NAME

       QwtMatrixRasterData - A class representing a matrix of values as raster data.

SYNOPSIS

       #include <qwt_matrix_raster_data.h>

       Inherits QwtRasterData.

   Public Types
       enum ResampleMode { NearestNeighbour, BilinearInterpolation } Resampling algorithm The
           default setting is NearestNeighbour;. "

   Public Member Functions
       QwtMatrixRasterData ()
           Constructor.
       virtual ~QwtMatrixRasterData ()
           Destructor.
       void setResampleMode (ResampleMode mode)
           Set the resampling algorithm.
       ResampleMode resampleMode () const
       virtual void setInterval (Qt::Axis, const QwtInterval &)
           Assign the bounding interval for an axis.
       void setValueMatrix (const QVector< double > &values, int numColumns)
           Assign a value matrix.
       const QVector< double > valueMatrix () const
       void setValue (int row, int col, double value)
           Change a single value in the matrix.
       int numColumns () const
       int numRows () const
       virtual QRectF pixelHint (const QRectF &) const
           Calculate the pixel hint.
       virtual double value (double x, double y) const

Detailed Description

       A class representing a matrix of values as raster data.

       QwtMatrixRasterData implements an interface for a matrix of equidistant values, that can
       be used by a QwtPlotRasterItem. It implements a couple of resampling algorithms, to
       provide values for positions, that or not on the value matrix.

Member Enumeration Documentation

   enum QwtMatrixRasterData::ResampleMode
       Resampling algorithm The default setting is NearestNeighbour;.

       Enumerator

       NearestNeighbour
              Return the value from the matrix, that is nearest to the the requested position.

       BilinearInterpolation
              Interpolate the value from the distances and values of the 4 surrounding values in
              the matrix,

Member Function Documentation

   int QwtMatrixRasterData::numColumns () const
       Returns:
           Number of columns of the value matrix

       See also:
           valueMatrix(), numRows(), setValueMatrix()

   int QwtMatrixRasterData::numRows () const
       Returns:
           Number of rows of the value matrix

       See also:
           valueMatrix(), numColumns(), setValueMatrix()

   QRectF QwtMatrixRasterData::pixelHint (const QRectF & area) const [virtual]
       Calculate the 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.

       • NearestNeighbour
          pixelHint() returns the surrounding pixel of the top left value in the matrix.

       • BilinearInterpolation
          Returns an empty rectangle recommending to render in target device ( f.e. screen )
         resolution.

       Parameters:
           area Requested area, ignored

       Returns:
           Calculated hint

       See also:
           ResampleMode, setMatrix(), setInterval()

       Reimplemented from QwtRasterData.

   QwtMatrixRasterData::ResampleMode QwtMatrixRasterData::resampleMode () const
       Returns:
           resampling algorithm

       See also:
           setResampleMode(), value()

   void QwtMatrixRasterData::setInterval (Qt::Axis axis, const QwtInterval & interval) [virtual]
       Assign the bounding interval for an axis. Setting the bounding intervals for the X/Y axis
       is mandatory to define the positions for the values of the value matrix. The interval in Z
       direction defines the possible range for the values in the matrix, what is f.e used by
       QwtPlotSpectrogram to map values to colors. The Z-interval might be the bounding interval
       of the values in the matrix, but usually it isn't. ( f.e a interval of 0.0-100.0 for
       values in percentage )

       Parameters:
           axis X, Y or Z axis
           interval Interval

       See also:
           QwtRasterData::interval(), setValueMatrix()

       Reimplemented from QwtRasterData.

   void QwtMatrixRasterData::setResampleMode (ResampleMode mode)
       Set the resampling algorithm.

       Parameters:
           mode Resampling mode

       See also:
           resampleMode(), value()

   void QwtMatrixRasterData::setValue (int row, int col, double value)
       Change a single value in the matrix.

       Parameters:
           row Row index
           col Column index
           value New value

       See also:
           value(), setValueMatrix()

   void QwtMatrixRasterData::setValueMatrix (const QVector< double > & values, int numColumns)
       Assign a value matrix. The positions of the values are calculated by dividing the bounding
       rectangle of the X/Y intervals into equidistant rectangles ( pixels ). Each value
       corresponds to the center of a pixel.

       Parameters:
           values Vector of values
           numColumns Number of columns

       See also:
           valueMatrix(), numColumns(), numRows(), setInterval()()

   double QwtMatrixRasterData::value (double x, double y) const [virtual]
       Returns:
           the value at a raster position

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

       See also:
           ResampleMode

       Implements QwtRasterData.

   const QVector< double > QwtMatrixRasterData::valueMatrix () const
       Returns:
           Value matrix

       See also:
           setValueMatrix(), numColumns(), numRows(), setInterval()

Author

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