Ptex
Public Member Functions | Static Public Member Functions | Protected Member Functions | List of all members
PtexCache Class Referenceabstract

File-handle and memory cache for reading ptex files. More...

#include <Ptexture.h>

Public Member Functions

virtual void release ()=0
 Release resources held by this pointer (pointer becomes invalid).
 
virtual void setSearchPath (const char *path)=0
 Set a search path for finding textures. More...
 
virtual const char * getSearchPath ()=0
 Query the search path. More...
 
virtual PtexTextureget (const char *path, Ptex::String &error)=0
 Open a texture. More...
 
virtual void purge (PtexTexture *texture)=0
 Remove a texture file from the cache. More...
 
virtual void purge (const char *path)=0
 Remove a texture file from the cache by pathname. More...
 
virtual void purgeAll ()=0
 Remove all texture files from the cache. More...
 

Static Public Member Functions

static PtexCachecreate (int maxFiles=0, int maxMem=0, bool premultiply=false, PtexInputHandler *handler=0)
 Create a cache with the specified limits. More...
 

Protected Member Functions

virtual ~PtexCache ()
 Destructor not for public use. Use release() instead.
 

Detailed Description

File-handle and memory cache for reading ptex files.

The PtexCache class allows cached read access to multiple ptex files while constraining the open file count and memory usage to specified limits. File and data objects accessed via the cache are added back to the cache when their release method is called. Released objects are maintained in an LRU list and only destroyed when the specified resource limits are exceeded.

The cache is fully multi-threaded. Cached data will be shared among all threads that have access to the cache, and the data are protected with internal locks. See PtexCache.cpp for details about the caching and locking implementation.

Member Function Documentation

static PtexCache* PtexCache::create ( int  maxFiles = 0,
int  maxMem = 0,
bool  premultiply = false,
PtexInputHandler handler = 0 
)
static

Create a cache with the specified limits.

Parameters
maxFilesMaximum open file handles. If unspecified, limit is set to 100 open files.
maxMemMaximum allocated memory, in bytes. If unspecified, limit is set to 100MB.
premultiplyIf true, textures will be premultiplied by the alpha channel (if any) when read from disk. See PtexTexture and PtexWriter for more details.
handlerIf specified, all input calls made through this cache will be directed through the handler.
virtual PtexTexture* PtexCache::get ( const char *  path,
Ptex::String error 
)
pure virtual

Open a texture.

If the specified path was previously opened, and the open file limit hasn't been exceeded, then a pointer to the already open file will be returned.

If the specified path hasn't been opened yet or was closed, either to maintain the open file limit or because the file was explicitly purged from the cache, then the file will be newly opened. If the path is relative (i.e. doesn't begin with a '/') then the search path will be used to locate the file.

The texture file will stay open until the PtexTexture::release method is called, at which point the texture will be returned to the cache. Once released, the file will be closed when either the file handle limit is reached, the cached is released, or when the texture is purged (see purge methods below).

If texture could not be opened, null will be returned and an error string will be set.

Parameters
pathFile path. If path is relative, search path will be used to find the file.
errorError string set if texture could not be opened.
virtual const char* PtexCache::getSearchPath ( )
pure virtual

Query the search path.

Returns string set via setSearchPath.

virtual void PtexCache::purge ( PtexTexture texture)
pure virtual

Remove a texture file from the cache.

The texture file will remain open and accessible until the file handle is released, but any future cache accesses for that file will open the file anew.

virtual void PtexCache::purge ( const char *  path)
pure virtual

Remove a texture file from the cache by pathname.

The path must match the full path as opened. This function will not search for the file, but if a search path was used, the path must match the path as found by the search path.

virtual void PtexCache::purgeAll ( )
pure virtual

Remove all texture files from the cache.

Open files with active PtexTexture* handles remain open until released.

virtual void PtexCache::setSearchPath ( const char *  path)
pure virtual

Set a search path for finding textures.

Note: if an input handler is installed the search path will be ignored.

Parameters
pathcolon-delimited search path.