Region + follow mouse = magnifier

[Vladimir-csp]

If it is possible to make a region follow mouse, wl-mirror could act as screen magnifier.

[Ferdi265]

There is no way to get the mouse position in wayland if the mouse is not currently over your own window, so this would require extra compositor support.

some compositors (e.g. sway, hyprland) might have ways to get the current mouse position via IPC, wo you could script that outside wl-mirror in a similar way to what wl-present does.

[Ferdi265]

if this is easily scriptable on a compositor, I would very gladly accept a PR for an example script that implements a magnifier, since it's a really cool demo.

[Ferdi265]

It seems like there is no feature to get the current mouse coordinates on sway, but there is an IPC command for it on hyprland (hyprctl cursorpos). The latter can be scripted, but doesn't provide for a great experience since there is no way to be notified of any cursor changes, so you have to constantly poll it.

Here's a very hacky proof-of-concept script for hyprland that demonstrates the possibility:

#!/bin/bash
# usage: ./magnify.sh eDP-1
# usage: ./magnify.sh eDP-1 200 

DEFAULT_SIZE=100

magnify-region() {
    SIZE=${1:-$DEFAULT_SIZE}
    POS=$(hyprctl cursorpos)
    IFS=',' read -r X Y <<< "$POS"
    echo "$((X-SIZE/2)),$((Y-SIZE/2)) $((SIZE))x$((SIZE))"
}

magnify() {
    SIZE=${1:-$DEFAULT_SIZE}
    while sleep .1; do
        wl-present set-region "$(magnify-region "$SIZE")"
    done
}

wl-present mirror "${1:-eDP-1}" &
magnify "${2:-$DEFAULT_SIZE}"
trap 'killall wl-mirror' EXIT

This doesn't provide a great experience, but shows that if at some point compositors provide better ways to get the cursor position, this could be implementable.

[Ferdi265]

Of note: IIRC it's possible for compositors to provide the cursor image as a separate layer in the XDG Portals / Pipewire screen capture protocol (see #16). Technically wl-mirror could also extract mouse coordinates from there once that protocol is implemented, and that would be a much more consistent source of the cursor position for magnification. This would still be a hack though, since it's not guaranteed that a compositor provides the cursor as a separate layer or displays it at all.

[Ferdi265]

Since there isn't a good way to get the cursor position in Wayland right now I might either close this issue or mark this as an "upstream bug" since there isn't much we can do as a regular Wayland client that would solve this in a satisfactory fashion.

[Vladimir-csp]

Well, till something comes up in the protocols...