cache - Get or Set Image Pixels
Description: ImageMagick - a robust collection of tools and libraries to read, write and manipulate an image in any of the popular image formats. ImageMagick allows dynamic creation of GIFs, making it suitable for Web applications.
Keywords: ImageMagick,PerlMagick,GraphicsMagick,Magick++,Image,Magick,Magic,Pixel,Perl,Wand

NAME SYNOPSIS FUNCTION DESCRIPTIONS AcquireImagePixels AcquireOnePixel DestroyCacheInfo DestroyImagePixels GetImagePixels GetImageVirtualPixelMethod GetIndexes GetOnePixel GetPixels ModifyCache ReferenceCache SetImagePixels SetImageVirtualPixelMethod # NAME cache - Get or Set Image Pixels # SYNOPSIS const PixelPacket * AcquireImagePixels( const Image *image, const long x, const long y, const unsigned long columns, const unsigned long rows, ExceptionInfo *exception ); PixelPacket AcquireOnePixel( const Image image, const long x, const long y, ExceptionInfo exception ); void DestroyCacheInfo( Cache cache ); void DestroyImagePixels( Image *image ); PixelPacket * GetImagePixels( Image *image, const long x, const long y, const unsigned long columns, const unsigned long rows ); VirtualPixelMethod GetImageVirtualPixelMethod( const Image *image ); IndexPacket * GetIndexes( const Image *image ); PixelPacket * GetOnePixel( const Image image, const long x, const long y ); PixelPacket * GetPixels( const Image image ); 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 ); SetImageVirtualPixelMethod( const Image *image, const VirtualPixelMethod method ); unsigned int SyncImagePixels( Image *image ); # FUNCTION DESCRIPTIONS ## AcquireImagePixels AcquireImagePixels() acquires pixels from the in-memory or disk pixel cache as defined by the geometry parameters. A pointer to the pixel is returned if the pixels are transferred, otherwise a NULL is returned. If you plan to modify the pixels, use GetImagePixels ( ) instead. 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: `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 AcquireOnePixel() returns a single pixel at the specified ( x, y ) location. The image background color is returned if an error occurs. If you plan to modify the pixel, use GetOnePixel ( ) instead. 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: `AcquireOnePixel()` returns a pixel at the specified (x,y) location. image: The image. x,y: These values define the location of the pixel to return. exception: Return any errors or warnings in this structure. ## DestroyCacheInfo DestroyCacheInfo() deallocates memory associated with the pixel cache. The format of the DestroyCacheInfo() method is: void DestroyCacheInfo ( Cache cache ); A description of each parameter follows: cache: Specifies a pointer to a Cache structure. ## DestroyImagePixels 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. ## GetImagePixels GetImagePixels() 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 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: `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. ## GetImageVirtualPixelMethod GetImageVirtualPixelMethod() gets the "virtual pixels" method for the image. A virtual pixel is any pixel access that is outside the boundaries of the image cache. The format of the GetImageVirtualPixelMethod() method is: VirtualPixelMethod GetImageVirtualPixelMethod ( const Image *image ); A description of each parameter follows: image: The image. ## GetIndexes GetIndexes() returns the indexes associated with the last call to SetImagePixels ( ) or GetImagePixels ( ) . The format of the GetIndexes() method is: IndexPacket *GetIndexes ( const Image *image ); A description of each parameter follows: indexes: `GetIndexes()` returns the indexes associated with the last call to `SetImagePixels()` or GetImagePixels(). image: The image. ## GetOnePixel 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: image: The image. x,y: These values define the location of the pixel to return. ## GetPixels GetPixels() returns the pixels associated with the last call to SetImagePixels ( ) or GetImagePixels ( ) . The format of the GetPixels() method is: PixelPacket *GetPixels ( const Image image ); A description of each parameter follows: pixels: `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 pixel cache to be modified, updating the provided cache pointer to point to a 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 pixel cache 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 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 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 long x, const long y, const unsigned long columns, const unsigned long rows ); A description of each parameter follows: pixels: 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. ## SetImageVirtualPixelMethod SetImageVirtualPixelMethod() sets the "virtual pixels" method for the image. A virtual pixel is any pixel access that is outside the boundaries of the image cache. The format of the SetImageVirtualPixelMethod() method is: SetImageVirtualPixelMethod ( const Image *image, const VirtualPixelMethod method ); A description of each parameter follows: image: The image. type: choose from these access types:
          EdgeVPType:  the edge pixels of the image extend infinitely.
          Any pixel outside the image is assigned the same value as the
          pixel at the edge closest to it.
          TileVPType:  the image extends periodically or tiled.  The pixels
          wrap around the edges of the image.
          MirrorVPType:  mirror the image at the boundaries.
          ConstantVPType:  every value outside the image is a constant as
          defines by the pixel parameter.
    =head2 SyncImagePixels
SyncImagePixels() 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 SyncImagePixels() method is: unsigned int SyncImagePixels ( Image *image ); A description of each parameter follows: status: `SyncImagePixels()` returns True if the image pixels are transferred to the in-memory or disk cache otherwise False. image: The image. "Image manipulation software that works like magick"