Version 3 does not send xdg_output.done events, instead guaranteeing that
all xdg_output.* events are sent before wl_output.done. This saves us from
doing the work twice.
Currently, we scale the desktop up to the next largest integer, and rely on
the wayland compositor to scale it back down to the correct size.
This is obviously undesirable.
In this commit, we attempt to detect the actual fractional scaling by finding
the current active mode in wl_output, and dividing it by the logical screen
size reported by xdg_output, taking into consideration screen rotation.
We then use wp_viewporter to set the exact buffer and viewport sizes if
fractional scaling is needed.
Instead of damaging the entire surface when rendering a cursor move,
we can use the EGL_KHR_swap_buffers_with_damage extension to only
damage the part of the window covered by the cursor. This should
reduce the cursor movement latency on Wayland.
The only addition to v4 was `wl_surface_damage_buffer`, which we do not
use.
This change should allow running on more compositors (even though v4 is
already old -- 5 years now).
Ref
3384f69ecf.
The Wayland display server is getting unwieldy due to the sheer size.
To make it easier to edit in the future, I split it into many components
based on logical boundaries.
