NAME

cache - Methods to Get or Set Image Pixels


SYNOPSIS

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

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

void DestroyImagePixels( Image *image );

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

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

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

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

unsigned int ModifyCache( Image *image );

Cache ReferenceCache( Cache cache_info );

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

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


FUNCTION DESCRIPTIONS

AcquireImagePixels

Method AcquireImagePixels ( ) acquires pixels from the in-memory or disk pixelcache as defined by the geometry parameters. A pointer to the pixels isreturned if the pixels are transferred, otherwise a NULL is returned.;
The format of the AcquireImagePixels ( ) method is:;
const PixelPacket *AcquireImagePixels ( const Image *image, const long x, const long y, const unsigned long columns, const unsigned long rows, ExceptionInfo *exception );

A description of each parameter follows:

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

image:
The image.

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

exception:
Return any errors or warnings in this structure.

AcquireOnePixel

Method AcquireOnePixel ( ) returns a single pixel at the specified ( x, y );

location. The image background color is returned if an error occurs.

The format of the AcquireOnePixel ( ) method is:;
PixelPacket AcquireOnePixel ( const Image image, const long x, const long y, ExceptionInfo exception );

A description of each parameter follows:

pixels: Method AcquireOnePixel ( ) 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.

exception:
Return any errors or warnings in this structure.

DestroyImagePixels

Method DestroyImagePixels ( ) deallocates memory associated with the pixelcache.;
The format of the DestroyImagePixels ( ) method is:;
void DestroyImagePixels ( 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 long x, const long y, const unsigned long columns, const unsigned long rows );

A description of each parameter follows:

status: Method GetImagePixels ( ) returns a pointer to the pixels if they 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 indexes associated with the last call toSetImagePixels ( ) or GetImagePixels ( ) .;
The format of the GetIndexes ( ) method is:;
IndexPacket *GetIndexes ( const Image *image );

A description of each parameter follows:

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

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 long x, const long 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.

GetPixels

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

image:
The image.

ModifyCache

ModifyCache ( ) ensures that there is only a single reference to the pixelcache to be modified, updating the provided cache pointer to point toa clone of the original pixel cache if necessary.;

The format of the ModifyCache method is:

unsigned int ModifyCache ( Image *image );

A description of each parameter follows:

image:
The image.

ReferenceCache

ReferenceCache ( ) increments the reference count associated with the pixelcache returning a pointer to the cache.;

The format of the ReferenceCache method is:

Cache ReferenceCache ( Cache cache_info );

A description of each parameter follows:

cache_info:
The cache_info.

SetImagePixels

Method SetImagePixels ( ) allocates an area to store image pixels as definedby the region rectangle and returns a pointer to the area. This area issubsequently transferred from the pixel cache with SyncImagePixels ( ) . Apointer to the pixels is returned if the pixels are transferred, otherwisea NULL is returned.;
The format of the SetImagePixels ( ) method is:;
PixelPacket *SetImagePixels ( Image *image, const long x, const long y, const unsigned long columns, const unsigned long rows );

A description of each parameter follows:

pixels:
Method SetImagePixels returns a pointer to the pixels if they 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.