Add AppStream metadata

[Balló György]

AppStream[1] is a cross-distribution effort for enhancing the way we interact with the software repositories provided by (Linux) distributions by standardizing software component metadata.

Please include a metainfo file like the attached one in the upstream project, and install it into '/usr/share/metainfo' folder during the build process, so distributions could use it.

[1] https://www.freedesktop.org/wiki/Distributions/AppStream/

[Arthur Borsboom (arthurborsboom)]

The metainfo file has been added to the source code.
However, I still need to implement a way to get this file copied to the appropriate directory.

[Arthur Borsboom (arthurborsboom)]

Hi Balló,

I have made some additions to the Makefile to copy the metadata file on the "make install" command.
Would you mind to validate if this is correct?

[Balló György (ballogy)]

It ignores the DESTDIR, so it's not correct.

I recommend to do something like this:
- Rename xpad.appdata.xml to xpad.appdata.xml.in, and add underscores to the <summary> and <p> elements:
https://gitlab.gnome.org/GNOME/gnome-subtitles/blob/master/data/org.gnome.GnomeSubtitles.appdata.xml.in#L8

- Use this code to merge translations and install the file:
https://gitlab.gnome.org/GNOME/gnome-subtitles/blob/master/data/Makefile.am#L6

- Add it to po/POTFILES.in and POTFILES.skip:
https://gitlab.gnome.org/GNOME/gnome-subtitles/blob/master/po/POTFILES.in#L4
https://gitlab.gnome.org/GNOME/gnome-subtitles/blob/master/po/POTFILES.skip#L1

[Arthur Borsboom (arthurborsboom)]

Hi Balló,

Thanks for your feedback and examples.
I have mimicked parts of the example and applied it to the Xpad package.

Would you mind to verify again if it is correct?

[Balló György (ballogy)]

Yes, it's good now. Thanks! :)

You probably want to remove the generated file 'xpad.appdata.xml' from the root directory of source.

[Arthur Borsboom (arthurborsboom)]

Thanks for the last hint and your previous help.
This will be part of Xpad v5.4