png.h

hl2 source code. Do not use it illegal.

   png_byte color_type; /* color type of row */
   png_byte bit_depth; /* bit depth of row */
   png_byte channels; /* number of channels (1, 2, 3, or 4) */
   png_byte pixel_depth; /* bits per pixel (depth * channels) */
} png_row_info;

typedef png_row_info FAR * png_row_infop;
typedef png_row_info FAR * FAR * png_row_infopp;

/* These are the function types for the I/O functions and for the functions
 * that allow the user to override the default I/O functions with his or her
 * own.  The png_error_ptr type should match that of user-supplied warning
 * and error functions, while the png_rw_ptr type should match that of the
 * user read/write data functions.
 */
typedef struct png_struct_def png_struct;
typedef png_struct FAR * png_structp;

typedef void (*png_error_ptr) PNGARG((png_structp, png_const_charp));
typedef void (*png_rw_ptr) PNGARG((png_structp, png_bytep, png_size_t));
typedef void (*png_flush_ptr) PNGARG((png_structp));
typedef void (*png_read_status_ptr) PNGARG((png_structp, png_uint_32, int));
typedef void (*png_write_status_ptr) PNGARG((png_structp, png_uint_32, int));
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
typedef void (*png_progressive_info_ptr) PNGARG((png_structp, png_infop));
typedef void (*png_progressive_end_ptr) PNGARG((png_structp, png_infop));
typedef void (*png_progressive_row_ptr) PNGARG((png_structp, png_bytep,
   png_uint_32, int));
#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */

#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
    defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
typedef void (*png_user_transform_ptr) PNGARG((png_structp,
    png_row_infop, png_bytep));
#endif /* PNG_READ|WRITE_USER_TRANSFORM_SUPPORTED */

typedef png_voidp (*png_malloc_ptr) PNGARG((png_structp, png_size_t));
typedef void (*png_free_ptr) PNGARG((png_structp, png_structp));

/* The structure that holds the information to read and write PNG files.
 * The only people who need to care about what is inside of this are the
 * people who will be modifying the library for their own special needs.
 * It should NOT be accessed directly by an application, except to store
 * the jmp_buf.
 */

struct png_struct_def
{
   jmp_buf jmpbuf;            /* used in png_error */

   png_error_ptr error_fn;    /* function for printing errors and aborting */
   png_error_ptr warning_fn;  /* function for printing warnings */
   png_voidp error_ptr;       /* user supplied struct for error functions */
   png_rw_ptr write_data_fn;  /* function for writing output data */
   png_rw_ptr read_data_fn;   /* function for reading input data */
#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
    defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
   png_user_transform_ptr read_user_transform_fn; /* user read transform */
   png_user_transform_ptr write_user_transform_fn; /* user write transform */
#endif
   png_voidp io_ptr;          /* ptr to application struct for I/O functions*/

   png_uint_32 mode;          /* tells us where we are in the PNG file */
   png_uint_32 flags;         /* flags indicating various things to libpng */
   png_uint_32 transformations; /* which transformations to perform */

   z_stream zstream;          /* pointer to decompression structure (below) */
   png_bytep zbuf;            /* buffer for zlib */
   png_size_t zbuf_size;      /* size of zbuf */
   int zlib_level;            /* holds zlib compression level */
   int zlib_method;           /* holds zlib compression method */
   int zlib_window_bits;      /* holds zlib compression window bits */
   int zlib_mem_level;        /* holds zlib compression memory level */
   int zlib_strategy;         /* holds zlib compression strategy */

   png_uint_32 width;         /* width of image in pixels */
   png_uint_32 height;        /* height of image in pixels */
   png_uint_32 num_rows;      /* number of rows in current pass */
   png_uint_32 usr_width;     /* width of row at start of write */
   png_uint_32 rowbytes;      /* size of row in bytes */
   png_uint_32 irowbytes;     /* size of current interlaced row in bytes */
   png_uint_32 iwidth;        /* width of current interlaced row in pixels */
   png_uint_32 row_number;    /* current row in interlace pass */
   png_bytep prev_row;        /* buffer to save previous (unfiltered) row */
   png_bytep row_buf;         /* buffer to save current (unfiltered) row */
   png_bytep sub_row;         /* buffer to save "sub" row when filtering */
   png_bytep up_row;          /* buffer to save "up" row when filtering */
   png_bytep avg_row;         /* buffer to save "avg" row when filtering */
   png_bytep paeth_row;       /* buffer to save "Paeth" row when filtering */
   png_row_info row_info;     /* used for transformation routines */

   png_uint_32 idat_size;     /* current IDAT size for read */
   png_uint_32 crc;           /* current chunk CRC value */
   png_colorp palette;        /* palette from the input file */
   png_uint_16 num_palette;   /* number of color entries in palette */
   png_uint_16 num_trans;     /* number of transparency values */
   png_byte chunk_name[5];    /* null-terminated name of current chunk */
   png_byte compression;      /* file compression type (always 0) */
   png_byte filter;           /* file filter type (always 0) */
   png_byte interlaced;       /* PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
   png_byte pass;             /* current interlace pass (0 - 6) */
   png_byte do_filter;        /* row filter flags (see PNG_FILTER_ below ) */
   png_byte color_type;       /* color type of file */
   png_byte bit_depth;        /* bit depth of file */
   png_byte usr_bit_depth;    /* bit depth of users row */
   png_byte pixel_depth;      /* number of bits per pixel */
   png_byte channels;         /* number of channels in file */
   png_byte usr_channels;     /* channels at start of write */
   png_byte sig_bytes;        /* magic bytes read/written from start of file */

#if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
   png_uint_16 filler;           /* filler bytes for pixel expansion */
#endif /* PNG_READ_FILLER_SUPPORTED */
#if defined(PNG_READ_bKGD_SUPPORTED)
   png_byte background_gamma_type;
   float background_gamma;
   png_color_16 background;   /* background color in screen gamma space */
#if defined(PNG_READ_GAMMA_SUPPORTED)
   png_color_16 background_1; /* background normalized to gamma 1.0 */
#endif /* PNG_READ_GAMMA && PNG_READ_bKGD_SUPPORTED */
#endif /* PNG_READ_bKGD_SUPPORTED */
#if defined(PNG_WRITE_FLUSH_SUPPORTED)
   png_flush_ptr output_flush_fn;/* Function for flushing output */
   png_uint_32 flush_dist;    /* how many rows apart to flush, 0 - no flush */
   png_uint_32 flush_rows;    /* number of rows written since last flush */
#endif /* PNG_WRITE_FLUSH_SUPPORTED */
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
   int gamma_shift;      /* number of "insignificant" bits 16-bit gamma */
   float gamma;          /* file gamma value */
   float screen_gamma;   /* screen gamma value (display_gamma/viewing_gamma */
#endif /* PNG_READ_GAMMA_SUPPORTED */
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
   png_bytep gamma_table;     /* gamma table for 8 bit depth files */
   png_bytep gamma_from_1;    /* converts from 1.0 to screen */
   png_bytep gamma_to_1;      /* converts from file to 1.0 */
   png_uint_16pp gamma_16_table; /* gamma table for 16 bit depth files */
   png_uint_16pp gamma_16_from_1; /* converts from 1.0 to screen */
   png_uint_16pp gamma_16_to_1; /* converts from file to 1.0 */
#endif /* PNG_READ_GAMMA_SUPPORTED || PNG_WRITE_GAMMA_SUPPORTED */
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined (PNG_READ_sBIT_SUPPORTED)
   png_color_8 sig_bit;       /* significant bits in each available channel */
#endif /* PNG_READ_GAMMA_SUPPORTED || PNG_READ_sBIT_SUPPORTED */
#if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
   png_color_8 shift;         /* shift for significant bit tranformation */
#endif /* PNG_READ_SHIFT_SUPPORTED || PNG_WRITE_SHIFT_SUPPORTED */
#if defined(PNG_READ_tRNS_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) \
 || defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
   png_bytep trans;           /* transparency values for paletted files */
   png_color_16 trans_values; /* transparency values for non-paletted files */
#endif /* PNG_READ|WRITE_tRNS_SUPPORTED||PNG_READ_EXPAND|BACKGROUND_SUPPORTED */
   png_read_status_ptr read_row_fn;   /* called after each row is decoded */
   png_write_status_ptr write_row_fn; /* called after each row is encoded */
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
   png_progressive_info_ptr info_fn; /* called after header data fully read */
   png_progressive_row_ptr row_fn;   /* called after each prog. row is decoded */
   png_progressive_end_ptr end_fn;   /* called after image is complete */
   png_bytep save_buffer_ptr;        /* current location in save_buffer */
   png_bytep save_buffer;            /* buffer for previously read data */
   png_bytep current_buffer_ptr;     /* current location in current_buffer */
   png_bytep current_buffer;         /* buffer for recently used data */
   png_uint_32 push_length;          /* size of current input chunk */
   png_uint_32 skip_length;          /* bytes to skip in input data */
   png_size_t save_buffer_size;      /* amount of data now in save_buffer */
   png_size_t save_buffer_max;       /* total size of save_buffer */
   png_size_t buffer_size;           /* total amount of available input data */
   png_size_t current_buffer_size;   /* amount of data now in current_buffer */
   int process_mode;                 /* what push library is currently doing */
   int cur_palette;                  /* current push library palette index */
#if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED)
   png_size_t current_text_size;     /* current size of text input data */
   png_size_t current_text_left;     /* how much text left to read in input */
   png_charp current_text;           /* current text chunk buffer */
   png_charp current_text_ptr;       /* current location in current_text */
#endif /* PNG_PROGRESSIVE_READ_SUPPORTED && PNG_READ_tEXt/zTXt_SUPPORTED */
#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
#if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
/* for the Borland special 64K segment handler */
   png_bytepp offset_table_ptr;
   png_bytep offset_table;
   png_uint_16 offset_table_number;
   png_uint_16 offset_table_count;
   png_uint_16 offset_table_count_free;
#endif /* __TURBOC__&&!_Windows&&!__FLAT__ */
#if defined(PNG_READ_DITHER_SUPPORTED)
   png_bytep palette_lookup;         /* lookup table for dithering */
   png_bytep dither_index;           /* index translation for palette files */
#endif /* PNG_READ_DITHER_SUPPORTED */
#if defined(PNG_READ_DITHER_SUPPORTED) || defined(PNG_READ_hIST_SUPPORTED)
   png_uint_16p hist;                /* histogram */
#endif
#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
   png_byte heuristic_method;        /* heuristic for row filter selection */
   png_byte num_prev_filters;        /* number of weights for previous rows */
   png_bytep prev_filters;           /* filter type(s) of previous row(s) */
   png_uint_16p filter_weights;      /* weight(s) for previous line(s) */
   png_uint_16p inv_filter_weights;  /* 1/weight(s) for previous line(s) */
   png_uint_16p filter_costs;        /* relative filter calculation cost */
   png_uint_16p inv_filter_costs;    /* 1/relative filter calculation cost */
#endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
#if defined(PNG_TIME_RFC1123_SUPPORTED)
   png_charp time_buffer;            /* String to hold RFC 1123 time text */
#endif /* PNG_TIME_RFC1123_SUPPORTED */
#ifdef PNG_USER_MEM_SUPPORTED
   png_voidp mem_ptr;                /* user supplied struct for mem functions */
   png_malloc_ptr malloc_fn;         /* function for allocating memory */
   png_free_ptr free_fn;             /* function for freeing memory */
#endif /* PNG_USER_MEM_SUPPORTED */
#if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
   png_byte rgb_to_gray_status;
   png_byte rgb_to_gray_red_coeff;
   png_byte rgb_to_gray_green_coeff;
   png_byte rgb_to_gray_blue_coeff;
#endif
};

typedef png_struct FAR * FAR * png_structpp;

/* Here are the function definitions most commonly used.  This is not
 * the place to find out how to use libpng.  See libpng.txt for the
 * full explanation, see example.c for the summary.  This just provides
 * a simple one line of the use of each function.
 */

/* Tell lib we have already handled the first <num_bytes> magic bytes.
 * Handling more than 8 bytes from the beginning of the file is an error.
 */
extern PNG_EXPORT(void,png_set_sig_bytes) PNGARG((png_structp png_ptr,
   int num_bytes));

/* Check sig[start] through sig[start + num_to_check - 1] to see if it's a
 * PNG file.  Returns zero if the supplied bytes match the 8-byte PNG
 * signature, and non-zero otherwise.  Having num_to_check == 0 or
 * start > 7 will always fail (ie return non-zero).
 */
extern PNG_EXPORT(int,png_sig_cmp) PNGARG((png_bytep sig, png_size_t start,
   png_size_t num_to_check));

/* Simple signature checking function.  This is the same as calling
 * png_check_sig(sig, n) := !png_sig_cmp(sig, 0, n).
 */
extern PNG_EXPORT(int,png_check_sig) PNGARG((png_bytep sig, int num));

/* Allocate and initialize png_ptr struct for reading, and any other memory. */
extern PNG_EXPORT(png_structp,png_create_read_struct)
   PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,
   png_error_ptr error_fn, png_error_ptr warn_fn));

/* Allocate and initialize png_ptr struct for writing, and any other memory */
extern PNG_EXPORT(png_structp,png_create_write_struct)
   PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,
   png_error_ptr error_fn, png_error_ptr warn_fn));

#ifdef PNG_USER_MEM_SUPPORTED
extern PNG_EXPORT(png_structp,png_create_read_struct_2)
   PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,
   png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
   png_malloc_ptr malloc_fn, png_free_ptr free_fn));
extern PNG_EXPORT(png_structp,png_create_write_struct_2)
   PNGARG((png_const_charp user_png_ver, png_voidp error_ptr,
   png_error_ptr error_fn, png_error_ptr warn_fn, png_voidp mem_ptr,
   png_malloc_ptr malloc_fn, png_free_ptr free_fn));
#endif

/* Write a PNG chunk - size, type, (optional) data, CRC. */
extern PNG_EXPORT(void,png_write_chunk) PNGARG((png_structp png_ptr,
   png_bytep chunk_name, png_bytep data, png_size_t length));

/* Write the start of a PNG chunk - length and chunk name. */
extern PNG_EXPORT(void,png_write_chunk_start) PNGARG((png_structp png_ptr,
   png_bytep chunk_name, png_uint_32 length));