Iterator for sequentially processing raster cells. More...

#include <qgsrasteriterator.h>

Public Member Functions
	QgsRasterIterator (QgsRasterInterface *input)
	Constructor for QgsRasterIterator, iterating over the specified input raster source. More...

const QgsRasterInterface *	input () const
	Returns the input raster interface which is being iterated over. More...

int	maximumTileHeight () const
	Returns the minimum tile width returned during iteration. More...

int	maximumTileWidth () const
	Returns the maximum tile width returned during iteration. More...

bool	next (int bandNumber, int &columns, int &rows, int &topLeftColumn, int &topLeftRow, QgsRectangle &blockExtent)
	Fetches details of the next part of the raster data. More...

bool	readNextRasterPart (int bandNumber, int &nCols, int &nRows, QgsRasterBlock **block, int &topLeftCol, int &topLeftRow)
	Fetches next part of raster data, caller takes ownership of the block and caller should delete the block. More...

bool	readNextRasterPart (int bandNumber, int &nCols, int &nRows, std::unique_ptr< QgsRasterBlock > &block, int &topLeftCol, int &topLeftRow, QgsRectangle *blockExtent=nullptr)
	Fetches next part of raster data. More...

void	setMaximumTileHeight (int h)
	Sets the minimum tile height returned during iteration. More...

void	setMaximumTileWidth (int w)
	Sets the maximum tile width returned during iteration. More...

void	startRasterRead (int bandNumber, qgssize nCols, qgssize nRows, const QgsRectangle &extent, QgsRasterBlockFeedback *feedback=nullptr)
	Start reading of raster band. More...

void	stopRasterRead (int bandNumber)
	Cancels the raster iteration and resets the iterator. More...

Static Public Attributes
static const int	DEFAULT_MAXIMUM_TILE_HEIGHT = 2000
	Default maximum tile height. More...

static const int	DEFAULT_MAXIMUM_TILE_WIDTH = 2000
	Default maximum tile width. More...

Detailed Description

Iterator for sequentially processing raster cells.

Definition at line 34 of file qgsrasteriterator.h.

Constructor & Destructor Documentation

◆ QgsRasterIterator()

QgsRasterIterator::QgsRasterIterator ( QgsRasterInterface * input )

Constructor for QgsRasterIterator, iterating over the specified input raster source.

Definition at line 21 of file qgsrasteriterator.cpp.

Member Function Documentation

◆ input()

const QgsRasterInterface* QgsRasterIterator::input ( ) const

inline

Returns the input raster interface which is being iterated over.

Definition at line 117 of file qgsrasteriterator.h.

◆ maximumTileHeight()

int QgsRasterIterator::maximumTileHeight ( ) const

inline

Returns the minimum tile width returned during iteration.

See also: setMaximumTileHeight(); maximumTileWidth()

Definition at line 145 of file qgsrasteriterator.h.

◆ maximumTileWidth()

int QgsRasterIterator::maximumTileWidth ( ) const

inline

Returns the maximum tile width returned during iteration.

See also: setMaximumTileWidth(); maximumTileHeight()

Definition at line 131 of file qgsrasteriterator.h.

◆ next()

bool QgsRasterIterator::next	(	int	bandNumber,
		int &	columns,
		int &	rows,
		int &	topLeftColumn,
		int &	topLeftRow,
		QgsRectangle &	blockExtent
	)

Fetches details of the next part of the raster data.

This method does NOT actually fetch the raster data itself, rather it calculates and iterates over the details of the raster alone.

It's useful for iterating over several layers using a target "reference" layer. E.g. summing the pixels in n rasters whilst aligning the result to a reference layer which is not being summed.

Note that calling this method also advances the iterator, just like calling readNextRasterPart().

Parameters

bandNumber	band to read
columns	number of columns on output device
rows	number of rows on output device
topLeftColumn	top left column
topLeftRow	top left row
blockExtent	exact extent of returned raster block

Returns: false if the last part was already returned

Since: QGIS 3.6

Definition at line 60 of file qgsrasteriterator.cpp.

◆ readNextRasterPart() [1/2]

bool QgsRasterIterator::readNextRasterPart	(	int	bandNumber,
		int &	nCols,
		int &	nRows,
		QgsRasterBlock **	block,
		int &	topLeftCol,
		int &	topLeftRow
	)

Fetches next part of raster data, caller takes ownership of the block and caller should delete the block.

Parameters

bandNumber	band to read
nCols	number of columns on output device
nRows	number of rows on output device
block	address of block pointer
topLeftCol	top left column
topLeftRow	top left row

Returns: false if the last part was already returned

Definition at line 65 of file qgsrasteriterator.cpp.

◆ readNextRasterPart() [2/2]

bool QgsRasterIterator::readNextRasterPart	(	int	bandNumber,
		int &	nCols,
		int &	nRows,
		std::unique_ptr< QgsRasterBlock > &	block,
		int &	topLeftCol,
		int &	topLeftRow,
		QgsRectangle *	blockExtent = `nullptr`
	)

Fetches next part of raster data.

Parameters

bandNumber	band to read
nCols	number of columns on output device
nRows	number of rows on output device
block	address of block pointer
topLeftCol	top left column
topLeftRow	top left row
blockExtent	optional storage for exact extent of returned raster block

Returns: false if the last part was already returned

Note: Not available in Python bindings

Since: QGIS 3.2

Definition at line 78 of file qgsrasteriterator.cpp.

◆ setMaximumTileHeight()

void QgsRasterIterator::setMaximumTileHeight ( int h )

inline

Sets the minimum tile height returned during iteration.

See also: maximumTileHeight(); setMaximumTileWidth()

Definition at line 138 of file qgsrasteriterator.h.

◆ setMaximumTileWidth()

void QgsRasterIterator::setMaximumTileWidth ( int w )

inline

Sets the maximum tile width returned during iteration.

See also: maximumTileWidth(); setMaximumTileHeight()

Definition at line 124 of file qgsrasteriterator.h.

◆ startRasterRead()

void QgsRasterIterator::startRasterRead	(	int	bandNumber,
		qgssize	nCols,
		qgssize	nRows,
		const QgsRectangle &	extent,
		QgsRasterBlockFeedback *	feedback = `nullptr`
	)

Start reading of raster band.

Raster data can then be retrieved by calling readNextRasterPart until it returns false.

Parameters

bandNumber	number of raster band to read
nCols	number of columns
nRows	number of rows
extent	area to read
feedback	optional raster feedback object for cancellation/preview. Added in QGIS 3.0.

Definition at line 38 of file qgsrasteriterator.cpp.

◆ stopRasterRead()

void QgsRasterIterator::stopRasterRead ( int bandNumber )

Cancels the raster iteration and resets the iterator.

Definition at line 148 of file qgsrasteriterator.cpp.

Member Data Documentation

◆ DEFAULT_MAXIMUM_TILE_HEIGHT

const int QgsRasterIterator::DEFAULT_MAXIMUM_TILE_HEIGHT = 2000

static

Default maximum tile height.

Definition at line 151 of file qgsrasteriterator.h.

◆ DEFAULT_MAXIMUM_TILE_WIDTH

const int QgsRasterIterator::DEFAULT_MAXIMUM_TILE_WIDTH = 2000

static

Default maximum tile width.

Definition at line 148 of file qgsrasteriterator.h.

The documentation for this class was generated from the following files:

/build/qgis-3.18.1+99unstable/src/core/raster/qgsrasteriterator.h
/build/qgis-3.18.1+99unstable/src/core/raster/qgsrasteriterator.cpp

Public Member Functions

Static Public Attributes

Detailed Description

Constructor & Destructor Documentation

◆ QgsRasterIterator()

Member Function Documentation

◆ input()

◆ maximumTileHeight()

◆ maximumTileWidth()

◆ next()

◆ readNextRasterPart() [1/2]

◆ readNextRasterPart() [2/2]

◆ setMaximumTileHeight()

◆ setMaximumTileWidth()

◆ startRasterRead()

◆ stopRasterRead()

Member Data Documentation

◆ DEFAULT_MAXIMUM_TILE_HEIGHT

◆ DEFAULT_MAXIMUM_TILE_WIDTH