QwtMatrixRasterData - Man Page

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, BicubicInterpolation }
Resampling algorithm The default setting is NearestNeighbour;.

QwtMatrixRasterData ()
Constructor.
virtual ~QwtMatrixRasterData ()
Destructor.
void setResampleMode (ResampleMode mode)
Set the resampling algorithm.
ResampleMode resampleMode () const
void setInterval (Qt::Axis, const QwtInterval &)
Assign the bounding interval for an axis.
virtual QwtInterval interval (Qt::Axis axis) const override final
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 override
Calculate the pixel hint.
virtual double value (double x, double y) const override

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.

Definition at line 28 of file qwt_matrix_raster_data.h.

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,
BicubicInterpolation: Interpolate the value from the 16 surrounding values in the matrix using hermite bicubic interpolation

Definition at line 35 of file qwt_matrix_raster_data.h.

Member Function Documentation

QwtInterval QwtMatrixRasterData::interval (Qt::Axis axis) const [final], [override], [virtual]

Returns: Bounding interval for an axis
See also: setInterval

Implements QwtRasterData.

Definition at line 134 of file qwt_matrix_raster_data.cpp.

int QwtMatrixRasterData::numColumns () const

Returns: Number of columns of the value matrix
See also: valueMatrix(), numRows(), setValueMatrix()

Definition at line 195 of file qwt_matrix_raster_data.cpp.

int QwtMatrixRasterData::numRows () const

Returns: Number of rows of the value matrix
See also: valueMatrix(), numColumns(), setValueMatrix()

Definition at line 204 of file qwt_matrix_raster_data.cpp.

QRectF QwtMatrixRasterData::pixelHint (const QRectF & area) const [override], [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.

Definition at line 229 of file qwt_matrix_raster_data.cpp.

QwtMatrixRasterData::ResampleMode QwtMatrixRasterData::resampleMode () const

Returns: resampling algorithm
See also: setResampleMode(), value()

Definition at line 99 of file qwt_matrix_raster_data.cpp.

void QwtMatrixRasterData::setInterval (Qt::Axis axis, const QwtInterval & interval)

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()

Definition at line 120 of file qwt_matrix_raster_data.cpp.

void QwtMatrixRasterData::setResampleMode (ResampleMode mode)

Set the resampling algorithm.

Parameters: mode Resampling mode
See also: resampleMode(), value()

Definition at line 90 of file qwt_matrix_raster_data.cpp.

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()

Definition at line 181 of file qwt_matrix_raster_data.cpp.

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()()

Definition at line 155 of file qwt_matrix_raster_data.cpp.

double QwtMatrixRasterData::value (double x, double y) const [override], [virtual]

Returns: the value at a raster position
Parameters: x X value in plot coordinates
y Y value in plot coordinates
See also: ResampleMode