QwtSyntheticPointData(3) Qwt User's Guide QwtSyntheticPointData(3)
NAME
QwtSyntheticPointData -
Synthetic point data.
SYNOPSIS
#include <qwt_series_data.h>
Inherits QwtSeriesData< QPointF >.
Public Member Functions
QwtSyntheticPointData (size_t size, const QwtInterval &=QwtInterval())
void setSize (size_t size)
size_t size () const
void setInterval (const QwtInterval &)
QwtInterval interval () const
virtual QRectF boundingRect () const
virtual QPointF sample (size_t i) const
virtual double y (double x) const =0
virtual double x (uint index) const
virtual void setRectOfInterest (const QRectF &)
QRectF rectOfInterest () const
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 'rect 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(SinusData());
curve->attach(&plot);
plot.show();
return a.exec();
}
.fi
Constructor &; Destructor Documentation
QwtSyntheticPointData::QwtSyntheticPointData (size_tsize, const QwtInterval &interval = QwtInterval()) Constructor
Parameters:
size Number of points
interval Bounding interval for the points
See also:
setInterval(), setSize()
Member Function Documentation
QRectF QwtSyntheticPointData::boundingRect () const [virtual]
Calculate the bounding rect. 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 >.
QwtInterval QwtSyntheticPointData::interval () const Returns:
Bounding interval
See also:
setInterval(), size()
QRectF QwtSyntheticPointData::rectOfInterest () const Returns:
See also:
setRectOfInterest()
QPointF QwtSyntheticPointData::sample (size_tindex) 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 >.
void QwtSyntheticPointData::setInterval (const QwtInterval &interval) Set the bounding interval
Parameters:
interval Interval
See also:
interval(), setSize()
void QwtSyntheticPointData::setRectOfInterest (const QRectF &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< QPointF >.
void QwtSyntheticPointData::setSize (size_tsize) 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< QPointF >.
double QwtSyntheticPointData::x (uintindex) 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 (doublex) const [pure virtual] Calculate a y value for a x value
Parameters:
x x value
Returns:
Corresponding y value
Author
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Version 6.0.0 Fri Apr 15 2011 QwtSyntheticPointData(3)