QwtSyntheticPointData Class Reference

Synthetic point data. More...

#include <qwt_point_data.h>

Inheritance diagram for QwtSyntheticPointData:

Public Member Functions
virtual QRectF	boundingRect () const QWT_OVERRIDE
	Calculate the bounding rectangle. More...
QwtInterval	interval () const
	QwtSyntheticPointData (size_t size, const QwtInterval &=QwtInterval())
QRectF	rectOfInterest () const
virtual QPointF	sample (size_t index) const QWT_OVERRIDE
void	setInterval (const QwtInterval &)
virtual void	setRectOfInterest (const QRectF &) QWT_OVERRIDE
void	setSize (size_t size)
virtual size_t	size () const QWT_OVERRIDE
virtual double	x (uint index) const
virtual double	y (double x) const =0
Public Member Functions inherited from QwtSeriesData< QPointF >
virtual QRectF	boundingRect () const
	QwtSeriesData ()
	Constructor. More...
virtual size_t	size () const=0
virtual	~QwtSeriesData ()
	Destructor. More...

Private Attributes
QwtInterval	m_interval
QwtInterval	m_intervalOfInterest
QRectF	m_rectOfInterest
size_t	m_size

Additional Inherited Members
Protected Attributes inherited from QwtSeriesData< QPointF >
QRectF	cachedBoundingRect
	Can be used to cache a calculated bounding rectangle. More...

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( QwtAxis::XBottom, 0.0, 10.0 );
   plot.setAxisScale( QwtAxis::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 157 of file qwt_point_data.h.

Constructor & Destructor Documentation

QwtSyntheticPointData()

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 20 of file qwt_point_data.cpp.

Member Function Documentation

boundingRect()

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

Definition at line 105 of file qwt_point_data.cpp.

interval()

QwtInterval QwtSyntheticPointData::interval

(

)

const

Returns

Bounding interval

See also

setInterval(), size()

Definition at line 62 of file qwt_point_data.cpp.

rectOfInterest()

QRectF QwtSyntheticPointData::rectOfInterest

(

)

const

Returns

"rectangle of interest"

See also

setRectOfInterest()

Definition at line 89 of file qwt_point_data.cpp.

sample()

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 125 of file qwt_point_data.cpp.

setInterval()

void QwtSyntheticPointData::setInterval

(

const QwtInterval &

interval

)

Set the bounding interval

Parameters

interval

Interval

See also

interval(), setSize()

Definition at line 53 of file qwt_point_data.cpp.

setRectOfInterest()

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 78 of file qwt_point_data.cpp.

setSize()

void QwtSyntheticPointData::setSize

(

size_t

size

)

Change the number of points

Parameters

size	Number of points

See also

size(), setInterval()

Definition at line 33 of file qwt_point_data.cpp.

size()

size_t QwtSyntheticPointData::size ( ) const

virtual

Returns

Number of points

See also

setSize(), interval()

Definition at line 42 of file qwt_point_data.cpp.

x()

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

Returns

Calculated x coordinate

See also

interval(), rectOfInterest(), y()

Definition at line 148 of file qwt_point_data.cpp.

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

Member Data Documentation

m_interval

QwtInterval QwtSyntheticPointData::m_interval

private

Definition at line 186 of file qwt_point_data.h.

m_intervalOfInterest

QwtInterval QwtSyntheticPointData::m_intervalOfInterest

private

Definition at line 188 of file qwt_point_data.h.

m_rectOfInterest

QRectF QwtSyntheticPointData::m_rectOfInterest

private

Definition at line 187 of file qwt_point_data.h.

m_size

size_t QwtSyntheticPointData::m_size

private

Definition at line 185 of file qwt_point_data.h.

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The documentation for this class was generated from the following files:

• qwt_point_data.h
• qwt_point_data.cpp