DD::Image::ImageCacheReadI Class Referenceabstract

Holder of temporary data to read files from cache: More...

Inherited by DD::Image::FileStreamRead, ImageCacheRead, and ImageCacheWriteRead.

Public Member Functions

virtual size_t read (void *to, size_t n)=0
 
bool tryRead (void *t, size_t n)
 
virtual void seek (size_t to)=0
 
virtual void seekRelative (off_t offset)=0
 
virtual void close ()=0
 
virtual int uniqueID () const =0
 

Detailed Description

Holder of temporary data to read files from cache:

Member Function Documentation

virtual size_t DD::Image::ImageCacheReadI::read ( void *  to,
size_t  n 
)
pure virtual

Read a block of data from a file opened with Image_Cache::open(). Returns number of bytes read.

Referenced by DD::Image::ViewerCache::read_from_cache().

bool DD::Image::ImageCacheReadI::tryRead ( void *  t,
size_t  n 
)
inline

Try to read a certain number of bytes. If it fails to read that number, return false.

virtual void DD::Image::ImageCacheReadI::seek ( size_t  to)
pure virtual

Move the file pointer to an absolute position in the file.

virtual void DD::Image::ImageCacheReadI::seekRelative ( off_t  offset)
pure virtual

Move the file pointer by n bytes.

Referenced by DD::Image::ViewerCache::read_from_cache().

virtual void DD::Image::ImageCacheReadI::close ( )
pure virtual

Close the file and delete the r data structure.

Referenced by DD::Image::ViewerCache::BoxPresent(), and DD::Image::ViewerCache::read_from_cache().

virtual int DD::Image::ImageCacheReadI::uniqueID ( ) const
pure virtual

get a unique ID for the memory-cached data, or 0 if the data was not in the memory cache. if the contents of the memory-cached data change (or if the data is removed from the memory cache and then reloaded) this number will increase.

Referenced by DD::Image::ViewerCache::BoxPresent().



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