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- NAME
- SYNOPSIS
- FUNCTION DESCRIPTIONS
  - AcquireCacheView
  - CloseCacheView
  - GetCacheView
  - GetCacheViewIndexes
  - GetCacheViewPixels
  - OpenCacheView
  - SetCacheView
  - SyncCacheView

## NAME

cache_view - Low-level access to image pixels with multiple views

## SYNOPSIS

const PixelPacket * AcquireCacheView( const ViewInfo *view, const long x, const long y, const unsigned long columns, const unsigned long rows, ExceptionInfo *exception );

void CloseCacheView( ViewInfo *view );

PixelPacket * GetCacheView( ViewInfo *view, const long x, const long y, const unsigned long columns, const unsigned long rows );

IndexPacket * GetCacheViewIndexes( const ViewInfo *view );

PixelPacket * GetCacheViewPixels( const ViewInfo *view );

ViewInfo * OpenCacheView( Image *image );

PixelPacket * SetCacheView( ViewInfo *view, const long x, const long y, const unsigned long columns, const unsigned long rows );

unsigned int SyncCacheView( ViewInfo *view );

## FUNCTION DESCRIPTIONS

### AcquireCacheView

Method AcquireCacheView 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 AcquireCacheView method is:

> const PixelPacket *AcquireCacheView ( const ViewInfo *view, const long x, const long y, const unsigned long columns, const unsigned long rows, ExceptionInfo *exception );

A description of each parameter follows:

  pixels:
    Method GetCacheView returns a null pointer if an error occurs, otherwise a pointer to the view pixels.

  view:
    The address of a structure of type ViewInfo.

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

  exception:
    Return any errors or warnings in this structure.

### CloseCacheView

> CloseCacheView() closes the specified view returned by a previous call to OpenCacheView ( ) .

The format of the CloseCacheView method is:

> void CloseCacheView ( ViewInfo *view );

A description of each parameter follows:

  view:
    The address of a structure of type ViewInfo.

### GetCacheView

> GetCacheView() 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 GetCacheView method is:

> PixelPacket *GetCacheView ( ViewInfo *view, const long x, const long y, const unsigned long columns, const unsigned long rows );

A description of each parameter follows:

  pixels:
    Method GetCacheView returns a null pointer if an error occurs, otherwise a pointer to the view pixels.

  view:
    The address of a structure of type ViewInfo.

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

### GetCacheViewIndexes

Method GetCacheViewIndexes returns the indexes associated with the specified view.

The format of the GetCacheViewIndexes method is:

> IndexPacket *GetCacheViewIndexes ( const ViewInfo *view );

A description of each parameter follows:

  indexes:
    Method GetCacheViewIndexes returns the indexes associated with the specified view.

  view:
    The address of a structure of type ViewInfo.

### GetCacheViewPixels

> GetCacheViewPixels() returns the pixels associated with the specified specified view.

The format of the GetCacheViewPixels method is:

> PixelPacket *GetCacheViewPixels ( const ViewInfo *view );

A description of each parameter follows:

  view:
    The address of a structure of type ViewInfo.

### OpenCacheView

> OpenCacheView() opens a view into the pixel cache.

The format of the OpenCacheView method is:

> ViewInfo *OpenCacheView ( Image *image );

A description of each parameter follows:

  image:
    The image.

### SetCacheView

> SetCacheView() 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 SetCacheView method is:

> PixelPacket *SetCacheView ( ViewInfo *view, const long x, const long y, const unsigned long columns, const unsigned long rows );

A description of each parameter follows:

  view:
    The address of a structure of type ViewInfo.

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

### SyncCacheView

> SyncCacheView() saves the view pixels to the in-memory or disk cache. The method returns True if the pixel region is synced, otherwise False.

The format of the SyncCacheView method is:

> unsigned int SyncCacheView ( ViewInfo *view );

A description of each parameter follows:

  view:
    The address of a structure of type ViewInfo.