Build a dynamically loadable module for resvg

libvips/foreign/foreign.c

@@ -3006,7 +3006,7 @@ vips_foreign_operation_init( void )
 	vips_foreign_load_pdf_source_get_type(); 
 #endif /*HAVE_PDFIUM*/
 
-#if defined(HAVE_RSVG) || defined(HAVE_RESVG)
+#if (defined(HAVE_RSVG) || defined(HAVE_RESVG)) && !defined(RESVG_MODULE)
 	vips_foreign_load_svg_file_get_type(); 
 	vips_foreign_load_svg_buffer_get_type(); 
 #ifdef HAVE_RSVG

libvips/foreign/meson.build

@@ -44,7 +44,6 @@ foreign_sources = files(
     'rawsave.c',
     'spngload.c',
     'spngsave.c',
-    'svgload.c',
     'tiff2vips.c',
     'tiff.c',
     'tiffload.c',
@@ -123,6 +122,14 @@ endif
 
 libvips_sources += foreign_sources
 
+resvg_module_sources = files(
+    'svgload.c',
+)
+
+if not resvg_module
+    foreign_sources += resvg_module_sources
+endif
+
 foreign_lib = static_library('foreign',
     foreign_sources,
     foreign_headers,

libvips/meson.build

@@ -165,3 +165,18 @@ if openslide_module
         install_dir: module_dir
     )
 endif
+
+if resvg_module
+    shared_module('vips-resvg',
+        'module/resvg.c',
+        resvg_module_sources,
+        c_args: module_c_args,
+        link_args: module_link_args,
+        name_prefix: '',
+        name_suffix: module_suffix,
+        dependencies: [gmodule_dep, libvips_dep, resvg_dep],
+        gnu_symbol_visibility: 'hidden',
+        install: true,
+        install_dir: module_dir
+    )
+endif

libvips/module/resvg.c

@@ -0,0 +1,70 @@
+/* resvg as a dynamically loadable module
+ *
+ * 17/1/23 kleisauke
+ * 	- initial
+ */
+
+/*
+
+    This file is part of VIPS.
+
+    VIPS is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+    02110-1301  USA
+
+ */
+
+/*
+
+    These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
+
+ */
+
+/*
+#define DEBUG
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif /*HAVE_CONFIG_H*/
+#include <glib/gi18n-lib.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <vips/vips.h>
+#include <vips/debug.h>
+#include <vips/internal.h>
+
+#if defined(HAVE_RESVG) && defined(RESVG_MODULE)
+
+/* This is called on module load.
+ */
+G_MODULE_EXPORT const gchar *
+g_module_check_init( GModule *module )
+{
+#ifdef DEBUG
+	printf( "vips_resvg: module init\n" ); 
+#endif /*DEBUG*/
+
+	extern GType vips_foreign_load_svg_file_get_type( void );
+	extern GType vips_foreign_load_svg_buffer_get_type( void );
+
+	vips_foreign_load_svg_file_get_type(); 
+	vips_foreign_load_svg_buffer_get_type();
+
+	return( NULL );
+}
+
+#endif /*defined(HAVE_RESVG) && defined(RESVG_MODULE)*/

meson.build

@@ -371,13 +371,18 @@ if librsvg_found
     cfg_var.set('HAVE_RSVG', '1')
 endif
 
-# libresvg doesn't ship pkg-config files, so we can't use dependency().
-libresvg_dep = cc.find_library('resvg', has_headers: ['resvg.h'], required: get_option('resvg'))
-libresvg_found = libresvg_dep.found()
-if libresvg_found
-    # It's annoying that I have to spell out the `include_directories` here, but without it Meson can build
-    # but `compile_commands.json` doesn't have the -I$PREFIX/include, making code analysis tools & VSCode fail.
-    libvips_deps += declare_dependency(dependencies: [libresvg_dep], include_directories: [include_directories(get_option('prefix') / get_option('includedir'))], link_args: ['-ldl'])
+# only if librsvg not found
+resvg_dep = disabler()
+resvg_module = false
+if not librsvg_found
+    # resvg doesn't ship pkg-config files, so we can't use dependency()
+    resvg_dep = cc.find_library('resvg', has_headers: ['resvg.h'], required: get_option('resvg'))
+    resvg_module = modules_enabled and not get_option('resvg-module').disabled()
+    if resvg_module
+        cfg_var.set('RESVG_MODULE', '1')
+    else
+        libvips_deps += resvg_dep
+    endif
     cfg_var.set('HAVE_RESVG', '1')
 endif
 
@@ -644,7 +649,7 @@ build_summary = {
      'PDF load with PDFium': [pdfium_dep.found()],
      'PDF load with poppler-glib': [libpoppler_found, ' (dynamic module: ', libpoppler_module, ')'],
      'SVG load with librsvg': [librsvg_found],
-     'SVG load with libresvg': [libresvg_found],
+     'SVG load with libresvg': [resvg_dep.found(), ' (dynamic module: ', resvg_module, ')'],
      'EXR load with OpenEXR': [openexr_dep.found()],
      'OpenSlide load': [openslide_dep.found(), ' (dynamic module: ', openslide_module, ')'],
      'Matlab load with libmatio': [matio_dep.found()],

meson_options.txt

@@ -193,6 +193,11 @@ option('resvg',
   value: 'auto',
   description: 'Build with resvg')
 
+option('resvg-module',
+  type: 'feature',
+  value: 'auto',
+  description: 'Build resvg as module')
+
 option('spng',
   type: 'feature',
   value: 'auto',