there are two x extensions for working with monitors (especially
multiple): xinerama and randr. xinerama is old, feature-poor and in
general isn't used anymore compared to the randr: new, feature-rich and
widely-used. for some reason we were using both of them, so let's drop
xinerama to keep things simple, clean and small. and to be modern.
the drop was done in three steps:
* first step was to replace all the xinerama-based code with the
randr-based one and to replace or remove all the xinerama mentions;
* second step was to replace the xinerama's terminology with the
randr's one. xinerama was referring only to the word "screen", while
randr refers to multiple words and i think the word "monitor" is the
most suitable for us and, hopefully, clear both to a contributor and
to an end user;
* third step was to refactor the new randr-based code if needed and to
address related todo's (mostly about moving related functions
elsewhere).
all the steps were done well except addressing a leftover todo about
moving the win_update_monitor function to the x.c which wasn't done.
the xinerama-shadow-crop option was renamed to crop-shadow-to-monitor,
but it's previous name is still accepted, has effect and the
deprecation message is printed to preserve backwards-compatibility.
Use the DPMS extension to detect if screen is turned off, and unredirect
if it is. This also helps working around the problem where OpenGL
buffers lose data when screen is turned off, causing screen to flicker
later when it turns back on if use-damage is enabled.
Unfortunately the DPMS extension doesn't define an event, so we have to
periodically poll the screen state.
Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>
