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

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Version 6.1.4                                    Wed Jan 2 2019                                 QwtRasterData(3)

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 ).

enumQwtRasterData::ConrecFlag
       Flags to modify the contour algorithm.

       EnumeratorIgnoreAllVerticesOnLevel
              Ignore all vertices on the same level.

       IgnoreOutOfRange
              Ignore all values, that are out of range.

QwtRasterData::ContourLinesQwtRasterData::contourLines(constQRectF&rect,constQSize&raster,constQList<double>&levels,ConrecFlagsflags)const[virtual]
       Calculate contour lines

       Parameters:rect Bounding rectangle for the contour lines
           raster Number of data pixels of the raster data
           levels List of limits, where to insert contour lines
           flags Flags to customize the contouring algorithm

       Returns:
           Calculated contour lines

       An        adaption        of        CONREC,        a         simple         contouring         algorithm.
       http://local.wasp.uwa.edu.au/~pbourke/papers/conrec/voidQwtRasterData::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.

       Seealso:initRaster(), value()voidQwtRasterData::initRaster(constQRectF&area,constQSize&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:area Area of the raster
           raster Number of horizontal and vertical pixels

       Seealso:initRaster(), value()constQwtInterval&QwtRasterData::interval(Qt::Axisaxis)const[inline]Returns:
           Bounding interval for a axis

       Seealso:setIntervalQRectFQwtRasterData::pixelHint(constQRectF&area)const[virtual]
       Pixel hint. pixelHint() returns the geometry of a pixel, that can be used to calculate the resolution and
       alignment of the plot item, that is representing the data.

       Width  and  height  of  the  hint  need  to be the horizontal and vertical distances between 2 neighbored
       points. The center of the hint has to be the position of any point ( it doesn't matter which one ).

       An empty hint indicates, that there are values for any detail level.

       Limiting the resolution of the image might significantly improve the performance and heavily  reduce  the
       amount of memory when rendering a QImage from the raster data.

       The  default  implementation  returns  an  empty rectangle recommending to render in target device ( f.e.
       screen ) resolution.

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

       Returns:
           Bounding rectangle of a pixel

       Reimplemented in QwtMatrixRasterData.

   voidQwtRasterData::setInterval(Qt::Axisaxis,constQwtInterval&interval)[virtual]
       Set the bounding interval for the x, y or z coordinates.

       Parameters:axis Axis
           interval Bounding interval

       Seealso:interval()

       Reimplemented in QwtMatrixRasterData.

   virtualdoubleQwtRasterData::value(doublex,doubley)const[purevirtual]Returns:
           the value at a raster position

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

       Implemented in QwtMatrixRasterData.

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

       #include <qwt_raster_data.h>

       Inherited by QwtMatrixRasterData.

   PublicTypes
       enum ConrecFlag { IgnoreAllVerticesOnLevel = 0x01, IgnoreOutOfRange = 0x02 }
           Flags to modify the contour algorithm.
       typedef QMap< double, QPolygonF > ContourLines
           Contour lines.
       typedef QFlags< ConrecFlag > ConrecFlags
           Flags to modify the contour algorithm.

   PublicMemberFunctionsQwtRasterData ()
           Constructor.
       virtual ~QwtRasterData ()
           Destructor.
       virtual void setInterval (Qt::Axis, const QwtInterval &)
       const QwtInterval & interval (Qt::Axis) const
       virtual QRectF pixelHint (const QRectF &) const
           Pixel hint.
       virtual void initRaster (const QRectF &, const QSize &raster)
           Initialize a raster.
       virtual void discardRaster ()
           Discard a raster.
       virtual double value (double x, double y) const =0
       virtual ContourLinescontourLines (const QRectF &rect, const QSize &raster, const QList< double >
           &levels, ConrecFlags) const