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Screen Sharing

Screensharing in Wayland is done with the help of Portals. Portals were initially designed to allow applications sandboxes via Flatpak to access resources of the desktop, but have since gained popularity outside of the realm of Flatpaks. In our case, we can use the screen sharing portal to allow applications to access the contents of the Wayland compositor.

Note

Please be aware that you will only be able to share a single screen with this method, not individual windows.

Setup

Installation

First, we need to install xdg-desktop-portal-wlr. Unfortunately, Mir only has support for v0.5.0 of this software, so we will need to checkout the source at a particualr commit:

git clone https://github.com/emersion/xdg-desktop-portal-wlr
cd xdg-desktop-portal-wlr
git checkout 7c0f352  # This is release 0.5.0

Next, we can build the project: 

meson setup builddir
cd builddir
ninja -j4
sudo ninja install

Configuration

First, let's add a new environment variable to our Mir configuration: 

# ~/.config/miracle-wm.yaml

environment_variables:
  - key: XDG_CURRENT_DESKTOP
    value: mir

Next, create a file at ~/.config/xdg-desktop-portal/mir-portals.conf and write: 

# ~/.config/xdg-desktop-portal/mir-portals.conf

[preferred]
default=gtk
org.freedesktop.impl.portal.Screenshot=wlr
org.freedesktop.impl.portal.ScreenCast=wlr

Next, create a file at ~/.config/xdg-desktop-portal-wlr/config and write:

# ~/.config/xdg-desktop-portal-wlr/config

[screencast]
output_name=HDMI-A-1
max_fps=30
#exec_before=disable_notifications.sh
#exec_after=enable_notifications.sh
chooser_type=simple
chooser_cmd=slurp -f %o -or

Finally modify /usr/share/xdg-desktop-portal/portals/wlr.portal to include "Mir" in the "UseIn" value:

# /usr/share/xdg-desktop-portal/portals/wlr.portal

[portal]
DBusName=org.freedesktop.impl.portal.desktop.wlr
Interfaces=org.freedesktop.impl.portal.Screenshot;org.freedesktop.impl.portal.ScreenCast;
UseIn=wlroots;sway;Wayfire;river;phosh;Hyprland;Mir;

Running

First, create a script somewhere called run_xdg_desktop_portal_wlr.sh with the following contents:

# /usr/local/bin/run_xdg_desktop_portal_wlr.sh

# Export WAYLAND_DISPLAY and XDG_CURRENT_DESKTOP to dbus
dbus-update-activation-environment --systemd WAYLAND_DISPLAY XDG_CURRENT_DESKTOP=mir

# Stop xdg-desktop-portal
systemctl --user stop xdg-desktop-portal

# Also, you may want do stop any other portal service that you have enabled, e.g.:
systemctl --user stop xdg-desktop-portal-gtk

# Start xdg-desktop-portal-*
systemctl --user start xdg-desktop-portal
systemctl --user start xdg-desktop-portal-wlr

In your miracle-wm.yaml configuration file, add:

# ~/.confg/miracle-wm.yaml

startup_apps:
  - command: run_xdg_desktop_portal_wlr.sh

Restart your compositor and then open up obs-studio or Google Meet and see that you are able to share your screen.