This is a method for distributing MAME using the Flatpak format. The main reason for this is on locked down systems that only allow sandboxed user applications.
The use of Flatpak here is not intended to secure MAME or provide any isolation from the rest of your system. MAME requires access to many of your systems resources including, but not limited to, devices for controllers, X11 sessions, filesystems writable for configuration and readable for data files, networking, and audio. The Flatpak provided sandbox must be opened up in many areas for MAME to function properly.
build_icons.sh will download the logo from the https://www.mamedev.org site and resize it to various sizes to use as an icon.
build_local.sh will invoke the flatpak-builder application to compile MAME and generate a Flatpak package.
org.mamedev.MAME.yaml is the main Flatpak manifest that includes build and install information.
An explanation for some of the options included in the `org.mamedev.MAME.yaml' manifest file.
org.kde.Platform is used for its Qt support, required to build the MAME debugger.
--device=all added to allow various input devices, controllers, etc.
--persist=.mame writable location used for cfg, diff, nvram, etc.
--filesystem=host:ro primarily to be used for external data, roms, samples, etc.
The default ini paths include the home ~/.mame directory and two relative paths '.' and 'ini'. The relative paths are not helpful inside the sandbox, and the ~/.mame contents shouldn't be overwritten with each new MAME release. Instead the default ini search path is patched to $HOME/.mame;/app/share/mame/ini. This will allow a default base ini in /app/share/mame/ini/mame.ini and can be overridden in ~/.mame/mame.ini.