Initial support for dynamic loadable modules with GModule

configure.ac

@@ -399,8 +399,8 @@ AC_CHECK_LIB(m,hypot,[AC_DEFINE(HAVE_HYPOT,1,[have hypot() in libm.])])
 AC_CHECK_LIB(m,atan2,[AC_DEFINE(HAVE_ATAN2,1,[have atan2() in libm.])])
 
 # have to have these parts of glib ... we need glib 2.15 for gio
-PKG_CHECK_MODULES(REQUIRED, glib-2.0 >= 2.40 gmodule-2.0 gobject-2.0 gio-2.0)
-PACKAGES_USED="$PACKAGES_USED glib-2.0 gmodule-2.0 gobject-2.0 gio-2.0"
+PKG_CHECK_MODULES(REQUIRED, glib-2.0 >= 2.40 gmodule-no-export-2.0 gobject-2.0 gio-2.0)
+PACKAGES_USED="$PACKAGES_USED glib-2.0 gmodule-no-export-2.0 gobject-2.0 gio-2.0"
 
 # from 2.62 we have datetime
 PKG_CHECK_MODULES(DATE_TIME_FORMAT_ISO8601, glib-2.0 >= 2.62,
@@ -437,6 +437,30 @@ PKG_CHECK_MODULES(HAVE_CHECKED_MUL, glib-2.0 >= 2.48,
   ]
 )
 
+AC_MSG_CHECKING([whether to build dynamic modules])
+
+AC_ARG_ENABLE([modules], 
+  AS_HELP_STRING([--disable-modules], [disable dynamic modules (default: enabled)]))
+
+gmodule_supported_bool=false
+gmodule_supported_flag=no
+gmodule_with_flag=yes
+
+if test x"$enable_modules" = x"no"; then
+  AC_MSG_RESULT(no)
+else
+  AC_MSG_RESULT(yes)
+  AC_MSG_CHECKING(whether dynamic modules work)
+  gmodule_supported_bool=`$PKG_CONFIG gmodule-no-export-2.0 --variable gmodule_supported`
+  if $gmodule_supported_bool; then
+    gmodule_supported_flag=yes
+    gmodule_with_flag='module'
+    AC_MSG_RESULT(yes)
+  else
+    AC_MSG_RESULT(no)
+  fi
+fi
+
 # check for gtk-doc
 GTK_DOC_CHECK([1.14],[--flavour no-tmpl])
 
@@ -1334,6 +1358,7 @@ VIPS_LIBS="$VIPS_LIBS $REQUIRED_LIBS -lm"
 VIPS_CONFIG="\
 enable debug: $enable_debug, \
 enable deprecated library components: $enable_deprecated, \
+enable modules: $gmodule_supported_flag, \
 enable docs with gtkdoc: $enable_gtk_doc, \
 gobject introspection:  $found_introspection, \
 RAD load/save: $with_radiance, \
@@ -1434,6 +1459,7 @@ AC_MSG_RESULT([dnl
 ## Build options
 enable debug:                           $enable_debug
 enable deprecated library components:   $enable_deprecated
+enable modules:                         $gmodule_supported_flag
 enable docs with gtkdoc:                $enable_gtk_doc
 gobject introspection:                  $found_introspection
 RAD load/save:                          $with_radiance

libvips/Makefile.am

@@ -61,6 +61,7 @@ libvips_la_LDFLAGS = \
 	-version-info @LIBRARY_CURRENT@:@LIBRARY_REVISION@:@LIBRARY_AGE@ 
 
 EXTRA_DIST = \
+	module \
 	$(OPTIONAL_DIST_DIR)
 
 CLEANFILES = 
@@ -72,6 +73,35 @@ install-exec-hook:
 	cp soname.h $(DESTDIR)$(pkgincludedir) && \
 	rm soname.h
 
+# Modules
+
+module_LTLIBRARIES = 
+
+# All modules within the $VIPSHOME/lib/vips-modules-MAJOR.MINOR
+# directory are automatically loaded on vips_init.
+
+moduledir = @VIPS_LIBDIR@/vips-modules-@VIPS_MAJOR_VERSION@.@VIPS_MINOR_VERSION@
+
+MODULE_CPPFLAGS = \
+	-I${top_srcdir}/libvips/include \
+	$(REQUIRED_CFLAGS)
+
+MODULE_LDFLAGS = \
+	-no-undefined \
+	-shared \
+	-module \
+	-avoid-version
+
+MODULE_LIBADD = \
+	libvips.la \
+	$(REQUIRED_LIBS)
+
+# Note that only the GObject part should be included in a
+# dynamically loadable module. The C definitions are always
+# included in the main library.
+
+# Introspection
+
 -include $(INTROSPECTION_MAKEFILE)
 INTROSPECTION_GIRS =
 INTROSPECTION_SCANNER_ARGS = --add-include-path=$(srcdir)

libvips/foreign/Makefile.am

@@ -72,6 +72,9 @@ libforeign_la_SOURCES = \
 	webpload.c \
 	webpsave.c
 
+# We still need to include the GObject part of a loader/saver
+# if it is not built as a dynamically loadable module.
+
 EXTRA_DIST = libnsgif
 
 AM_CPPFLAGS = -I${top_srcdir}/libvips/include @VIPS_CFLAGS@ @VIPS_INCLUDES@

libvips/iofuncs/init.c

@@ -510,13 +510,18 @@ vips_init( const char *argv0 )
 	vips_mosaicing_operation_init();
 	vips_g_input_stream_get_type(); 
 
-	/* Load any vips8 plugins from the vips libdir. Keep going, even if
-	 * some plugins fail to load. 
+	/* Load any vips8 modules from the vips libdir. Keep going, even if
+	 * some modules fail to load. 
+	 */
+	(void) vips_load_plugins( "%s/vips-modules-%d.%d", 
+		libdir, VIPS_MAJOR_VERSION, VIPS_MINOR_VERSION );
+
+#if ENABLE_DEPRECATED
+	/* Load any vips8 plugins from the vips libdir.
 	 */
 	(void) vips_load_plugins( "%s/vips-plugins-%d.%d", 
 		libdir, VIPS_MAJOR_VERSION, VIPS_MINOR_VERSION );
 
-#if ENABLE_DEPRECATED
 	/* Load up any vips7 plugins in the vips libdir. We don't error on 
 	 * failure, it's too annoying to have VIPS refuse to start because of 
 	 * a broken plugin.