src/png/pngpriv.h

   1 /* pngpriv.h - private declarations for use inside libpng
   2  *
   3  * For conditions of distribution and use, see copyright notice in png.h
   4  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
   5  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   6  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   7  *
   8  * Last changed in libpng 1.5.6 [November 3, 2011]
   9  *
  10  * This code is released under the libpng license.
  11  * For conditions of distribution and use, see the disclaimer
  12  * and license in png.h
  13  */
  14
  15 /* The symbols declared in this file (including the functions declared
  16  * as PNG_EXTERN) are PRIVATE.  They are not part of the libpng public
  17  * interface, and are not recommended for use by regular applications.
  18  * Some of them may become public in the future; others may stay private,
  19  * change in an incompatible way, or even disappear.
  20  * Although the libpng users are not forbidden to include this header,
  21  * they should be well aware of the issues that may arise from doing so.
  22  */
  23
  24 #ifndef PNGPRIV_H
  25 #define PNGPRIV_H
  26
  27 /* Feature Test Macros.  The following are defined here to ensure that correctly
  28  * implemented libraries reveal the APIs libpng needs to build and hide those
  29  * that are not needed and potentially damaging to the compilation.
  30  *
  31  * Feature Test Macros must be defined before any system header is included (see
  32  * POSIX 1003.1 2.8.2 "POSIX Symbols."
  33  *
  34  * These macros only have an effect if the operating system supports either
  35  * POSIX 1003.1 or C99, or both.  On other operating systems (particularly
  36  * Windows/Visual Studio) there is no effect; the OS specific tests below are
  37  * still required (as of 2011-05-02.)
  38  */
  39 #define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
  40
  41 /* This is required for the definition of abort(), used as a last ditch
  42  * error handler when all else fails.
  43  */
  44 #include <stdlib.h>
  45
  46 /* This is used to find 'offsetof', used below for alignment tests. */
  47 #include <stddef.h>
  48
  49 #define PNGLIB_BUILD /*libpng is being built, not used*/
  50
  51 #ifdef PNG_USER_CONFIG
  52 #  include "pngusr.h"
  53    /* These should have been defined in pngusr.h */
  54 #  ifndef PNG_USER_PRIVATEBUILD
  55 #    define PNG_USER_PRIVATEBUILD "Custom libpng build"
  56 #  endif
  57 #  ifndef PNG_USER_DLLFNAME_POSTFIX
  58 #    define PNG_USER_DLLFNAME_POSTFIX "Cb"
  59 #  endif
  60 #endif
  61
  62 /* Is this a build of a DLL where compilation of the object modules requires
  63  * different preprocessor settings to those required for a simple library?  If
  64  * so PNG_BUILD_DLL must be set.
  65  *
  66  * If libpng is used inside a DLL but that DLL does not export the libpng APIs
  67  * PNG_BUILD_DLL must not be set.  To avoid the code below kicking in build a
  68  * static library of libpng then link the DLL against that.
  69  */
  70 #ifndef PNG_BUILD_DLL
  71 #  ifdef DLL_EXPORT
  72       /* This is set by libtool when files are compiled for a DLL; libtool
  73        * always compiles twice, even on systems where it isn't necessary.  Set
  74        * PNG_BUILD_DLL in case it is necessary:
  75        */
  76 #     define PNG_BUILD_DLL
  77 #  else
  78 #     ifdef _WINDLL
  79          /* This is set by the Microsoft Visual Studio IDE in projects that
  80           * build a DLL.  It can't easily be removed from those projects (it
  81           * isn't visible in the Visual Studio UI) so it is a fairly reliable
  82           * indication that PNG_IMPEXP needs to be set to the DLL export
  83           * attributes.
  84           */
  85 #        define PNG_BUILD_DLL
  86 #     else
  87 #        ifdef __DLL__
  88             /* This is set by the Borland C system when compiling for a DLL
  89              * (as above.)
  90              */
  91 #           define PNG_BUILD_DLL
  92 #        else
  93             /* Add additional compiler cases here. */
  94 #        endif
  95 #     endif
  96 #  endif
  97 #endif /* Setting PNG_BUILD_DLL if required */
  98
  99 /* See pngconf.h for more details: the builder of the library may set this on
 100  * the command line to the right thing for the specific compilation system or it
 101  * may be automagically set above (at present we know of no system where it does
 102  * need to be set on the command line.)
 103  *
 104  * PNG_IMPEXP must be set here when building the library to prevent pngconf.h
 105  * setting it to the "import" setting for a DLL build.
 106  */
 107 #ifndef PNG_IMPEXP
 108 #  ifdef PNG_BUILD_DLL
 109 #     define PNG_IMPEXP PNG_DLL_EXPORT
 110 #  else
 111       /* Not building a DLL, or the DLL doesn't require specific export
 112        * definitions.
 113        */
 114 #     define PNG_IMPEXP
 115 #  endif
 116 #endif
 117
 118 /* No warnings for private or deprecated functions in the build: */
 119 #ifndef PNG_DEPRECATED
 120 #  define PNG_DEPRECATED
 121 #endif
 122 #ifndef PNG_PRIVATE
 123 #  define PNG_PRIVATE
 124 #endif
 125
 126 #include "png.h"
 127 #include "pnginfo.h"
 128 #include "pngstruct.h"
 129
 130 /* pngconf.h does not set PNG_DLL_EXPORT unless it is required, so: */
 131 #ifndef PNG_DLL_EXPORT
 132 #  define PNG_DLL_EXPORT
 133 #endif
 134
 135 /* This is used for 16 bit gamma tables - only the top level pointers are const,
 136  * this could be changed:
 137  */
 138 typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 139
 140 /* Added at libpng-1.2.9 */
 141 /* Moved to pngpriv.h at libpng-1.5.0 */
 142
 143 /* config.h is created by and PNG_CONFIGURE_LIBPNG is set by the "configure"
 144  * script.  We may need it here to get the correct configuration on things
 145  * like limits.
 146  */
 147 #ifdef PNG_CONFIGURE_LIBPNG
 148 #  ifdef HAVE_CONFIG_H
 149 #    include "config.h"
 150 #  endif
 151 #endif
 152
 153 /* Moved to pngpriv.h at libpng-1.5.0 */
 154 /* NOTE: some of these may have been used in external applications as
 155  * these definitions were exposed in pngconf.h prior to 1.5.
 156  */
 157
 158 /* If you are running on a machine where you cannot allocate more
 159  * than 64K of memory at once, uncomment this.  While libpng will not
 160  * normally need that much memory in a chunk (unless you load up a very
 161  * large file), zlib needs to know how big of a chunk it can use, and
 162  * libpng thus makes sure to check any memory allocation to verify it
 163  * will fit into memory.
 164  *
 165  * zlib provides 'MAXSEG_64K' which, if defined, indicates the
 166  * same limit and pngconf.h (already included) sets the limit
 167  * if certain operating systems are detected.
 168  */
 169 #if defined(MAXSEG_64K) && !defined(PNG_MAX_MALLOC_64K)
 170 #  define PNG_MAX_MALLOC_64K
 171 #endif
 172
 173 #ifndef PNG_UNUSED
 174 /* Unused formal parameter warnings are silenced using the following macro
 175  * which is expected to have no bad effects on performance (optimizing
 176  * compilers will probably remove it entirely).  Note that if you replace
 177  * it with something other than whitespace, you must include the terminating
 178  * semicolon.
 179  */
 180 #  define PNG_UNUSED(param) (void)param;
 181 #endif
 182
 183 /* Just a little check that someone hasn't tried to define something
 184  * contradictory.
 185  */
 186 #if (PNG_ZBUF_SIZE > 65536L) && defined(PNG_MAX_MALLOC_64K)
 187 #  undef PNG_ZBUF_SIZE
 188 #  define PNG_ZBUF_SIZE 65536L
 189 #endif
 190
 191 /* PNG_STATIC is used to mark internal file scope functions if they need to be
 192  * accessed for implementation tests (see the code in tests/?*).
 193  */
 194 #ifndef PNG_STATIC
 195 #   define PNG_STATIC static
 196 #endif
 197
 198 /* If warnings or errors are turned off the code is disabled or redirected here.
 199  * From 1.5.4 functions have been added to allow very limited formatting of
 200  * error and warning messages - this code will also be disabled here.
 201  */
 202 #ifdef PNG_WARNINGS_SUPPORTED
 203 #  define PNG_WARNING_PARAMETERS(p) png_warning_parameters p;
 204 #else
 205 #  define png_warning(s1,s2) ((void)(s1))
 206 #  define png_chunk_warning(s1,s2) ((void)(s1))
 207 #  define png_warning_parameter(p,number,string) ((void)0)
 208 #  define png_warning_parameter_unsigned(p,number,format,value) ((void)0)
 209 #  define png_warning_parameter_signed(p,number,format,value) ((void)0)
 210 #  define png_formatted_warning(pp,p,message) ((void)(pp))
 211 #  define PNG_WARNING_PARAMETERS(p)
 212 #endif
 213 #ifndef PNG_ERROR_TEXT_SUPPORTED
 214 #  define png_error(s1,s2) png_err(s1)
 215 #  define png_chunk_error(s1,s2) png_err(s1)
 216 #  define png_fixed_error(s1,s2) png_err(s1)
 217 #endif
 218
 219 #ifndef PNG_EXTERN
 220 /* The functions exported by PNG_EXTERN are internal functions, which
 221  * aren't usually used outside the library (as far as I know), so it is
 222  * debatable if they should be exported at all.  In the future, when it
 223  * is possible to have run-time registry of chunk-handling functions,
 224  * some of these might be made available again.
 225 #  define PNG_EXTERN extern
 226  */
 227 #  define PNG_EXTERN
 228 #endif
 229
 230 /* Some fixed point APIs are still required even if not exported because
 231  * they get used by the corresponding floating point APIs.  This magic
 232  * deals with this:
 233  */
 234 #ifdef PNG_FIXED_POINT_SUPPORTED
 235 #  define PNGFAPI PNGAPI
 236 #else
 237 #  define PNGFAPI /* PRIVATE */
 238 #endif
 239
 240 /* Other defines specific to compilers can go here.  Try to keep
 241  * them inside an appropriate ifdef/endif pair for portability.
 242  */
 243 #if defined(PNG_FLOATING_POINT_SUPPORTED) ||\
 244     defined(PNG_FLOATING_ARITHMETIC_SUPPORTED)
 245    /* png.c requires the following ANSI-C constants if the conversion of
 246     * floating point to ASCII is implemented therein:
 247     *
 248     *  DBL_DIG  Maximum number of decimal digits (can be set to any constant)
 249     *  DBL_MIN  Smallest normalized fp number (can be set to an arbitrary value)
 250     *  DBL_MAX  Maximum floating point number (can be set to an arbitrary value)
 251     */
 252 #  include <float.h>
 253
 254 #  if ( ( (defined(__MWERKS__) && defined(macintosh)) || defined(applec) || \
 255     defined(THINK_C) || defined(TARGET_OS_MAC) ) && !wxOSX_USE_IPHONE ) || defined(__SC__)
 256      /* We need to check that <math.h> hasn't already been included earlier
 257       * as it seems it doesn't agree with <fp.h>, yet we should really use
 258       * <fp.h> if possible.
 259       */
 260 #    if !defined(__MATH_H__) && !defined(__MATH_H) && !defined(__cmath__)
 261 #      include <fp.h>
 262 #    endif
 263 #  else
 264 #    include <math.h>
 265 #  endif
 266 #  if defined(_AMIGA) && defined(__SASC) && defined(_M68881)
 267      /* Amiga SAS/C: We must include builtin FPU functions when compiling using
 268       * MATH=68881
 269       */
 270 #    include <m68881.h>
 271 #  endif
 272 #endif
 273
 274 /* This provides the non-ANSI (far) memory allocation routines. */
 275 #if defined(__TURBOC__) && defined(__MSDOS__)
 276 #  include <mem.h>
 277 #  include <alloc.h>
 278 #endif
 279
 280 #if defined(WIN32) || defined(_Windows) || defined(_WINDOWS) || \
 281     defined(_WIN32) || defined(__WIN32__)
 282 #  include <windows.h>  /* defines _WINDOWS_ macro */
 283 #endif
 284
 285 /* Moved here around 1.5.0beta36 from pngconf.h */
 286 /* Users may want to use these so they are not private.  Any library
 287  * functions that are passed far data must be model-independent.
 288  */
 289
 290 /* Memory model/platform independent fns */
 291 #ifndef PNG_ABORT
 292 #  ifdef _WINDOWS_
 293 #    define PNG_ABORT() ExitProcess(0)
 294 #  else
 295 #    define PNG_ABORT() abort()
 296 #  endif
 297 #endif
 298
 299 #ifdef USE_FAR_KEYWORD
 300 /* Use this to make far-to-near assignments */
 301 #  define CHECK   1
 302 #  define NOCHECK 0
 303 #  define CVT_PTR(ptr) (png_far_to_near(png_ptr,ptr,CHECK))
 304 #  define CVT_PTR_NOCHECK(ptr) (png_far_to_near(png_ptr,ptr,NOCHECK))
 305 #  define png_strlen  _fstrlen
 306 #  define png_memcmp  _fmemcmp    /* SJT: added */
 307 #  define png_memcpy  _fmemcpy
 308 #  define png_memset  _fmemset
 309 #else
 310 #  ifdef _WINDOWS_  /* Favor Windows over C runtime fns */
 311 #    define CVT_PTR(ptr)         (ptr)
 312 #    define CVT_PTR_NOCHECK(ptr) (ptr)
 313 #    define png_strlen  lstrlenA
 314 #    define png_memcmp  memcmp
 315 #    define png_memcpy  CopyMemory
 316 #    define png_memset  memset
 317 #  else
 318 #    define CVT_PTR(ptr)         (ptr)
 319 #    define CVT_PTR_NOCHECK(ptr) (ptr)
 320 #    define png_strlen  strlen
 321 #    define png_memcmp  memcmp      /* SJT: added */
 322 #    define png_memcpy  memcpy
 323 #    define png_memset  memset
 324 #  endif
 325 #endif
 326
 327 /* These macros may need to be architecture dependent. */
 328 #define PNG_ALIGN_NONE   0 /* do not use data alignment */
 329 #define PNG_ALIGN_ALWAYS 1 /* assume unaligned accesses are OK */
 330 #ifdef offsetof
 331 #  define PNG_ALIGN_OFFSET 2 /* use offsetof to determine alignment */
 332 #else
 333 #  define PNG_ALIGN_OFFSET -1 /* prevent the use of this */
 334 #endif
 335 #define PNG_ALIGN_SIZE   3 /* use sizeof to determine alignment */
 336
 337 #ifndef PNG_ALIGN_TYPE
 338    /* Default to using aligned access optimizations and requiring alignment to a
 339     * multiple of the data type size.  Override in a compiler specific fashion
 340     * if necessary by inserting tests here:
 341     */
 342 #  define PNG_ALIGN_TYPE PNG_ALIGN_SIZE
 343 #endif
 344
 345 #if PNG_ALIGN_TYPE == PNG_ALIGN_SIZE
 346    /* This is used because in some compiler implementations non-aligned
 347     * structure members are supported, so the offsetof approach below fails.
 348     * Set PNG_ALIGN_TO_SIZE=0 for compiler combinations where unaligned access
 349     * is good for performance.  Do not do this unless you have tested the result
 350     * and understand it.
 351     */
 352 #  define png_alignof(type) (sizeof (type))
 353 #else
 354 #  if PNG_ALIGN_TYPE == PNG_ALIGN_OFFSET
 355 #     define png_alignof(type) offsetof(struct{char c; type t;}, t)
 356 #  else
 357 #     if PNG_ALIGN_TYPE == PNG_ALIGN_ALWAYS
 358 #        define png_alignof(type) (1)
 359 #     endif
 360       /* Else leave png_alignof undefined to prevent use thereof */
 361 #  endif
 362 #endif
 363
 364 /* This implicitly assumes alignment is always to a power of 2. */
 365 #ifdef png_alignof
 366 #  define png_isaligned(ptr, type)\
 367    ((((const char*)ptr-(const char*)0) & (png_alignof(type)-1)) == 0)
 368 #else
 369 #  define png_isaligned(ptr, type) 0
 370 #endif
 371
 372 /* End of memory model/platform independent support */
 373 /* End of 1.5.0beta36 move from pngconf.h */
 374
 375 /* CONSTANTS and UTILITY MACROS
 376  * These are used internally by libpng and not exposed in the API
 377  */
 378
 379 /* Various modes of operation.  Note that after an init, mode is set to
 380  * zero automatically when the structure is created.  Three of these
 381  * are defined in png.h because they need to be visible to applications
 382  * that call png_set_unknown_chunk().
 383  */
 384 /* #define PNG_HAVE_IHDR            0x01 (defined in png.h) */
 385 /* #define PNG_HAVE_PLTE            0x02 (defined in png.h) */
 386 #define PNG_HAVE_IDAT               0x04
 387 /* #define PNG_AFTER_IDAT           0x08 (defined in png.h) */
 388 #define PNG_HAVE_IEND               0x10
 389 #define PNG_HAVE_gAMA               0x20
 390 #define PNG_HAVE_cHRM               0x40
 391 #define PNG_HAVE_sRGB               0x80
 392 #define PNG_HAVE_CHUNK_HEADER      0x100
 393 #define PNG_WROTE_tIME             0x200
 394 #define PNG_WROTE_INFO_BEFORE_PLTE 0x400
 395 #define PNG_BACKGROUND_IS_GRAY     0x800
 396 #define PNG_HAVE_PNG_SIGNATURE    0x1000
 397 #define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000 /* Have another chunk after IDAT */
 398
 399 /* Flags for the transformations the PNG library does on the image data */
 400 #define PNG_BGR                 0x0001
 401 #define PNG_INTERLACE           0x0002
 402 #define PNG_PACK                0x0004
 403 #define PNG_SHIFT               0x0008
 404 #define PNG_SWAP_BYTES          0x0010
 405 #define PNG_INVERT_MONO         0x0020
 406 #define PNG_QUANTIZE            0x0040
 407 #define PNG_COMPOSE             0x0080     /* Was PNG_BACKGROUND */
 408 #define PNG_BACKGROUND_EXPAND   0x0100
 409 #define PNG_EXPAND_16           0x0200     /* Added to libpng 1.5.2 */
 410 #define PNG_16_TO_8             0x0400     /* Becomes 'chop' in 1.5.4 */
 411 #define PNG_RGBA                0x0800
 412 #define PNG_EXPAND              0x1000
 413 #define PNG_GAMMA               0x2000
 414 #define PNG_GRAY_TO_RGB         0x4000
 415 #define PNG_FILLER              0x8000
 416 #define PNG_PACKSWAP           0x10000
 417 #define PNG_SWAP_ALPHA         0x20000
 418 #define PNG_STRIP_ALPHA        0x40000
 419 #define PNG_INVERT_ALPHA       0x80000
 420 #define PNG_USER_TRANSFORM    0x100000
 421 #define PNG_RGB_TO_GRAY_ERR   0x200000
 422 #define PNG_RGB_TO_GRAY_WARN  0x400000
 423 #define PNG_RGB_TO_GRAY       0x600000 /* two bits, RGB_TO_GRAY_ERR|WARN */
 424 #define PNG_ENCODE_ALPHA      0x800000 /* Added to libpng-1.5.4 */
 425 #define PNG_ADD_ALPHA         0x1000000 /* Added to libpng-1.2.7 */
 426 #define PNG_EXPAND_tRNS       0x2000000 /* Added to libpng-1.2.9 */
 427 #define PNG_SCALE_16_TO_8     0x4000000 /* Added to libpng-1.5.4 */
 428                        /*   0x8000000 unused */
 429                        /*  0x10000000 unused */
 430                        /*  0x20000000 unused */
 431                        /*  0x40000000 unused */
 432 /* Flags for png_create_struct */
 433 #define PNG_STRUCT_PNG   0x0001
 434 #define PNG_STRUCT_INFO  0x0002
 435
 436 /* Scaling factor for filter heuristic weighting calculations */
 437 #define PNG_WEIGHT_FACTOR (1<<(PNG_WEIGHT_SHIFT))
 438 #define PNG_COST_FACTOR (1<<(PNG_COST_SHIFT))
 439
 440 /* Flags for the png_ptr->flags rather than declaring a byte for each one */
 441 #define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001
 442 #define PNG_FLAG_ZLIB_CUSTOM_LEVEL        0x0002
 443 #define PNG_FLAG_ZLIB_CUSTOM_MEM_LEVEL    0x0004
 444 #define PNG_FLAG_ZLIB_CUSTOM_WINDOW_BITS  0x0008
 445 #define PNG_FLAG_ZLIB_CUSTOM_METHOD       0x0010
 446 #define PNG_FLAG_ZLIB_FINISHED            0x0020
 447 #define PNG_FLAG_ROW_INIT                 0x0040
 448 #define PNG_FLAG_FILLER_AFTER             0x0080
 449 #define PNG_FLAG_CRC_ANCILLARY_USE        0x0100
 450 #define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200
 451 #define PNG_FLAG_CRC_CRITICAL_USE         0x0400
 452 #define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800
 453 #define PNG_FLAG_ASSUME_sRGB              0x1000  /* Added to libpng-1.5.4 */
 454 #define PNG_FLAG_OPTIMIZE_ALPHA           0x2000  /* Added to libpng-1.5.4 */
 455 #define PNG_FLAG_DETECT_UNINITIALIZED     0x4000  /* Added to libpng-1.5.4 */
 456 #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000
 457 #define PNG_FLAG_KEEP_UNSAFE_CHUNKS       0x10000
 458 #define PNG_FLAG_LIBRARY_MISMATCH         0x20000
 459 #define PNG_FLAG_STRIP_ERROR_NUMBERS      0x40000
 460 #define PNG_FLAG_STRIP_ERROR_TEXT         0x80000
 461 #define PNG_FLAG_MALLOC_NULL_MEM_OK       0x100000
 462                                   /*      0x200000  unused */
 463                                   /*      0x400000  unused */
 464 #define PNG_FLAG_BENIGN_ERRORS_WARN       0x800000  /* Added to libpng-1.4.0 */
 465 #define PNG_FLAG_ZTXT_CUSTOM_STRATEGY    0x1000000  /* 5 lines added */
 466 #define PNG_FLAG_ZTXT_CUSTOM_LEVEL       0x2000000  /* to libpng-1.5.4 */
 467 #define PNG_FLAG_ZTXT_CUSTOM_MEM_LEVEL   0x4000000
 468 #define PNG_FLAG_ZTXT_CUSTOM_WINDOW_BITS 0x8000000
 469 #define PNG_FLAG_ZTXT_CUSTOM_METHOD      0x10000000
 470                                   /*     0x20000000  unused */
 471                                   /*     0x40000000  unused */
 472
 473 #define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
 474                                      PNG_FLAG_CRC_ANCILLARY_NOWARN)
 475
 476 #define PNG_FLAG_CRC_CRITICAL_MASK  (PNG_FLAG_CRC_CRITICAL_USE | \
 477                                      PNG_FLAG_CRC_CRITICAL_IGNORE)
 478
 479 #define PNG_FLAG_CRC_MASK           (PNG_FLAG_CRC_ANCILLARY_MASK | \
 480                                      PNG_FLAG_CRC_CRITICAL_MASK)
 481
 482 /* zlib.h declares a magic type 'uInt' that limits the amount of data that zlib
 483  * can handle at once.  This type need be no larger than 16 bits (so maximum of
 484  * 65535), this define allows us to discover how big it is, but limited by the
 485  * maximuum for png_size_t.  The value can be overriden in a library build
 486  * (pngusr.h, or set it in CPPFLAGS) and it works to set it to a considerably
 487  * lower value (e.g. 255 works).  A lower value may help memory usage (slightly)
 488  * and may even improve performance on some systems (and degrade it on others.)
 489  */
 490 #ifndef ZLIB_IO_MAX
 491 #  define ZLIB_IO_MAX ((uInt)-1)
 492 #endif
 493
 494 /* Save typing and make code easier to understand */
 495
 496 #define PNG_COLOR_DIST(c1, c2) (abs((int)((c1).red) - (int)((c2).red)) + \
 497    abs((int)((c1).green) - (int)((c2).green)) + \
 498    abs((int)((c1).blue) - (int)((c2).blue)))
 499
 500 /* Added to libpng-1.2.6 JB */
 501 #define PNG_ROWBYTES(pixel_bits, width) \
 502     ((pixel_bits) >= 8 ? \
 503     ((png_size_t)(width) * (((png_size_t)(pixel_bits)) >> 3)) : \
 504     (( ((png_size_t)(width) * ((png_size_t)(pixel_bits))) + 7) >> 3) )
 505
 506 /* PNG_OUT_OF_RANGE returns true if value is outside the range
 507  * ideal-delta..ideal+delta.  Each argument is evaluated twice.
 508  * "ideal" and "delta" should be constants, normally simple
 509  * integers, "value" a variable. Added to libpng-1.2.6 JB
 510  */
 511 #define PNG_OUT_OF_RANGE(value, ideal, delta) \
 512    ( (value) < (ideal)-(delta) || (value) > (ideal)+(delta) )
 513
 514 /* Conversions between fixed and floating point, only defined if
 515  * required (to make sure the code doesn't accidentally use float
 516  * when it is supposedly disabled.)
 517  */
 518 #ifdef PNG_FLOATING_POINT_SUPPORTED
 519 /* The floating point conversion can't overflow, though it can and
 520  * does lose accuracy relative to the original fixed point value.
 521  * In practice this doesn't matter because png_fixed_point only
 522  * stores numbers with very low precision.  The png_ptr and s
 523  * arguments are unused by default but are there in case error
 524  * checking becomes a requirement.
 525  */
 526 #define png_float(png_ptr, fixed, s) (.00001 * (fixed))
 527
 528 /* The fixed point conversion performs range checking and evaluates
 529  * its argument multiple times, so must be used with care.  The
 530  * range checking uses the PNG specification values for a signed
 531  * 32 bit fixed point value except that the values are deliberately
 532  * rounded-to-zero to an integral value - 21474 (21474.83 is roughly
 533  * (2^31-1) * 100000). 's' is a string that describes the value being
 534  * converted.
 535  *
 536  * NOTE: this macro will raise a png_error if the range check fails,
 537  * therefore it is normally only appropriate to use this on values
 538  * that come from API calls or other sources where an out of range
 539  * error indicates a programming error, not a data error!
 540  *
 541  * NOTE: by default this is off - the macro is not used - because the
 542  * function call saves a lot of code.
 543  */
 544 #ifdef PNG_FIXED_POINT_MACRO_SUPPORTED
 545 #define png_fixed(png_ptr, fp, s) ((fp) <= 21474 && (fp) >= -21474 ?\
 546     ((png_fixed_point)(100000 * (fp))) : (png_fixed_error(png_ptr, s),0))
 547 #else
 548 PNG_EXTERN png_fixed_point png_fixed PNGARG((png_structp png_ptr, double fp,
 549    png_const_charp text));
 550 #endif
 551 #endif
 552
 553 /* Constants for known chunk types.  If you need to add a chunk, define the name
 554  * here.  For historical reasons these constants have the form png_<name>; i.e.
 555  * the prefix is lower case.  Please use decimal values as the parameters to
 556  * match the ISO PNG specification and to avoid relying on the C locale
 557  * interpretation of character values.
 558  *
 559  * Prior to 1.5.6 these constants were strings, as of 1.5.6 png_uint_32 values
 560  * are computed and a new macro (PNG_STRING_FROM_CHUNK) added to allow a string
 561  * to be generated if required.
 562  *
 563  * PNG_32b correctly produces a value shifted by up to 24 bits, even on
 564  * architectures where (int) is only 16 bits.
 565  */
 566 #define PNG_32b(b,s) ((png_uint_32)(b) << (s))
 567 #define PNG_CHUNK(b1,b2,b3,b4) \
 568    (PNG_32b(b1,24) | PNG_32b(b2,16) | PNG_32b(b3,8) | PNG_32b(b4,0))
 569
 570 #define png_IHDR PNG_CHUNK( 73,  72,  68,  82)
 571 #define png_IDAT PNG_CHUNK( 73,  68,  65,  84)
 572 #define png_IEND PNG_CHUNK( 73,  69,  78,  68)
 573 #define png_PLTE PNG_CHUNK( 80,  76,  84,  69)
 574 #define png_bKGD PNG_CHUNK( 98,  75,  71,  68)
 575 #define png_cHRM PNG_CHUNK( 99,  72,  82,  77)
 576 #define png_gAMA PNG_CHUNK(103,  65,  77,  65)
 577 #define png_hIST PNG_CHUNK(104,  73,  83,  84)
 578 #define png_iCCP PNG_CHUNK(105,  67,  67,  80)
 579 #define png_iTXt PNG_CHUNK(105,  84,  88, 116)
 580 #define png_oFFs PNG_CHUNK(111,  70,  70, 115)
 581 #define png_pCAL PNG_CHUNK(112,  67,  65,  76)
 582 #define png_sCAL PNG_CHUNK(115,  67,  65,  76)
 583 #define png_pHYs PNG_CHUNK(112,  72,  89, 115)
 584 #define png_sBIT PNG_CHUNK(115,  66,  73,  84)
 585 #define png_sPLT PNG_CHUNK(115,  80,  76,  84)
 586 #define png_sRGB PNG_CHUNK(115,  82,  71,  66)
 587 #define png_sTER PNG_CHUNK(115,  84,  69,  82)
 588 #define png_tEXt PNG_CHUNK(116,  69,  88, 116)
 589 #define png_tIME PNG_CHUNK(116,  73,  77,  69)
 590 #define png_tRNS PNG_CHUNK(116,  82,  78,  83)
 591 #define png_zTXt PNG_CHUNK(122,  84,  88, 116)
 592
 593 /* The following will work on (signed char*) strings, whereas the get_uint_32
 594  * macro will fail on top-bit-set values because of the sign extension.
 595  */
 596 #define PNG_CHUNK_FROM_STRING(s)\
 597    PNG_CHUNK(0xff&(s)[0], 0xff&(s)[1], 0xff&(s)[2], 0xff&(s)[3])
 598
 599 /* This uses (char), not (png_byte) to avoid warnings on systems where (char) is
 600  * signed and the argument is a (char[])  This macro will fail miserably on
 601  * systems where (char) is more than 8 bits.
 602  */
 603 #define PNG_STRING_FROM_CHUNK(s,c)\
 604    (void)(((char*)(s))[0]=(char)((c)>>24), ((char*)(s))[1]=(char)((c)>>16),\
 605    ((char*)(s))[2]=(char)((c)>>8), ((char*)(s))[3]=(char)((c)))
 606
 607 /* Do the same but terminate with a null character. */
 608 #define PNG_CSTRING_FROM_CHUNK(s,c)\
 609    (void)(PNG_STRING_FROM_CHUNK(s,c), ((char*)(s))[4] = 0)
 610
 611 /* Test on flag values as defined in the spec (section 5.4): */
 612 #define PNG_CHUNK_ANCILLIARY(c)   (1 & ((c) >> 29))
 613 #define PNG_CHUNK_CRITICAL(c)     (!PNG_CHUNK_ANCILLIARY(c))
 614 #define PNG_CHUNK_PRIVATE(c)      (1 & ((c) >> 21))
 615 #define PNG_CHUNK_RESERVED(c)     (1 & ((c) >> 13))
 616 #define PNG_CHUNK_SAFE_TO_COPY(c) (1 & ((c) >>  5))
 617
 618 /* Gamma values (new at libpng-1.5.4): */
 619 #define PNG_GAMMA_MAC_OLD 151724  /* Assume '1.8' is really 2.2/1.45! */
 620 #define PNG_GAMMA_MAC_INVERSE 65909
 621 #define PNG_GAMMA_sRGB_INVERSE 45455
 622
 623
 624 /* Inhibit C++ name-mangling for libpng functions but not for system calls. */
 625 #ifdef __cplusplus
 626 extern "C" {
 627 #endif /* __cplusplus */
 628
 629 /* These functions are used internally in the code.  They generally
 630  * shouldn't be used unless you are writing code to add or replace some
 631  * functionality in libpng.  More information about most functions can
 632  * be found in the files where the functions are located.
 633  */
 634
 635 /* Check the user version string for compatibility, returns false if the version
 636  * numbers aren't compatible.
 637  */
 638 PNG_EXTERN int png_user_version_check(png_structp png_ptr,
 639    png_const_charp user_png_ver);
 640
 641 /* Allocate memory for an internal libpng struct */
 642 PNG_EXTERN PNG_FUNCTION(png_voidp,png_create_struct,PNGARG((int type)),
 643    PNG_ALLOCATED);
 644
 645 /* Free memory from internal libpng struct */
 646 PNG_EXTERN void png_destroy_struct PNGARG((png_voidp struct_ptr));
 647
 648 PNG_EXTERN PNG_FUNCTION(png_voidp,png_create_struct_2,
 649    PNGARG((int type, png_malloc_ptr malloc_fn, png_voidp mem_ptr)),
 650    PNG_ALLOCATED);
 651 PNG_EXTERN void png_destroy_struct_2 PNGARG((png_voidp struct_ptr,
 652     png_free_ptr free_fn, png_voidp mem_ptr));
 653
 654 /* Free any memory that info_ptr points to and reset struct. */
 655 PNG_EXTERN void png_info_destroy PNGARG((png_structp png_ptr,
 656     png_infop info_ptr));
 657
 658 /* Function to allocate memory for zlib.  PNGAPI is disallowed. */
 659 PNG_EXTERN PNG_FUNCTION(voidpf,png_zalloc,PNGARG((voidpf png_ptr, uInt items,
 660    uInt size)),PNG_ALLOCATED);
 661
 662 /* Function to free memory for zlib.  PNGAPI is disallowed. */
 663 PNG_EXTERN void png_zfree PNGARG((voidpf png_ptr, voidpf ptr));
 664
 665 /* Next four functions are used internally as callbacks.  PNGCBAPI is required
 666  * but not PNG_EXPORT.  PNGAPI added at libpng version 1.2.3, changed to
 667  * PNGCBAPI at 1.5.0
 668  */
 669
 670 PNG_EXTERN void PNGCBAPI png_default_read_data PNGARG((png_structp png_ptr,
 671     png_bytep data, png_size_t length));
 672
 673 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
 674 PNG_EXTERN void PNGCBAPI png_push_fill_buffer PNGARG((png_structp png_ptr,
 675     png_bytep buffer, png_size_t length));
 676 #endif
 677
 678 PNG_EXTERN void PNGCBAPI png_default_write_data PNGARG((png_structp png_ptr,
 679     png_bytep data, png_size_t length));
 680
 681 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 682 #  ifdef PNG_STDIO_SUPPORTED
 683 PNG_EXTERN void PNGCBAPI png_default_flush PNGARG((png_structp png_ptr));
 684 #  endif
 685 #endif
 686
 687 /* Reset the CRC variable */
 688 PNG_EXTERN void png_reset_crc PNGARG((png_structp png_ptr));
 689
 690 /* Write the "data" buffer to whatever output you are using */
 691 PNG_EXTERN void png_write_data PNGARG((png_structp png_ptr,
 692     png_const_bytep data, png_size_t length));
 693
 694 /* Read and check the PNG file signature */
 695 PNG_EXTERN void png_read_sig PNGARG((png_structp png_ptr, png_infop info_ptr));
 696
 697 /* Read the chunk header (length + type name) */
 698 PNG_EXTERN png_uint_32 png_read_chunk_header PNGARG((png_structp png_ptr));
 699
 700 /* Read data from whatever input you are using into the "data" buffer */
 701 PNG_EXTERN void png_read_data PNGARG((png_structp png_ptr, png_bytep data,
 702     png_size_t length));
 703
 704 /* Read bytes into buf, and update png_ptr->crc */
 705 PNG_EXTERN void png_crc_read PNGARG((png_structp png_ptr, png_bytep buf,
 706     png_size_t length));
 707
 708 /* Decompress data in a chunk that uses compression */
 709 #if defined(PNG_READ_COMPRESSED_TEXT_SUPPORTED)
 710 PNG_EXTERN void png_decompress_chunk PNGARG((png_structp png_ptr,
 711     int comp_type, png_size_t chunklength, png_size_t prefix_length,
 712     png_size_t *data_length));
 713 #endif
 714
 715 /* Read "skip" bytes, read the file crc, and (optionally) verify png_ptr->crc */
 716 PNG_EXTERN int png_crc_finish PNGARG((png_structp png_ptr, png_uint_32 skip));
 717
 718 /* Read the CRC from the file and compare it to the libpng calculated CRC */
 719 PNG_EXTERN int png_crc_error PNGARG((png_structp png_ptr));
 720
 721 /* Calculate the CRC over a section of data.  Note that we are only
 722  * passing a maximum of 64K on systems that have this as a memory limit,
 723  * since this is the maximum buffer size we can specify.
 724  */
 725 PNG_EXTERN void png_calculate_crc PNGARG((png_structp png_ptr,
 726     png_const_bytep ptr, png_size_t length));
 727
 728 #ifdef PNG_WRITE_FLUSH_SUPPORTED
 729 PNG_EXTERN void png_flush PNGARG((png_structp png_ptr));
 730 #endif
 731
 732 /* Write various chunks */
 733
 734 /* Write the IHDR chunk, and update the png_struct with the necessary
 735  * information.
 736  */
 737 PNG_EXTERN void png_write_IHDR PNGARG((png_structp png_ptr, png_uint_32 width,
 738     png_uint_32 height,
 739     int bit_depth, int color_type, int compression_method, int filter_method,
 740     int interlace_method));
 741
 742 PNG_EXTERN void png_write_PLTE PNGARG((png_structp png_ptr,
 743     png_const_colorp palette, png_uint_32 num_pal));
 744
 745 PNG_EXTERN void png_write_IDAT PNGARG((png_structp png_ptr, png_bytep data,
 746     png_size_t length));
 747
 748 PNG_EXTERN void png_write_IEND PNGARG((png_structp png_ptr));
 749
 750 #ifdef PNG_WRITE_gAMA_SUPPORTED
 751 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 752 PNG_EXTERN void png_write_gAMA PNGARG((png_structp png_ptr, double file_gamma));
 753 #  endif
 754 #  ifdef PNG_FIXED_POINT_SUPPORTED
 755 PNG_EXTERN void png_write_gAMA_fixed PNGARG((png_structp png_ptr,
 756     png_fixed_point file_gamma));
 757 #  endif
 758 #endif
 759
 760 #ifdef PNG_WRITE_sBIT_SUPPORTED
 761 PNG_EXTERN void png_write_sBIT PNGARG((png_structp png_ptr,
 762     png_const_color_8p sbit, int color_type));
 763 #endif
 764
 765 #ifdef PNG_WRITE_cHRM_SUPPORTED
 766 #  ifdef PNG_FLOATING_POINT_SUPPORTED
 767 PNG_EXTERN void png_write_cHRM PNGARG((png_structp png_ptr,
 768     double white_x, double white_y,
 769     double red_x, double red_y, double green_x, double green_y,
 770     double blue_x, double blue_y));
 771 #  endif
 772 PNG_EXTERN void png_write_cHRM_fixed PNGARG((png_structp png_ptr,
 773     png_fixed_point int_white_x, png_fixed_point int_white_y,
 774     png_fixed_point int_red_x, png_fixed_point int_red_y, png_fixed_point
 775     int_green_x, png_fixed_point int_green_y, png_fixed_point int_blue_x,
 776     png_fixed_point int_blue_y));
 777 #endif
 778
 779 #ifdef PNG_WRITE_sRGB_SUPPORTED
 780 PNG_EXTERN void png_write_sRGB PNGARG((png_structp png_ptr,
 781     int intent));
 782 #endif
 783
 784 #ifdef PNG_WRITE_iCCP_SUPPORTED
 785 PNG_EXTERN void png_write_iCCP PNGARG((png_structp png_ptr,
 786     png_const_charp name, int compression_type,
 787     png_const_charp profile, int proflen));
 788    /* Note to maintainer: profile should be png_bytep */
 789 #endif
 790
 791 #ifdef PNG_WRITE_sPLT_SUPPORTED
 792 PNG_EXTERN void png_write_sPLT PNGARG((png_structp png_ptr,
 793     png_const_sPLT_tp palette));
 794 #endif
 795
 796 #ifdef PNG_WRITE_tRNS_SUPPORTED
 797 PNG_EXTERN void png_write_tRNS PNGARG((png_structp png_ptr,
 798     png_const_bytep trans, png_const_color_16p values, int number,
 799     int color_type));
 800 #endif
 801
 802 #ifdef PNG_WRITE_bKGD_SUPPORTED
 803 PNG_EXTERN void png_write_bKGD PNGARG((png_structp png_ptr,
 804     png_const_color_16p values, int color_type));
 805 #endif
 806
 807 #ifdef PNG_WRITE_hIST_SUPPORTED
 808 PNG_EXTERN void png_write_hIST PNGARG((png_structp png_ptr,
 809     png_const_uint_16p hist, int num_hist));
 810 #endif
 811
 812 /* Chunks that have keywords */
 813 #if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_pCAL_SUPPORTED) || \
 814     defined(PNG_WRITE_iCCP_SUPPORTED) || defined(PNG_WRITE_sPLT_SUPPORTED)
 815 PNG_EXTERN png_size_t png_check_keyword PNGARG((png_structp png_ptr,
 816     png_const_charp key, png_charpp new_key));
 817 #endif
 818
 819 #ifdef PNG_WRITE_tEXt_SUPPORTED
 820 PNG_EXTERN void png_write_tEXt PNGARG((png_structp png_ptr, png_const_charp key,
 821     png_const_charp text, png_size_t text_len));
 822 #endif
 823
 824 #ifdef PNG_WRITE_zTXt_SUPPORTED
 825 PNG_EXTERN void png_write_zTXt PNGARG((png_structp png_ptr, png_const_charp key,
 826     png_const_charp text, png_size_t text_len, int compression));
 827 #endif
 828
 829 #ifdef PNG_WRITE_iTXt_SUPPORTED
 830 PNG_EXTERN void png_write_iTXt PNGARG((png_structp png_ptr,
 831     int compression, png_const_charp key, png_const_charp lang,
 832     png_const_charp lang_key, png_const_charp text));
 833 #endif
 834
 835 #ifdef PNG_TEXT_SUPPORTED  /* Added at version 1.0.14 and 1.2.4 */
 836 PNG_EXTERN int png_set_text_2 PNGARG((png_structp png_ptr,
 837     png_infop info_ptr, png_const_textp text_ptr, int num_text));
 838 #endif
 839
 840 #ifdef PNG_WRITE_oFFs_SUPPORTED
 841 PNG_EXTERN void png_write_oFFs PNGARG((png_structp png_ptr,
 842     png_int_32 x_offset, png_int_32 y_offset, int unit_type));
 843 #endif
 844
 845 #ifdef PNG_WRITE_pCAL_SUPPORTED
 846 PNG_EXTERN void png_write_pCAL PNGARG((png_structp png_ptr, png_charp purpose,
 847     png_int_32 X0, png_int_32 X1, int type, int nparams,
 848     png_const_charp units, png_charpp params));
 849 #endif
 850
 851 #ifdef PNG_WRITE_pHYs_SUPPORTED
 852 PNG_EXTERN void png_write_pHYs PNGARG((png_structp png_ptr,
 853     png_uint_32 x_pixels_per_unit, png_uint_32 y_pixels_per_unit,
 854     int unit_type));
 855 #endif
 856
 857 #ifdef PNG_WRITE_tIME_SUPPORTED
 858 PNG_EXTERN void png_write_tIME PNGARG((png_structp png_ptr,
 859     png_const_timep mod_time));
 860 #endif
 861
 862 #ifdef PNG_WRITE_sCAL_SUPPORTED
 863 PNG_EXTERN void png_write_sCAL_s PNGARG((png_structp png_ptr,
 864     int unit, png_const_charp width, png_const_charp height));
 865 #endif
 866
 867 /* Called when finished processing a row of data */
 868 PNG_EXTERN void png_write_finish_row PNGARG((png_structp png_ptr));
 869
 870 /* Internal use only.   Called before first row of data */
 871 PNG_EXTERN void png_write_start_row PNGARG((png_structp png_ptr));
 872
 873 /* Combine a row of data, dealing with alpha, etc. if requested.  'row' is an
 874  * array of png_ptr->width pixels.  If the image is not interlaced or this
 875  * is the final pass this just does a png_memcpy, otherwise the "display" flag
 876  * is used to determine whether to copy pixels that are not in the current pass.
 877  *
 878  * Because 'png_do_read_interlace' (below) replicates pixels this allows this
 879  * function to achieve the documented 'blocky' appearance during interlaced read
 880  * if display is 1 and the 'sparkle' appearance, where existing pixels in 'row'
 881  * are not changed if they are not in the current pass, when display is 0.
 882  *
 883  * 'display' must be 0 or 1, otherwise the memcpy will be done regardless.
 884  *
 885  * The API always reads from the png_struct row buffer and always assumes that
 886  * it is full width (png_do_read_interlace has already been called.)
 887  *
 888  * This function is only ever used to write to row buffers provided by the
 889  * caller of the relevant libpng API and the row must have already been
 890  * transformed by the read transformations.
 891  *
 892  * The PNG_USE_COMPILE_TIME_MASKS option causes generation of pre-computed
 893  * bitmasks for use within the code, otherwise runtime generated masks are used.
 894  * The default is compile time masks.
 895  */
 896 #ifndef PNG_USE_COMPILE_TIME_MASKS
 897 #  define PNG_USE_COMPILE_TIME_MASKS 1
 898 #endif
 899 PNG_EXTERN void png_combine_row PNGARG((png_structp png_ptr, png_bytep row,
 900     int display));
 901
 902 #ifdef PNG_READ_INTERLACING_SUPPORTED
 903 /* Expand an interlaced row: the 'row_info' describes the pass data that has
 904  * been read in and must correspond to the pixels in 'row', the pixels are
 905  * expanded (moved apart) in 'row' to match the final layout, when doing this
 906  * the pixels are *replicated* to the intervening space.  This is essential for
 907  * the correct operation of png_combine_row, above.
 908  */
 909 PNG_EXTERN void png_do_read_interlace PNGARG((png_row_infop row_info,
 910     png_bytep row, int pass, png_uint_32 transformations));
 911 #endif
 912
 913 /* GRR TO DO (2.0 or whenever):  simplify other internal calling interfaces */
 914
 915 #ifdef PNG_WRITE_INTERLACING_SUPPORTED
 916 /* Grab pixels out of a row for an interlaced pass */
 917 PNG_EXTERN void png_do_write_interlace PNGARG((png_row_infop row_info,
 918     png_bytep row, int pass));
 919 #endif
 920
 921 /* Unfilter a row: check the filter value before calling this, there is no point
 922  * calling it for PNG_FILTER_VALUE_NONE.
 923  */
 924 PNG_EXTERN void png_read_filter_row PNGARG((png_row_infop row_info,
 925     png_bytep row, png_const_bytep prev_row, int filter));
 926
 927 /* Choose the best filter to use and filter the row data */
 928 PNG_EXTERN void png_write_find_filter PNGARG((png_structp png_ptr,
 929     png_row_infop row_info));
 930
 931 /* Finish a row while reading, dealing with interlacing passes, etc. */
 932 PNG_EXTERN void png_read_finish_row PNGARG((png_structp png_ptr));
 933
 934 /* Initialize the row buffers, etc. */
 935 PNG_EXTERN void png_read_start_row PNGARG((png_structp png_ptr));
 936
 937 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
 938 /* Optional call to update the users info structure */
 939 PNG_EXTERN void png_read_transform_info PNGARG((png_structp png_ptr,
 940     png_infop info_ptr));
 941 #endif
 942
 943 /* These are the functions that do the transformations */
 944 #ifdef PNG_READ_FILLER_SUPPORTED
 945 PNG_EXTERN void png_do_read_filler PNGARG((png_row_infop row_info,
 946     png_bytep row, png_uint_32 filler, png_uint_32 flags));
 947 #endif
 948
 949 #ifdef PNG_READ_SWAP_ALPHA_SUPPORTED
 950 PNG_EXTERN void png_do_read_swap_alpha PNGARG((png_row_infop row_info,
 951     png_bytep row));
 952 #endif
 953
 954 #ifdef PNG_WRITE_SWAP_ALPHA_SUPPORTED
 955 PNG_EXTERN void png_do_write_swap_alpha PNGARG((png_row_infop row_info,
 956     png_bytep row));
 957 #endif
 958
 959 #ifdef PNG_READ_INVERT_ALPHA_SUPPORTED
 960 PNG_EXTERN void png_do_read_invert_alpha PNGARG((png_row_infop row_info,
 961     png_bytep row));
 962 #endif
 963
 964 #ifdef PNG_WRITE_INVERT_ALPHA_SUPPORTED
 965 PNG_EXTERN void png_do_write_invert_alpha PNGARG((png_row_infop row_info,
 966     png_bytep row));
 967 #endif
 968
 969 #if defined(PNG_WRITE_FILLER_SUPPORTED) || \
 970     defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
 971 PNG_EXTERN void png_do_strip_channel PNGARG((png_row_infop row_info,
 972     png_bytep row, int at_start));
 973 #endif
 974
 975 #ifdef PNG_16BIT_SUPPORTED
 976 #if defined(PNG_READ_SWAP_SUPPORTED) || defined(PNG_WRITE_SWAP_SUPPORTED)
 977 PNG_EXTERN void png_do_swap PNGARG((png_row_infop row_info,
 978     png_bytep row));
 979 #endif
 980 #endif
 981
 982 #if defined(PNG_READ_PACKSWAP_SUPPORTED) || \
 983     defined(PNG_WRITE_PACKSWAP_SUPPORTED)
 984 PNG_EXTERN void png_do_packswap PNGARG((png_row_infop row_info,
 985     png_bytep row));
 986 #endif
 987
 988 #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
 989 PNG_EXTERN int png_do_rgb_to_gray PNGARG((png_structp png_ptr,
 990     png_row_infop row_info, png_bytep row));
 991 #endif
 992
 993 #ifdef PNG_READ_GRAY_TO_RGB_SUPPORTED
 994 PNG_EXTERN void png_do_gray_to_rgb PNGARG((png_row_infop row_info,
 995     png_bytep row));
 996 #endif
 997
 998 #ifdef PNG_READ_PACK_SUPPORTED
 999 PNG_EXTERN void png_do_unpack PNGARG((png_row_infop row_info,
1000     png_bytep row));
1001 #endif
1002
1003 #ifdef PNG_READ_SHIFT_SUPPORTED
1004 PNG_EXTERN void png_do_unshift PNGARG((png_row_infop row_info,
1005     png_bytep row, png_const_color_8p sig_bits));
1006 #endif
1007
1008 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
1009 PNG_EXTERN void png_do_invert PNGARG((png_row_infop row_info,
1010     png_bytep row));
1011 #endif
1012
1013 #ifdef PNG_READ_SCALE_16_TO_8_SUPPORTED
1014 PNG_EXTERN void png_do_scale_16_to_8 PNGARG((png_row_infop row_info,
1015     png_bytep row));
1016 #endif
1017
1018 #ifdef PNG_READ_STRIP_16_TO_8_SUPPORTED
1019 PNG_EXTERN void png_do_chop PNGARG((png_row_infop row_info,
1020     png_bytep row));
1021 #endif
1022
1023 #ifdef PNG_READ_QUANTIZE_SUPPORTED
1024 PNG_EXTERN void png_do_quantize PNGARG((png_row_infop row_info,
1025     png_bytep row, png_const_bytep palette_lookup,
1026     png_const_bytep quantize_lookup));
1027
1028 #  ifdef PNG_CORRECT_PALETTE_SUPPORTED
1029 PNG_EXTERN void png_correct_palette PNGARG((png_structp png_ptr,
1030     png_colorp palette, int num_palette));
1031 #  endif
1032 #endif
1033
1034 #if defined(PNG_READ_BGR_SUPPORTED) || defined(PNG_WRITE_BGR_SUPPORTED)
1035 PNG_EXTERN void png_do_bgr PNGARG((png_row_infop row_info,
1036     png_bytep row));
1037 #endif
1038
1039 #ifdef PNG_WRITE_PACK_SUPPORTED
1040 PNG_EXTERN void png_do_pack PNGARG((png_row_infop row_info,
1041    png_bytep row, png_uint_32 bit_depth));
1042 #endif
1043
1044 #ifdef PNG_WRITE_SHIFT_SUPPORTED
1045 PNG_EXTERN void png_do_shift PNGARG((png_row_infop row_info,
1046     png_bytep row, png_const_color_8p bit_depth));
1047 #endif
1048
1049 #if defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
1050     defined(PNG_READ_ALPHA_MODE_SUPPORTED)
1051 PNG_EXTERN void png_do_compose PNGARG((png_row_infop row_info,
1052     png_bytep row, png_structp png_ptr));
1053 #endif
1054
1055 #ifdef PNG_READ_GAMMA_SUPPORTED
1056 PNG_EXTERN void png_do_gamma PNGARG((png_row_infop row_info,
1057     png_bytep row, png_structp png_ptr));
1058 #endif
1059
1060 #ifdef PNG_READ_ALPHA_MODE_SUPPORTED
1061 PNG_EXTERN void png_do_encode_alpha PNGARG((png_row_infop row_info,
1062    png_bytep row, png_structp png_ptr));
1063 #endif
1064
1065 #ifdef PNG_READ_EXPAND_SUPPORTED
1066 PNG_EXTERN void png_do_expand_palette PNGARG((png_row_infop row_info,
1067     png_bytep row, png_const_colorp palette, png_const_bytep trans,
1068     int num_trans));
1069 PNG_EXTERN void png_do_expand PNGARG((png_row_infop row_info,
1070     png_bytep row, png_const_color_16p trans_color));
1071 #endif
1072
1073 #ifdef PNG_READ_EXPAND_16_SUPPORTED
1074 PNG_EXTERN void png_do_expand_16 PNGARG((png_row_infop row_info,
1075     png_bytep row));
1076 #endif
1077
1078 /* The following decodes the appropriate chunks, and does error correction,
1079  * then calls the appropriate callback for the chunk if it is valid.
1080  */
1081
1082 /* Decode the IHDR chunk */
1083 PNG_EXTERN void png_handle_IHDR PNGARG((png_structp png_ptr, png_infop info_ptr,
1084     png_uint_32 length));
1085 PNG_EXTERN void png_handle_PLTE PNGARG((png_structp png_ptr, png_infop info_ptr,
1086     png_uint_32 length));
1087 PNG_EXTERN void png_handle_IEND PNGARG((png_structp png_ptr, png_infop info_ptr,
1088     png_uint_32 length));
1089
1090 #ifdef PNG_READ_bKGD_SUPPORTED
1091 PNG_EXTERN void png_handle_bKGD PNGARG((png_structp png_ptr, png_infop info_ptr,
1092     png_uint_32 length));
1093 #endif
1094
1095 #ifdef PNG_READ_cHRM_SUPPORTED
1096 PNG_EXTERN void png_handle_cHRM PNGARG((png_structp png_ptr, png_infop info_ptr,
1097     png_uint_32 length));
1098 #endif
1099
1100 #ifdef PNG_READ_gAMA_SUPPORTED
1101 PNG_EXTERN void png_handle_gAMA PNGARG((png_structp png_ptr, png_infop info_ptr,
1102     png_uint_32 length));
1103 #endif
1104
1105 #ifdef PNG_READ_hIST_SUPPORTED
1106 PNG_EXTERN void png_handle_hIST PNGARG((png_structp png_ptr, png_infop info_ptr,
1107     png_uint_32 length));
1108 #endif
1109
1110 #ifdef PNG_READ_iCCP_SUPPORTED
1111 PNG_EXTERN void png_handle_iCCP PNGARG((png_structp png_ptr, png_infop info_ptr,
1112     png_uint_32 length));
1113 #endif /* PNG_READ_iCCP_SUPPORTED */
1114
1115 #ifdef PNG_READ_iTXt_SUPPORTED
1116 PNG_EXTERN void png_handle_iTXt PNGARG((png_structp png_ptr, png_infop info_ptr,
1117     png_uint_32 length));
1118 #endif
1119
1120 #ifdef PNG_READ_oFFs_SUPPORTED
1121 PNG_EXTERN void png_handle_oFFs PNGARG((png_structp png_ptr, png_infop info_ptr,
1122     png_uint_32 length));
1123 #endif
1124
1125 #ifdef PNG_READ_pCAL_SUPPORTED
1126 PNG_EXTERN void png_handle_pCAL PNGARG((png_structp png_ptr, png_infop info_ptr,
1127     png_uint_32 length));
1128 #endif
1129
1130 #ifdef PNG_READ_pHYs_SUPPORTED
1131 PNG_EXTERN void png_handle_pHYs PNGARG((png_structp png_ptr, png_infop info_ptr,
1132     png_uint_32 length));
1133 #endif
1134
1135 #ifdef PNG_READ_sBIT_SUPPORTED
1136 PNG_EXTERN void png_handle_sBIT PNGARG((png_structp png_ptr, png_infop info_ptr,
1137     png_uint_32 length));
1138 #endif
1139
1140 #ifdef PNG_READ_sCAL_SUPPORTED
1141 PNG_EXTERN void png_handle_sCAL PNGARG((png_structp png_ptr, png_infop info_ptr,
1142     png_uint_32 length));
1143 #endif
1144
1145 #ifdef PNG_READ_sPLT_SUPPORTED
1146 PNG_EXTERN void png_handle_sPLT PNGARG((png_structp png_ptr, png_infop info_ptr,
1147     png_uint_32 length));
1148 #endif /* PNG_READ_sPLT_SUPPORTED */
1149
1150 #ifdef PNG_READ_sRGB_SUPPORTED
1151 PNG_EXTERN void png_handle_sRGB PNGARG((png_structp png_ptr, png_infop info_ptr,
1152     png_uint_32 length));
1153 #endif
1154
1155 #ifdef PNG_READ_tEXt_SUPPORTED
1156 PNG_EXTERN void png_handle_tEXt PNGARG((png_structp png_ptr, png_infop info_ptr,
1157     png_uint_32 length));
1158 #endif
1159
1160 #ifdef PNG_READ_tIME_SUPPORTED
1161 PNG_EXTERN void png_handle_tIME PNGARG((png_structp png_ptr, png_infop info_ptr,
1162     png_uint_32 length));
1163 #endif
1164
1165 #ifdef PNG_READ_tRNS_SUPPORTED
1166 PNG_EXTERN void png_handle_tRNS PNGARG((png_structp png_ptr, png_infop info_ptr,
1167     png_uint_32 length));
1168 #endif
1169
1170 #ifdef PNG_READ_zTXt_SUPPORTED
1171 PNG_EXTERN void png_handle_zTXt PNGARG((png_structp png_ptr, png_infop info_ptr,
1172     png_uint_32 length));
1173 #endif
1174
1175 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1176 PNG_EXTERN void png_handle_unknown PNGARG((png_structp png_ptr,
1177     png_infop info_ptr, png_uint_32 length));
1178 #endif
1179
1180 PNG_EXTERN void png_check_chunk_name PNGARG((png_structp png_ptr,
1181     png_uint_32 chunk_name));
1182
1183 #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
1184 /* Exactly as png_handle_as_unknown() except that the argument is a 32-bit chunk
1185  * name, not a string.
1186  */
1187 PNG_EXTERN int png_chunk_unknown_handling PNGARG((png_structp png_ptr,
1188     png_uint_32 chunk_name));
1189 #endif
1190
1191 /* Handle the transformations for reading and writing */
1192 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1193 PNG_EXTERN void png_do_read_transformations PNGARG((png_structp png_ptr,
1194    png_row_infop row_info));
1195 #endif
1196 #ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
1197 PNG_EXTERN void png_do_write_transformations PNGARG((png_structp png_ptr,
1198    png_row_infop row_info));
1199 #endif
1200
1201 #ifdef PNG_READ_TRANSFORMS_SUPPORTED
1202 PNG_EXTERN void png_init_read_transformations PNGARG((png_structp png_ptr));
1203 #endif
1204
1205 #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
1206 PNG_EXTERN void png_push_read_chunk PNGARG((png_structp png_ptr,
1207     png_infop info_ptr));
1208 PNG_EXTERN void png_push_read_sig PNGARG((png_structp png_ptr,
1209     png_infop info_ptr));
1210 PNG_EXTERN void png_push_check_crc PNGARG((png_structp png_ptr));
1211 PNG_EXTERN void png_push_crc_skip PNGARG((png_structp png_ptr,
1212     png_uint_32 length));
1213 PNG_EXTERN void png_push_crc_finish PNGARG((png_structp png_ptr));
1214 PNG_EXTERN void png_push_save_buffer PNGARG((png_structp png_ptr));
1215 PNG_EXTERN void png_push_restore_buffer PNGARG((png_structp png_ptr,
1216     png_bytep buffer, png_size_t buffer_length));
1217 PNG_EXTERN void png_push_read_IDAT PNGARG((png_structp png_ptr));
1218 PNG_EXTERN void png_process_IDAT_data PNGARG((png_structp png_ptr,
1219     png_bytep buffer, png_size_t buffer_length));
1220 PNG_EXTERN void png_push_process_row PNGARG((png_structp png_ptr));
1221 PNG_EXTERN void png_push_handle_unknown PNGARG((png_structp png_ptr,
1222    png_infop info_ptr, png_uint_32 length));
1223 PNG_EXTERN void png_push_have_info PNGARG((png_structp png_ptr,
1224    png_infop info_ptr));
1225 PNG_EXTERN void png_push_have_end PNGARG((png_structp png_ptr,
1226    png_infop info_ptr));
1227 PNG_EXTERN void png_push_have_row PNGARG((png_structp png_ptr, png_bytep row));
1228 PNG_EXTERN void png_push_read_end PNGARG((png_structp png_ptr,
1229     png_infop info_ptr));
1230 PNG_EXTERN void png_process_some_data PNGARG((png_structp png_ptr,
1231     png_infop info_ptr));
1232 PNG_EXTERN void png_read_push_finish_row PNGARG((png_structp png_ptr));
1233 #  ifdef PNG_READ_tEXt_SUPPORTED
1234 PNG_EXTERN void png_push_handle_tEXt PNGARG((png_structp png_ptr,
1235     png_infop info_ptr, png_uint_32 length));
1236 PNG_EXTERN void png_push_read_tEXt PNGARG((png_structp png_ptr,
1237     png_infop info_ptr));
1238 #  endif
1239 #  ifdef PNG_READ_zTXt_SUPPORTED
1240 PNG_EXTERN void png_push_handle_zTXt PNGARG((png_structp png_ptr,
1241     png_infop info_ptr, png_uint_32 length));
1242 PNG_EXTERN void png_push_read_zTXt PNGARG((png_structp png_ptr,
1243     png_infop info_ptr));
1244 #  endif
1245 #  ifdef PNG_READ_iTXt_SUPPORTED
1246 PNG_EXTERN void png_push_handle_iTXt PNGARG((png_structp png_ptr,
1247     png_infop info_ptr, png_uint_32 length));
1248 PNG_EXTERN void png_push_read_iTXt PNGARG((png_structp png_ptr,
1249     png_infop info_ptr));
1250 #  endif
1251
1252 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
1253
1254 #ifdef PNG_MNG_FEATURES_SUPPORTED
1255 PNG_EXTERN void png_do_read_intrapixel PNGARG((png_row_infop row_info,
1256     png_bytep row));
1257 PNG_EXTERN void png_do_write_intrapixel PNGARG((png_row_infop row_info,
1258     png_bytep row));
1259 #endif
1260
1261 /* Added at libpng version 1.4.0 */
1262 #ifdef PNG_CHECK_cHRM_SUPPORTED
1263 PNG_EXTERN int png_check_cHRM_fixed PNGARG((png_structp png_ptr,
1264     png_fixed_point int_white_x, png_fixed_point int_white_y,
1265     png_fixed_point int_red_x, png_fixed_point int_red_y, png_fixed_point
1266     int_green_x, png_fixed_point int_green_y, png_fixed_point int_blue_x,
1267     png_fixed_point int_blue_y));
1268 #endif
1269
1270 #ifdef PNG_CHECK_cHRM_SUPPORTED
1271 /* Added at libpng version 1.2.34 and 1.4.0 */
1272 /* Currently only used by png_check_cHRM_fixed */
1273 PNG_EXTERN void png_64bit_product PNGARG((long v1, long v2,
1274     unsigned long *hi_product, unsigned long *lo_product));
1275 #endif
1276
1277 #ifdef PNG_cHRM_SUPPORTED
1278 /* Added at libpng version 1.5.5 */
1279 typedef struct png_xy
1280 {
1281    png_fixed_point redx, redy;
1282    png_fixed_point greenx, greeny;
1283    png_fixed_point bluex, bluey;
1284    png_fixed_point whitex, whitey;
1285 } png_xy;
1286
1287 typedef struct png_XYZ
1288 {
1289    png_fixed_point redX, redY, redZ;
1290    png_fixed_point greenX, greenY, greenZ;
1291    png_fixed_point blueX, blueY, blueZ;
1292 } png_XYZ;
1293
1294 /* The conversion APIs return 0 on success, non-zero on a parameter error. They
1295  * allow conversion between the above representations of a color encoding.  When
1296  * converting from XYZ end points to chromaticities the absolute magnitude of
1297  * the end points is lost, when converting back the sum of the Y values of the
1298  * three end points will be 1.0
1299  */
1300 PNG_EXTERN int png_xy_from_XYZ PNGARG((png_xy *xy, png_XYZ XYZ));
1301 PNG_EXTERN int png_XYZ_from_xy PNGARG((png_XYZ *XYZ, png_xy xy));
1302 PNG_EXTERN int png_XYZ_from_xy_checked PNGARG((png_structp png_ptr,
1303    png_XYZ *XYZ, png_xy xy));
1304 #endif
1305
1306 /* Added at libpng version 1.4.0 */
1307 PNG_EXTERN void png_check_IHDR PNGARG((png_structp png_ptr,
1308     png_uint_32 width, png_uint_32 height, int bit_depth,
1309     int color_type, int interlace_type, int compression_type,
1310     int filter_type));
1311
1312 /* Free all memory used by the read (old method - NOT DLL EXPORTED) */
1313 PNG_EXTERN void png_read_destroy PNGARG((png_structp png_ptr,
1314     png_infop info_ptr, png_infop end_info_ptr));
1315
1316 /* Free any memory used in png_ptr struct (old method - NOT DLL EXPORTED) */
1317 PNG_EXTERN void png_write_destroy PNGARG((png_structp png_ptr));
1318
1319 #ifdef USE_FAR_KEYWORD  /* memory model conversion function */
1320 PNG_EXTERN void *png_far_to_near PNGARG((png_structp png_ptr, png_voidp ptr,
1321     int check));
1322 #endif /* USE_FAR_KEYWORD */
1323
1324 #if defined(PNG_FLOATING_POINT_SUPPORTED) && defined(PNG_ERROR_TEXT_SUPPORTED)
1325 PNG_EXTERN PNG_FUNCTION(void, png_fixed_error, (png_structp png_ptr,
1326    png_const_charp name),PNG_NORETURN);
1327 #endif
1328
1329 /* Puts 'string' into 'buffer' at buffer[pos], taking care never to overwrite
1330  * the end.  Always leaves the buffer nul terminated.  Never errors out (and
1331  * there is no error code.)
1332  */
1333 PNG_EXTERN size_t png_safecat(png_charp buffer, size_t bufsize, size_t pos,
1334     png_const_charp string);
1335
1336 /* Various internal functions to handle formatted warning messages, currently
1337  * only implemented for warnings.
1338  */
1339 #if defined(PNG_WARNINGS_SUPPORTED) || defined(PNG_TIME_RFC1123_SUPPORTED)
1340 /* Utility to dump an unsigned value into a buffer, given a start pointer and
1341  * and end pointer (which should point just *beyond* the end of the buffer!)
1342  * Returns the pointer to the start of the formatted string.  This utility only
1343  * does unsigned values.
1344  */
1345 PNG_EXTERN png_charp png_format_number(png_const_charp start, png_charp end,
1346    int format, png_alloc_size_t number);
1347
1348 /* Convenience macro that takes an array: */
1349 #define PNG_FORMAT_NUMBER(buffer,format,number) \
1350    png_format_number(buffer, buffer + (sizeof buffer), format, number)
1351
1352 /* Suggested size for a number buffer (enough for 64 bits and a sign!) */
1353 #define PNG_NUMBER_BUFFER_SIZE 24
1354
1355 /* These are the integer formats currently supported, the name is formed from
1356  * the standard printf(3) format string.
1357  */
1358 #define PNG_NUMBER_FORMAT_u     1 /* chose unsigned API! */
1359 #define PNG_NUMBER_FORMAT_02u   2
1360 #define PNG_NUMBER_FORMAT_d     1 /* chose signed API! */
1361 #define PNG_NUMBER_FORMAT_02d   2
1362 #define PNG_NUMBER_FORMAT_x     3
1363 #define PNG_NUMBER_FORMAT_02x   4
1364 #define PNG_NUMBER_FORMAT_fixed 5 /* choose the signed API */
1365 #endif
1366
1367 #ifdef PNG_WARNINGS_SUPPORTED
1368 /* New defines and members adding in libpng-1.5.4 */
1369 #  define PNG_WARNING_PARAMETER_SIZE 32
1370 #  define PNG_WARNING_PARAMETER_COUNT 8
1371
1372 /* An l-value of this type has to be passed to the APIs below to cache the
1373  * values of the parameters to a formatted warning message.
1374  */
1375 typedef char png_warning_parameters[PNG_WARNING_PARAMETER_COUNT][
1376    PNG_WARNING_PARAMETER_SIZE];
1377
1378 PNG_EXTERN void png_warning_parameter(png_warning_parameters p, int number,
1379     png_const_charp string);
1380     /* Parameters are limited in size to PNG_WARNING_PARAMETER_SIZE characters,
1381      * including the trailing '\0'.
1382      */
1383 PNG_EXTERN void png_warning_parameter_unsigned(png_warning_parameters p,
1384     int number, int format, png_alloc_size_t value);
1385     /* Use png_alloc_size_t because it is an unsigned type as big as any we
1386      * need to output.  Use the following for a signed value.
1387      */
1388 PNG_EXTERN void png_warning_parameter_signed(png_warning_parameters p,
1389     int number, int format, png_int_32 value);
1390
1391 PNG_EXTERN void png_formatted_warning(png_structp png_ptr,
1392     png_warning_parameters p, png_const_charp message);
1393     /* 'message' follows the X/Open approach of using @1, @2 to insert
1394      * parameters previously supplied using the above functions.  Errors in
1395      * specifying the paramters will simple result in garbage substitutions.
1396      */
1397 #endif
1398
1399 /* ASCII to FP interfaces, currently only implemented if sCAL
1400  * support is required.
1401  */
1402 #if defined(PNG_READ_sCAL_SUPPORTED)
1403 /* MAX_DIGITS is actually the maximum number of characters in an sCAL
1404  * width or height, derived from the precision (number of significant
1405  * digits - a build time settable option) and assumpitions about the
1406  * maximum ridiculous exponent.
1407  */
1408 #define PNG_sCAL_MAX_DIGITS (PNG_sCAL_PRECISION+1/*.*/+1/*E*/+10/*exponent*/)
1409
1410 #ifdef PNG_FLOATING_POINT_SUPPORTED
1411 PNG_EXTERN void png_ascii_from_fp PNGARG((png_structp png_ptr, png_charp ascii,
1412     png_size_t size, double fp, unsigned int precision));
1413 #endif /* FLOATING_POINT */
1414
1415 #ifdef PNG_FIXED_POINT_SUPPORTED
1416 PNG_EXTERN void png_ascii_from_fixed PNGARG((png_structp png_ptr,
1417     png_charp ascii, png_size_t size, png_fixed_point fp));
1418 #endif /* FIXED_POINT */
1419 #endif /* READ_sCAL */
1420
1421 #if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
1422 /* An internal API to validate the format of a floating point number.
1423  * The result is the index of the next character.  If the number is
1424  * not valid it will be the index of a character in the supposed number.
1425  *
1426  * The format of a number is defined in the PNG extensions specification
1427  * and this API is strictly conformant to that spec, not anyone elses!
1428  *
1429  * The format as a regular expression is:
1430  *
1431  * [+-]?[0-9]+.?([Ee][+-]?[0-9]+)?
1432  *
1433  * or:
1434  *
1435  * [+-]?.[0-9]+(.[0-9]+)?([Ee][+-]?[0-9]+)?
1436  *
1437  * The complexity is that either integer or fraction must be present and the
1438  * fraction is permitted to have no digits only if the integer is present.
1439  *
1440  * NOTE: The dangling E problem.
1441  *   There is a PNG valid floating point number in the following:
1442  *
1443  *       PNG floating point numb1.ers are not greedy.
1444  *
1445  *   Working this out requires *TWO* character lookahead (because of the
1446  *   sign), the parser does not do this - it will fail at the 'r' - this
1447  *   doesn't matter for PNG sCAL chunk values, but it requires more care
1448  *   if the value were ever to be embedded in something more complex.  Use
1449  *   ANSI-C strtod if you need the lookahead.
1450  */
1451 /* State table for the parser. */
1452 #define PNG_FP_INTEGER    0  /* before or in integer */
1453 #define PNG_FP_FRACTION   1  /* before or in fraction */
1454 #define PNG_FP_EXPONENT   2  /* before or in exponent */
1455 #define PNG_FP_STATE      3  /* mask for the above */
1456 #define PNG_FP_SAW_SIGN   4  /* Saw +/- in current state */
1457 #define PNG_FP_SAW_DIGIT  8  /* Saw a digit in current state */
1458 #define PNG_FP_SAW_DOT   16  /* Saw a dot in current state */
1459 #define PNG_FP_SAW_E     32  /* Saw an E (or e) in current state */
1460 #define PNG_FP_SAW_ANY   60  /* Saw any of the above 4 */
1461
1462 /* These three values don't affect the parser.  They are set but not used.
1463  */
1464 #define PNG_FP_WAS_VALID 64  /* Preceding substring is a valid fp number */
1465 #define PNG_FP_NEGATIVE 128  /* A negative number, including "-0" */
1466 #define PNG_FP_NONZERO  256  /* A non-zero value */
1467 #define PNG_FP_STICKY   448  /* The above three flags */
1468
1469 /* This is available for the caller to store in 'state' if required.  Do not
1470  * call the parser after setting it (the parser sometimes clears it.)
1471  */
1472 #define PNG_FP_INVALID  512  /* Available for callers as a distinct value */
1473
1474 /* Result codes for the parser (boolean - true meants ok, false means
1475  * not ok yet.)
1476  */
1477 #define PNG_FP_MAYBE      0  /* The number may be valid in the future */
1478 #define PNG_FP_OK         1  /* The number is valid */
1479
1480 /* Tests on the sticky non-zero and negative flags.  To pass these checks
1481  * the state must also indicate that the whole number is valid - this is
1482  * achieved by testing PNG_FP_SAW_DIGIT (see the implementation for why this
1483  * is equivalent to PNG_FP_OK above.)
1484  */
1485 #define PNG_FP_NZ_MASK (PNG_FP_SAW_DIGIT | PNG_FP_NEGATIVE | PNG_FP_NONZERO)
1486    /* NZ_MASK: the string is valid and a non-zero negative value */
1487 #define PNG_FP_Z_MASK (PNG_FP_SAW_DIGIT | PNG_FP_NONZERO)
1488    /* Z MASK: the string is valid and a non-zero value. */
1489    /* PNG_FP_SAW_DIGIT: the string is valid. */
1490 #define PNG_FP_IS_ZERO(state) (((state) & PNG_FP_Z_MASK) == PNG_FP_SAW_DIGIT)
1491 #define PNG_FP_IS_POSITIVE(state) (((state) & PNG_FP_NZ_MASK) == PNG_FP_Z_MASK)
1492 #define PNG_FP_IS_NEGATIVE(state) (((state) & PNG_FP_NZ_MASK) == PNG_FP_NZ_MASK)
1493
1494 /* The actual parser.  This can be called repeatedly, it updates
1495  * the index into the string and the state variable (which must
1496  * be initialzed to 0).  It returns a result code, as above.  There
1497  * is no point calling the parser any more if it fails to advance to
1498  * the end of the string - it is stuck on an invalid character (or
1499  * terminated by '\0').
1500  *
1501  * Note that the pointer will consume an E or even an E+ then leave
1502  * a 'maybe' state even though a preceding integer.fraction is valid.
1503  * The PNG_FP_WAS_VALID flag indicates that a preceding substring was
1504  * a valid number.  It's possible to recover from this by calling
1505  * the parser again (from the start, with state 0) but with a string
1506  * that omits the last character (i.e. set the size to the index of
1507  * the problem character.)  This has not been tested within libpng.
1508  */
1509 PNG_EXTERN int png_check_fp_number PNGARG((png_const_charp string,
1510     png_size_t size, int *statep, png_size_tp whereami));
1511
1512 /* This is the same but it checks a complete string and returns true
1513  * only if it just contains a floating point number.  As of 1.5.4 this
1514  * function also returns the state at the end of parsing the number if
1515  * it was valid (otherwise it returns 0.)  This can be used for testing
1516  * for negative or zero values using the sticky flag.
1517  */
1518 PNG_EXTERN int png_check_fp_string PNGARG((png_const_charp string,
1519     png_size_t size));
1520 #endif /* pCAL || sCAL */
1521
1522 #if defined(PNG_READ_GAMMA_SUPPORTED) ||\
1523     defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG_READ_pHYs_SUPPORTED)
1524 /* Added at libpng version 1.5.0 */
1525 /* This is a utility to provide a*times/div (rounded) and indicate
1526  * if there is an overflow.  The result is a boolean - false (0)
1527  * for overflow, true (1) if no overflow, in which case *res
1528  * holds the result.
1529  */
1530 PNG_EXTERN int png_muldiv PNGARG((png_fixed_point_p res, png_fixed_point a,
1531     png_int_32 multiplied_by, png_int_32 divided_by));
1532 #endif
1533
1534 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
1535 /* Same deal, but issue a warning on overflow and return 0. */
1536 PNG_EXTERN png_fixed_point png_muldiv_warn PNGARG((png_structp png_ptr,
1537     png_fixed_point a, png_int_32 multiplied_by, png_int_32 divided_by));
1538 #endif
1539
1540 #ifdef PNG_READ_GAMMA_SUPPORTED
1541 /* Calculate a reciprocal - used for gamma values.  This returns
1542  * 0 if the argument is 0 in order to maintain an undefined value,
1543  * there are no warnings.
1544  */
1545 PNG_EXTERN png_fixed_point png_reciprocal PNGARG((png_fixed_point a));
1546
1547 /* The same but gives a reciprocal of the product of two fixed point
1548  * values.  Accuracy is suitable for gamma calculations but this is
1549  * not exact - use png_muldiv for that.
1550  */
1551 PNG_EXTERN png_fixed_point png_reciprocal2 PNGARG((png_fixed_point a,
1552     png_fixed_point b));
1553 #endif
1554
1555 #ifdef PNG_READ_GAMMA_SUPPORTED
1556 /* Internal fixed point gamma correction.  These APIs are called as
1557  * required to convert single values - they don't need to be fast,
1558  * they are not used when processing image pixel values.
1559  *
1560  * While the input is an 'unsigned' value it must actually be the
1561  * correct bit value - 0..255 or 0..65535 as required.
1562  */
1563 PNG_EXTERN png_uint_16 png_gamma_correct PNGARG((png_structp png_ptr,
1564     unsigned int value, png_fixed_point gamma_value));
1565 PNG_EXTERN int png_gamma_significant PNGARG((png_fixed_point gamma_value));
1566 PNG_EXTERN png_uint_16 png_gamma_16bit_correct PNGARG((unsigned int value,
1567     png_fixed_point gamma_value));
1568 PNG_EXTERN png_byte png_gamma_8bit_correct PNGARG((unsigned int value,
1569     png_fixed_point gamma_value));
1570 PNG_EXTERN void png_destroy_gamma_table(png_structp png_ptr);
1571 PNG_EXTERN void png_build_gamma_table PNGARG((png_structp png_ptr,
1572     int bit_depth));
1573 #endif
1574
1575 /* Maintainer: Put new private prototypes here ^ and in libpngpf.3 */
1576
1577
1578 #include "pngdebug.h"
1579
1580 #ifdef __cplusplus
1581 }
1582 #endif
1583
1584 #endif /* PNGPRIV_H */