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

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

Public Types inherited from QwtRasterData

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

Public Member Functions

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

Public Member Functions inherited from QwtRasterData

QwtRasterData ()
Constructor.
virtual ˜QwtRasterData ()
Destructor.
void setAttribute (Attribute, bool on=true)
bool testAttribute (Attribute) const
virtual void initRaster (const QRectF &, const QSize &raster)
Initialize a raster.
virtual void discardRaster ()
Discard a raster.
virtual ContourLines contourLines (const QRectF &rect, const QSize &raster, const QList< double > &levels, ConrecFlags) 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.

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.

Constructor & Destructor Documentation

QwtMatrixRasterData::QwtMatrixRasterData ()

Constructor.

Definition at line 72 of file qwt_matrix_raster_data.cpp.

QwtMatrixRasterData::˜QwtMatrixRasterData () [virtual]

Destructor.

Definition at line 79 of file qwt_matrix_raster_data.cpp.

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

Implements QwtRasterData.

Definition at line 256 of file qwt_matrix_raster_data.cpp.

const QVector< double > QwtMatrixRasterData::valueMatrix () const

Returns

Value matrix

See also

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

Definition at line 167 of file qwt_matrix_raster_data.cpp.

Author

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

Updated 2026-06-01 - jenkler.se | uex.se