Imported from libpng-1.0.9beta6.tar
diff --git a/pngwutil.c b/pngwutil.c
index 4d669da..53039a5 100644
--- a/pngwutil.c
+++ b/pngwutil.c
@@ -1,7 +1,7 @@
/* pngwutil.c - utilities to write a PNG file
*
- * libpng 1.0.9beta5 - December 15, 2000
+ * libpng 1.0.9beta6 - December 18, 2000
* For conditions of distribution and use, see copyright notice in png.h
* Copyright (c) 1998, 1999, 2000 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -131,6 +131,8 @@
/* write the rest of the 8 byte signature */
png_write_data(png_ptr, &png_signature[png_ptr->sig_bytes],
(png_size_t)8 - png_ptr->sig_bytes);
+ if(png_ptr->sig_bytes < 3)
+ png_ptr->mode |= PNG_HAVE_PNG_SIGNATURE;
}
#if defined(PNG_WRITE_TEXT_SUPPORTED) || defined(PNG_WRITE_iCCP_SUPPORTED)
@@ -419,9 +421,21 @@
compression_type = PNG_COMPRESSION_TYPE_BASE;
}
+ /* Write filter_method 64 (intrapixel differencing) only if
+ * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and
+ * 2. Libpng did not write a PNG signature (this filter_method is only
+ * used in PNG datastreams that are embedded in MNG datastreams) and
+ * 3. The application called png_permit_mng_features with a mask that
+ * included PNG_FLAG_MNG_FILTER_64 and
+ * 4. The filter_method is 64 and
+ * 5. The color_type is RGB or RGBA
+ */
if (
#if defined(PNG_MNG_FEATURES_SUPPORTED)
!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) &&
+ ((png_ptr->mode&PNG_HAVE_PNG_SIGNATURE) == 0) &&
+ (color_type == PNG_COLOR_TYPE_RGB ||
+ color_type == PNG_COLOR_TYPE_RGB_ALPHA) &&
(filter_type == PNG_INTRAPIXEL_DIFFERENCING)) &&
#endif
filter_type != PNG_FILTER_TYPE_BASE)