NAME

cache - Methods to Get or Set Image Pixels

SYNOPSIS

void CloseImagePixels( Image *image );

void ClosePixelCache( Image *image );

unsigned int CompressCache( Cache cache );

DestroyCache( void );

void DestroyImagePixels( Image *image );

void DestroyPixelCache( Image *image );

status: Method GetImagePixels( )returns a pointer to the pixels is returned if the pixels are transferred, otherwise a NULL is returned.;

indexes: Method GetIndexes( )returns the colormap indexes associated with the last call to the SetImagePixels( )or GetImagePixels( )methods.;

indexes: Method GetIndexesFromCache( )returns the colormap indexes associated with the last call to the SetPixelCache( )or GetPixelCache( )methods.;

pixels: Method GetOnePixel( )returns a pixel at the specified( x, y );

PixelPacket * GetOnePixelFromCache( const Image image, const int x, const int y );

PixelPacket * GetPixelCache( Image *image, const int x, const int y, const unsigned int columns, const unsigned int rows );

pixels: Method GetPixels( )returns the pixels associated with the last call to the SetImagePixels( )or GetImagePixels( )methods.;

PixelPacket * GetPixelsFromCache( const Image image );

PixelPacket * SetImagePixels( Image *image, const int x, const int y, const unsigned int columns, const unsigned int rows );

PixelPacket * SetPixelCache( Image *image, const int x, const int y, const unsigned int columns, const unsigned int rows );

unsigned int SyncImagePixels( Image *image );

unsigned int SyncPixelCache( Image *image );

unsigned int UncompressCache( Cache cache );

unsigned int WriteCacheInfo( Image *image );

FUNCTION DESCRIPTIONS

CloseImagePixels

Method CloseImagePixels closes the pixel cache. Use this method to prevent too many file descriptors from being allocated when reading an image sequence. File descriptors are only used for a disk-based cache. This is essentially a no-op for a memory-based cache.

The format of the CloseImagePixels method is:

void CloseImagePixels ( Image *image );

A description of each parameter follows:

image:
The image.

ClosePixelCache

Method ClosePixelCache closes the pixel cache. Use this method to prevent too many file descriptors from being allocated when reading an image sequence. File descriptors are only used for a disk-based cache. This is essentially a no-op for a memory-based cache.

The format of the ClosePixelCache method is:

void ClosePixelCache ( Image *image );

A description of each parameter follows:

image:
The image.

CompressCache

Method CompressCache compresses the disk-based pixel cache.

The format of the CompressCache method is:

unsigned int CompressCache ( Cache cache );

A description of each parameter follows:

cache:
Specifies a pointer to a Cache structure.

DestroyCache

Method DestroyCache destroys the cache environment.

The format of the DestroyCache method is:

DestroyCache ( void );

DestroyImagePixels

Method DestroyImagePixels deallocates memory associated with the pixel cache.

The format of the DestroyImagePixels method is:

void DestroyImagePixels ( Image *image );

A description of each parameter follows:

image:
The image.

DestroyPixelCache

Method DestroyPixelCache deallocates memory associated with the pixel cache.

The format of the DestroyPixelCache method is:

void DestroyPixelCache ( Image *image );

A description of each parameter follows:

image:
The image.

GetImagePixels

Method GetImagePixels ( ) gets pixels from the in-memory or disk pixel cacheas defined by the geometry parameters. A pointer to the pixels is returnedif the pixels are transferred, otherwise a NULL is returned.;

The format of the GetImagePixels method is:

PixelPacket *GetImagePixels ( Image *image, const int x, const int y, const unsigned int columns, const unsigned int rows );

A description of each parameter follows:

status: Method GetImagePixels ( ) returns a pointer to the pixels is returned if the pixels are transferred, otherwise a NULL is returned.;

image:
The image.

x,y,columns,rows:
These values define the perimeter of a region of pixels.

GetIndexes

Method GetIndexes ( ) returns the colormap indexes associated with the lastcall to the SetImagePixels ( ) or GetImagePixels ( ) methods.;

The format of the GetIndexes method is:

IndexPacket *GetIndexes ( const Image *image );

A description of each parameter follows:

indexes: Method GetIndexes ( ) returns the colormap indexes associated with the last call to the SetImagePixels ( ) or GetImagePixels ( ) methods.;

image:
The image.

GetIndexesFromCache

Method GetIndexesFromCache returns the colormap indexes associated with the last call to the SetPixelCache() or GetPixelCache() methods.

The format of the GetIndexesFromCache method is:

IndexPacket *GetIndexesFromCache ( const Image *image );

A description of each parameter follows:

indexes: Method GetIndexesFromCache ( ) returns the colormap indexes associated with the last call to the SetPixelCache ( ) or GetPixelCache ( ) methods.;

image:
The image.

GetOnePixel

Method GetOnePixel ( ) returns a single pixel at the specified ( x, y ) location.The image background color is returned if an error occurs.;

The format of the GetOnePixel method is:

PixelPacket *GetOnePixel ( const Image image, const int x, const int y );

A description of each parameter follows:

pixels: Method GetOnePixel ( ) returns a pixel at the specified ( x, y ); 
    location.
=over 4

image:
The image.

x,y:
These values define the location of the pixel to return.

GetOnePixelFromCache

Method GetOnePixelFromCache returns a single pixel at the specified (x,y) location. The image background color is returned if an error occurs.

The format of the GetOnePixelFromCache method is:

PixelPacket *GetOnePixelFromCache ( const Image image, const int x, const int y );

A description of each parameter follows:

pixels:
Method GetOnePixelFromCache returns a pixel at the specified (x,y) location.

image:
The image.

x,y:
These values define the location of the pixel to return.

GetPixels

Method GetPixels ( ) returns the pixels associated with the last call to theSetImagePixels ( ) or GetImagePixels ( ) methods.;

The format of the GetPixels method is:

PixelPacket *GetPixels ( const Image image );

A description of each parameter follows:

pixels: Method GetPixels ( ) returns the pixels associated with the last call to the SetImagePixels ( ) or GetImagePixels ( ) methods.;

image:
The image.

GetPixelCache

Method GetPixelCache gets pixels from the in-memory or disk pixel cache as defined by the geometry parameters. A pointer to the pixels is returned if the pixels are transferred, otherwise a NULL is returned.

The format of the GetPixelCache method is:

PixelPacket *GetPixelCache ( Image *image, const int x, const int y, const unsigned int columns, const unsigned int rows );

A description of each parameter follows:

status:
Method GetPixelCache returns a pointer to the pixels is returned if the pixels are transferred, otherwise a NULL is returned.

image:
The image.

x,y,columns,rows:
These values define the perimeter of a region of pixels.

GetPixelsFromCache

Method GetPixelsFromCache returns the pixels associated with the last call to the SetPixelCache() or GetPixelCache() methods.

The format of the GetPixelsFromCache method is:

PixelPacket *GetPixelsFromCache ( const Image image );

A description of each parameter follows:

pixels:
Method GetPixelsFromCache returns the pixels associated with the last call to the SetPixelCache() or GetPixelCache() methods.

image:
The image.

SetImagePixels

Method SetImagePixels allocates an area to store image pixels as defined by the region rectangle and returns a pointer to the area. This area is subsequently transferred from the pixel cache with method SyncImagePixels. A pointer to the pixels is returned if the pixels are transferred, otherwise a NULL is returned.

The format of the SetImagePixels method is:

PixelPacket *SetImagePixels ( Image *image, const int x, const int y, const unsigned int columns, const unsigned int rows );

A description of each parameter follows:

pixels:
Method SetImagePixels returns a pointer to the pixels is returned if the pixels are transferred, otherwise a NULL is returned.

image:
The image.

x,y,columns,rows:
These values define the perimeter of a region of pixels.

SetPixelCache

Method SetPixelCache allocates an area to store image pixels as defined by the region rectangle and returns a pointer to the area. This area is subsequently transferred from the pixel cache with method SyncPixelCache. A pointer to the pixels is returned if the pixels are transferred, otherwise a NULL is returned.

The format of the SetPixelCache method is:

PixelPacket *SetPixelCache ( Image *image, const int x, const int y, const unsigned int columns, const unsigned int rows );

A description of each parameter follows:

pixels:
Method SetPixelCache returns a pointer to the pixels is returned if the pixels are transferred, otherwise a NULL is returned.

image:
The image.

x,y,columns,rows:
These values define the perimeter of a region of pixels.

SyncImagePixels

Method SyncImagePixels ( ) saves the image pixels to the in-memory or diskcache. The method returns True if the pixel region is synced, otherwiseFalse.;

The format of the SyncImagePixels method is:

unsigned int SyncImagePixels ( Image *image );

A description of each parameter follows:

status:
Method SyncImagePixels returns True if the image pixels are transferred to the in-memory or disk cache otherwise False.

image:
The image.

SyncPixelCache

Method SyncPixelCache saves the image pixels to the in-memory or disk cache. The method returns True if the pixel region is synced, otherwise False.

The format of the SyncPixelCache method is:

unsigned int SyncPixelCache ( Image *image );

A description of each parameter follows:

status:
Method SyncPixelCache returns True if the image pixels are transferred to the in-memory or disk cache otherwise False.

image:
The image.

UncompressCache

Method UncompressCache uncompresses the disk-based pixel cache.

The format of the UncompressCache method is:

unsigned int UncompressCache ( Cache cache );

A description of each parameter follows:

cache:
Specifies a pointer to a Cache structure.

WriteCacheInfo

Method WriteCacheInfo writes the persistent cache meta information to a file on disk.

The format of the WriteCacheInfo method is:

unsigned int WriteCacheInfo ( Image *image );

A description of each parameter follows:

status:
Method WriteCacheInfo returns True if the cache meta information is written to the specified file, otherwise False.

image:
The image.