trusty (3) QwtSyntheticPointData.3.gz

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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