main: Init public GObject types in hdy_init()

This will avoid our users to manually ensure libhandy widget types are
loaded before using them in GtkBuilder templates.

Fixes Librem5/libhandy#20

doc/meson.build

@@ -5,6 +5,7 @@ subdir('xml')
 private_headers = [
     'config.h',
     'gtkprogresstrackerprivate.h',
+    'hdy-main-private.h',
 ]
 
 images = [

src/gen-public-types.sh

+#!/bin/sh
+
+set -e
+
+echo '/* This file was generated by gen-plublic-types.sh, do not edit it. */
+'
+
+for var in "$@"
+do
+  echo "#include \"$var\""
+done
+
+echo '#include "hdy-main-private.h"
+
+void
+hdy_init_public_types (void)
+{'
+
+sed -ne 's/^#define \+\(HDY_TYPE_[A-Z0-9_]\+\) \+.*/  g_type_ensure (\1);/p' "$@" | sort
+
+echo '}
+'

src/hdy-main-private.h

+/*
+ * Copyright (C) 2018 Purism SPC
+ *
+ * SPDX-License-Identifier: LGPL-2.1+
+ */
+#pragma once
+
+#include "hdy-main.h"
+
+#if !defined(_HANDY_INSIDE) && !defined(HANDY_COMPILATION)
+#error "Only <handy.h> can be included directly."
+#endif
+
+G_BEGIN_DECLS
+
+/* Initializes the public GObject types, which is needed to ensure they are
+ * discoverable, for example so they can easily be used with GtkBuilder.
+ *
+ * The function is implemented in hdy-public-types.c which is generated at
+ * compile time by gen-public-types.sh
+ */
+void hdy_init_public_types (void);
+
+G_END_DECLS

src/hdy-main.c

@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: LGPL-2.1+
  */
 #include "config.h"
-#include "hdy-main.h"
+#include "hdy-main-private.h"
 #include <glib/gi18n.h>
 
 static gint hdy_initialized = FALSE;
@@ -41,6 +41,7 @@ hdy_init (int *argc, char ***argv)
   textdomain (GETTEXT_PACKAGE);
   bind_textdomain_codeset (GETTEXT_PACKAGE, "UTF-8");
   bindtextdomain (GETTEXT_PACKAGE, LOCALEDIR);
+  hdy_init_public_types ();
 
   hdy_initialized = TRUE;
 

src/meson.build

@@ -61,6 +61,18 @@ src_headers = [
   'hdy-title-bar.h',
 ]
 
+sed = find_program('sed', required: true)
+gen_public_types = find_program('gen-public-types.sh', required: true)
+
+libhandy_init_public_types = custom_target('hdy-public-types.c',
+  output : 'hdy-public-types.c',
+  input : [src_headers, libhandy_generated_headers],
+  command : [gen_public_types, '@INPUT@'],
+  capture: true,
+  install : true,
+  install_dir : 'subdir',
+)
+
 src_sources = [
   'gtkprogresstracker.c',
   'hdy-arrows.c',
@@ -87,6 +99,7 @@ libhandy_sources = [
   libhandy_public_sources,
   libhandy_private_sources,
   libhandy_resources,
+  libhandy_init_public_types,
 ]
 
 glib_min_version = '>= 2.44'