manuals: document "mime-xdg" class and MIME_XDG_PACKAGES

(From yocto-docs rev: 4415d95358497b23f0a7b10f9ee31203ccc01eff)

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/documentation/ref-manual/classes.rst b/documentation/ref-manual/classes.rst
index d27deb8c08..139f854172 100644
--- a/documentation/ref-manual/classes.rst
+++ b/documentation/ref-manual/classes.rst
@@ -1577,6 +1577,27 @@ The ``mime`` class generates the proper post-install and post-remove
 These scriptlets call ``update-mime-database`` to add the MIME types to
 the shared database.
 
+.. _ref-classes-mime-xdg:
+
+``mime-xdg.bbclass``
+====================
+
+The :ref:`mime-xdg <ref-classes-mime-xdg>` class generates the proper
+post-install and post-remove (postinst/postrm) scriptlets for packages
+that install ``.desktop`` files containing ``MimeType`` entries.
+These scriptlets call ``update-desktop-database`` to add the MIME types
+to the database of MIME types handled by desktop files.
+
+Thanks to this class, when users open a file through a file browser
+on recently created images, they don't have to choose the application
+to open the file from the pool of all known applications, even the ones
+that cannot open the selected file.
+
+If you have recipes installing their ``.desktop`` files as absolute
+symbolic links, the detection of such files cannot be done by the current
+implementation of this class. In this case, you have to add the corresponding
+package names to the :term:`MIME_XDG_PACKAGES` variable.
+
 .. _ref-classes-mirrors:
 
 ``mirrors.bbclass``