[Enhancement] Add Overscan/Underscan support

[ObscenityIB]

Currently, it seems only X11 tools have overscan support.

Using way-displays on a 1080p external monitor, set to 1080p, has the edges cut off.

Scaling to 0.75 doesn't seem to work as a way to mitigate the cropping.

Not many displays offer a setting for overscan or "pc mode", so a software solution would be needed in this case.

[alex-courtis]

Unfortunately there doesn't appear to be API to do this in wlroots or wayland.

My guess is that it's not a necessary use case ~2018. It would likely result in a distorted image on an LCD monitor, only being appropriate for a CRT monitor.

What's your use case here? What video card / laptop / machine are you using? Which monitor are you using?

Can you experiment with a different machine and a different monitor?

[alex-courtis]

It may be possible with some hackitry around a custom mode and position however sway would get upset with that as it assumes contiguous displays - any gap will result in difficulties like #146

[ObscenityIB]

I see, I've been tinkering for a while now but haven't figured anything out.

Short of buying a display that supports software overscan settings.

The current display I'm using is a Toshiba 40CV550A, from 2009.
Previously, I tested a more modern JVC display from 2014 with smart features, but that one is detected as replugging every few seconds, and kicks the refresh rate down or up by 1Hz each time.
I've also tried a Sony display, which had the same overscan issue.

Maybe I can find a new one that works from this decade that is affordable.

[alex-courtis]

The current display I'm using is a Toshiba 40CV550A, from 2009.

I see. Looking at the manual that TV doesn't mention overscan. Smart features are Bad News.

I don't think I can justify writing a lot of hacky code to support 15 year old hardware. Overscan seems like a bizarre feature from marketing rather than product management...

If you're short on money could you look at a more recent TV at, say, a thrift shop? My neighbours just gave away their old TV when they upgraded!