QwtRasterData(3)

NAME
QwtRasterData -

SYNOPSIS

Inherited by QwtPlotSpectrogram::PrivateData::DummyData.

Detailed Description

QwtRasterData defines an interface to any type of raster data.

Definition at line 53 of file qwt_raster_data.h.

  Public Types
enum ConrecAttribute { IgnoreAllVerticesOnLevel = 1, IgnoreOutOfRange = 2 }
typedef QMap< double, QPolygonF > ContourLines

  Public Member Functions
QwtRasterData ()
QwtRasterData (const QwtDoubleRect &)
virtual ~QwtRasterData ()
virtual QwtRasterData * copy () const=0
virtual void setBoundingRect (const QwtDoubleRect &)
QwtDoubleRect boundingRect () const
virtual QSize rasterHint (const QwtDoubleRect &) const
virtual void initRaster (const QwtDoubleRect &, const QSize &raster)
virtual void discardRaster ()
virtual double value (double x, double y) const=0
virtual QwtDoubleInterval range () const=0
virtual ContourLines contourLines (const QwtDoubleRect &rect, const QSize &raster, const QList< double > &levels, int flags) const

Member Function Documentation

  virtual QwtRasterData* QwtRasterData::copy () const [pure virtual]

Clone the data.

Referenced by QwtPlotSpectrogram::setData().

  QSize QwtRasterData::rasterHint (const QwtDoubleRect &) const [virtual]

Find the raster of the data for an area.

The resolution is the number of horizontal and vertical pixels that the data can return for an area. An invalid resolution indicates that the data can return values for any detail level.

The resolution will limit the size of the image that is rendered from the data. F.e. this might be important when printing a spectrogram to a A0 printer with 600 dpi.

The default implementation returns an invalid resolution (size)

Parameters:
    rect In most implementations the resolution of the data doesn't depend on the requested rectangle.

Returns:
    Resolution, as number of horizontal and vertical pixels

Definition at line 258 of file qwt_raster_data.cpp.

  void QwtRasterData::initRaster (const QwtDoubleRect &, const QSize & raster) [virtual]

Initialize a raster.

Before the composition of an image QwtPlotSpectrogram calls initRaster, announcing the area and its resolution that will be requested.

The default implementation does nothing, but for data sets that are stored in files, it might be good idea to reimplement initRaster, where the data is resampled and loaded into memory.

Parameters:
    rect Area of the raster
    raster Number of horizontal and vertical pixels

See also:
    initRaster(), value()

Definition at line 222 of file qwt_raster_data.cpp.

  void QwtRasterData::discardRaster () [virtual]

Discard a raster.

After the composition of an image QwtPlotSpectrogram calls discardRaster().

The default implementation does nothing, but if data has been loaded in initRaster(), it could deleted now.

See also:
    initRaster(), value()

Definition at line 236 of file qwt_raster_data.cpp.

  virtual double QwtRasterData::value (double x, double y) const [pure virtual]

Returns:
    the value at a raster position

  virtual QwtDoubleInterval QwtRasterData::range () const [pure virtual]

Returns:
    the range of the values

  QwtRasterData::ContourLines QwtRasterData::contourLines (const QwtDoubleRect & rect, const QSize & raster, const QList< double > & levels, int flags) const [virtual]

Calculate contour lines

An adaption of CONREC, a simple contouring algorithm. http://astronomy.swin.edu.au/~pbourke/projection/conrec

Definition at line 270 of file qwt_raster_data.cpp.

References QwtDoubleInterval::contains(), and QwtDoubleInterval::isValid().

Author

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