/* color type masks */#define PNG_COLOR_MASK_PALETTE    1#define PNG_COLOR_MASK_COLOR      2#define PNG_COLOR_MASK_ALPHA      4/* color types.  Note that not all combinations are legal */#define PNG_COLOR_TYPE_GRAY 0#define PNG_COLOR_TYPE_PALETTE  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_PALETTE)#define PNG_COLOR_TYPE_RGB        (PNG_COLOR_MASK_COLOR)#define PNG_COLOR_TYPE_RGB_ALPHA  (PNG_COLOR_MASK_COLOR | PNG_COLOR_MASK_ALPHA)#define PNG_COLOR_TYPE_GRAY_ALPHA (PNG_COLOR_MASK_ALPHA)/* aliases */#define PNG_COLOR_TYPE_RGBA  PNG_COLOR_TYPE_RGB_ALPHA#define PNG_COLOR_TYPE_GA  PNG_COLOR_TYPE_GRAY_ALPHA/* This is for compression type. PNG 1.0-1.2 only define the single type. */#define PNG_COMPRESSION_TYPE_BASE 0 /* Deflate method 8, 32K window */#define PNG_COMPRESSION_TYPE_DEFAULT PNG_COMPRESSION_TYPE_BASE/* This is for filter type. PNG 1.0-1.2 only define the single type. */#define PNG_FILTER_TYPE_BASE      0 /* Single row per-byte filtering */#define PNG_INTRAPIXEL_DIFFERENCING 64 /* Used only in MNG datastreams */#define PNG_FILTER_TYPE_DEFAULT   PNG_FILTER_TYPE_BASE/* These are for the interlacing type.  These values should NOT be changed. */#define PNG_INTERLACE_NONE        0 /* Non-interlaced image */#define PNG_INTERLACE_ADAM7       1 /* Adam7 interlacing */#define PNG_INTERLACE_LAST        2 /* Not a valid value *//* These are for the oFFs chunk.  These values should NOT be changed. */#define PNG_OFFSET_PIXEL          0 /* Offset in pixels */#define PNG_OFFSET_MICROMETER     1 /* Offset in micrometers (1/10^6 meter) */#define PNG_OFFSET_LAST           2 /* Not a valid value *//* These are for the pCAL chunk.  These values should NOT be changed. */#define PNG_EQUATION_LINEAR       0 /* Linear transformation */#define PNG_EQUATION_BASE_E       1 /* Exponential base e transform */#define PNG_EQUATION_ARBITRARY    2 /* Arbitrary base exponential transform */#define PNG_EQUATION_HYPERBOLIC   3 /* Hyperbolic sine transformation */#define PNG_EQUATION_LAST         4 /* Not a valid value *//* These are for the sCAL chunk.  These values should NOT be changed. */#define PNG_SCALE_UNKNOWN         0 /* unknown unit (image scale) */#define PNG_SCALE_METER           1 /* meters per pixel */#define PNG_SCALE_RADIAN          2 /* radians per pixel */#define PNG_SCALE_LAST            3 /* Not a valid value *//* These are for the pHYs chunk.  These values should NOT be changed. */#define PNG_RESOLUTION_UNKNOWN    0 /* pixels/unknown unit (aspect ratio) */#define PNG_RESOLUTION_METER      1 /* pixels/meter */#define PNG_RESOLUTION_LAST       2 /* Not a valid value *//* These are for the sRGB chunk.  These values should NOT be changed. */#define PNG_sRGB_INTENT_PERCEPTUAL 0#define PNG_sRGB_INTENT_RELATIVE   1#define PNG_sRGB_INTENT_SATURATION 2#define PNG_sRGB_INTENT_ABSOLUTE   3#define PNG_sRGB_INTENT_LAST       4 /* Not a valid value *//* This is for text chunks */#define PNG_KEYWORD_MAX_LENGTH     79/* Maximum number of entries in PLTE/sPLT/tRNS arrays */#define PNG_MAX_PALETTE_LENGTH    256/* These determine if an ancillary chunk's data has been successfully read * from the PNG header, or if the application has filled in the corresponding * data in the info_struct to be written into the output file.  The values * of the PNG_INFO_<chunk> defines should NOT be changed. */#define PNG_INFO_gAMA 0x0001#define PNG_INFO_sBIT 0x0002#define PNG_INFO_cHRM 0x0004#define PNG_INFO_PLTE 0x0008#define PNG_INFO_tRNS 0x0010#define PNG_INFO_bKGD 0x0020#define PNG_INFO_hIST 0x0040#define PNG_INFO_pHYs 0x0080#define PNG_INFO_oFFs 0x0100#define PNG_INFO_tIME 0x0200#define PNG_INFO_pCAL 0x0400#define PNG_INFO_sRGB 0x0800   /* GR-P, 0.96a */#define PNG_INFO_iCCP 0x1000   /* ESR, 1.0.6 */#define PNG_INFO_sPLT 0x2000   /* ESR, 1.0.6 */#define PNG_INFO_sCAL 0x4000   /* ESR, 1.0.6 */#define PNG_INFO_IDAT 0x8000L  /* ESR, 1.0.6 *//* This is used for the transformation routines, as some of them * change these values for the row.  It also should enable using * the routines for other purposes. */typedef struct png_row_info_struct{   png_uint_32 width; /* width of row */   png_uint_32 rowbytes; /* number of bytes in row */   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 (PNGAPI *png_error_ptr) PNGARG((png_structp, png_const_charp));typedef void (PNGAPI *png_rw_ptr) PNGARG((png_structp, png_bytep, png_size_t));typedef void (PNGAPI *png_flush_ptr) PNGARG((png_structp));typedef void (PNGAPI *png_read_status_ptr) PNGARG((png_structp, png_uint_32,   int));typedef void (PNGAPI *png_write_status_ptr) PNGARG((png_structp, png_uint_32,   int));#ifdef PNG_PROGRESSIVE_READ_SUPPORTEDtypedef void (PNGAPI *png_progressive_info_ptr) PNGARG((png_structp, png_infop));typedef void (PNGAPI *png_progressive_end_ptr) PNGARG((png_structp, png_infop));typedef void (PNGAPI *png_progressive_row_ptr) PNGARG((png_structp, png_bytep,   png_uint_32, int));#endif#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \    defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED) || \    defined(PNG_LEGACY_SUPPORTED)typedef void (PNGAPI *png_user_transform_ptr) PNGARG((png_structp,    png_row_infop, png_bytep));#endif#if defined(PNG_USER_CHUNKS_SUPPORTED)typedef int (PNGAPI *png_user_chunk_ptr) PNGARG((png_structp, png_unknown_chunkp));#endif#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)typedef void (PNGAPI *png_unknown_chunk_ptr) PNGARG((png_structp));#endif/* Transform masks for the high-level interface */#define PNG_TRANSFORM_IDENTITY       0x0000    /* read and write */#define PNG_TRANSFORM_STRIP_16       0x0001    /* read only */#define PNG_TRANSFORM_STRIP_ALPHA    0x0002    /* read only */#define PNG_TRANSFORM_PACKING        0x0004    /* read and write */#define PNG_TRANSFORM_PACKSWAP       0x0008    /* read and write */#define PNG_TRANSFORM_EXPAND         0x0010    /* read only */#define PNG_TRANSFORM_INVERT_MONO    0x0020    /* read and write */#define PNG_TRANSFORM_SHIFT          0x0040    /* read and write */#define PNG_TRANSFORM_BGR            0x0080    /* read and write */#define PNG_TRANSFORM_SWAP_ALPHA     0x0100    /* read and write */#define PNG_TRANSFORM_SWAP_ENDIAN    0x0200    /* read and write */#define PNG_TRANSFORM_INVERT_ALPHA   0x0400    /* read and write */#define PNG_TRANSFORM_STRIP_FILLER   0x0800    /* WRITE only *//* Flags for MNG supported features */#define PNG_FLAG_MNG_EMPTY_PLTE     0x01#define PNG_FLAG_MNG_FILTER_64      0x04#define PNG_ALL_MNG_FEATURES        0x05typedef png_voidp (*png_malloc_ptr) PNGARG((png_structp, png_size_t));typedef void (*png_free_ptr) PNGARG((png_structp, png_voidp));/* 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{#ifdef PNG_SETJMP_SUPPORTED   jmp_buf jmpbuf;            /* used in png_error */#endif   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 */   png_voidp io_ptr;          /* ptr to application struct for I/O functions */#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED)   png_user_transform_ptr read_user_transform_fn; /* user read transform */#endif#if defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)   png_user_transform_ptr write_user_transform_fn; /* user write transform */#endif/* These were added in libpng-1.0.2 */#if defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)#if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \    defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)   png_voidp user_transform_ptr; /* user supplied struct for user transform */   png_byte user_transform_depth;    /* bit depth of user transformed pixels */   png_byte user_transform_channels; /* channels in user transformed pixels */#endif#endif   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)#ifdef PNG_LEGACY_SUPPORTED   png_byte filler;           /* filler byte for pixel expansion */#else   png_uint_16 filler;           /* filler bytes for pixel expansion */#endif#endif#if defined(PNG_bKGD_SUPPORTED)   png_byte background_gamma_type;#  ifdef PNG_FLOATING_POINT_SUPPORTED   float background_gamma;#  endif   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#endif /* PNG_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#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)   int gamma_shift;      /* number of "insignificant" bits 16-bit gamma */#ifdef PNG_FLOATING_POINT_SUPPORTED   float gamma;          /* file gamma value */   float screen_gamma;   /* screen gamma value (display_exponent) */#endif#endif#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#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_sBIT_SUPPORTED)   png_color_8 sig_bit;       /* significant bits in each available channel */#endif#if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)   png_color_8 shift;         /* shift for significant bit tranformation */#endif