NAME

       QwtSyntheticPointData - Synthetic point data.

SYNOPSIS

       #include <qwt_point_data.h>

       Inherits QwtSeriesData< QPointF >.

   Public Member Functions
       QwtSyntheticPointData (size_t size, const QwtInterval &=QwtInterval())
       void setSize (size_t size)
       virtual size_t size () const
       void setInterval (const QwtInterval &)
       QwtInterval interval () const
       virtual QRectF boundingRect () const
           Calculate the bounding rectangle.
       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

   Additional Inherited Members

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();
       }

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()

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 >.

   QwtInterval QwtSyntheticPointData::interval () const
       Returns:
           Bounding interval

       See also:
           setInterval(), size()

   QRectF QwtSyntheticPointData::rectOfInterest () const
       Returns:

       See also:
           setRectOfInterest()

   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 >.

   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 '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 >.

   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< QPointF >.

   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()

   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

Author

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