[devel] Removed the ACCURATE and LEGACY options (they are no longer useable)

Fixed some compiliation problems with scaling options.

ANNOUNCE

@@ -195,7 +195,9 @@ Version 1.5.4beta01 [June 14, 2011]
 
 Version 1.5.4beta02 [June 14, 2011]
   Fixed and clarified LEGACY 16-to-8 scaling code.
-  Added png_set_chop_16() API.
+  Added png_set_chop_16() API, to match inaccurate results from previous
+    libpng versions.
+  Removed the ACCURATE and LEGACY options (they are no longer useable)
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net:
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CHANGES

@@ -3458,7 +3458,9 @@ Version 1.5.4beta01 [June 14, 2011]
 
 Version 1.5.4beta02 [June 14, 2011]
   Fixed and clarified LEGACY 16-to-8 scaling code.
-  Added png_set_chop_16() API.
+  Added png_set_chop_16() API, to match inaccurate results from previous
+    libpng versions.
+  Removed the ACCURATE and LEGACY options (they are no longer useable)
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

example.c

@@ -2,7 +2,7 @@
 #if 0 /* in case someone actually tries to compile this */
 
 /* example.c - an example of using libpng
- * Last changed in libpng 1.5.3 [(PENDING RELEASE)]
+ * Last changed in libpng 1.5.4 [(PENDING RELEASE)]
  * This file has been placed in the public domain by the authors.
  * Maintained 1998-2011 Glenn Randers-Pehrson
  * Maintained 1996, 1997 Andreas Dilger)

png.h

@@ -1423,6 +1423,8 @@ PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structp png_ptr,
 #endif
 
 #ifdef PNG_READ_16_TO_8_SUPPORTED
+/* The following is always done from 1.5.4: */
+#define PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
 /* Scale a 16-bit depth file down to 8-bit, accurately. */
 PNG_EXPORT(48, void, png_set_strip_16, (png_structp png_ptr));
 /* Strip the second byte of information from a 16-bit depth file. */

pngconf.h

@@ -1,7 +1,7 @@
 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.5.4beta01 - June 14, 2011
+ * libpng version 1.5.4beta02 - June 14, 2011
  *
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)

pngerror.c

@@ -1,7 +1,7 @@
 
 /* pngerror.c - stub functions for i/o and memory allocation
  *
- * Last changed in libpng 1.5.3 [(PENDING RELEASE)]
+ * Last changed in libpng 1.5.4 [(PENDING RELEASE)]
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

pngmem.c

@@ -1,7 +1,7 @@
 
 /* pngmem.c - stub functions for memory allocation
  *
- * Last changed in libpng 1.5.3 [(PENDING RELEASE)]
+ * Last changed in libpng 1.5.4 [(PENDING RELEASE)]
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

pngpriv.h

@@ -6,7 +6,7 @@
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
- * Last changed in libpng 1.5.3 [(PENDING RELEASE)]
+ * Last changed in libpng 1.5.4 [(PENDING RELEASE)]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
@@ -298,7 +298,7 @@ typedef PNG_CONST png_uint_16p FAR * png_const_uint_16pp;
 #define PNG_ENCODE_ALPHA      0x800000L  /* Added to libpng-1.5.3 */
 #define PNG_ADD_ALPHA         0x1000000L  /* Added to libpng-1.2.7 */
 #define PNG_EXPAND_tRNS       0x2000000L  /* Added to libpng-1.2.9 */
-                       /*   0x4000000L  unused */
+#define PNG_CHOP_16_TO_8      0x4000000L
                        /*   0x8000000L  unused */
                        /*  0x10000000L  unused */
                        /*  0x20000000L  unused */
@@ -820,8 +820,13 @@ PNG_EXTERN void png_do_invert PNGARG((png_row_infop row_info,
 #endif
 
 #ifdef PNG_READ_16_TO_8_SUPPORTED
+PNG_EXTERN void png_do_scale_16_to_8 PNGARG((png_row_infop row_info,
+    png_bytep row));
+
 PNG_EXTERN void png_do_chop PNGARG((png_row_infop row_info,
     png_bytep row));
+PNG_EXTERN void png_do_scale_16_to_8 PNGARG((png_row_infop row_info,
+    png_bytep row));
 #endif
 
 #ifdef PNG_READ_QUANTIZE_SUPPORTED

pngread.c

@@ -1,7 +1,7 @@
 
 /* pngread.c - read a PNG file
  *
- * Last changed in libpng 1.5.3 [(PENDING RELEASE)]
+ * Last changed in libpng 1.5.4 [(PENDING RELEASE)]
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

pngrtran.c

@@ -1453,11 +1453,7 @@ png_init_read_transformations(png_structp png_ptr)
        * The PNG_BACKGROUND_EXPAND code above does not expand to 16 bits at
        * present, so that case is ok (until do_expand_16 is moved.)
        */
-#ifdef PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
 #     define CHOP(x) (x)=((png_uint_16)(((png_uint_32)(x)*255+32895) >> 16))
-#else
-#     define CHOP(x) ((png_uint_16)((2*(png_uint_32)(x) + 257)/514))
-#endif
       CHOP(png_ptr->background.red);
       CHOP(png_ptr->background.green);
       CHOP(png_ptr->background.blue);

pngrutil.c

@@ -1,7 +1,7 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.5.3 [(PENDING RELEASE)]
+ * Last changed in libpng 1.5.4 [(PENDING RELEASE)]
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

pngstruct.h

@@ -5,7 +5,7 @@
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  *
- * Last changed in libpng 1.5.3 [(PENDING RELEASE)]
+ * Last changed in libpng 1.5.4 [(PENDING RELEASE)]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer

pngtrans.c

@@ -1,7 +1,7 @@
 
 /* pngtrans.c - transforms the data in a row (used by both readers and writers)
  *
- * Last changed in libpng 1.5.3 [(PENDING RELEASE)]
+ * Last changed in libpng 1.5.4 [(PENDING RELEASE)]
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

pngvalid.c

@@ -1,7 +1,7 @@
 
 /* pngvalid.c - validate libpng by constructing then reading png files.
  *
- * Last changed in libpng 1.5.3 [(PENDING RELEASE)]
+ * Last changed in libpng 1.5.4 [(PENDING RELEASE)]
  * Copyright (c) 2011 Glenn Randers-Pehrson
  * Written by John Cunningham Bowler
  *
@@ -5265,6 +5265,8 @@ image_transform_png_set_strip_16_mod(PNG_CONST image_transform *this,
 #     ifndef PNG_READ_16_TO_8_ACCURATE_SCALE_SUPPORTED
          /* The strip 16 algorithm drops the low 8 bits rather than calculating
           * 1/257, so we need to adjust the permitted errors appropriately:
+          * Notice that this is only relevant prior to the addition of the
+          * png_set_chop_16 API in 1.5.4 (but 1.5.4+ always defines the above!)
           */
          {
             PNG_CONST double d = (255-128.5)/65535;
@@ -5294,6 +5296,60 @@ image_transform_png_set_strip_16_add(image_transform *this,
 IT(strip_16);
 #undef PT
 #define PT ITSTRUCT(strip_16)
+
+#if PNG_LIBPNG_VER >= 10504 /* API added in 1.5.4 */
+/* png_set_chop_16 */
+static void
+image_transform_png_set_chop_16_set(PNG_CONST image_transform *this,
+    transform_display *that, png_structp pp, png_infop pi)
+{
+   png_set_chop_16(pp);
+   this->next->set(this->next, that, pp, pi);
+}
+
+static void
+image_transform_png_set_chop_16_mod(PNG_CONST image_transform *this,
+    image_pixel *that, png_structp pp, PNG_CONST transform_display *display)
+{
+   if (that->bit_depth == 16)
+   {
+      that->sample_depth = that->bit_depth = 8;
+      if (that->red_sBIT > 8) that->red_sBIT = 8;
+      if (that->green_sBIT > 8) that->green_sBIT = 8;
+      if (that->blue_sBIT > 8) that->blue_sBIT = 8;
+      if (that->alpha_sBIT > 8) that->alpha_sBIT = 8;
+
+      /* From 1.5.4 there is a separate API to do the low byte drop; see the
+       * comments above for why this requires the following:
+       */
+      {
+         PNG_CONST double d = (255-128.5)/65535;
+         that->rede += d;
+         that->greene += d;
+         that->bluee += d;
+         that->alphae += d;
+      }
+   }
+
+   this->next->mod(this->next, that, pp, display);
+}
+
+static int
+image_transform_png_set_chop_16_add(image_transform *this,
+    PNG_CONST image_transform **that, png_byte colour_type, png_byte bit_depth)
+{
+   UNUSED(colour_type)
+
+   this->next = *that;
+   *that = this;
+
+   return bit_depth > 8;
+}
+
+IT(chop_16);
+#undef PT
+#define PT ITSTRUCT(chop_16)
+#endif /* From libpng 1.5.4 */
 #endif /* PNG_READ_16_TO_8_SUPPORTED */
 
 #ifdef PNG_READ_STRIP_ALPHA_SUPPORTED

pngwrite.c

@@ -1,7 +1,7 @@
 
 /* pngwrite.c - general routines to write a PNG file
  *
- * Last changed in libpng 1.5.3 [(PENDING RELEASE)]
+ * Last changed in libpng 1.5.4 [(PENDING RELEASE)]
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

pngwtran.c

@@ -1,7 +1,7 @@
 
 /* pngwtran.c - transforms the data in a row for PNG writers
  *
- * Last changed in libpng 1.5.3 [(PENDING RELEASE)]
+ * Last changed in libpng 1.5.4 [(PENDING RELEASE)]
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

pngwutil.c

@@ -1,7 +1,7 @@
 
 /* pngwutil.c - utilities to write a PNG file
  *
- * Last changed in libpng 1.5.3 [(PENDING RELEASE)]
+ * Last changed in libpng 1.5.4 [(PENDING RELEASE)]
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

scripts/symbols.def

@@ -5,7 +5,7 @@
 LIBRARY
 
 EXPORTS
-;Version 1.5.4beta01
+;Version 1.5.4beta02
  png_access_version_number @1
  png_set_sig_bytes @2
  png_sig_cmp @3
@@ -234,3 +234,4 @@ EXPORTS
  png_set_text_compression_method @226
  png_set_alpha_mode @227
  png_set_alpha_mode_fixed @228
+ png_set_chop_16 @229