mediafile: Turn into an extension point

This way, we can support external libraries providing implementations of
GtkMediaFile.

We also add a media backend called 'nomedia' that can be enabled to not
compile any support for GtkMediaFile. This is useful when people want to
statically compile GTK into an application that does not use media.
For now, this option is the default.

We also support a new environment variable GTK_MEDIA that allows
selecting the implementation to use.
GTK_MEDIA=help can be used to get info about the available
implementations.

1 files changed, 29 insertions, 0 deletions

diff --git a/gtk/gtkmediafileprivate.h b/gtk/gtkmediafileprivate.h
new file mode 100644
index 0000000000..b328183bef
--- /dev/null
+++ b/gtk/gtkmediafileprivate.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright © 2018 Benjamin Otte
+ *
+ * This library 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 2.1 of the License, or (at your option) any later version.
+ *
+ * This library 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 library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Authors: Benjamin Otte <otte@gnome.org>
+ */
+
+#ifndef __GTK_MEDIA_FILE_PRIVATE_H__
+#define __GTK_MEDIA_FILE_PRIVATE_H__
+
+#include "gtkmediafile.h"
+
+
+void            gtk_media_file_extension_init                   (void);
+
+
+#endif /* __GTK_MEDIA_FILE_PRIVATE_H__ */