From 79fc8fa0d9373db28c233bcddfb531b8d136b215 Mon Sep 17 00:00:00 2001
From: Glenn Randers-Pehrson <glennrp at users.sourceforge.net>
Date: Sun, 4 Aug 2013 14:05:39 -0500
Subject: [PATCH] [libpng17] Exit loop over tRNS array once a transparent pixel
 is found

(performance report by PoChun Chang).
---
 pngrtran.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/pngrtran.c b/pngrtran.c
index bf439f392..3c7f40bd5 100644
--- a/pngrtran.c
+++ b/pngrtran.c
@@ -1357,12 +1357,18 @@ png_init_palette_transformations(png_structrp png_ptr)
 
       /* Ignore if all the entries are opaque (unlikely!) */
       for (i=0; i<png_ptr->num_trans; ++i)
+      {
          if (png_ptr->trans_alpha[i] == 255)
             continue;
          else if (png_ptr->trans_alpha[i] == 0)
             input_has_transparency = 1;
          else
+         {
+            input_has_transparency = 1;
             input_has_alpha = 1;
+            break;
+         }
+      }
    }
 
    /* If no alpha we can optimize. */