[gtk] widget-factory: Speed up build

[Matthias Clasen <matthiasc src gnome org>]

commit d7e117f52b14f4571a3e6aaa5405b61e3efc6161
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Sep 30 22:41:36 2021 -0400

    widget-factory: Speed up build
    
    Avoid serializing the gresource blob into a C string
    and running gcc over it. Instead, use ld to put it
    directly into an .o file and add it to the build.
    
    The build system machinations here were copied from
    gobject/tests/meson.build, and should ideally be part
    of the meson gnome module.

 demos/widget-factory/meson.build | 67 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 63 insertions(+), 4 deletions(-)
---
diff --git a/demos/widget-factory/meson.build b/demos/widget-factory/meson.build
index 6b09db3e2b..2763111570 100644
--- a/demos/widget-factory/meson.build
+++ b/demos/widget-factory/meson.build
@@ -1,9 +1,68 @@
 # demos/widget-factory
 
-widgetfactory_resources = gnome.compile_resources('widgetfactory_resources',
-  'widget-factory.gresource.xml',
-  source_dir: '.',
-)
+objcopy_supports_add_symbol = false
+objcopy = find_program('objcopy', required : false)
+if objcopy.found()
+  objcopy_supports_add_symbol = run_command(objcopy, '--help').stdout().contains('--add-symbol')
+endif
+
+ld = find_program('ld', required : false)
+
+if build_machine.system() == 'linux' and objcopy.found() and objcopy_supports_add_symbol and ld.found()
+  glib_compile_resources = find_program('glib-compile-resources')
+
+  # Create the resource blob
+  widgetfactory_gresource = custom_target('widgetfactory.gresource',
+      input : 'widget-factory.gresource.xml',
+      output : 'widgetfactory.gresource',
+      command : [glib_compile_resources,
+                 '--target=@OUTPUT@',
+                 '--sourcedir=' + meson.current_source_dir(),
+                 '--sourcedir=' + meson.current_build_dir(),
+                 '@INPUT@'])
+
+  # Create resource data file
+  widgetfactory_resources_c = custom_target('widgetfactory_resources.c',
+      input : 'widget-factory.gresource.xml',
+      output : 'widgetfactory_resources.c',
+      command : [glib_compile_resources,
+                 '--target=@OUTPUT@',
+                 '--sourcedir=' + meson.current_source_dir(),
+                 '--sourcedir=' + meson.current_build_dir(),
+                 '--generate-source',
+                 '--external-data',
+                 '--c-name', '_g_binary_widgetfactory',
+                 '@INPUT@'])
+
+  # Create object file containing resource data
+  widgetfactory_resources_binary = custom_target('widgetfactory_resources.o',
+      input : widgetfactory_gresource,
+      output : 'widgetfactory_resources.o',
+      command : [ld,
+                 '-r',
+                 '-b','binary',
+                 '@INPUT@',
+                 '-o','@OUTPUT@'])
+
+  # Rename symbol to match the one in the C file
+  widgetfactory_resources_o = custom_target('widgetfactory_resources2.o',
+    input : widgetfactory_resources_binary,
+    output : 'widgetfactory_resources2.o',
+    command : [objcopy,
+                 '--add-symbol','_g_binary_widgetfactory_resource_data=.data:0',
+                 '@INPUT@',
+                 '@OUTPUT@'])
+
+  widgetfactory_resources = [
+      widgetfactory_resources_c,
+      widgetfactory_resources_o,
+    ]
+else
+  widgetfactory_resources = gnome.compile_resources('widgetfactory_resources',
+    'widget-factory.gresource.xml',
+    source_dir: '.',
+  )
+endif
 
 executable('gtk4-widget-factory',
   sources: ['widget-factory.c', 'gtkloader.c', widgetfactory_resources],