make libgsf-1 an optional dependency

dzsave vanishes if you don't have it, but you can still build vips

ChangeLog

@@ -21,7 +21,7 @@
 - vips_system() now supports many input images and you can change image
   argument order
 - support 16-bit palette TIFFs, plus palette TIFFs can have an alpha
-- libgsf is now required 
+- libgsf-1 is now an optional dependancy 
 - dzsave can directly write a ZIP file 
 - add ".vips" as an alternative suffix for vips files
 - added vips_tiffload_buffer()

README.md

@@ -144,6 +144,10 @@ The IJG JPEG library.
 
 If available, libvips adds support for EXIF metadata in JPEG files.
 
+## libgsf-1
+
+If available, libvips adds support for creating image pyramids with dzsave. 
+
 ## libtiff
 
 The TIFF library. It needs to be built with support for JPEG and

configure.ac

@@ -314,8 +314,8 @@ AC_CHECK_LIB(m,hypot,[AC_DEFINE(HAVE_HYPOT,1,[have hypot() in libm.])])
 
 # have to have these
 # need glib 2.6 for GOption
-PKG_CHECK_MODULES(REQUIRED, glib-2.0 >= 2.6 gmodule-2.0 libxml-2.0 gobject-2.0 libgsf-1)
+PKG_CHECK_MODULES(REQUIRED, glib-2.0 >= 2.6 gmodule-2.0 libxml-2.0 gobject-2.0)
-PACKAGES_USED="$PACKAGES_USED glib-2.0 libxml-2.0 gmodule-2.0 gobject-2.0 libgsf-1"
+PACKAGES_USED="$PACKAGES_USED glib-2.0 libxml-2.0 gmodule-2.0 gobject-2.0"
 
 # after 2.28 we have a monotonic timer
 PKG_CHECK_MODULES(MONOTONIC, glib-2.0 >= 2.28,[
@@ -350,6 +350,18 @@ GTK_DOC_CHECK([1.14],[--flavour no-tmpl])
 
 # optional supporting libraries
 
+AC_ARG_WITH([gsf], 
+  AS_HELP_STRING([--without-gsf], [build without libgsf-1 (default: test)]))
+
+if test x"$with_gsf" != "xno"; then
+  PKG_CHECK_MODULES(GSF, libgsf-1,
+    [AC_DEFINE(HAVE_GSF,1,[define if you have libgsf-1 installed.])
+     with_gsf=yes
+     PACKAGES_USED="$PACKAGES_USED libgsf-1"],
+    [AC_MSG_WARN([libgsf-1 not found; disabling dzsave support]) 
+     with_gsf=no])
+fi
+
 AC_ARG_WITH([fftw], 
   AS_HELP_STRING([--without-fftw], [build without fftw (default: test)]))
 
@@ -770,5 +782,7 @@ file import/export with libpng: 	$with_png
   (requires libpng-1.2.9 or later)
 file import/export with libtiff:	$with_tiff
 file import/export with libjpeg:	$with_jpeg
+image pyramid export:			$with_gsf
+  (requires libgsf-1)
 use libexif to load/save JPEG metadata: $with_libexif
 build Python binding: 			$with_python])

libvips/foreign/dzsave.c

@@ -114,11 +114,13 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include <gsf/gsf.h>
-
 #include <vips/vips.h>
 #include <vips/internal.h>
 
+#ifdef HAVE_GSF
+
+#include <gsf/gsf.h>
+
 /* Round N down to P boundary. 
  */
 #define ROUND_DOWN(N,P) ((N) - ((N) % P)) 
@@ -129,7 +131,7 @@
 
 /* Simple wrapper around libgsf.
  *
- * We need to be able to do scattered writes to structred files. So while
+ * We need to be able to do scattered writes to structured files. So while
  * building a zip (for example) we need to be able to write to file/a/b.jpg,
  * then to file/c/d.jpg, then back to file/a/e.jpg. This is tricky with the
  * libgsf API which is happier doing writes in order.
@@ -1802,6 +1804,8 @@ vips_foreign_save_dz_init( VipsForeignSaveDz *dz )
 	dz->container = VIPS_FOREIGN_DZ_CONTAINER_FS; 
 }
 
+#endif /*HAVE_GSF*/
+
 /**
  * vips_dzsave:
  * @in: image to save 
@@ -1857,4 +1861,3 @@ vips_dzsave( VipsImage *in, const char *name, ... )
 
 	return( result );
 }
-

libvips/foreign/foreign.c

@@ -1702,7 +1702,10 @@ vips_foreign_operation_init( void )
 	vips_foreign_save_raw_fd_get_type(); 
 	vips_foreign_load_vips_get_type(); 
 	vips_foreign_save_vips_get_type(); 
+
+#ifdef HAVE_GSF
 	vips_foreign_save_dz_get_type(); 
+#endif /*HAVE_GSF*/
 
 #ifdef HAVE_PNG
 	vips_foreign_load_png_get_type(); 

libvips/iofuncs/init.c

@@ -76,7 +76,9 @@
 #include <limits.h>
 #include <string.h>
 
+#ifdef HAVE_GSF
 #include <gsf/gsf.h>
+#endif /*HAVE_GSF*/
 
 #include <vips/vips.h>
 #include <vips/thread.h>
@@ -307,9 +309,11 @@ vips__init( const char *argv0 )
 	 */
 	vips_vector_init();
 
+#ifdef HAVE_GSF
 	/* Use this for structured file write.
 	 */
 	gsf_init();
+#endif /*HAVE_GSF*/
 
 	/* Register vips_shutdown(). This may well not get called and many
 	 * platforms don't support it anyway.
@@ -436,7 +440,9 @@ vips_shutdown( void )
 
 	vips__thread_profile_stop();
 
+#ifdef HAVE_GSF
 	gsf_shutdown(); 
+#endif /*HAVE_GSF*/
 
 	/* In dev releases, always show leaks. But not more than once, it's
 	 * annoying.