NAME

       QwtSeriesData< T > - Abstract interface for iterating over samples.

SYNOPSIS

       #include <qwt_series_data.h>

       Inherited by QwtArraySeriesData< T >.

   Public Member Functions
       QwtSeriesData ()
           Constructor.
       virtual ~QwtSeriesData ()
           Destructor.
       virtual size_t size () const =0
       virtual T sample (size_t i) const =0
       virtual QRectF boundingRect () const =0
       virtual void setRectOfInterest (const QRectF &rect)

   Protected Attributes
       QRectF d_boundingRect
           Can be used to cache a calculated bounding rectangle.

Detailed Description

   template<typename T>
       class QwtSeriesData< T >" Abstract interface for iterating over samples.

       Qwt offers several implementations of the QwtSeriesData API, but in situations, where data
       of an application specific format needs to be displayed, without having to copy it, it is
       recommended to implement an individual data access.

       A subclass of QwtSeriesData<QPointF> must implement:

       • size()
          Should return number of data points.

       • sample()
          Should return values x and y values of the sample at specific position as QPointF
         object.

       • boundingRect()
          Should return the bounding rectangle of the data series. It is used for autoscaling and
         might help certain algorithms for displaying the data. You can use qwtBoundingRect() for
         an implementation but often it is possible to implement a more efficient algorithm
         depending on the characteristics of the series. The member d_boundingRect is intended
         for caching the calculated rectangle.

Member Function Documentation

   template<typename T> virtual QRectF QwtSeriesData< T >::boundingRect () const [pure virtual]
       Calculate the bounding rect of all samples

       The bounding rect is necessary for autoscaling and can be used for a couple of painting
       optimizations.

       qwtBoundingRect(...) offers slow implementations iterating over the samples. For large
       sets it is recommended to implement something faster f.e. by caching the bounding
       rectangle.

       Returns:
           Bounding rectangle

       Implemented in QwtTradingChartData, QwtSetSeriesData, QwtIntervalSeriesData,
       QwtPoint3DSeriesData, QwtPointSeriesData, QwtSyntheticPointData, QwtCPointerData, and
       QwtPointArrayData.

   template<typename T> virtual T QwtSeriesData< T >::sample (size_t i) const [pure virtual]
       Return a sample

       Parameters:
           i Index

       Returns:
           Sample at position i

       Implemented in QwtArraySeriesData< T >, QwtArraySeriesData< QwtIntervalSample >,
       QwtArraySeriesData< QwtOHLCSample >, QwtArraySeriesData< QPointF >, QwtArraySeriesData<
       QwtPoint3D >, QwtArraySeriesData< QwtSetSample >, QwtSyntheticPointData, QwtCPointerData,
       and QwtPointArrayData.

   template<typename T > void QwtSeriesData< T >::setRectOfInterest (const QRectF & rect)
       [virtual]
       Set a the 'rect of interest'

       QwtPlotSeriesItem defines the current area of the plot canvas as 'rectangle of interest' (
       QwtPlotSeriesItem::updateScaleDiv() ). It can be used to implement different levels of
       details.

       The default implementation does nothing.

       Parameters:
           rect Rectangle of interest

       Reimplemented in QwtSyntheticPointData.

   template<typename T> virtual size_t QwtSeriesData< T >::size () const [pure virtual]
       Returns:
           Number of samples

       Implemented in QwtArraySeriesData< T >, QwtArraySeriesData< QwtIntervalSample >,
       QwtArraySeriesData< QwtOHLCSample >, QwtArraySeriesData< QPointF >, QwtArraySeriesData<
       QwtPoint3D >, QwtArraySeriesData< QwtSetSample >, QwtSyntheticPointData, QwtCPointerData,
       and QwtPointArrayData.

Author

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