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QwtRasterData

QwtRasterData

Section: C Library Functions (3) Updated: 22 Mar 2009
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NAME

QwtRasterData - QwtRasterData defines an interface to any type of raster data.

 

SYNOPSIS


#include <qwt_raster_data.h>

Inherited by QwtPlotSpectrogram::QwtPlotSpectrogram::PrivateData::QwtPlotSpectrogram::PrivateData::DummyData.

 

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
 

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 ).  

Member Enumeration Documentation

 

enum QwtRasterData::ConrecAttribute

Attribute to modify the contour algorithm.

 

Constructor & Destructor Documentation

 

QwtRasterData::QwtRasterData ()

Constructor.

 

QwtRasterData::QwtRasterData (const QwtDoubleRect & boundingRect)

Constructor

Parameters:

boundingRect Bounding rectangle

See also:

setBoundingRect()

 

QwtRasterData::~QwtRasterData () [virtual]

Destructor.

 

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/  

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

Clone the data.

 

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

 

Author

Generated automatically by Doxygen for Qwt User's Guide from the source code.


 

Index

NAME
SYNOPSIS
Public Types
Public Member Functions
Detailed Description
Member Enumeration Documentation
enum QwtRasterData::ConrecAttribute
Constructor & Destructor Documentation
QwtRasterData::QwtRasterData ()
QwtRasterData::QwtRasterData (const QwtDoubleRect & boundingRect)
QwtRasterData::~QwtRasterData () [virtual]
Member Function Documentation
QwtDoubleRect QwtRasterData::boundingRect () const
QwtRasterData::ContourLines QwtRasterData::contourLines (const QwtDoubleRect & rect, const QSize & raster, const QList< double > & levels, int flags) const [virtual]
virtual QwtRasterData* QwtRasterData::copy () const [pure virtual]
void QwtRasterData::discardRaster () [virtual]
void QwtRasterData::initRaster (const QwtDoubleRect &, const QSize & raster) [virtual]
virtual QwtDoubleInterval QwtRasterData::range () const [pure virtual]
QSize QwtRasterData::rasterHint (const QwtDoubleRect &) const [virtual]
void QwtRasterData::setBoundingRect (const QwtDoubleRect & boundingRect) [virtual]
virtual double QwtRasterData::value (double x, double y) const [pure virtual]
Author

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Time: 21:53:53 GMT, April 16, 2011