From 6ba6e1287bbd875cd14095e2baf36a978d88c32e Mon Sep 17 00:00:00 2001
From: Tobias Frost <tobi@debian.org>
Date: Wed, 18 May 2016 02:19:55 -0400
Subject: Fix libpng16 issue, png_set_filler is invalid for low bit depth gray output, from Debian

---
(limited to 'xcf2png.c')

diff --git a/xcf2png.c b/xcf2png.c
index 6721f3d..4afe78d 100644
--- a/xcf2png.c
+++ b/xcf2png.c
@@ -208,8 +208,11 @@ init_output(void)
 #endif
     break ;
   case PNG_COLOR_TYPE_GRAY:
-    png_set_filler(libpng,0,PNG_FILLER_AFTER);
+  {
+    // only supported with more than 8 bits, otherwise emit error: png_set_filler is invalid for low bit depth gray output'
+    if (bit_depth >= 8) png_set_filler(libpng,0,PNG_FILLER_AFTER);
     break ;
+  }
   case PNG_COLOR_TYPE_GRAY_ALPHA:
   case PNG_COLOR_TYPE_PALETTE:
     break ;
--
cgit v0.9.1