bug#11678: Trunk fails to compile on RHEL 5 machines

[Paul Eggert <eggert@cs.ucla.edu>]

Tags: patch

The Emacs trunk doesn't build on CentOS 5 due to an ImageMagick
problem.  Here's a proposed patch.  I'm CC:ing this to Manoj
Srivastava, since he reported it on emacs-devel in
<http://lists.gnu.org/archive/html/emacs-devel/2012-06/msg00188.html>.
I don't have easy access to CentOS 5 with ImageMagick so I haven't
tested this there, but it does work on Ubuntu 12.04.

=== modified file 'ChangeLog'
--- ChangeLog	2012-06-11 23:17:11 +0000
+++ ChangeLog	2012-06-12 01:13:39 +0000
@@ -1,3 +1,8 @@
+2012-06-12  Paul Eggert  <eggert@cs.ucla.edu>
+
+	* configure.in: When using ImageMagick, check for
+	MagickMergeImageLayers.
+
 2012-06-11  Glenn Morris  <rgm@gnu.org>
 
 	* configure.in (SYSTEM_TYPE): New AC_DEFINE.

=== modified file 'configure.in'
--- configure.in	2012-06-11 23:17:11 +0000
+++ configure.in	2012-06-12 01:13:39 +0000
@@ -1854,7 +1854,7 @@
       AC_DEFINE(HAVE_IMAGEMAGICK, 1, [Define to 1 if using imagemagick.])
       CFLAGS="$CFLAGS $IMAGEMAGICK_CFLAGS"
       LIBS="$IMAGEMAGICK_LIBS $LIBS"
-      AC_CHECK_FUNCS(MagickExportImagePixels)
+      AC_CHECK_FUNCS(MagickExportImagePixels MagickMergeImageLayers)
     fi
   fi
 fi

=== modified file 'etc/ChangeLog'
--- etc/ChangeLog	2012-06-10 13:20:58 +0000
+++ etc/ChangeLog	2012-06-12 01:13:39 +0000
@@ -1,3 +1,7 @@
+2012-06-12  Paul Eggert  <eggert@cs.ucla.edu>
+
+	* NEWS: Transparency support requires ImageMagic 6.3.8 or later.
+
 2012-06-04  Paul Eggert  <eggert@cs.ucla.edu>
 
 	* PROBLEMS (68000 C compiler problems): Remove obsolete section.

=== modified file 'etc/NEWS'
--- etc/NEWS	2012-06-11 14:42:55 +0000
+++ etc/NEWS	2012-06-12 01:13:39 +0000
@@ -81,7 +81,8 @@
 treated as images.
 
 *** Images displayed via ImageMagick now support transparency and the
-:background image spec property.
+:background image spec property.  Transparency support requires
+ImageMagick 6.3.8 or later.
 
 ** String values for `initial-buffer-choice' also apply to emacsclient
 frames, if emacsclient is only told to open a new frame without

=== modified file 'src/ChangeLog'
--- src/ChangeLog	2012-06-12 00:30:18 +0000
+++ src/ChangeLog	2012-06-12 01:13:39 +0000
@@ -1,5 +1,8 @@
 2012-06-12  Paul Eggert  <eggert@cs.ucla.edu>
 
+	* image.c (imagemagick_load_image) [!HAVE_MAGICKMERGEIMAGELAYERS]:
+	Don't invoke MagickMergeImageLayers.
+
 	* image.c (imagemagick_load_image): Remove unused label.
 
 2012-06-11  Glenn Morris  <rgm@gnu.org>

=== modified file 'src/image.c'
--- src/image.c	2012-06-12 00:30:18 +0000
+++ src/image.c	2012-06-12 01:13:39 +0000
@@ -7776,6 +7776,7 @@
   height = MagickGetImageHeight (image_wand);
   width = MagickGetImageWidth (image_wand);
 
+#if HAVE_MAGICKMERGEIMAGELAYERS
   /* Set the canvas background color to the frame or specified
      background, and flatten the image.  Note: as of ImageMagick
      6.6.0, SVG image transparency is not handled properly
@@ -7787,6 +7788,7 @@
     DestroyMagickWand (image_wand);
     image_wand = new_wand;
   }
+#endif
 
   if (! (width <= INT_MAX && height <= INT_MAX
 	 && check_image_size (f, width, height)))