Edit File: ftsystem.h
/***************************************************************************/ /* */ /* 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 */
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