From 23eaf93867cf73de691a9b68611d01664f30e8bd Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Mon, 18 Apr 2016 15:21:11 +0100
Subject: [PATCH] fix build with graphicsmagick

GM is still using the old page interface of subimage/subrange, IM has
deprecated that in favour of scene/number_scenes

we were accidentally just supporting the new IM system ... this change
adds support for GM as well, plus a configure test to pick one

see https://github.com/jcupitt/libvips/issues/423
---
 ChangeLog                     |  1 +
 configure.ac                  | 13 +++++++++++++
 libvips/foreign/magick2vips.c | 18 ++++++++++++++----
 3 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 2ad08c9a..cd1c9112 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,7 @@
 - rename vips wrapper script, it was still vips-8.2, thanks Benjamin
 - export C++ operator overloads for MSVC linking [Lovell]
 - insist on giflib4
+- fix magickload @page with GraphicsMagick
 
 29/1/16 started 8.3
 - add vips_reduce*() ... a fast path for affine downsize
diff --git a/configure.ac b/configure.ac
index bc3ec0fc..afd5f078 100644
--- a/configure.ac
+++ b/configure.ac
@@ -488,6 +488,19 @@ if test x"$with_magick" != "xno"; then
   LIBS=$save_LIBS
 fi
 
+if test x"$with_magick" != "xno"; then
+  # do we have number_scenes in image_info ... imagemagick uses this, gm
+  # still uses subrange
+  save_CFLAGS=$CFLAGS
+  CFLAGS="$CFLAGS $MAGICK_CFLAGS"
+  AC_CHECK_MEMBER([struct _ImageInfo.number_scenes],
+    AC_DEFINE(HAVE_NUMBER_SCENES,1,
+	      [define if your magick has ImageInfo.number_scenes.]),
+    [],
+    [#include <magick/api.h>])
+  CFLAGS=$save_CFLAGS
+fi
+
 # orc
 AC_ARG_WITH([orc], 
   AS_HELP_STRING([--without-orc], [build without orc (default: test)]))
diff --git a/libvips/foreign/magick2vips.c b/libvips/foreign/magick2vips.c
index ae3d4e5f..288cbf51 100644
--- a/libvips/foreign/magick2vips.c
+++ b/libvips/foreign/magick2vips.c
@@ -49,6 +49,8 @@
  * 	  fd during file read, handy for large numbers of input images 
  * 14/2/16
  * 	- add @page option, 0 by default
+ * 18/4/16
+ * 	- fix @page with graphicsmagick
  */
 
 /*
@@ -217,16 +219,24 @@ read_new( const char *filename, VipsImage *im,
 #endif /*HAVE_SETIMAGEOPTION*/
 
 	if( !all_frames ) {
+#ifdef HAVE_NUMBER_SCENES 
+		 /* I can't find docs for these fields, but this seems to work.
+		  */
 		char page[256];
 
-		/* Just pick a specific page.
-		 *
-		 * I can't find docs for these fields, but this seems to work.
-		 */
 		read->image_info->scene = read->page;
 		read->image_info->number_scenes = 1;
+
+		/* Some IMs must have the string version set as well.
+		 */
 		vips_snprintf( page, 256, "%d", read->page );
 		read->image_info->scenes = strdup( page );
+#else /*!HAVE_NUMBER_SCENES*/
+		/* This works with GM 1.2.31 and probably others.
+		 */
+		read->image_info->subimage = read->page;
+		read->image_info->subrange = 1;
+#endif
 	}
 
 #ifdef DEBUG