From: Cristy <urban-warrior@imagemagick.org>
Date: Fri, 9 Dec 2016 15:40:04 +0000 (-0500)
Subject: Enable alpha channel if background color is non-opaque
X-Git-Tag: 7.0.3-10~10
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=a739e8f74eed904807e288615a94479fdc110c94;p=imagemagick

Enable alpha channel if background color is non-opaque
---

diff --git a/ChangeLog b/ChangeLog
index b51477ebe..f75b90662 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,8 @@
     https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=29105).
   * Respect connected-components:area-threshold define (reference
     https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=31006). 
+  * Enable alpha channel if background color is non-opaque (reference
+    https://www.imagemagick.org/discourse-server/viewtopic.php?f=3&t=31016).
 
 2016-12-05  7.0.3-9 Cristy  <quetzlzacatenango@image...>
   * Release ImageMagick version 7.0.3-9, GIT revision 19139:6fed3f1:20161205.
diff --git a/MagickCore/image.c b/MagickCore/image.c
index 685d3acea..ae1f3a20e 100644
--- a/MagickCore/image.c
+++ b/MagickCore/image.c
@@ -49,6 +49,7 @@
 #include "MagickCore/cache.h"
 #include "MagickCore/cache-private.h"
 #include "MagickCore/cache-view.h"
+#include "MagickCore/channel.h"
 #include "MagickCore/client.h"
 #include "MagickCore/color.h"
 #include "MagickCore/color-private.h"
@@ -2240,6 +2241,9 @@ MagickExport MagickBooleanType SetImageBackgroundColor(Image *image,
   assert(image->signature == MagickCoreSignature);
   if (SetImageStorageClass(image,DirectClass,exception) == MagickFalse)
     return(MagickFalse);
+  if ((image->background_color.alpha != OpaqueAlpha) &&
+      (image->alpha_trait == UndefinedPixelTrait))
+    (void) SetImageAlphaChannel(image,OnAlphaChannel,exception);
   ConformPixelInfo(image,&image->background_color,&background,exception);
   /*
     Set image background color.