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|
/***************************************************************************/
/* */
/* ftsystem.h */
/* */
/* FreeType low-level system interface definition (specification). */
/* */
/* Copyright 1996-2018 by */
/* David Turner, Robert Wilhelm, and Werner Lemberg. */
/* */
/* This file is part of the FreeType project, and may only be used, */
/* modified, and distributed under the terms of the FreeType project */
/* license, LICENSE.TXT. By continuing to use, modify, or distribute */
/* this file you indicate that you have read the license and */
/* understand and accept it fully. */
/* */
/***************************************************************************/
#ifndef FTSYSTEM_H_
#define FTSYSTEM_H_
#include <ft2build.h>
FT_BEGIN_HEADER
/*************************************************************************/
/* */
/* <Section> */
/* system_interface */
/* */
/* <Title> */
/* System Interface */
/* */
/* <Abstract> */
/* How FreeType manages memory and i/o. */
/* */
/* <Description> */
/* This section contains various definitions related to memory */
/* management and i/o access. You need to understand this */
/* information if you want to use a custom memory manager or you own */
/* i/o streams. */
/* */
/*************************************************************************/
/*************************************************************************/
/* */
/* M E M O R Y M A N A G E M E N T */
/* */
/*************************************************************************/
/*************************************************************************
*
* @type:
* FT_Memory
*
* @description:
* A handle to a given memory manager object, defined with an
* @FT_MemoryRec structure.
*
*/
typedef struct FT_MemoryRec_* FT_Memory;
/*************************************************************************
*
* @functype:
* FT_Alloc_Func
*
* @description:
* A function used to allocate `size' bytes from `memory'.
*
* @input:
* memory ::
* A handle to the source memory manager.
*
* size ::
* The size in bytes to allocate.
*
* @return:
* Address of new memory block. 0~in case of failure.
*
*/
typedef void*
(*FT_Alloc_Func)( FT_Memory memory,
long size );
/*************************************************************************
*
* @functype:
* FT_Free_Func
*
* @description:
* A function used to release a given block of memory.
*
* @input:
* memory ::
* A handle to the source memory manager.
*
* block ::
* The address of the target memory block.
*
*/
typedef void
(*FT_Free_Func)( FT_Memory memory,
void* block );
/*************************************************************************
*
* @functype:
* FT_Realloc_Func
*
* @description:
* A function used to re-allocate a given block of memory.
*
* @input:
* memory ::
* A handle to the source memory manager.
*
* cur_size ::
* The block's current size in bytes.
*
* new_size ::
* The block's requested new size.
*
* block ::
* The block's current address.
*
* @return:
* New block address. 0~in case of memory shortage.
*
* @note:
* In case of error, the old block must still be available.
*
*/
typedef void*
(*FT_Realloc_Func)( FT_Memory memory,
long cur_size,
long new_size,
void* block );
/*************************************************************************
*
* @struct:
* FT_MemoryRec
*
* @description:
* A structure used to describe a given memory manager to FreeType~2.
*
* @fields:
* user ::
* A generic typeless pointer for user data.
*
* alloc ::
* A pointer type to an allocation function.
*
* free ::
* A pointer type to an memory freeing function.
*
* realloc ::
* A pointer type to a reallocation function.
*
*/
struct FT_MemoryRec_
{
void* user;
FT_Alloc_Func alloc;
FT_Free_Func free;
FT_Realloc_Func realloc;
};
/*************************************************************************/
/* */
/* I / O M A N A G E M E N T */
/* */
/*************************************************************************/
/*************************************************************************
*
* @type:
* FT_Stream
*
* @description:
* A handle to an input stream.
*
* @also:
* See @FT_StreamRec for the publicly accessible fields of a given
* stream object.
*
*/
typedef struct FT_StreamRec_* FT_Stream;
/*************************************************************************
*
* @struct:
* FT_StreamDesc
*
* @description:
* A union type used to store either a long or a pointer. This is used
* to store a file descriptor or a `FILE*' in an input stream.
*
*/
typedef union FT_StreamDesc_
{
long value;
void* pointer;
} FT_StreamDesc;
/*************************************************************************
*
* @functype:
* FT_Stream_IoFunc
*
* @description:
* A function used to seek and read data from a given input stream.
*
* @input:
* stream ::
* A handle to the source stream.
*
* offset ::
* The offset of read in stream (always from start).
*
* buffer ::
* The address of the read buffer.
*
* count ::
* The number of bytes to read from the stream.
*
* @return:
* The number of bytes effectively read by the stream.
*
* @note:
* This function might be called to perform a seek or skip operation
* with a `count' of~0. A non-zero return value then indicates an
* error.
*
*/
typedef unsigned long
(*FT_Stream_IoFunc)( FT_Stream stream,
unsigned long offset,
unsigned char* buffer,
unsigned long count );
/*************************************************************************
*
* @functype:
* FT_Stream_CloseFunc
*
* @description:
* A function used to close a given input stream.
*
* @input:
* stream ::
* A handle to the target stream.
*
*/
typedef void
(*FT_Stream_CloseFunc)( FT_Stream stream );
/*************************************************************************
*
* @struct:
* FT_StreamRec
*
* @description:
* A structure used to describe an input stream.
*
* @input:
* base ::
* For memory-based streams, this is the address of the first stream
* byte in memory. This field should always be set to NULL for
* disk-based streams.
*
* size ::
* The stream size in bytes.
*
* In case of compressed streams where the size is unknown before
* actually doing the decompression, the value is set to 0x7FFFFFFF.
* (Note that this size value can occur for normal streams also; it is
* thus just a hint.)
*
* pos ::
* The current position within the stream.
*
* descriptor ::
* This field is a union that can hold an integer or a pointer. It is
* used by stream implementations to store file descriptors or `FILE*'
* pointers.
*
* pathname ::
* This field is completely ignored by FreeType. However, it is often
* useful during debugging to use it to store the stream's filename
* (where available).
*
* read ::
* The stream's input function.
*
* close ::
* The stream's close function.
*
* memory ::
* The memory manager to use to preload frames. This is set
* internally by FreeType and shouldn't be touched by stream
* implementations.
*
* cursor ::
* This field is set and used internally by FreeType when parsing
* frames.
*
* limit ::
* This field is set and used internally by FreeType when parsing
* frames.
*
*/
typedef struct FT_StreamRec_
{
unsigned char* base;
unsigned long size;
unsigned long pos;
FT_StreamDesc descriptor;
FT_StreamDesc pathname;
FT_Stream_IoFunc read;
FT_Stream_CloseFunc close;
FT_Memory memory;
unsigned char* cursor;
unsigned char* limit;
} FT_StreamRec;
/* */
FT_END_HEADER
#endif /* FTSYSTEM_H_ */
/* END */
|
