GDALCachedPixelAccessor< Type, TILE_SIZE, CACHED_TILE_COUNT > Class Template Reference

Class to have reasonably fast random pixel access to a raster band, when accessing multiple pixels that are close to each other. More...

#include <gdalcachedpixelaccessor.h>

Public Member Functions
	GDALCachedPixelAccessor (GDALRasterBand *poBand)
	Constructor. More...
	~GDALCachedPixelAccessor ()
	Destructor. More...
void	SetBand (GDALRasterBand *poBand)
	Assign the raster band if not known at construction time.
Type	Get (int nX, int nY, bool *pbSuccess=nullptr)
	Get the value of a pixel. More...
bool	Set (int nX, int nY, Type val)
	Set the value of a pixel. More...
bool	FlushCache ()
	Flush content of modified tiles and drop caches. More...
void	ResetModifiedFlag ()
	Reset the modified flag for cached tiles.

Detailed Description

template<class Type, int TILE_SIZE, int CACHED_TILE_COUNT = 4>
class GDALCachedPixelAccessor< Type, TILE_SIZE, CACHED_TILE_COUNT >

Class to have reasonably fast random pixel access to a raster band, when accessing multiple pixels that are close to each other.

This gives faster access than using GDALRasterBand::RasterIO() with a 1x1 window.

Since

GDAL 3.5

Constructor & Destructor Documentation

GDALCachedPixelAccessor()

template<class Type , int TILE_SIZE, int CACHED_TILE_COUNT>

GDALCachedPixelAccessor< Type, TILE_SIZE, CACHED_TILE_COUNT >::GDALCachedPixelAccessor ( GDALRasterBand *  poBand )

explicit

Constructor.

The template accepts the following parameters:

• Type: should be one of GByte, GUInt16, GInt16, GUInt32, GInt32, GUInt64, GInt64, float or double
• TILE_SIZE: the tile size for the cache of GDALCachedPixelAccessor. Use a power of two for faster computation. It doesn't need to be the same of the underlying raster
• CACHED_TILE_COUNT: number of tiles to cache. Should be >= 1. Defaults to 4.

Parameters

poBand

Raster band.

~GDALCachedPixelAccessor()

template<class Type , int TILE_SIZE, int CACHED_TILE_COUNT>

GDALCachedPixelAccessor< Type, TILE_SIZE, CACHED_TILE_COUNT >::~GDALCachedPixelAccessor

Destructor.

Will call FlushCache()

Member Function Documentation

FlushCache()

template<class Type , int TILE_SIZE, int CACHED_TILE_COUNT>

bool GDALCachedPixelAccessor< Type, TILE_SIZE, CACHED_TILE_COUNT >::FlushCache

Flush content of modified tiles and drop caches.

Returns

true if success

Get()

template<class Type , int TILE_SIZE, int CACHED_TILE_COUNT>

Type GDALCachedPixelAccessor< Type, TILE_SIZE, CACHED_TILE_COUNT >::Get ( int  nX, int  nY, bool *  pbSuccess = nullptr  )

inline

Get the value of a pixel.

No bound checking of nX, nY is done.

Parameters

	nX	X coordinate (between 0 and GetXSize()-1)
	nY	Y coordinate (between 0 and GetYSize()-1)
[out]	pbSuccess	Optional pointer to a success flag

Returns

the pixel value

Set()

template<class Type , int TILE_SIZE, int CACHED_TILE_COUNT>

bool GDALCachedPixelAccessor< Type, TILE_SIZE, CACHED_TILE_COUNT >::Set ( int  nX, int  nY, Type  val  )

inline

Set the value of a pixel.

The actual modification of the underlying raster is deferred until the tile is implicit flushed while loading a new tile, or an explicit call to FlushCache().

The destructor of GDALCachedPixelAccessor will take care of calling FlushCache(), if the user hasn't done it explicitly.

No bound checking of nX, nY is done.

Parameters

nX	X coordinate (between 0 and GetXSize()-1)
nY	Y coordinate (between 0 and GetYSize()-1)
val	pixel value

Returns

true if success

---

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

• gdalcachedpixelaccessor.h