This will be used by the update check to verify you are running a new
version since last time. In the future, it might even allow to handle
some types of config migrations if ever we update some things in-between
micro releases. Until now, we could only detect minor updates through
the config folder name (and even this was limited as the config folder
can be specified, in which case we would not even know what version the
files were for).
Maybe we could start also warning in cases of downgrading too, which can
break some configuration files (though there is not much we can do about
it other than warn as there is no time machine!).
Last point: if the new config value "last-run-version" doesn't exist, it
simply means the config folder was run for a GIMP before this point in
time/commit. So we just show the welcome dialog.
The About dialog refreshes the release information relatively to
currently running version before being displayed. No check of the remote
JSON file is done, it only verifies whether any stored released
version/revision is not same (or even lower) than the actually running
version. Indeed existence of a stored release means that a newer version
exists at check time only. On later run, this stored information may
have become deprecated.
When an update is available, a big frame is visible, proposing to go to
the download page. Now a button is also available to explicitly request
for an update check in other cases (bypassing the wait delay for a
future startup).
GIMP will now process the remote gimp_versions json file to look if one
is using the last version of GIMP. This initial code doesn't act up yet
on this information. This will come in further commits.
Here are the characteristics:
- Since this requires internet access, a new checkbox is available in
the Preferences dialog, allowing to disable version checks. Note that
it is enabled by default as it is an important security feature, but
it has to be deactivatable.
- The remote access is done as an async operation because we don't want
it to block the startup in any way (for whatever reason). Also it
doesn't output errors if it fails to not be a bother (you don't
technically need internet access for an image program).
- We don't check at every startup. At each successful check, we save a
timestamp to prevent too frequent useless checks (I set it the timer
to a week or more for now).