1 /*

     2 CHANGES - changes for libpng

     3 

     4 version 0.2

     5   added reader into png.h

     6   fixed small problems in stub file

     7 

     8 version 0.3

     9   added pull reader

    10   split up pngwrite.c to several files

    11   added pnglib.txt

    12   added example.c

    13   cleaned up writer, adding a few new transformations

    14   fixed some bugs in writer

    15   interfaced with zlib 0.5

    16   added K&R support

    17   added check for 64 KB blocks for 16 bit machines

    18 

    19 version 0.4

    20   cleaned up code and commented code

    21   simplified time handling into png_time

    22   created png_color_16 and png_color_8 to handle color needs

    23   cleaned up color type defines

    24   fixed various bugs

    25   made various names more consistent

    26   interfaced with zlib 0.71

    27   cleaned up zTXt reader and writer (using zlib's Reset functions)

    28   split transformations into pngrtran.c and pngwtran.c

    29 

    30 version 0.5

    31   interfaced with zlib 0.8

    32   fixed many reading and writing bugs

    33   saved using 3 spaces instead of tabs

    34 

    35 version 0.6

    36   added png_large_malloc() and png_large_free()

    37   added png_size_t

    38   cleaned up some compiler warnings

    39   added png_start_read_image()

    40 

    41 version 0.7

    42   cleaned up lots of bugs

    43   finished dithering and other stuff

    44   added test program

    45   changed name from pnglib to libpng

    46 

    47 version 0.71 [June, 1995]

    48   changed pngtest.png for zlib 0.93

    49   fixed error in libpng.txt and example.c

    50 

    51 version 0.8

    52   cleaned up some bugs

    53   added png_set_filler()

    54   split up pngstub.c into pngmem.c, pngio.c, and pngerror.c

    55   added #define's to remove unwanted code

    56   moved png_info_init() to png.c

    57   added old_size into png_realloc()

    58   added functions to manually set filtering and compression info

    59   changed compression parameters based on image type

    60   optimized filter selection code

    61   added version info

    62   changed external functions passing floats to doubles (k&r problems?)

    63   put all the configurable stuff in pngconf.h

    64   enabled png_set_shift to work with paletted images on read

    65   added png_read_update_info() - updates info structure with

    66      transformations

    67 

    68 version 0.81 [August, 1995]

    69   incorporated Tim Wegner's medium model code (thanks, Tim)

    70 

    71 version 0.82 [September, 1995]

    72   [unspecified changes]

    73 

    74 version 0.85 [December, 1995]

    75   added more medium model code (almost everything's a far)

    76   added i/o, error, and memory callback functions

    77   fixed some bugs (16 bit, 4 bit interlaced, etc.)

    78   added first run progressive reader (barely tested)

    79 

    80 version 0.86 [January, 1996]

    81   fixed bugs

    82   improved documentation

    83 

    84 version 0.87 [January, 1996]

    85   fixed medium model bugs

    86   fixed other bugs introduced in 0.85 and 0.86

    87   added some minor documentation

    88 

    89 version 0.88 [January, 1996]

    90   fixed progressive bugs

    91   replaced tabs with spaces

    92   cleaned up documentation

    93   added callbacks for read/write and warning/error functions

    94 

    95 version 0.89 [July, 1996]

    96   added new initialization API to make libpng work better with shared libs

    97      we now have png_create_read_struct(), png_create_write_struct(),

    98      png_create_info_struct(), png_destroy_read_struct(), and

    99      png_destroy_write_struct() instead of the separate calls to

   100      malloc and png_read_init(), png_info_init(), and png_write_init()

   101   changed warning/error callback functions to fix bug - this means you

   102      should use the new initialization API if you were using the old

   103      png_set_message_fn() calls, and that the old API no longer exists

   104      so that people are aware that they need to change their code

   105   changed filter selection API to allow selection of multiple filters

   106      since it didn't work in previous versions of libpng anyways

   107   optimized filter selection code

   108   fixed png_set_background() to allow using an arbitrary RGB color for

   109      paletted images

   110   fixed gamma and background correction for paletted images, so

   111      png_correct_palette is not needed unless you are correcting an

   112      external palette (you will need to #define PNG_CORRECT_PALETTE_SUPPORTED

   113      in pngconf.h) - if nobody uses this, it may disappear in the future.

   114   fixed bug with Borland 64K memory allocation (Alexander Lehmann)

   115   fixed bug in interlace handling (Smarasderagd, I think)

   116   added more error checking for writing and image to reduce invalid files

   117   separated read and write functions so that they won't both be linked

   118      into a binary when only reading or writing functionality is used

   119   new pngtest image also has interlacing and zTXt

   120   updated documentation to reflect new API

   121 

   122 version 0.90 [January, 1997]

   123   made CRC errors/warnings on critical and ancillary chunks configurable

   124   libpng will use the zlib CRC routines by (compile-time) default

   125   changed DOS small/medium model memory support - needs zlib 1.04 (Tim Wegner)

   126   added external C++ wrapper statements to png.h (Gilles Dauphin)

   127   allow PNG file to be read when some or all of file signature has already

   128      been read from the beginning of the stream.  ****This affects the size

   129      of info_struct and invalidates all programs that use a shared libpng****

   130   fixed png_filler() declarations

   131   fixed? background color conversions

   132   fixed order of error function pointers to match documentation

   133   current chunk name is now available in png_struct to reduce the number

   134      of nearly identical error messages (will simplify multi-lingual

   135      support when available)

   136   try to get ready for unknown-chunk callback functions:

   137      - previously read critical chunks are flagged, so the chunk handling

   138        routines can determine if the chunk is in the right place

   139      - all chunk handling routines have the same prototypes, so we will

   140        be able to handle all chunks via a callback mechanism

   141   try to fix Linux "setjmp" buffer size problems

   142   removed png_large_malloc, png_large_free, and png_realloc functions.

   143 

   144 version 0.95 [March, 1997]

   145   fixed bug in pngwutil.c allocating "up_row" twice and "avg_row" never

   146   fixed bug in PNG file signature compares when start != 0

   147   changed parameter type of png_set_filler(...filler...) from png_byte

   148      to png_uint_32

   149   added test for MACOS to ensure that both math.h and fp.h are not #included

   150   added macros for libpng to be compiled as a Windows DLL (Andreas Kupries)

   151   added "packswap" transformation, which changes the endianness of

   152      packed-pixel bytes (Kevin Bracey)

   153   added "strip_alpha" transformation, which removes the alpha channel of

   154      input images without using it (not necessarily a good idea)

   155   added "swap_alpha" transformation, which puts the alpha channel in front

   156      of the color bytes instead of after

   157   removed all implicit variable tests which assume NULL == 0 (I think)

   158   changed several variables to "png_size_t" to show 16/32-bit limitations

   159   added new pCAL chunk read/write support

   160   added experimental filter selection weighting (Greg Roelofs)

   161   removed old png_set_rgbx() and png_set_xrgb() functions that have been

   162      obsolete for about 2 years now (use png_set_filler() instead)

   163   added macros to read 16- and 32-bit ints directly from buffer, to be

   164      used only on those systems that support it (namely PowerPC and 680x0)

   165      With some testing, this may become the default for MACOS/PPC systems.

   166   only calculate CRC on data if we are going to use it

   167   added macros for zTXt compression type PNG_zTXt_COMPRESSION_???

   168   added macros for simple libpng debugging output selectable at compile time

   169   removed PNG_READ_END_MODE in progressive reader (Smarasderagd)

   170   more description of info_struct in libpng.txt and png.h

   171   more instructions in example.c

   172   more chunk types tested in pngtest.c

   173   renamed pngrcb.c to pngset.c, and all png_read_<chunk> functions to be

   174      png_set_<chunk>.  We now have corresponding png_get_<chunk>

   175      functions in pngget.c to get information in info_ptr.  This isolates

   176      the application from the internal organization of png_info_struct

   177      (good for shared library implementations).

   178 

   179 version 0.96 [May, 1997]

   180   fixed serious bug with < 8bpp images introduced in 0.95

   181   fixed 256-color transparency bug (Greg Roelofs)

   182   fixed up documentation (Greg Roelofs, Laszlo Nyul)

   183   fixed "error" in pngconf.h for Linux setjmp() behaviour

   184   fixed DOS medium model support (Tim Wegner)

   185   fixed png_check_keyword() for case with error in static string text

   186   added read of CRC after IEND chunk for embedded PNGs (Laszlo Nyul)

   187   added typecasts to quiet compiler errors

   188   added more debugging info

   189 

   190 version 0.97 [January, 1998]

   191   removed PNG_USE_OWN_CRC capability

   192   relocated png_set_crc_action from pngrutil.c to pngrtran.c

   193   fixed typecasts of "new_key", etc. (Andreas Dilger)

   194   added RFC 1152 [sic] date support

   195   fixed bug in gamma handling of 4-bit grayscale

   196   added 2-bit grayscale gamma handling (Glenn R-P)

   197   added more typecasts. 65536L becomes (png_uint_32)65536L, etc. (Glenn R-P)

   198   minor corrections in libpng.txt

   199   added simple sRGB support (Glenn R-P)

   200   easier conditional compiling, e.g. define PNG_READ/WRITE_NOT_FULLY_SUPPORTED;

   201      all configurable options can be selected from command-line instead

   202      of having to edit pngconf.h (Glenn R-P)

   203   fixed memory leak in pngwrite.c (free info_ptr->text) (Glenn R-P)

   204   added more conditions for png_do_background, to avoid changing

   205      black pixels to background when a background is supplied and

   206      no pixels are transparent

   207   repaired PNG_NO_STDIO behaviour

   208   tested NODIV support and made it default behaviour (Greg Roelofs)

   209   added "-m" option and PNGTEST_DEBUG_MEMORY to pngtest (John Bowler)

   210   regularized version numbering scheme and bumped shared-library major

   211      version number to 2 to avoid problems with libpng 0.89 apps (Greg Roelofs)

   212 

   213 version 0.98 [January, 1998]

   214   cleaned up some typos in libpng.txt and in code documentation

   215   fixed memory leaks in pCAL chunk processing (Glenn R-P and John Bowler)

   216   cosmetic change "display_gamma" to "screen_gamma" in pngrtran.c

   217   changed recommendation about file_gamma for PC images to .51 from .45,

   218      in example.c and libpng.txt, added comments to distinguish between

   219      screen_gamma, viewing_gamma, and display_gamma.

   220   changed all references to RFC1152 to read RFC1123 and changed the

   221      PNG_TIME_RFC1152_SUPPORTED macro to PNG_TIME_RFC1123_SUPPORTED

   222   added png_invert_alpha capability (Glenn R-P -- suggestion by Jon Vincent)

   223   changed srgb_intent from png_byte to int to avoid compiler bugs

   224 

   225 version 0.99 [January 30, 1998]

   226   free info_ptr->text instead of end_info_ptr->text in pngread.c (John Bowler)

   227   fixed a longstanding "packswap" bug in pngtrans.c

   228   fixed some inconsistencies in pngconf.h that prevented compiling with

   229      PNG_READ_GAMMA_SUPPORTED and PNG_READ_hIST_SUPPORTED undefined

   230   fixed some typos and made other minor rearrangement of libpng.txt (Andreas)

   231   changed recommendation about file_gamma for PC images to .50 from .51 in

   232      example.c and libpng.txt, and changed file_gamma for sRGB images to .45

   233   added a number of functions to access information from the png structure

   234      png_get_image_height(), etc. (Glenn R-P, suggestion by Brad Pettit)

   235   added TARGET_MACOS similar to zlib-1.0.8

   236   define PNG_ALWAYS_EXTERN when __MWERKS__ && WIN32 are defined

   237   added type casting to all png_malloc() function calls

   238 version 0.99a [January 31, 1998]

   239   Added type casts and parentheses to all returns that return a value.(Tim W.)

   240 version 0.99b [February 4, 1998]

   241   Added type cast png_uint_32 on malloc function calls where needed.

   242   Changed type of num_hist from png_uint_32 to int (same as num_palette).

   243   Added checks for rowbytes overflow, in case png_size_t is less than 32 bits.

   244   Renamed makefile.elf to makefile.lnx.

   245 version 0.99c [February 7, 1998]

   246   More type casting.  Removed erroneous overflow test in pngmem.c.

   247   Added png_buffered_memcpy() and png_buffered_memset(), apply them to rowbytes.

   248   Added UNIX manual pages libpng.3 (incorporating libpng.txt) and  png.5.

   249 version 0.99d [February 11, 1998]

   250   Renamed "far_to_near()" "png_far_to_near()"

   251   Revised libpng.3

   252   Version 99c "buffered" operations didn't work as intended.  Replaced them

   253     with png_memcpy_check() and png_memset_check().

   254   Added many "if (png_ptr == NULL) return" to quell compiler warnings about

   255     unused png_ptr, mostly in pngget.c and pngset.c.

   256   Check for overlength tRNS chunk present when indexed-color PLTE is read.

   257   Cleaned up spelling errors in libpng.3/libpng.txt

   258   Corrected a problem with png_get_tRNS() which returned undefined trans array

   259 version 0.99e [February 28, 1998]

   260   Corrected png_get_tRNS() again.

   261   Add parentheses for easier reading of pngget.c, fixed "||" should be "&&".

   262   Touched up example.c to make more of it compileable, although the entire

   263     file still can't be compiled (Willem van Schaik)

   264   Fixed a bug in png_do_shift() (Bryan Tsai)

   265   Added a space in png.h prototype for png_write_chunk_start()

   266   Replaced pngtest.png with one created with zlib 1.1.1

   267   Changed pngtest to report PASS even when file size is different (Jean-loup G.)

   268   Corrected some logic errors in png_do_invert_alpha() (Chris Patterson)

   269 version 0.99f [March 5, 1998]

   270   Corrected a bug in pngpread() introduced in version 99c (Kevin Bracey)

   271   Moved makefiles into a "scripts" directory, and added INSTALL instruction file

   272   Added makefile.os2 and pngos2.def (A. Zabolotny) and makefile.s2x (W. Sebok)

   273   Added pointers to "note on libpng versions" in makefile.lnx and README

   274   Added row callback feature when reading and writing nonprogressive rows

   275      and added a test of this feature in pngtest.c

   276   Added user transform callbacks, with test of the feature in pngtest.c

   277 version 0.99g [March 6, 1998, morning]

   278   Minor changes to pngtest.c to suppress compiler warnings.

   279   Removed "beta" language from documentation.

   280 version 0.99h [March 6, 1998, evening]

   281   Minor changes to previous minor changes to pngtest.c

   282   Changed PNG_READ_NOT_FULLY_SUPPORTED to PNG_READ_TRANSFORMS_NOT_SUPPORTED

   283   and added PNG_PROGRESSIVE_READ_NOT_SUPPORTED macro

   284   Added user transform capability

   285 

   286 version 1.00 [March 7, 1998]

   287   Changed several typedefs in pngrutil.c

   288   Added makefile.wat (Pawel Mrochen), updated makefile.tc3 (Willem van Schaik)

   289   replaced "while(1)" with "for(;;)"

   290   added PNGARG() to prototypes in pngtest.c and removed some prototypes

   291   updated some of the makefiles (Tom Lane)

   292   changed some typedefs (s_start, etc.) in pngrutil.c

   293   fixed dimensions of "short_months" array in pngwrite.c

   294   Replaced ansi2knr.c with the one from jpeg-v6

   295 

   296 version 1.0.0 [March 8, 1998]

   297   Changed name from 1.00 to 1.0.0 (Adam Costello)

   298   Added smakefile.ppc (with SCOPTIONS.ppc) for Amiga PPC (Andreas Kleinert)

   299 version 1.0.0a [March 9, 1998]

   300   Fixed three bugs in pngrtran.c to make gamma+background handling consistent

   301   (Greg Roelofs)

   302   Changed format of the PNG_LIBPNG_VER integer to xyyzz instead of xyz

   303   for major, minor, and bugfix releases.  This is 10001. (Adam Costello,

   304   Tom Lane)

   305   Make months range from 1-12 in png_convert_to_rfc1123

   306 version 1.0.0b [March 13, 1998]

   307   Quieted compiler complaints about two empty "for" loops in pngrutil.c

   308   Minor changes to makefile.s2x

   309   Removed #ifdef/#endif around a png_free() in pngread.c

   310 

   311 version 1.0.1 [March 14, 1998]

   312   Changed makefile.s2x to reduce security risk of using a relative pathname

   313   Fixed some typos in the documentation (Greg).

   314   Fixed a problem with value of "channels" returned by png_read_update_info()

   315 version 1.0.1a [April 21, 1998]

   316   Optimized Paeth calculations by replacing abs() function calls with intrinsics

   317   plus other loop optimizations. Improves avg decoding speed by about 20%.

   318   Commented out i386istic "align" compiler flags in makefile.lnx.

   319   Reduced the default warning level in some makefiles, to make them consistent.

   320   Removed references to IJG and JPEG in the ansi2knr.c copyright statement.

   321   Fixed a bug in png_do_strip_filler with XXRRGGBB => RRGGBB transformation.

   322   Added grayscale and 16-bit capability to png_do_read_filler().

   323   Fixed a bug in pngset.c, introduced in version 0.99c, that sets rowbytes

   324     too large when writing an image with bit_depth < 8 (Bob Dellaca).

   325   Corrected some bugs in the experimental weighted filtering heuristics.

   326   Moved a misplaced pngrutil code block that truncates tRNS if it has more

   327     than num_palette entries -- test was done before num_palette was defined.

   328   Fixed a png_convert_to_rfc1123() bug that converts day 31 to 0 (Steve Eddins).

   329   Changed compiler flags in makefile.wat for better optimization (Pawel Mrochen).

   330 version 1.0.1b [May 2, 1998]

   331   Relocated png_do_gray_to_rgb() within png_do_read_transformations() (Greg).

   332   Relocated the png_composite macros from pngrtran.c to png.h (Greg).

   333   Added makefile.sco (contributed by Mike Hopkirk).

   334   Fixed two bugs (missing definitions of "istop") introduced in libpng-1.0.1a.

   335   Fixed a bug in pngrtran.c that would set channels=5 under some circumstances.

   336   More work on the Paeth-filtering, achieving imperceptible speedup (A Kleinert).

   337   More work on loop optimization which may help when compiled with C++ compilers.

   338   Added warnings when people try to use transforms they've defined out.

   339   Collapsed 4 "i" and "c" loops into single "i" loops in pngrtran and pngwtran.

   340   Revised paragraph about png_set_expand() in libpng.txt and libpng.3 (Greg)

   341 version 1.0.1c [May 11, 1998]

   342   Fixed a bug in pngrtran.c (introduced in libpng-1.0.1a) where the masks for

   343     filler bytes should have been 0xff instead of 0xf.

   344   Added max_pixel_depth=32 in pngrutil.c when using FILLER with palette images.

   345   Moved PNG_WRITE_WEIGHTED_FILTER_SUPPORTED and PNG_WRITE_FLUSH_SUPPORTED

   346     out of the PNG_WRITE_TRANSFORMS_NOT_SUPPORTED block of pngconf.h

   347   Added "PNG_NO_WRITE_TRANSFORMS" etc., as alternatives for *_NOT_SUPPORTED,

   348     for consistency, in pngconf.h

   349   Added individual "ifndef PNG_NO_[CAPABILITY]" in pngconf.h to make it easier

   350     to remove unwanted capabilities via the compile line

   351   Made some corrections to grammar (which, it's) in documentation (Greg).

   352   Corrected example.c, use of row_pointers in png_write_image().

   353 version 1.0.1d [May 24, 1998]

   354   Corrected several statements that used side effects illegally in pngrutil.c

   355     and pngtrans.c, that were introduced in version 1.0.1b

   356   Revised png_read_rows() to avoid repeated if-testing for NULL (A Kleinert)

   357   More corrections to example.c, use of row_pointers in png_write_image()

   358     and png_read_rows().

   359   Added pngdll.mak and pngdef.pas to scripts directory, contributed by

   360     Bob Dellaca, to make a png32bd.dll with Borland C++ 4.5

   361   Fixed error in example.c with png_set_text: num_text is 3, not 2 (Guido V.)

   362   Changed several loops from count-down to count-up, for consistency.

   363 version 1.0.1e [June 6, 1998]

   364   Revised libpng.txt and libpng.3 description of png_set_read|write_fn(), and

   365     added warnings when people try to set png_read_fn and png_write_fn in

   366     the same structure.

   367   Added a test such that png_do_gamma will be done when num_trans==0

   368     for truecolor images that have defined a background.  This corrects an

   369     error that was introduced in libpng-0.90 that can cause gamma processing

   370     to be skipped.

   371   Added tests in png.h to include "trans" and "trans_values" in structures

   372     when PNG_READ_BACKGROUND_SUPPORTED or PNG_READ_EXPAND_SUPPORTED is defined.

   373   Add png_free(png_ptr->time_buffer) in png_destroy_read_struct()

   374   Moved png_convert_to_rfc_1123() from pngwrite.c to png.c

   375   Added capability for user-provided malloc_fn() and free_fn() functions,

   376     and revised pngtest.c to demonstrate their use, replacing the

   377     PNGTEST_DEBUG_MEM feature.

   378   Added makefile.w32, for Microsoft C++ 4.0 and later (Tim Wegner).

   379 

   380 version 1.0.2 [June 14, 1998]

   381   Fixed two bugs in makefile.bor .

   382 version 1.0.2a [December 30, 1998]

   383   Replaced and extended code that was removed from png_set_filler() in 1.0.1a.

   384   Fixed a bug in png_do_filler() that made it fail to write filler bytes in

   385     the left-most pixel of each row (Kevin Bracey).

   386   Changed "static pngcharp tIME_string" to "static char tIME_string[30]"

   387     in pngtest.c (Duncan Simpson).

   388   Fixed a bug in pngtest.c that caused pngtest to try to write a tIME chunk

   389     even when no tIME chunk was present in the source file.

   390   Fixed a problem in pngrutil.c: gray_to_rgb didn't always work with 16-bit.

   391   Fixed a problem in png_read_push_finish_row(), which would not skip some

   392     passes that it should skip, for images that are less than 3 pixels high.

   393   Interchanged the order of calls to png_do_swap() and png_do_shift()

   394     in pngwtran.c (John Cromer).

   395   Added #ifdef PNG_DEBUG/#endif surrounding use of PNG_DEBUG in png.h .

   396   Changed "bad adaptive filter type" from error to warning in pngrutil.c .

   397   Fixed a documentation error about default filtering with 8-bit indexed-color.

   398   Separated the PNG_NO_STDIO macro into PNG_NO_STDIO and PNG_NO_CONSOLE_IO

   399     (L. Peter Deutsch).

   400   Added png_set_rgb_to_gray() and png_get_rgb_to_gray_status() functions.

   401   Added png_get_copyright() and png_get_header_version() functions.

   402   Revised comments on png_set_progressive_read_fn() in libpng.txt and example.c

   403   Added information about debugging in libpng.txt and libpng.3 .

   404   Changed "ln -sf" to "ln -s -f" in makefile.s2x, makefile.lnx, and makefile.sco.

   405   Removed lines after Dynamic Dependencies" in makefile.aco .

   406   Revised makefile.dec to make a shared library (Jeremie Petit).

   407   Removed trailing blanks from all files.

   408 version 1.0.2a [January 6, 1999]

   409   Removed misplaced #endif and #ifdef PNG_NO_EXTERN near the end of png.h

   410   Added "if" tests to silence complaints about unused png_ptr in png.h and png.c

   411   Changed "check_if_png" function in example.c to return true (nonzero) if PNG.

   412   Changed libpng.txt to demonstrate png_sig_cmp() instead of png_check_sig()

   413     which is obsolete.

   414 

   415 version 1.0.3 [January 14, 1999]

   416   Added makefile.hux, for Hewlett Packard HPUX 10.20 and 11.00 (Jim Rice)

   417   Added a statement of Y2K compliance in png.h, libpng.3, and Y2KINFO.

   418 version 1.0.3a [August 12, 1999]

   419   Added check for PNG_READ_INTERLACE_SUPPORTED in pngread.c; issue a warning

   420      if an attempt is made to read an interlaced image when it's not supported.

   421   Added check if png_ptr->trans is defined before freeing it in pngread.c

   422   Modified the Y2K statement to include versions back to version 0.71

   423   Fixed a bug in the check for valid IHDR bit_depth/color_types in pngrutil.c

   424   Modified makefile.wat (added -zp8 flag, ".symbolic", changed some comments)

   425   Replaced leading blanks with tab characters in makefile.hux

   426   Changed "dworkin.wustl.edu" to "ccrc.wustl.edu" in various documents.

   427   Changed (float)red and (float)green to (double)red, (double)green

   428      in png_set_rgb_to_gray() to avoid "promotion" problems in AIX.

   429   Fixed a bug in pngconf.h that omitted <stdio.h> when PNG_DEBUG==0 (K Bracey).

   430   Reformatted libpng.3 and libpngpf.3 with proper fonts (script by J. vanZandt).

   431   Updated documentation to refer to the PNG-1.2 specification.

   432   Removed ansi2knr.c and left pointers to the latest source for ansi2knr.c

   433     in makefile.knr, INSTALL, and README (L. Peter Deutsch)

   434   Fixed bugs in calculation of the length of rowbytes when adding alpha

   435     channels to 16-bit images, in pngrtran.c (Chris Nokleberg)

   436   Added function png_set_user_transform_info() to store user_transform_ptr,

   437     user_depth, and user_channels into the png_struct, and a function

   438     png_get_user_transform_ptr() to retrieve the pointer (Chris Nokleberg)

   439   Added function png_set_empty_plte_permitted() to make libpng useable

   440     in MNG applications.

   441   Corrected the typedef for png_free_ptr in png.h (Jesse Jones).

   442   Correct gamma with srgb is 45455 instead of 45000 in pngrutil.c, to be

   443     consistent with PNG-1.2, and allow variance of 500 before complaining.

   444   Added assembler code contributed by Intel in file pngvcrd.c and modified

   445     makefile.w32 to use it (Nirav Chhatrapati, INTEL Corporation, Gilles Vollant)

   446   Changed "ln -s -f" to "ln -f -s" in the makefiles to make Solaris happy.

   447   Added some aliases for png_set_expand() in pngrtran.c, namely

   448     png_set_expand_PLTE(), png_set_expand_depth(), and png_set_expand_tRNS()

   449     (Greg Roelofs, in "PNG: The Definitive Guide").

   450   Added makefile.beo for BEOS on X86, contributed by Sander Stok.

   451 version 1.0.3b [August 26, 1999]

   452   Replaced 2147483647L several places with PNG_MAX_UINT macro, defined in png.h

   453   Changed leading blanks to tabs in all makefiles.

   454   Define PNG_USE_PNGVCRD in makefile.w32, to get MMX assembler code.

   455   Made alternate versions of  png_set_expand() in pngrtran.c, namely

   456     png_set_gray_1_2_4_to_8, png_set_palette_to_rgb, and png_set_tRNS_to_alpha

   457     (Greg Roelofs, in "PNG: The Definitive Guide").  Deleted the 1.0.3a aliases.

   458   Relocated start of 'extern "C"' block in png.h so it doesn't include pngconf.h

   459   Revised calculation of num_blocks in pngmem.c to avoid a potentially

   460     negative shift distance, whose results are undefined in the C language.

   461   Added a check in pngset.c to prevent writing multiple tIME chunks.

   462   Added a check in pngwrite.c to detect invalid small window_bits sizes.

   463 version 1.0.3d [September 4, 1999]

   464   Fixed type casting of igamma in pngrutil.c

   465   Added new png_expand functions to scripts/pngdef.pas and pngos2.def

   466   Added a demo read_user_transform_fn that examines the row filters in pngtest.c

   467 

   468 version 1.0.4 [September 24, 1999]

   469   Define PNG_ALWAYS_EXTERN in pngconf.h if __STDC__ is defined

   470   Delete #define PNG_INTERNAL and include "png.h" from pngasmrd.h

   471   Made several minor corrections to pngtest.c

   472   Renamed the makefiles with longer but more user friendly extensions.

   473   Copied the PNG copyright and license to a separate LICENSE file.

   474   Revised documentation, png.h, and example.c to remove reference to

   475     "viewing_gamma" which no longer appears in the PNG specification.

   476   Revised pngvcrd.c to use MMX code for interlacing only on the final pass.

   477   Updated pngvcrd.c to use the faster C filter algorithms from libpng-1.0.1a

   478   Split makefile.win32vc into two versions, makefile.vcawin32 (uses MMX

   479     assembler code) and makefile.vcwin32 (doesn't).

   480   Added a CPU timing report to pngtest.c (enabled by defining PNGTEST_TIMING)

   481   Added a copy of pngnow.png to the distribution.

   482 version 1.0.4a [September 25, 1999]

   483   Increase max_pixel_depth in pngrutil.c if a user transform needs it.

   484   Changed several division operations to right-shifts in pngvcrd.c

   485 version 1.0.4b [September 30, 1999]

   486   Added parentheses in line 3732 of pngvcrd.c

   487   Added a comment in makefile.linux warning about buggy -O3 in pgcc 2.95.1

   488 version 1.0.4c [October 1, 1999]

   489   Added a "png_check_version" function in png.c and pngtest.c that will generate

   490     a helpful compiler error if an old png.h is found in the search path.

   491   Changed type of png_user_transform_depth|channels from int to png_byte.

   492 version 1.0.4d [October 6, 1999]

   493   Changed 0.45 to 0.45455 in png_set_sRGB()

   494   Removed unused PLTE entries from pngnow.png

   495   Re-enabled some parts of pngvcrd.c (png_combine_row) that work properly.

   496 version 1.0.4e [October 10, 1999]

   497   Fixed sign error in pngvcrd.c (Greg Roelofs)

   498   Replaced some instances of memcpy with simple assignments in pngvcrd (GR-P)

   499 version 1.0.4f [October 15, 1999]

   500   Surrounded example.c code with #if 0 .. #endif to prevent people from

   501     inadvertently trying to compile it.

   502   Changed png_get_header_version() from a function to a macro in png.h

   503   Added type casting mostly in pngrtran.c and pngwtran.c

   504   Removed some pointless "ptr = NULL" in pngmem.c

   505   Added a "contrib" directory containing the source code from Greg's book.

   506 

   507 version 1.0.5 [October 15, 1999]

   508   Minor editing of the INSTALL and README files.

   509 version 1.0.5a [October 23, 1999]

   510   Added contrib/pngsuite and contrib/pngminus (Willem van Schaik)

   511   Fixed a typo in the png_set_sRGB() function call in example.c (Jan Nijtmans)

   512   Further optimization and bugfix of pngvcrd.c

   513   Revised pngset.c so that it does not allocate or free memory in the user's

   514     text_ptr structure.  Instead, it makes its own copy.

   515   Created separate write_end_info_struct in pngtest.c for a more severe test.

   516   Added code in pngwrite.c to free info_ptr->text[i].key to stop a memory leak.

   517 version 1.0.5b [November 23, 1999]

   518   Moved PNG_FLAG_HAVE_CHUNK_HEADER, PNG_FLAG_BACKGROUND_IS_GRAY and

   519     PNG_FLAG_WROTE_tIME from flags to mode.

   520   Added png_write_info_before_PLTE() function.

   521   Fixed some typecasting in contrib/gregbook/*.c

   522   Updated scripts/makevms.com and added makevms.com to contrib/gregbook

   523     and contrib/pngminus (Martin Zinser)

   524 version 1.0.5c [November 26, 1999]

   525   Moved png_get_header_version from png.h to png.c, to accommodate ansi2knr.

   526   Removed all global arrays (according to PNG_NO_GLOBAL_ARRAYS macro), to

   527     accommodate making DLL's: Moved usr_png_ver from global variable to function

   528     png_get_header_ver() in png.c.  Moved png_sig to png_sig_bytes in png.c and

   529     eliminated use of png_sig in pngwutil.c.  Moved the various png_CHNK arrays

   530     into pngtypes.h.  Eliminated use of global png_pass arrays.  Declared the

   531     png_CHNK and png_pass arrays to be "const".  Made the global arrays

   532     available to applications (although none are used in libpng itself) when

   533     PNG_NO_GLOBAL_ARRAYS is not defined or when PNG_GLOBAL_ARRAYS is defined.

   534   Removed some extraneous "-I" from contrib/pngminus/makefile.std

   535   Changed the PNG_sRGB_INTENT macros in png.h to be consistent with PNG-1.2.

   536   Change PNG_SRGB_INTENT to PNG_sRGB_INTENT in libpng.txt and libpng.3

   537 version 1.0.5d [November 29, 1999]

   538   Add type cast (png_const_charp) two places in png.c

   539   Eliminated pngtypes.h; use macros instead to declare PNG_CHNK arrays.

   540   Renamed "PNG_GLOBAL_ARRAYS" to "PNG_USE_GLOBAL_ARRAYS" and made available

   541     to applications a macro "PNG_USE_LOCAL_ARRAYS".

   542   Remove all the new declarations with #ifdef/#endif when

   543     PNG_USE_GLOBAL_ARRAYS is defined.

   544   Added PNG_EXPORT_VAR macro to accommodate making DLL's.

   545 version 1.0.5e [November 30, 1999]

   546   Added iCCP, iTXt, and sPLT support; added "lang" member to the png_text

   547     structure; refactored the inflate/deflate support to make adding new chunks

   548     with trailing compressed parts easier in the future, and added new functions

   549     png_free_iCCP, png_free_pCAL, png_free_sPLT, png_free_text, png_get_iCCP,

   550     png_get_spalettes, png_set_iCCP, png_set_spalettes (Eric S. Raymond).

   551   NOTE: Applications that write text chunks MUST define png_text->lang

   552     before calling png_set_text(). It must be set to NULL if you want to

   553     write tEXt or zTXt chunks.  If you want your application to be able to

   554     run with older versions of libpng, use

   555 

   556       #ifdef PNG_iTXt_SUPPORTED

   557          png_text[i].lang = NULL;

   558       #endif

   559 

   560   Changed png_get_oFFs() and png_set_oFFs() to use signed rather than unsigned

   561     offsets (Eric S. Raymond).

   562   Combined PNG_READ_cHNK_SUPPORTED and PNG_WRITE_cHNK_SUPPORTED macros into

   563     PNG_cHNK_SUPPORTED and combined the three types of PNG_text_SUPPORTED

   564     macros, leaving the separate macros also available.

   565   Removed comments on #endifs at the end of many short, non-nested #if-blocks.

   566 version 1.0.5f [December 6, 1999]

   567   Changed makefile.solaris to issue a warning about potential problems when

   568     the ucb "ld" is in the path ahead of the ccs "ld".

   569   Removed "- [date]" from the "synopsis" line in libpng.3 and libpngpf.3.

   570   Added sCAL chunk support (Eric S. Raymond).

   571 version 1.0.5g [December 7, 1999]

   572   Fixed "png_free_spallettes" typo in png.h

   573   Added code to handle new chunks in pngpread.c

   574   Moved PNG_CHNK string macro definitions outside of PNG_NO_EXTERN block

   575   Added "translated_key" to png_text structure and png_write_iTXt().

   576   Added code in pngwrite.c to work around a newly discovered zlib bug.

   577 version 1.0.5h [December 10, 1999]

   578   NOTE: regarding the note for version 1.0.5e, the following must also

   579     be included in your code:

   580         png_text[i].translated_key = NULL;

   581   Unknown chunk handling is now supported.

   582   Option to eliminate all floating point support was added.  Some new

   583     fixed-point functions such as png_set_gAMA_fixed() were added.

   584   Expanded tabs and removed trailing blanks in source files.

   585 version 1.0.5i [December 13, 1999]

   586   Added some type casts to silence compiler warnings.

   587   Renamed "png_free_spalette" to "png_free_spalettes" for consistency.

   588   Removed leading blanks from a #define in pngvcrd.c

   589   Added some parameters to the new png_set_keep_unknown_chunks() function.

   590   Added a test for up->location != 0 in the first instance of writing

   591     unknown chunks in pngwrite.c

   592   Changed "num" to "i" in png_free_spalettes() and png_free_unknowns() to

   593     prevent recursion.

   594   Added png_free_hIST() function.

   595   Various patches to fix bugs in the sCAL and integer cHRM processing,

   596     and to add some convenience macros for use with sCAL.

   597 version 1.0.5j [December 21, 1999]

   598   Changed "unit" parameter of png_write_sCAL from png_byte to int, to work

   599     around buggy compilers.

   600   Added new type "png_fixed_point" for integers that hold float*100000 values

   601   Restored backward compatibility of tEXt/zTXt chunk processing:

   602     Restored the first four members of png_text to the same order as v.1.0.5d.

   603     Added members "lang_key" and "itxt_length" to png_text struct.  Set

   604     text_length=0 when "text" contains iTXt data.  Use the "compression"

   605     member to distinguish among tEXt/zTXt/iTXt types.  Added

   606     PNG_ITXT_COMPRESSION_NONE (1) and PNG_ITXT_COMPRESSION_zTXt(2) macros.

   607     The "Note" above, about backward incompatibility of libpng-1.0.5e, no

   608     longer applies.

   609   Fixed png_read|write_iTXt() to read|write parameters in the right order,

   610     and to write the iTXt chunk after IDAT if it appears in the end_ptr.

   611   Added pnggccrd.c, version of pngvcrd.c Intel assembler for gcc (Greg Roelofs)

   612   Reversed the order of trying to write floating-point and fixed-point gAMA.

   613 version 1.0.5k [December 27, 1999]

   614   Added many parentheses, e.g., "if (a && b & c)" becomes "if (a && (b & c))"

   615   Added png_handle_as_unknown() function (Glenn)

   616   Added png_free_chunk_list() function and chunk_list and num_chunk_list members

   617     of png_ptr.

   618   Eliminated erroneous warnings about multiple sPLT chunks and sPLT-after-PLTE.

   619   Fixed a libpng-1.0.5h bug in pngrutil.c that was issuing erroneous warnings

   620     about ignoring incorrect gAMA with sRGB (gAMA was in fact not ignored)

   621   Added png_free_tRNS(); png_set_tRNS() now malloc's its own trans array (ESR).

   622   Define png_get_int_32 when oFFs chunk is supported as well as when pCAL is.

   623   Changed type of proflen from png_int_32 to png_uint_32 in png_get_iCCP().

   624 version 1.0.5l [January 1, 2000]

   625   Added functions png_set_read_user_chunk_fn() and png_get_user_chunk_ptr()

   626     for setting a callback function to handle unknown chunks and for

   627     retrieving the associated user pointer (Glenn).

   628 version 1.0.5m [January 7, 2000]

   629   Added high-level functions png_read_png(), png_write_png(), png_free_pixels().

   630 version 1.0.5n [January 9, 2000]

   631   Added png_free_PLTE() function, and modified png_set_PLTE() to malloc its

   632     own memory for info_ptr->palette.  This makes it safe for the calling

   633     application to free its copy of the palette any time after it calls

   634     png_set_PLTE().

   635 version 1.0.5o [January 20, 2000]

   636   Cosmetic changes only (removed some trailing blanks and TABs)

   637 version 1.0.5p [January 31, 2000]

   638   Renamed pngdll.mak to makefile.bd32

   639   Cosmetic changes in pngtest.c

   640 version 1.0.5q [February 5, 2000]

   641   Relocated the makefile.solaris warning about PATH problems.

   642   Fixed pngvcrd.c bug by pushing/popping registers in mmxsupport (Bruce Oberg)

   643   Revised makefile.gcmmx

   644   Added PNG_SETJMP_SUPPORTED, PNG_SETJMP_NOT_SUPPORTED, and PNG_ABORT() macros

   645 version 1.0.5r [February 7, 2000]

   646   Removed superfluous prototype for png_get_itxt from png.h

   647   Fixed a bug in pngrtran.c that improperly expanded the background color.

   648   Return *num_text=0 from png_get_text() when appropriate, and fix documentation

   649     of png_get_text() in libpng.txt/libpng.3.

   650 version 1.0.5s [February 18, 2000]

   651   Added "png_jmp_env()" macro to pngconf.h, to help people migrate to the

   652     new error handler that's planned for the next libpng release, and changed

   653     example.c, pngtest.c, and contrib programs to use this macro.

   654   Revised some of the DLL-export macros in pngconf.h (Greg Roelofs)

   655   Fixed a bug in png_read_png() that caused it to fail to expand some images

   656     that it should have expanded.

   657   Fixed some mistakes in the unused and undocumented INCH_CONVERSIONS functions

   658     in pngget.c

   659   Changed the allocation of palette, history, and trans arrays back to

   660     the version 1.0.5 method (linking instead of copying) which restores

   661     backward compatibility with version 1.0.5.  Added some remarks about

   662     that in example.c.  Added "free_me" member to info_ptr and png_ptr

   663     and added png_free_data() function.

   664   Updated makefile.linux and makefile.gccmmx to make directories conditionally.

   665   Made cosmetic changes to pngasmrd.h

   666   Added png_set_rows() and png_get_rows(), for use with png_read|write_png().

   667   Modified png_read_png() to allocate info_ptr->row_pointers only if it

   668     hasn't already been allocated.

   669 version 1.0.5t [March 4, 2000]

   670   Changed png_jmp_env() migration aiding macro to png_jmpbuf().

   671   Fixed "interlace" typo (should be "interlaced") in contrib/gregbook/read2-x.c

   672   Fixed bug with use of PNG_BEFORE_IHDR bit in png_ptr->mode, introduced when

   673     PNG_FLAG_HAVE_CHUNK_HEADER was moved into png_ptr->mode in version 1.0.5b

   674   Files in contrib/gregbook were revised to use png_jmpbuf() and to select

   675     a 24-bit visual if one is available, and to allow abbreviated options.

   676   Files in contrib/pngminus were revised to use the png_jmpbuf() macro.

   677   Removed spaces in makefile.linux and makefile.gcmmx, introduced in 1.0.5s

   678 version 1.0.5u [March 5, 2000]

   679   Simplified the code that detects old png.h in png.c and pngtest.c

   680   Renamed png_spalette (_p, _pp) to png_sPLT_t (_tp, _tpp)

   681   Increased precision of rgb_to_gray calculations from 8 to 15 bits and

   682     added png_set_rgb_to_gray_fixed() function.

   683   Added makefile.bc32 (32-bit Borland C++, C mode)

   684 version 1.0.5v [March 11, 2000]

   685   Added some parentheses to the png_jmpbuf macro definition.

   686   Updated references to the zlib home page, which has moved to freesoftware.com.

   687   Corrected bugs in documentation regarding png_read_row() and png_write_row().

   688   Updated documentation of png_rgb_to_gray calculations in libpng.3/libpng.txt.

   689   Renamed makefile.borland,turboc3 back to makefile.bor,tc3 as in version 1.0.3,

   690     revised borland makefiles; added makefile.ibmvac3 and makefile.gcc (Cosmin)

   691 

   692 version 1.0.6 [March 20, 2000]

   693   Minor revisions of makefile.bor, libpng.txt, and gregbook/rpng2-win.c

   694   Added makefile.sggcc (SGI IRIX with gcc)

   695 version 1.0.6d [April 7, 2000]

   696   Changed sprintf() to strcpy() in png_write_sCAL_s() to work without STDIO

   697   Added data_length parameter to png_decompress_chunk() function

   698   Revised documentation to remove reference to abandoned png_free_chnk functions

   699   Fixed an error in png_rgb_to_gray_fixed()

   700   Revised example.c, usage of png_destroy_write_struct().

   701   Renamed makefile.ibmvac3 to makefile.ibmc, added libpng.icc IBM project file

   702   Added a check for info_ptr->free_me&PNG_FREE_TEXT when freeing text in png.c

   703   Simplify png_sig_bytes() function to remove use of non-ISO-C strdup().

   704 version 1.0.6e [April 9, 2000]

   705   Added png_data_freer() function.

   706   In the code that checks for over-length tRNS chunks, added check of

   707     info_ptr->num_trans as well as png_ptr->num_trans (Matthias Benckmann)

   708   Minor revisions of libpng.txt/libpng.3.

   709   Check for existing data and free it if the free_me flag is set, in png_set_*()

   710     and png_handle_*().

   711   Only define PNG_WEIGHTED_FILTERS_SUPPORTED when PNG_FLOATING_POINT_SUPPORTED

   712     is defined.

   713   Changed several instances of PNG_NO_CONSOLE_ID to PNG_NO_STDIO in pngrutil.c

   714     and mentioned the purposes of the two macros in libpng.txt/libpng.3.

   715 version 1.0.6f [April 14, 2000]

   716   Revised png_set_iCCP() and png_set_rows() to avoid prematurely freeing data.

   717   Add checks in png_set_text() for NULL members of the input text structure.

   718   Revised libpng.txt/libpng.3.

   719   Removed superfluous prototype for png_set_itxt from png.h

   720   Removed "else" from pngread.c, after png_error(), and changed "0" to "length".

   721   Changed several png_errors about malformed ancillary chunks to png_warnings.

   722 version 1.0.6g [April 24, 2000]

   723   Added png_pass-* arrays to pnggccrd.c when PNG_USE_LOCAL_ARRAYS is defined.

   724   Relocated paragraph about png_set_background() in libpng.3/libpng.txt

   725     and other revisions (Matthias Benckmann)

   726   Relocated info_ptr->free_me, png_ptr->free_me, and other info_ptr and

   727     png_ptr members to restore binary compatibility with libpng-1.0.5

   728     (breaks compatibility with libpng-1.0.6).

   729 version 1.0.6h [April 24, 2000]

   730   Changed shared library so-number pattern from 2.x.y.z to xy.z (this builds

   731     libpng.so.10 & libpng.so.10.6h instead of libpng.so.2 & libpng.so.2.1.0.6h)

   732     This is a temporary change for test purposes.

   733 version 1.0.6i [May 2, 2000]

   734   Rearranged some members at the end of png_info and png_struct, to put

   735     unknown_chunks_num and free_me within the original size of the png_structs

   736     and free_me, png_read_user_fn, and png_free_fn within the original png_info,

   737     because some old applications allocate the structs directly instead of

   738     using png_create_*().

   739   Added documentation of user memory functions in libpng.txt/libpng.3

   740   Modified png_read_png so that it will use user_allocated row_pointers

   741     if present, unless free_me directs that it be freed, and added description

   742     of the use of png_set_rows() and png_get_rows() in libpng.txt/libpng.3.

   743   Added PNG_LEGACY_SUPPORTED macro, and #ifdef out all new (since version

   744     1.00) members of png_struct and png_info, to regain binary compatibility

   745     when you define this macro.  Capabilities lost in this event

   746     are user transforms (new in version 1.0.0),the user transform pointer

   747     (new in version 1.0.2), rgb_to_gray (new in 1.0.5), iCCP, sCAL, sPLT,

   748     the high-level interface, and unknown chunks support (all new in 1.0.6).

   749     This was necessary because of old applications that allocate the structs

   750     directly as authors were instructed to do in libpng-0.88 and earlier,

   751     instead of using png_create_*().

   752   Added modes PNG_CREATED_READ_STRUCT and PNG_CREATED_WRITE_STRUCT which

   753     can be used to detect codes that directly allocate the structs, and

   754     code to check these modes in png_read_init() and png_write_init() and

   755     generate a libpng error if the modes aren't set and PNG_LEGACY_SUPPORTED

   756     was not defined.

   757   Added makefile.intel and updated makefile.watcom (Pawel Mrochen)

   758 version 1.0.6j [May 3, 2000]

   759   Overloaded png_read_init() and png_write_init() with macros that convert

   760     calls to png_read_init_2() or png_write_init_2() that check the version

   761     and structure sizes.

   762 version 1.0.7beta11 [May 7, 2000]

   763   Removed the new PNG_CREATED_READ_STRUCT and PNG_CREATED_WRITE_STRUCT modes

   764     which are no longer used.

   765   Eliminated the three new members of png_text when PNG_LEGACY_SUPPORTED is

   766     defined or when neither PNG_READ_iTXt_SUPPORTED nor PNG_WRITE_iTXT_SUPPORTED

   767     is defined.

   768   Made PNG_NO_READ|WRITE_iTXt the default setting, to avoid memory

   769     overrun when old applications fill the info_ptr->text structure directly.

   770   Added PNGAPI macro, and added it to the definitions of all exported functions.

   771   Relocated version macro definitions ahead of the includes of zlib.h and

   772     pngconf.h in png.h.

   773 version 1.0.7beta12 [May 12, 2000]

   774   Revised pngset.c to avoid a problem with expanding the png_debug macro.

   775   Deleted some extraneous defines from pngconf.h

   776   Made PNG_NO_CONSOLE_IO the default condition when PNG_BUILD_DLL is defined.

   777   Use MSC _RPTn debugging instead of fprintf if _MSC_VER is defined.

   778   Added png_access_version_number() function.

   779   Check for mask&PNG_FREE_CHNK (for TEXT, SCAL, PCAL) in png_free_data().

   780   Expanded libpng.3/libpng.txt information about png_data_freer().

   781 version 1.0.7beta14 [May 17, 2000] (beta13 was not published)

   782   Changed pnggccrd.c and pngvcrd.c to handle bad adaptive filter types as

   783     warnings instead of errors, as pngrutil.c does.

   784   Set the PNG_INFO_IDAT valid flag in png_set_rows() so png_write_png()

   785     will actually write IDATs.

   786   Made the default PNG_USE_LOCAL_ARRAYS depend on PNG_DLL instead of WIN32.

   787   Make png_free_data() ignore its final parameter except when freeing data

   788     that can have multiple instances (text, sPLT, unknowns).

   789   Fixed a new bug in png_set_rows().

   790   Removed info_ptr->valid tests from png_free_data(), as in version 1.0.5.

   791   Added png_set_invalid() function.

   792   Fixed incorrect illustrations of png_destroy_write_struct() in example.c.

   793 version 1.0.7beta15 [May 30, 2000]

   794   Revised the deliberately erroneous Linux setjmp code in pngconf.h to produce

   795     fewer error messages.

   796   Rearranged checks for Z_OK to check the most likely path first in pngpread.c

   797     and pngwutil.c.

   798   Added checks in pngtest.c for png_create_*() returning NULL, and mentioned

   799     in libpng.txt/libpng.3 the need for applications to check this.

   800   Changed names of png_default_*() functions in pngtest to pngtest_*().

   801   Changed return type of png_get_x|y_offset_*() from png_uint_32 to png_int_32.

   802   Fixed some bugs in the unused PNG_INCH_CONVERSIONS functions in pngget.c

   803   Set each pointer to NULL after freeing it in png_free_data().

   804   Worked around a problem in pngconf.h; AIX's strings.h defines an "index"

   805     macro that conflicts with libpng's png_color_16.index. (Dimitri Papadapoulos)

   806   Added "msvc" directory with MSVC++ project files (Simon-Pierre Cadieux).

   807 version 1.0.7beta16 [June 4, 2000]

   808   Revised the workaround of AIX string.h "index" bug.

   809   Added a check for overlength PLTE chunk in pngrutil.c.

   810   Added PNG_NO_POINTER_INDEXING macro to use array-indexing instead of pointer

   811     indexing in pngrutil.c and pngwutil.c to accommodate a buggy compiler.

   812   Added a warning in png_decompress_chunk() when it runs out of data, e.g.

   813     when it tries to read an erroneous PhotoShop iCCP chunk.

   814   Added PNG_USE_DLL macro.

   815   Revised the copyright/disclaimer/license notice.

   816   Added contrib/msvctest directory

   817 version 1.0.7rc1 [June 9, 2000]

   818   Corrected the definition of PNG_TRANSFORM_INVERT_ALPHA  (0x0400 not 0x0200)

   819   Added contrib/visupng directory (Willem van Schaik)

   820 version 1.0.7beta18 [June 23, 2000]

   821   Revised PNGAPI definition, and pngvcrd.c to work with __GCC__

   822     and do not redefine PNGAPI if it is passed in via a compiler directive.

   823   Revised visupng/PngFile.c to remove returns from within the Try block.

   824   Removed leading underscores from "_PNG_H" and "_PNG_SAVE_BSD_SOURCE" macros.

   825   Updated contrib/visupng/cexcept.h to version 1.0.0.

   826   Fixed bugs in pngwrite.c and pngwutil.c that prevented writing iCCP chunks.

   827 version 1.0.7rc2 [June 28, 2000]

   828   Updated license to include disclaimers required by UCITA.

   829   Fixed "DJBPP" typo in pnggccrd.c introduced in beta18.

   830 

   831 version 1.0.7 [July 1, 2000]

   832   Revised the definition of "trans_values" in libpng.3/libpng.txt

   833 version 1.0.8beta1 [July 8, 2000]

   834   Added png_free(png_ptr, key) two places in pngpread.c to stop memory leaks.

   835   Changed PNG_NO_STDIO to PNG_NO_CONSOLE_IO, several places in pngrutil.c and

   836      pngwutil.c.

   837   Changed PNG_EXPORT_VAR to use PNG_IMPEXP, in pngconf.h.

   838   Removed unused "#include <assert.h>" from png.c

   839   Added WindowsCE support.

   840   Revised pnggccrd.c to work with gcc-2.95.2 and in the Cygwin environment.

   841 version 1.0.8beta2 [July 10, 2000]

   842   Added project files to the wince directory and made further revisions

   843      of pngtest.c, pngrio.c, and pngwio.c in support of WindowsCE.

   844 version 1.0.8beta3 [July 11, 2000]

   845   Only set the PNG_FLAG_FREE_TRNS or PNG_FREE_TRNS flag in png_handle_tRNS()

   846      for indexed-color input files to avoid potential double-freeing trans array

   847      under some unusual conditions; problem was introduced in version 1.0.6f.

   848   Further revisions to pngtest.c and files in the wince subdirectory.

   849 version 1.0.8beta4 [July 14, 2000]

   850   Added the files pngbar.png and pngbar.jpg to the distribution.

   851   Added makefile.cygwin, and cygwin support in pngconf.h

   852   Added PNG_NO_ZALLOC_ZERO macro (makes png_zalloc skip zeroing memory)

   853 version 1.0.8rc1 [July 16, 2000]

   854   Revised png_debug() macros and statements to eliminate compiler warnings.

   855 

   856 version 1.0.8 [July 24, 2000]

   857   Added png_flush() in pngwrite.c, after png_write_IEND().

   858   Updated makefile.hpux to build a shared library.

   859 version 1.0.9beta1 [November 10, 2000]

   860   Fixed typo in scripts/makefile.hpux

   861   Updated makevms.com in scripts and contrib/* and contrib/* (Martin Zinser)

   862   Fixed seqence-point bug in contrib/pngminus/png2pnm (Martin Zinser)

   863   Changed "cdrom.com" in documentation to "libpng.org"

   864   Revised pnggccrd.c to get it all working, and updated makefile.gcmmx (Greg).

   865   Changed type of "params" from voidp to png_voidp in png_read|write_png().

   866   Make sure PNGAPI and PNG_IMPEXP are defined in pngconf.h.

   867   Revised the 3 instances of WRITEFILE in pngtest.c.

   868   Relocated "msvc" and "wince" project subdirectories into "dll" subdirectory.

   869   Updated png.rc in dll/msvc project

   870   Revised makefile.dec to define and use LIBPATH and INCPATH

   871   Increased size of global png_libpng_ver[] array from 12 to 18 chars.

   872   Made global png_libpng_ver[], png_sig[] and png_pass_*[] arrays const.

   873   Removed duplicate png_crc_finish() from png_handle_bKGD() function.

   874   Added a warning when application calls png_read_update_info() multiple times.

   875   Revised makefile.cygwin

   876   Fixed bugs in iCCP support in pngrutil.c and pngwutil.c.

   877   Replaced png_set_empty_plte_permitted() with png_permit_mng_features().

   878 version 1.0.9beta2 [November 19, 2000]

   879   Renamed the "dll" subdirectory "projects".

   880   Added borland project files to "projects" subdirectory.

   881   Set VS_FF_PRERELEASE and VS_FF_PATCHED flags in msvc/png.rc when appropriate.

   882   Add error message in png_set_compression_buffer_size() when malloc fails.

   883 version 1.0.9beta3 [November 23, 2000]

   884   Revised PNG_LIBPNG_BUILD_TYPE macro in png.h, used in the msvc project.

   885   Removed the png_flush() in pngwrite.c that crashes some applications

   886     that don't set png_output_flush_fn.

   887   Added makefile.macosx and makefile.aix to scripts directory.

   888 version 1.0.9beta4 [December 1, 2000]

   889   Change png_chunk_warning to png_warning in png_check_keyword().

   890   Increased the first part of msg buffer from 16 to 18 in png_chunk_error().

   891 version 1.0.9beta5 [December 15, 2000]

   892   Added support for filter method 64 (for PNG datastreams embedded in MNG).

   893 version 1.0.9beta6 [December 18, 2000]

   894   Revised png_set_filter() to accept filter method 64 when appropriate.

   895   Added new PNG_HAVE_PNG_SIGNATURE bit to png_ptr->mode and use it to

   896     help prevent applications from using MNG features in PNG datastreams.

   897   Added png_permit_mng_features() function.

   898   Revised libpng.3/libpng.txt.  Changed "filter type" to "filter method".

   899 version 1.0.9rc1 [December 23, 2000]

   900   Revised test for PNG_HAVE_PNG_SIGNATURE in pngrutil.c

   901   Fixed error handling of unknown compression type in png_decompress_chunk().

   902   In pngconf.h, define __cdecl when _MSC_VER is defined.

   903 version 1.0.9beta7 [December 28, 2000]

   904   Changed PNG_TEXT_COMPRESSION_zTXt to PNG_COMPRESSION_TYPE_BASE several places.

   905   Revised memory management in png_set_hIST and png_handle_hIST in a backward

   906     compatible manner.  PLTE and tRNS were revised similarly.

   907   Revised the iCCP chunk reader to ignore trailing garbage.

   908 version 1.0.9beta8 [January 12, 2001]

   909   Moved pngasmrd.h into pngconf.h.

   910   Improved handling of out-of-spec garbage iCCP chunks generated by PhotoShop.

   911 version 1.0.9beta9 [January 15, 2001]

   912   Added png_set_invalid, png_permit_mng_features, and png_mmx_supported to

   913     wince and msvc project module definition files.

   914   Minor revision of makefile.cygwin.

   915   Fixed bug with progressive reading of narrow interlaced images in pngpread.c

   916 version 1.0.9beta10 [January 16, 2001]

   917   Do not typedef png_FILE_p in pngconf.h when PNG_NO_STDIO is defined.

   918   Fixed "png_mmx_supported" typo in project definition files.

   919 version 1.0.9beta11 [January 19, 2001]

   920   Updated makefile.sgi to make shared library.

   921   Removed png_mmx_support() function and disabled PNG_MNG_FEATURES_SUPPORTED

   922     by default, for the benefit of DLL forward compatibility.  These will

   923     be re-enabled in version 1.2.0.

   924 version 1.0.9rc2 [January 22, 2001]

   925   Revised cygwin support.

   926 

   927 version 1.0.9 [January 31, 2001]

   928   Added check of cygwin's ALL_STATIC in pngconf.h

   929   Added "-nommx" parameter to contrib/gregbook/rpng2-win and rpng2-x demos.

   930 version 1.0.10beta1 [March 14, 2001]

   931   Revised makefile.dec, makefile.sgi, and makefile.sggcc; added makefile.hpgcc.

   932   Reformatted libpng.3 to eliminate bad line breaks.

   933   Added checks for _mmx_supported in the read_filter_row function of pnggccrd.c

   934   Added prototype for png_mmx_support() near the top of pnggccrd.c

   935   Moved some error checking from png_handle_IHDR to png_set_IHDR.

   936   Added PNG_NO_READ_SUPPORTED and PNG_NO_WRITE_SUPPORTED macros.

   937   Revised png_mmx_support() function in pnggccrd.c

   938   Restored version 1.0.8 PNG_WRITE_EMPTY_PLTE_SUPPORTED behavior in pngwutil.c

   939   Fixed memory leak in contrib/visupng/PngFile.c

   940   Fixed bugs in png_combine_row() in pnggccrd.c and pngvcrd.c (C version)

   941   Added warnings when retrieving or setting gamma=0.

   942   Increased the first part of msg buffer from 16 to 18 in png_chunk_warning().

   943 version 1.0.10rc1 [March 23, 2001]

   944   Changed all instances of memcpy, strcpy, and strlen to png_memcpy, png_strcpy,

   945     and png_strlen.

   946   Revised png_mmx_supported() function in pnggccrd.c to return proper value.

   947   Fixed bug in progressive reading (pngpread.c) with small images (height < 8).

   948 

   949 version 1.0.10 [March 30, 2001]

   950   Deleted extraneous space (introduced in 1.0.9) from line 42 of makefile.cygwin

   951   Added beos project files (Chris Herborth)

   952 version 1.0.11beta1 [April 3, 2001]

   953   Added type casts on several png_malloc() calls (Dimitri Papadapoulos).

   954   Removed a no-longer needed AIX work-around from pngconf.h

   955   Changed several "//" single-line comments to C-style in pnggccrd.c

   956 version 1.0.11beta2 [April 11, 2001]

   957   Removed PNGAPI from several functions whose prototypes did not have PNGAPI.

   958   Updated scripts/pngos2.def

   959 version 1.0.11beta3 [April 14, 2001]

   960   Added checking the results of many instances of png_malloc() for NULL

   961 version 1.0.11beta4 [April 20, 2001]

   962   Undid the changes from version 1.0.11beta3.  Added a check for NULL return

   963     from user's malloc_fn().

   964   Removed some useless type casts of the NULL pointer.

   965   Added makefile.netbsd

   966 

   967 version 1.0.11 [April 27, 2001]

   968   Revised makefile.netbsd

   969 version 1.0.12beta1 [May 14, 2001]

   970   Test for Windows platform in pngconf.h when including malloc.h (Emmanuel Blot)

   971   Updated makefile.cygwin and handling of Cygwin's ALL_STATIC in pngconf.h

   972   Added some never-to-be-executed code in pnggccrd.c to quiet compiler warnings.

   973   Eliminated the png_error about apps using png_read|write_init().  Instead,

   974     libpng will reallocate the png_struct and info_struct if they are too small.

   975     This retains future binary compatibility for old applications written for

   976     libpng-0.88 and earlier.

   977 version 1.2.0beta1 [May 6, 2001]

   978   Bumped DLLNUM to 2.

   979   Re-enabled PNG_MNG_FEATURES_SUPPORTED and enabled PNG_ASSEMBLER_CODE_SUPPORTED

   980     by default.

   981   Added runtime selection of MMX features.

   982   Added png_set_strip_error_numbers function and related macros.

   983 version 1.2.0beta2 [May 7, 2001]

   984   Finished merging 1.2.0beta1 with version 1.0.11

   985   Added a check for attempts to read or write PLTE in grayscale PNG datastreams.

   986 version 1.2.0beta3 [May 17, 2001]

   987   Enabled user memory function by default.

   988   Modified png_create_struct so it passes user mem_ptr to user memory allocator.

   989   Increased png_mng_features flag from png_byte to png_uint_32.

   990   Bumped shared-library (so-number) and dll-number to 3.

   991 version 1.2.0beta4 [June 23, 2001]

   992   Check for missing profile length field in iCCP chunk and free chunk_data

   993      in case of truncated iCCP chunk.

   994   Bumped shared-library number to 3 in makefile.sgi and makefile.sggcc

   995   Bumped dll-number from 2 to 3 in makefile.cygwin

   996   Revised contrib/gregbook/rpng*-x.c to avoid a memory leak and to exit cleanly

   997      if user attempts to run it on an 8-bit display.

   998   Updated contrib/gregbook

   999   Use png_malloc instead of png_zalloc to allocate palette in pngset.c

  1000   Updated makefile.ibmc

  1001   Added some typecasts to eliminate gcc 3.0 warnings.  Changed prototypes

  1002      of png_write_oFFS width and height from png_uint_32 to png_int_32.

  1003   Updated example.c

  1004   Revised prototypes for png_debug_malloc and png_debug_free in pngtest.c

  1005 version 1.2.0beta5 [August 8, 2001]

  1006   Revised contrib/gregbook

  1007   Revised makefile.gcmmx

  1008   Revised pnggccrd.c to conditionally compile some thread-unsafe code only

  1009      when PNG_THREAD_UNSAFE_OK is defined.

  1010   Added tests to prevent pngwutil.c from writing a bKGD or tRNS chunk with

  1011      value exceeding 2^bit_depth-1

  1012   Revised makefile.sgi and makefile.sggcc

  1013   Replaced calls to fprintf(stderr,...) with png_warning() in pnggccrd.c

  1014   Removed restriction that do_invert_mono only operate on 1-bit opaque files

  1015 

  1016 version 1.2.0 [September 1, 2001]

  1017   Changed a png_warning() to png_debug() in pnggccrd.c

  1018   Fixed contrib/gregbook/rpng-x.c, rpng2-x.c to avoid crash with XFreeGC().

  1019 version 1.2.1beta1 [October 19, 2001]

  1020   Revised makefile.std in contrib/pngminus

  1021   Include background_1 in png_struct regardless of gamma support.

  1022   Revised makefile.netbsd and makefile.macosx, added makefile.darwin.

  1023   Revised example.c to provide more details about using row_callback().

  1024 version 1.2.1beta2 [October 25, 2001]

  1025   Added type cast to each NULL appearing in a function call, except for

  1026     WINCE functions.

  1027   Added makefile.so9.

  1028 version 1.2.1beta3 [October 27, 2001]

  1029   Removed type casts from all NULLs.

  1030   Simplified png_create_struct_2().

  1031 version 1.2.1beta4 [November 7, 2001]

  1032   Revised png_create_info_struct() and png_creat_struct_2().

  1033   Added error message if png_write_info() was omitted.

  1034   Type cast NULLs appearing in function calls when _NO_PROTO or

  1035     PNG_TYPECAST_NULL is defined.

  1036 version 1.2.1rc1 [November 24, 2001]

  1037   Type cast NULLs appearing in function calls except when PNG_NO_TYPECAST_NULL

  1038     is defined.

  1039   Changed typecast of "size" argument to png_size_t in pngmem.c calls to

  1040     the user malloc_fn, to agree with the prototype in png.h

  1041   Added a pop/push operation to pnggccrd.c, to preserve Eflag (Maxim Sobolev)

  1042   Updated makefile.sgi to recognize LIBPATH and INCPATH.

  1043   Updated various makefiles so "make clean" does not remove previous major

  1044     version of the shared library.

  1045 version 1.2.1rc2 [December 4, 2001]

  1046   Always allocate 256-entry internal palette, hist, and trans arrays, to

  1047     avoid out-of-bounds memory reference caused by invalid PNG datastreams.

  1048   Added a check for prefix_length > data_length in iCCP chunk handler.

  1049 

  1050 version 1.2.1 [December 7, 2001]

  1051   None.

  1052 version 1.2.2beta1 [February 22, 2002]

  1053   Fixed a bug with reading the length of iCCP profiles (Larry Reeves).

  1054   Revised makefile.linux, makefile.gcmmx, and makefile.sgi to generate

  1055     libpng.a, libpng12.so (not libpng.so.3), and libpng12/png.h

  1056   Revised makefile.darwin to remove "-undefined suppress" option.

  1057   Added checks for gamma and chromaticity values over 21474.83, which exceed

  1058     the limit for PNG unsigned 32-bit integers when encoded.

  1059   Revised calls to png_create_read_struct() and png_create_write_struct()

  1060     for simpler debugging.

  1061   Revised png_zalloc() so zlib handles errors (uses PNG_FLAG_MALLOC_NULL_MEM_OK)

  1062 version 1.2.2beta2 [February 23, 2002]

  1063   Check chunk_length and idat_size for invalid (over PNG_MAX_UINT) lengths.

  1064   Check for invalid image dimensions in png_get_IHDR.

  1065   Added missing "fi;" in the install target of the SGI makefiles.

  1066   Added install-static to all makefiles that make shared libraries.

  1067   Always do gamma compensation when image is partially transparent.

  1068 version 1.2.2beta3 [March 7, 2002]

  1069   Compute background.gray and background_1.gray even when color_type is RGB

  1070     in case image gets reduced to gray later.

  1071   Modified shared-library makefiles to install pkgconfig/libpngNN.pc.

  1072   Export (with PNGAPI) png_zalloc, png_zfree, and png_handle_as_unknown

  1073   Removed unused png_write_destroy_info prototype from png.h

  1074   Eliminated incorrect use of width_mmx from pnggccrd.c in pixel_bytes == 8 case

  1075   Added install-shared target to all makefiles that make shared libraries.

  1076   Stopped a double free of palette, hist, and trans when not using free_me.

  1077   Added makefile.32sunu for Sun Ultra 32 and makefile.64sunu for Sun Ultra 64.

  1078 version 1.2.2beta4 [March 8, 2002]

  1079   Compute background.gray and background_1.gray even when color_type is RGB

  1080     in case image gets reduced to gray later (Jason Summers).

  1081   Relocated a misplaced /bin/rm in the "install-shared" makefile targets

  1082   Added PNG_1_0_X macro which can be used to build a 1.0.x-compatible library.

  1083 version 1.2.2beta5 [March 26, 2002]

  1084   Added missing PNGAPI to several function definitions.

  1085   Check for invalid bit_depth or color_type in png_get_IHDR(), and

  1086     check for missing PLTE or IHDR in png_push_read_chunk() (Matthias Clasen).

  1087   Revised iTXt support to accept NULL for lang and lang_key.

  1088   Compute gamma for color components of background even when color_type is gray.

  1089   Changed "()" to "{}" in scripts/libpng.pc.in.

  1090   Revised makefiles to put png.h and pngconf.h only in $prefix/include/libpngNN

  1091   Revised makefiles to make symlink to libpng.so.NN in addition to libpngNN.so

  1092 version 1.2.2beta6 [March 31, 2002]

  1093 version 1.0.13beta1 [March 31, 2002]

  1094   Prevent png_zalloc() from trying to memset memory that it failed to acquire.

  1095   Add typecasts of PNG_MAX_UINT in pngset_cHRM_fixed() (Matt Holgate).

  1096   Ensure that the right function (user or default) is used to free the

  1097     png_struct after an error in png_create_read_struct_2().

  1098 version 1.2.2rc1 [April 7, 2002]

  1099 version 1.0.13rc1 [April 7, 2002]

  1100   Save the ebx register in pnggccrd.c (Sami Farin)

  1101   Add "mem_ptr = png_ptr->mem_ptr" in png_destroy_write_struct() (Paul Gardner).

  1102   Updated makefiles to put headers in include/libpng and remove old include/*.h.

  1103 

  1104 version 1.2.2 [April 15, 2002]

  1105 version 1.0.13 [April 15, 2002]

  1106   Revised description of png_set_filter() in libpng.3/libpng.txt.

  1107   Revised makefile.netbsd and added makefile.neNNbsd and makefile.freebsd

  1108 version 1.0.13patch01 [April 17, 2002]

  1109 version 1.2.2patch01 [April 17, 2002]

  1110   Changed ${PNGMAJ}.${PNGVER} bug to ${PNGVER} in makefile.sgi and makefile.sggcc

  1111   Fixed VER -> PNGVER typo in makefile.macosx and added install-static to install

  1112   Added install: target to makefile.32sunu and makefile.64sunu

  1113 version 1.0.13patch03 [April 18, 2002]

  1114 version 1.2.2patch03 [April 18, 2002]

  1115   Revised 15 makefiles to link libpng.a to libpngNN.a and the include libpng

  1116   subdirectory to libpngNN subdirectory without the full pathname.

  1117   Moved generation of libpng.pc from "install" to "all" in 15 makefiles.

  1118 version 1.2.3rc1 [April 28, 2002]

  1119   Added install-man target to 15 makefiles (Dimitri Papadopolous-Orfanos).

  1120   Added $(DESTDIR) feature to 24 makefiles (Tim Mooney)

  1121   Fixed bug with $prefix, should be $(prefix) in makefile.hpux.

  1122   Updated cygwin-specific portion of pngconf.h and revised makefile.cygwin

  1123   Added a link from libpngNN.pc to libpng.pc in 15 makefiles.

  1124   Added links from include/libpngNN/*.h to include/*.h in 24 makefiles.

  1125   Revised makefile.darwin to make relative links without full pathname.

  1126   Added setjmp() at the end of png_create_*_struct_2() in case user forgets

  1127     to put one in their application.

  1128   Restored png_zalloc() and png_zfree() prototypes to version 1.2.1 and

  1129     removed them from module definition files.

  1130 version 1.2.3rc2 [May 1, 2002]

  1131   Fixed bug in reporting number of channels in pngget.c and pngset.c,

  1132     that was introduced in version 1.2.2beta5.

  1133   Exported png_zalloc(), png_zfree(), png_default_read(), png_default_write(),

  1134     png_default_flush(), and png_push_fill_buffer() and included them in