#include <qwt_raster_data.h>

Inheritance diagram for QwtRasterData:

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

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

Detailed Description

QwtRasterData defines an interface to any type of raster data.

QwtRasterData is an abstract interface, that is used by QwtPlotRasterItem to find the values at the pixels of its raster.

Often a raster item is used to display values from a matrix. Then the derived raster data class needs to implement some sort of resampling, that maps the raster of the matrix into the requested raster of the raster item ( depending on resolution and scales of the canvas ).

Constructor & Destructor Documentation

QwtRasterData::QwtRasterData ( const QwtDoubleRect & boundingRect )

Constructor

Parameters:

boundingRect Bounding rectangle

See also:: setBoundingRect()

Member Function Documentation

QwtDoubleRect QwtRasterData::boundingRect ( ) const

Returns:: Bounding rectangle

See also:: boundingRect()

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://local.wasp.uwa.edu.au/~pbourke/papers/conrec/

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()

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()

virtual QwtDoubleInterval QwtRasterData::range ( ) const

pure virtual

Returns:: the range of the values

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

void QwtRasterData::setBoundingRect ( const QwtDoubleRect & boundingRect )

virtual

Set the bounding rect ( == area, un plot coordinates )

Parameters:

boundingRect Bounding rectangle

See also:: boundingRect()

virtual double QwtRasterData::value	(	double	x,
		double	y
	)		const

pure virtual

Returns:: the value at a raster position

Parameters:

x	X value in plot coordinates
y	Y value in plot coordinates

Public Types

Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation