Specifies the Caching Strategy the class will follow. Caching Strategy objects provide a common interface to the class for supporting multiple methods of caching the generated images.
The available Caching Strategy Objects are:
NullCaching_Strategy. Provides no caching strategy to the class. It should be used when we dont
want to cache the generated image
CacheToFile_Strategy. Caches the generated image in a file
CacheToPEARDB_Strategy. Caches the generated image in a database