QwtRasterData(3) Qwt User's Guide QwtRasterData(3)NAMEQwtRasterData-
SYNOPSIS
#include <qwt_raster_data.h>
Inherited by 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 ()
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 DescriptionQwtRasterData 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, intflags) 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 (doublex, doubley) const [pure virtual]
Returns:
the value at a raster position
Parameters:
x X value in plot coordinates
y Y value in plot coordinates
Author
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Version 5.2.3 Tue Nov 20 2012 QwtRasterData(3)
