wl-mirror - a simple Wayland output mirror client

wl-mirror attempts to provide a solution to sway's lack of output mirroring by mirroring an output onto a client surface.

Features

• Mirror an output onto a resizable window
• Mirror an output onto another output by fullscreening the window
• Reacts to changes in output scale
• Preserves aspect ratio
• Corrects for flipped or rotated outputs
• Supports custom flips or rotations
• Supports mirroring custom regions of outputs
• Supports receiving additional options on stdin for changing the mirrored screen or region on the fly (works best when used with pipectl)

Usage

usage: wl-mirror [options] <output>

options:
  -h,   --help             show this help
  -V,   --version          print version
  -v,   --verbose          enable debug logging
        --no-verbose       disable debug logging (default)
  -c,   --show-cursor      show the cursor on the mirrored screen (default)
        --no-show-cursor   don't show the cursor on the mirrored screen
  -i,   --invert-colors    invert colors in the mirrored screen
        --no-invert-colors don't invert colors in the mirrored screen (default)
  -f,   --freeze           freeze the current image on the screen
        --unfreeze         resume the screen capture after a freeze
        --toggle-freeze    toggle freeze state of screen capture
  -s l, --scaling linear   use linear scaling (default)
  -s n, --scaling nearest  use nearest neighbor scaling
  -s e, --scaling exact    only scale to exact multiples of the output size
  -b B  --backend B        use a specific backend for capturing the screen
  -t T, --transform T      apply custom transform T
  -r R, --region R         capture custom region R
        --no-region        capture the entire output (default)
  -S,   --stream           accept a stream of additional options on stdin

backends:
  - auto        automatically try the backends in order and use the first that works (default)
  - dmabuf      use the wlr-export-dmabuf-unstable-v1 protocol to capture outputs
  - screencopy  use the wlr-screencopy-unstable-v1 protocol to capture outputs

transforms:
  transforms are specified as a dash-separated list of flips followed by a rotation
  flips are applied before rotations
  - normal                         no transformation
  - flipX, flipY                   flip the X or Y coordinate
  - 0cw,  90cw,  180cw,  270cw     apply a clockwise rotation
  - 0ccw, 90ccw, 180ccw, 270ccw    apply a counter-clockwise rotation
  the following transformation options are provided for compatibility with sway output transforms
  - flipped                        flip the X coordinate
  - 0,    90,    180,    270       apply a clockwise rotation

regions:
  regions are specified in the format used by the slurp utility
  - '<x>,<y> <width>x<height> [output]'
  on start, the region is translated into output coordinates
  when the output moves, the captured region moves with it
  when a region is specified, the <output> argument is optional

stream mode:
  in stream mode, wl-mirror interprets lines on stdin as additional command line options
  - arguments can be quoted with single or double quotes, but every argument must be fully
    quoted or fully unquoted
  - unquoted arguments are split on whitespace
  - no escape sequences are implemented

The scripts/ folder contains examples on how wl-mirror can be used.

• wl-present is a small script to demonstrate the use of the -S option to interactively present on Sway.
  This script is especially useful when binding the wl-present subcommands to keyboard shortcuts.
• release.sh Generates a release tar ball for the currently checked out commit if there's a release tag on it.

Installation

wl-mirror is already packaged in many distros and can be installed via the package manager:

• Arch Linux AUR: yay -S wl-mirror or yay -S wl-mirror-git
• Fedora: dnf install wl-mirror
• Ubuntu: .deb file download in releases, official package in progress
• Debian: .deb file download in releases, official package in progress
• Alpine Linux: apk add wl-mirror wl-mirror-doc
• NixOS: nix profile install nixpkgs#wl-mirror
• Void Linux: xbps-install -S wl-mirror
• FreeBSD Ports: x11/wl-mirror
• DragonflyBSD Ports: x11/wl-mirror
• Gentoo GURU: gui-apps/wl-mirror
• LiGurOS: gui-apps/wl-mirror

Supported Wayland Compositors

wl-mirror should work on all Wayland compositors based on wlroots, such as sway or hyprland.

wl-mirror currently does not work on KDE and Gnome, due to wl-mirror not supporting the XDG Desktop Portal screen sharing protocol. This is being worked on (see issues #16 and #17).

Dependencies

• CMake
• pkg-config
• libwayland-client
• libwayland-egl
• libEGL
• libGLESv2
• wayland-scanner
• scdoc (for manual pages)

Script Dependencies

• pipectl (scripts/wl-present)
• slurp (scripts/wl-present)
• rofi or dmenu (scripts/wl-present)

Building

• Install Dependencies
• Clone Submodules (git submodule update --init)
• Run cmake -B build
• Run make -C build

CMake Options

• INSTALL_EXAMPLE_SCRIPTS: also install example scripts (default OFF)
• INSTALL_DOCUMENTATION: also build and install manual pages (default OFF)
• FORCE_SYSTEM_WL_PROTOCOLS: always use system-installed wayland-protocols, do not use submodules (default OFF)
• FORCE_SYSTEM_WLR_PROTOCOLS: always use system-installed wlr-protocols, do not use submodules (default OFF)
• WL_PROTOCOL_DIR: directory where system-installed wayland-protocols are located (default /usr/share/wayland-protocols)
• WLR_PROTOCOL_DIR: directory where system-installed wlr-protocols are located (default /usr/share/wlr-protocols)

Files

• src/main.c: main entrypoint
• src/options.c: CLI and stream option parsing
• src/wayland.c: Wayland and xdg_surface boilerplate
• src/egl.c: EGL boilerplate
• src/mirror.c: output mirroring code
• src/mirror-dmabuf.c: wlr-export-dmabuf-unstable-v1 backend code
• src/mirror-screencopy.c: wlr-screencopy-unstable-v1 backend code
• src/transform.c: matrix transformation code
• src/event.c: event loop and asynchronous option stream input