QwtMatrixRasterData(3) Qwt User's Guide QwtMatrixRasterData(3)

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

#include <qwt_matrix_raster_data.h>

Inherits QwtRasterData.


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


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

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.

Resampling algorithm The default setting is NearestNeighbour;.

Enumerator

Return the value from the matrix, that is nearest to the the requested position.
Interpolate the value from the distances and values of the 4 surrounding values in the matrix,

Returns:

Number of columns of the value matrix

See also:

valueMatrix(), numRows(), setValueMatrix()

Returns:

Number of rows of the value matrix

See also:

valueMatrix(), numColumns(), setValueMatrix()

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()

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.

Set the resampling algorithm.

Parameters:

mode Resampling mode

See also:

resampleMode(), value()

Change a single value in the matrix.

Parameters:

row Row index
col Column index
value New value

See also:

value(), setValueMatrix()

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()()

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.

Returns:

Value matrix

See also:

setValueMatrix(), numColumns(), numRows(), setInterval()

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

Wed Jan 2 2019 Version 6.1.4