QwtRasterData(3)

💖 QwtRasterData 💖

okay bestie, welcome to the QwtRasterData page from the Qwt User's Guide ✨ this one's from the Qwt library, and she's an abstract queen 👑

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✨ NAME ✨

QwtRasterData — that's her. that's the name. no further notes, she needs no introduction 💅

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🌸 SYNOPSIS 🌸

#include <qwt_raster_data.h>

Inherited by</purl> QwtPlotSpectrogram::PrivateData::DummyData 🫶

🎀 Public Types 🎀

• enum ConrecAttribute — and the values are, exactly:

enum ConrecAttribute { IgnoreAllVerticesOnLevel =  1, IgnoreOutOfRange = 2 }

• typedef QMap< double, QPolygonF > ContourLines — a whole typedef, slay 💖

🦋 Public Member Functions 🦋

no cap, here's the full roster, nothing skipped:

QwtRasterData ()
QwtRasterData (const QwtDoubleRect &)
virtual ~QwtRasterData ()
QwtDoubleRect boundingRect () const
virtual ContourLines contourLines (const QwtDoubleRect &rect, const QSize &raster, const QList< double > &levels, int flags) const
virtual QwtRasterData * copy () const =0
virtual void discardRaster ()
virtual void initRaster (const QwtDoubleRect &, const QSize &raster)
virtual QwtDoubleInterval range () const =0
virtual QSize rasterHint (const QwtDoubleRect &) const
virtual void setBoundingRect (const QwtDoubleRect &)
virtual double value (double x, double y) const =0

notice all those =0 at the end?? that's the abstract-interface energy, you cannot instantiate this girl directly, she's a blueprint and a vibe 👑

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🌈 Detailed Description 🌈

QwtRasterData defines an interface to any type of raster data. literally any. she's flexible like that 💅

QwtRasterData is an abstract interface, that is used by QwtPlotRasterItem to find the values at the pixels of its raster.

Often a raster item is used to display values from a matrix. Then the derived raster data class needs to implement some sort of resampling, that maps the raster of the matrix into the requested raster of the raster item ( depending on resolution and scales of the canvas ). iykyk 🧚

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💜 Constructor & Destructor Documentation 💜

QwtRasterData::QwtRasterData (const QwtDoubleRect &boundingRect)

Constructor 💖

Parameters:

• boundingRect — Bounding rectangle

See also: setBoundingRect()

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🍓 Member Function Documentation 🍓

QwtDoubleRect QwtRasterData::boundingRect () const

Returns:

• Bounding rectangle

See also: boundingRect() — yes bestie, she references herself, iconic behavior 🙈

QwtRasterData::ContourLines QwtRasterData::contourLines (const QwtDoubleRect &rect, const QSize &raster, const QList< double > &levels, int flags) const [virtual]

Calculate contour lines ✨

An adaption of CONREC, a simple contouring algorithm.

http://local.wasp.uwa.edu.au/~pbourke/papers/conrec/

void QwtRasterData::discardRaster () [virtual]

Discard a raster. After the composition of an image QwtPlotSpectrogram calls discardRaster().

The default implementation does nothing, but if data has been loaded in initRaster(), it could deleted now.

See also: initRaster(), value()

void QwtRasterData::initRaster (const QwtDoubleRect &, const QSize &raster) [virtual]

Initialize a raster. Before the composition of an image QwtPlotSpectrogram calls initRaster, announcing the area and its resolution that will be requested.

The default implementation does nothing, but for data sets that are stored in files, it might be good idea to reimplement initRaster, where the data is resampled and loaded into memory.

Parameters:

• rect — Area of the raster
• raster — Number of horizontal and vertical pixels

See also: initRaster(), value()

virtual QwtDoubleInterval QwtRasterData::range () const [pure virtual]

Returns:

• the range of the values

pure virtual, so if you're inheriting from her, this one is mandatory, no skipping bestie 💀

QSize QwtRasterData::rasterHint (const QwtDoubleRect &) const [virtual]

Find the raster of the data for an area. The resolution is the number of horizontal and vertical pixels that the data can return for an area. An invalid resolution indicates that the data can return values for any detail level.

The resolution will limit the size of the image that is rendered from the data. F.e. this might be important when printing a spectrogram to a A0 printer with 600 dpi.

The default implementation returns an invalid resolution (size) 🙈

Parameters:

• rect — In most implementations the resolution of the data doesn't depend on the requested rectangle.

Returns:

• Resolution, as number of horizontal and vertical pixels

void QwtRasterData::setBoundingRect (const QwtDoubleRect &boundingRect) [virtual]

Set the bounding rect ( == area, un plot coordinates )

Parameters:

• boundingRect — Bounding rectangle

See also: boundingRect()

virtual double QwtRasterData::value (double x, double y) const [pure virtual]

Returns:

• the value at a raster position

Parameters:

• x — X value in plot coordinates
• y — Y value in plot coordinates

another pure virtual — she's asking you, the derived class, to do the actual work. main character energy, honestly 👑

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⭐ Author ⭐

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

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and that's the whole page, bestie, every flag, every signature, every see-also, not a single crumb left behind 🫶

Version 5.2.3 — dated Tue Nov 20 2012 — from the Qwt User's Guide. mwah, go build something gorgeous with it 💖✨🎀