Base gamma adjustment on the gamma ramps at startup

[jonls]

When Redshift starts it simply overrides the current gamma ramps. The former gamma ramps are saved so they can be restored when Redshift exits, but they could also be used as a base for applying the redness adjustment on top. This would presumably allow people who have customized gamma ramps (for color correction or otherwise) to use Redshift on top of that.

[maandree]

A problem that can occur is that the settings accumulate, perhaps Redshift crashes
or Redshift is executed in one shot mode.

To avoid this I think the best solution is to save the curves to a /tmp file. Be sure
that the filename reflects host, user and X display, this avoids problems if you have
multiple users logged in, have different settings on different X display, or is using
Redshift over the network. The /tmp file should be removed if and only if Redshift
exists cleanly from continuous mode.

Additionally I think that it should only be used if explicitly specified.

[jonls]

I agree that it is not without issues. An option (default off) to enable this feature would probably suffice.

[maandree]

It suffices. But personally I mostly use one shot mode and
this is useless for one shot mode otherwise, unless you are
using some special software that can do changes to the ramps
that Redshift cannot.

[jonls]

Indeed, if using one shot mode multiple times it would not work. To support this use case the original gamma ramps would have to be saved to a file.

[maandree]

I think you can close this issue.