtual]

Calculate the bounding rect.

This implementation iterates over all points.

Returns:
Bounding rectangle

Implements QwtSeriesData< QwtDoublePoint >.

QwtDoubleInterval QwtSyntheticPointData::interval (  )  const

Returns:
Bounding interval
See also:
setInterval(), size()

QwtDoubleRect QwtSyntheticPointData::rectOfInterest (  )  const

Returns:
"rect of interest"
See also:
setRectOfInterest()

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

Calculate the point from an index

Parameters:
index Index
Returns:
QwtDoublePoint(x(index), y(x(index)));
Warning:
For invalid indices ( index < 0 || index >= size() ) (0, 0) is returned.

Implements QwtSeriesData< QwtDoublePoint >.

void QwtSyntheticPointData::setInterval ( const QwtDoubleInterval interval  ) 

Set the bounding interval

Parameters:
interval Interval
See also:
interval(), setSize()

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

Set a the "rect 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< QwtDoublePoint >.

void QwtSyntheticPointData::setSize ( size_t  size  ) 

Change the number of points

Parameters:
size Number of points
See also:
size(), setInterval()

size_t QwtSyntheticPointData::size (  )  const [virtual]

Returns:
Number of points
See also:
setSize(), interval()

Implements QwtSeriesData< QwtDoublePoint >.

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

Calculate a x-value from an index

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

See also:
interval(), rectOfInterest(), y()

virtual double QwtSyntheticPointData::y ( double  x  )  const [pure virtual]

Calculate a y value for a x value

Parameters:
x x value
Returns:
Corresponding y value


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