[master] Revise libpng*.txt

about calling png_set_IHDR() multiple times and about the order
of color samples in the tRNS chunk.

CHANGES

@@ -1179,7 +1179,7 @@ version 1.2.4beta3 [June 28, 2002]
   Plugged memory leak of row_buf in pngtest.c when there is a png_error().
   Detect buffer overflow in pngpread.c when IDAT is corrupted with extra data.
   Added "test-installed" target to makefile.32sunu, makefile.64sunu,
-    makefile.beos, makefile.darwin, makefile.dec, makefile.macosx, 
+    makefile.beos, makefile.darwin, makefile.dec, makefile.macosx,
     makefile.solaris, makefile.hpux, makefile.hpgcc, and makefile.so9.
 version 1.2.4rc1 and 1.0.14rc1 [July 2, 2002]
   Added "test-installed" target to makefile.cygwin and makefile.sco.
@@ -1387,7 +1387,7 @@ version 1.2.8beta5 [November 20, 2004]
   Use png_ptr->flags instead of png_ptr->transformations to pass
     PNG_STRIP_ALPHA info to png_do_strip_filler(), to preserve ABI
     compatibility.
-  Revised handling of SPECIALBUILD, PRIVATEBUILD, 
+  Revised handling of SPECIALBUILD, PRIVATEBUILD,
     PNG_LIBPNG_BUILD_SPECIAL_STRING and PNG_LIBPNG_BUILD_PRIVATE_STRING.
 version 1.2.8rc1 [November 24, 2004]
   Moved handling of BUILD macros from pngconf.h to png.h
@@ -1685,14 +1685,14 @@ version 1.2.16beta1 [January 6, 2007]
 
 version 1.2.16beta2 [January 16, 2007]
   Revised scripts/CMakeLists.txt
- 
+
 version 1.0.24, 1.2.16 [January 31, 2007]
   No changes.
- 
+
 version 1.2.17beta1 [March 6, 2007]
   Revised scripts/CMakeLists.txt to install both shared and static libraries.
   Deleted a redundant line from pngset.c.
- 
+
 version 1.2.17beta2 [April 26, 2007]
   Relocated misplaced test for png_ptr == NULL in pngpread.c
   Change "==" to "&" for testing PNG_RGB_TO_GRAY_ERR & PNG_RGB_TO_GRAY_WARN
@@ -1713,7 +1713,7 @@ version 1.2.17rc2 [May 8, 2007]
   Added png_ptr->unknown_chunk to hold working unknown chunk data, so it
     can be free'ed in case of error.  Revised unknown chunk handling in
     pngrutil.c and pngpread.c to use this structure.
- 
+
 version 1.2.17rc3 [May 8, 2007]
   Revised symbol-handling in configure script.
 
@@ -2389,21 +2389,24 @@ version 1.2.37beta03 [May 20, 2009]
     is only one makefile in those directories, and revised the README files
     accordingly.
   Reformated sources in libpng style (3-space indentation, comment format)
-  
+
 version 1.2.37rc01 [May 27, 2009]
   No changes.
 
 versions 1.2.37 and 1.0.45 [June 4, 2009]
-  Reformatted several remaining "else statement;" and "if () statment;" into
+  Reformatted several remaining "else statement;" and "if () statement;" into
     two lines.
   Added "#define PNG_NO_WRITE_SWAP" to contrib/pngminim/encoder/pngusr.h
     and "define PNG_NO_READ_SWAP" to decoder/pngusr.h and preader/pngusr.h
   Added sections about the git repository and our coding style to the
     documentation (merged from libpng-1.4.0beta62)
-  Added a section about using png_get_io_ptr() in configure scripts to detect
+  Added a section to the libpng documentation about using png_get_io_ptr()
-    the presence of libpng.
+    in configure scripts to detect the presence of libpng.
 
-versions 1.2.38 [June 5, 2009]
+versions 1.2.38 [June 8, 2009]
+  Revised libpng*.txt and libpng.3 to mention calling png_set_IHDR()
+    multiple times and to specify the sample order in the tRNS chunk,
+    because the ISO PNG specification has a typo in the tRNS table.
 
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libpng-1.2.38beta01.txt

@@ -1,6 +1,6 @@
 libpng.txt - A description on how to use and modify libpng
 
- libpng version 1.2.38beta01 - June 5, 2009
+ libpng version 1.2.38beta01 - June 8, 2009
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2009 Glenn Randers-Pehrson
@@ -9,7 +9,7 @@ libpng.txt - A description on how to use and modify libpng
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.2.38beta01 - June 5, 2009
+ libpng versions 0.97, January 1998, through 1.2.38beta01 - June 8, 2009
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2009 Glenn Randers-Pehrson
 
@@ -1817,6 +1817,10 @@ other png_set_*() functions, which might require access to some of
 the IHDR settings.  The remaining png_set_*() functions can be called
 in any order.
 
+If you wish, you can reset the compression_type, interlace_type, or
+filter_method later by calling png_set_IHDR() again; if you do this, the
+width, height, bit_depth, and color_type must be the same in each call.
+
     png_set_PLTE(png_ptr, info_ptr, palette,
        num_palette);
     palette        - the palette for the file
@@ -1878,8 +1882,9 @@ in any order.
        trans_values);
     trans          - array of transparent entries for
                      palette (PNG_INFO_tRNS)
-    trans_values   - graylevel or color sample values of
+    trans_values   - graylevel or color sample values
-                     the single transparent color for
+                     (in order red, green, blue) of the
+                     single transparent color for
                      non-paletted images (PNG_INFO_tRNS)
     num_trans      - number of transparent entries
                      (PNG_INFO_tRNS)
@@ -3016,7 +3021,7 @@ We don't use C++ style ("//") comments. We have, however,
 used them in the past in some now-abandoned MMX assembler
 code.
 
-Functions and their curly brackets are not indented, and
+Functions and their curly braces are not indented, and
 exported functions are marked with PNGAPI:
 
  /* This is a public function that is visible to
@@ -3060,7 +3065,7 @@ source.
 
 XIII. Y2K Compliance in libpng
 
-June 5, 2009
+June 8, 2009
 
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.