[libpng15] Restored unused FILTER_HEURISTIC macros removed at
libpng-1.5.23beta02 to png.h to avoid compatibility warnings.
diff --git a/CHANGES b/CHANGES
index c9a8d8b..30d84d0 100644
--- a/CHANGES
+++ b/CHANGES
@@ -4362,6 +4362,8 @@
Version 1.5.23rc01 [July 9, 2015]
Belatedly added Mans Rullgard to the list of Contributing Authors.
+ Restored unused FILTER_HEURISTIC macros removed at libpng-1.5.23beta02
+ to png.h to avoid compatibility warnings.
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diff --git a/png.h b/png.h
index cd544aa..02e822b 100644
--- a/png.h
+++ b/png.h
@@ -1679,6 +1679,12 @@
filter_weights, png_const_fixed_point_p filter_costs))
#endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
+/* The following are no longer used and will be removed from libpng-1.7: */
+#define PNG_FILTER_HEURISTIC_DEFAULT 0 /* Currently "UNWEIGHTED" */
+#define PNG_FILTER_HEURISTIC_UNWEIGHTED 1 /* Used by libpng < 0.95 */
+#define PNG_FILTER_HEURISTIC_WEIGHTED 2 /* Experimental feature */
+#define PNG_FILTER_HEURISTIC_LAST 3 /* Not a valid value */
+
#ifdef PNG_WRITE_SUPPORTED
/* Set the library compression level. Currently, valid values range from
* 0 - 9, corresponding directly to the zlib compression levels 0 - 9
