QwtMatrixRasterData(3)

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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