Constant fading duration

[ghost]

Have you looked for this feature in other issues and in the docs?

Yes, I searched in the issues for a fixed fade duration, that takes always the same amount of time. I found #6942 but this was more related to gamma control.

Is your feature request related to a problem? Please describe.
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I had an RGB controller in my bathroom. This is triggered by a motion sensor via Home Assistant. Generally the fading works smooth and nice in a time of about 2 seconds. But at the night I limited the maximum brightness to 20%. This is really cool because when I wake up late, it's not that blinding. But the disadvantage is that the duration of the fading is also just 20% of the time, when faded to 100%. This make it some kind of flashing because it reaches the maximum brightness within a really short time which can be really challenging for the eyes.

Describe the solution you'd like
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It would be great if the fading is a constant time. Longer fade distances will be reached in the same amount of time as shorter distances.

Describe alternatives you've considered
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I also already enabled the gamma control, which makes the transition more linear for the physiological characteristics of the eyes but this didn't satisfy my needs.

Additional context
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I checked out the code and looked for a nice place to put this functionality. I was neither able to build the code nor to test it. But I'd like to share the patch with you to present a possible solution.

constant_fade.txt

(Please, remember to close the issue when the problem has been addressed)

[s-hadinger]

It was a debate whether the fading should be fixed duration or fixed slew rate. It was decided to be fixed slew rate, but it shouldn't be difficult to have a fixed duration as an alternative. I guess it means yet another SetOption?.