QwtMatrixRasterData Class Reference

A class representing a matrix of values as raster data. More...

#include <qwt_matrix_raster_data.h>

Inheritance diagram for QwtMatrixRasterData:

Public Types
enum	ResampleMode { NearestNeighbour, BilinearInterpolation }
	Resampling algorithm The default setting is NearestNeighbour;. More...
Public Types inherited from QwtRasterData
enum	ConrecFlag { IgnoreAllVerticesOnLevel = 0x01, IgnoreOutOfRange = 0x02 }
	Flags to modify the contour algorithm. More...
typedef QMap< double, QPolygonF >	ContourLines
	Contour lines.
typedef QFlags< ConrecFlag >	ConrecFlags
	Flags to modify the contour algorithm.

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

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()