Mirror a monitor to another

[Balint66]

Hi!
I really love niri, that's my main wm that I use daily. Sadly, I can't fully move away from gnome, because right now mirroring the "primary" display to my "secondary" is not possible in niri.

I've tried to use wl-mirror to put it on the other display, but when that window loses focus, it stops updating.

I think it would be really cool, if there were an option to mirror a display to another, or an action to do this, without relying on an external tool.

[YaLTeR]

I agree it would be useful, but display mirroring is somewhat complicated. Also would require thinking how to configure it.

I've tried to use wl-mirror to put it on the other display, but when that window loses focus, it stops updating.

Maybe there's a way to make it work? It sounds like it should work for that case.

[selvmaya]

I have this issue (wl-mirror window freezing/not capturing correctly) on both my Lenovo Y540 laptop with a GTX1660TI and my desktop ITX build with a RTX4070. Both are running niri with proprietary nvidia drivers on Arch Linux.

Below are logs/info from testing on my desktop.

with `export-dmabuf` backend (fails)

$ wl-mirror -v -b export-dmabuf --fullscreen-output DP-1 DP-3
debug: main::main(): initializing stream
debug: main::main(): initializing wayland
debug: wayland::on_registry_add(): wl_compositor (version = 6, id = 1)
debug: wayland::on_registry_add(): wl_subcompositor (version = 1, id = 2)
debug: wayland::on_registry_add(): xdg_wm_base (version = 6, id = 3)
debug: wayland::on_registry_add(): zwlr_layer_shell_v1 (version = 4, id = 6)
debug: wayland::on_registry_add(): ext_session_lock_manager_v1 (version = 1, id = 7)
debug: wayland::on_registry_add(): wl_shm (version = 2, id = 8)
debug: wayland::on_registry_add(): zxdg_output_manager_v1 (version = 3, id = 9)
debug: wayland::on_registry_add(): wp_fractional_scale_manager_v1 (version = 1, id = 10)
debug: wayland::on_registry_add(): zwp_tablet_manager_v2 (version = 1, id = 11)
debug: wayland::on_registry_add(): zwp_pointer_gestures_v1 (version = 3, id = 12)
debug: wayland::on_registry_add(): zwp_relative_pointer_manager_v1 (version = 1, id = 13)
debug: wayland::on_registry_add(): zwp_pointer_constraints_v1 (version = 1, id = 14)
debug: wayland::on_registry_add(): ext_idle_notifier_v1 (version = 2, id = 15)
debug: wayland::on_registry_add(): zwp_idle_inhibit_manager_v1 (version = 1, id = 16)
debug: wayland::on_registry_add(): wl_data_device_manager (version = 3, id = 17)
debug: wayland::on_registry_add(): zwp_primary_selection_device_manager_v1 (version = 1, id = 18)
debug: wayland::on_registry_add(): zwlr_data_control_manager_v1 (version = 2, id = 19)
debug: wayland::on_registry_add(): ext_data_control_manager_v1 (version = 1, id = 20)
debug: wayland::on_registry_add(): wp_presentation (version = 2, id = 21)
debug: wayland::on_registry_add(): wp_security_context_manager_v1 (version = 1, id = 22)
debug: wayland::on_registry_add(): zwp_text_input_manager_v3 (version = 1, id = 23)
debug: wayland::on_registry_add(): zwp_input_method_manager_v2 (version = 1, id = 24)
debug: wayland::on_registry_add(): zwp_keyboard_shortcuts_inhibit_manager_v1 (version = 1, id = 25)
debug: wayland::on_registry_add(): zwp_virtual_keyboard_manager_v1 (version = 1, id = 26)
debug: wayland::on_registry_add(): zwlr_virtual_pointer_manager_v1 (version = 2, id = 27)
debug: wayland::on_registry_add(): zwlr_foreign_toplevel_manager_v1 (version = 3, id = 28)
debug: wayland::on_registry_add(): ext_workspace_manager_v1 (version = 1, id = 29)
debug: wayland::on_registry_add(): zwlr_output_manager_v1 (version = 4, id = 30)
debug: wayland::on_registry_add(): zwlr_screencopy_manager_v1 (version = 3, id = 31)
debug: wayland::on_registry_add(): wp_viewporter (version = 1, id = 32)
debug: wayland::on_registry_add(): zxdg_exporter_v2 (version = 1, id = 33)
debug: wayland::on_registry_add(): zxdg_importer_v2 (version = 1, id = 34)
debug: wayland::on_registry_add(): zwlr_gamma_control_manager_v1 (version = 1, id = 35)
debug: wayland::on_registry_add(): xdg_activation_v1 (version = 1, id = 36)
debug: wayland::on_registry_add(): mutter_x11_interop (version = 1, id = 37)
debug: wayland::on_registry_add(): wl_seat (version = 9, id = 38)
debug: wayland::on_registry_add(): wp_cursor_shape_manager_v1 (version = 2, id = 39)
debug: wayland::on_registry_add(): wl_eglstream_display (version = 1, id = 40)
debug: wayland::on_registry_add(): wl_drm (version = 2, id = 41)
debug: wayland::on_registry_add(): zwp_linux_dmabuf_v1 (version = 5, id = 42)
debug: wayland::on_registry_add(): wp_drm_lease_device_v1 (version = 1, id = 43)
debug: wayland::on_registry_add(): wl_output (version = 4, id = 44)
debug: wayland::on_registry_add(): wl_output (version = 4, id = 45)
debug: wayland::on_registry_add(): wl_output (version = 4, id = 46)
debug: main::main(): initializing EGL
debug: egl::init(): initialized EGL 1.5
debug: main::main(): configuring wayland window
debug: wayland::on_xdg_output_logical_size(): updating output (null) (size = 2560x1440, id = 44)
debug: wayland::on_xdg_output_name(): updating output DP-2 (id = 44)
debug: wayland::on_xdg_output_logical_position(): updating output (null) (position = 640,-1080, id = 45)
debug: wayland::on_xdg_output_logical_size(): updating output (null) (size = 1920x1080, id = 45)
debug: wayland::on_xdg_output_name(): updating output DP-3 (id = 45)
debug: wayland::on_output_geometry(): updating output (null) (transform = 270ccw, id = 46)
debug: wayland::on_xdg_output_logical_position(): updating output (null) (position = 2560,-240, id = 46)
debug: wayland::on_xdg_output_logical_size(): updating output (null) (size = 1050x1680, id = 46)
debug: wayland::on_xdg_output_name(): updating output DP-1 (id = 46)
debug: wayland::on_fractional_scale_preferred_scale(): scale = 1.0000
debug: wayland::on_xdg_toplevel_configure(): window resized to 1248x1378
debug: egl::resize_window(): resizing EGL window to 1248x1378
debug: egl::resize_viewport(): resizing viewport
debug: egl::resize_viewport(): win_width = 1248, win_height = 1378
debug: egl::resize_viewport(): view_width = 1248, view_height = 1248
debug: egl::resize_viewport(): viewport 0, 65, 1248, 1248
debug: wayland::on_surface_configure_finished(): window configured
debug: wayland::configure_window(): fullscreening on target output
debug: main::main(): initializing mirror
debug: options::find_output(): searching for output by name
debug: options::find_output(): found output with name DP-3
debug: main::main(): initializing mirror backend
error: mirror-export-dmabuf::init(): missing wlr_export_dmabuf_manager protocol
debug: main::cleanup(): deallocating resources
debug: mirror::cleanup(): destroying mirror objects
debug: egl::cleanup(): destroying EGL objects
debug: wayland::cleanup(): destroying wayland objects
debug: wayland::shm::cleanup(): destroying wayland shm objects

Not sure if this is the backend I'm suppposed to use: DMABUF is supposedly supported at least for screencasting in browsers like Arc.

with `auto`/unspecified backend

$ wl-mirror -v --fullscreen-output DP-1 DP-3
debug: main::main(): initializing stream
debug: main::main(): initializing wayland
debug: wayland::on_registry_add(): wl_compositor (version = 6, id = 1)
debug: wayland::on_registry_add(): wl_subcompositor (version = 1, id = 2)
debug: wayland::on_registry_add(): xdg_wm_base (version = 6, id = 3)
debug: wayland::on_registry_add(): zwlr_layer_shell_v1 (version = 4, id = 6)
debug: wayland::on_registry_add(): ext_session_lock_manager_v1 (version = 1, id = 7)
debug: wayland::on_registry_add(): wl_shm (version = 2, id = 8)
debug: wayland::on_registry_add(): zxdg_output_manager_v1 (version = 3, id = 9)
debug: wayland::on_registry_add(): wp_fractional_scale_manager_v1 (version = 1, id = 10)
debug: wayland::on_registry_add(): zwp_tablet_manager_v2 (version = 1, id = 11)
debug: wayland::on_registry_add(): zwp_pointer_gestures_v1 (version = 3, id = 12)
debug: wayland::on_registry_add(): zwp_relative_pointer_manager_v1 (version = 1, id = 13)
debug: wayland::on_registry_add(): zwp_pointer_constraints_v1 (version = 1, id = 14)
debug: wayland::on_registry_add(): ext_idle_notifier_v1 (version = 2, id = 15)
debug: wayland::on_registry_add(): zwp_idle_inhibit_manager_v1 (version = 1, id = 16)
debug: wayland::on_registry_add(): wl_data_device_manager (version = 3, id = 17)
debug: wayland::on_registry_add(): zwp_primary_selection_device_manager_v1 (version = 1, id = 18)
debug: wayland::on_registry_add(): zwlr_data_control_manager_v1 (version = 2, id = 19)
debug: wayland::on_registry_add(): ext_data_control_manager_v1 (version = 1, id = 20)
debug: wayland::on_registry_add(): wp_presentation (version = 2, id = 21)
debug: wayland::on_registry_add(): wp_security_context_manager_v1 (version = 1, id = 22)
debug: wayland::on_registry_add(): zwp_text_input_manager_v3 (version = 1, id = 23)
debug: wayland::on_registry_add(): zwp_input_method_manager_v2 (version = 1, id = 24)
debug: wayland::on_registry_add(): zwp_keyboard_shortcuts_inhibit_manager_v1 (version = 1, id = 25)
debug: wayland::on_registry_add(): zwp_virtual_keyboard_manager_v1 (version = 1, id = 26)
debug: wayland::on_registry_add(): zwlr_virtual_pointer_manager_v1 (version = 2, id = 27)
debug: wayland::on_registry_add(): zwlr_foreign_toplevel_manager_v1 (version = 3, id = 28)
debug: wayland::on_registry_add(): ext_workspace_manager_v1 (version = 1, id = 29)
debug: wayland::on_registry_add(): zwlr_output_manager_v1 (version = 4, id = 30)
debug: wayland::on_registry_add(): zwlr_screencopy_manager_v1 (version = 3, id = 31)
debug: wayland::on_registry_add(): wp_viewporter (version = 1, id = 32)
debug: wayland::on_registry_add(): zxdg_exporter_v2 (version = 1, id = 33)
debug: wayland::on_registry_add(): zxdg_importer_v2 (version = 1, id = 34)
debug: wayland::on_registry_add(): zwlr_gamma_control_manager_v1 (version = 1, id = 35)
debug: wayland::on_registry_add(): xdg_activation_v1 (version = 1, id = 36)
debug: wayland::on_registry_add(): mutter_x11_interop (version = 1, id = 37)
debug: wayland::on_registry_add(): wl_seat (version = 9, id = 38)
debug: wayland::on_registry_add(): wp_cursor_shape_manager_v1 (version = 2, id = 39)
debug: wayland::on_registry_add(): wl_eglstream_display (version = 1, id = 40)
debug: wayland::on_registry_add(): wl_drm (version = 2, id = 41)
debug: wayland::on_registry_add(): zwp_linux_dmabuf_v1 (version = 5, id = 42)
debug: wayland::on_registry_add(): wp_drm_lease_device_v1 (version = 1, id = 43)
debug: wayland::on_registry_add(): wl_output (version = 4, id = 44)
debug: wayland::on_registry_add(): wl_output (version = 4, id = 45)
debug: wayland::on_registry_add(): wl_output (version = 4, id = 46)
debug: main::main(): initializing EGL
debug: egl::init(): initialized EGL 1.5
debug: main::main(): configuring wayland window
debug: wayland::on_xdg_output_logical_size(): updating output (null) (size = 2560x1440, id = 44)
debug: wayland::on_xdg_output_name(): updating output DP-2 (id = 44)
debug: wayland::on_xdg_output_logical_position(): updating output (null) (position = 640,-1080, id = 45)
debug: wayland::on_xdg_output_logical_size(): updating output (null) (size = 1920x1080, id = 45)
debug: wayland::on_xdg_output_name(): updating output DP-3 (id = 45)
debug: wayland::on_output_geometry(): updating output (null) (transform = 270ccw, id = 46)
debug: wayland::on_xdg_output_logical_position(): updating output (null) (position = 2560,-240, id = 46)
debug: wayland::on_xdg_output_logical_size(): updating output (null) (size = 1050x1680, id = 46)
debug: wayland::on_xdg_output_name(): updating output DP-1 (id = 46)
debug: wayland::on_fractional_scale_preferred_scale(): scale = 1.0000
debug: wayland::on_xdg_toplevel_configure(): window resized to 1248x1378
debug: egl::resize_window(): resizing EGL window to 1248x1378
debug: egl::resize_viewport(): resizing viewport
debug: egl::resize_viewport(): win_width = 1248, win_height = 1378
debug: egl::resize_viewport(): view_width = 1248, view_height = 1248
debug: egl::resize_viewport(): viewport 0, 65, 1248, 1248
debug: wayland::on_surface_configure_finished(): window configured
debug: wayland::configure_window(): fullscreening on target output
debug: main::main(): initializing mirror
debug: options::find_output(): searching for output by name
debug: options::find_output(): found output with name DP-3
debug: main::main(): initializing mirror backend
debug: mirror::auto_backend_fallback(): selecting backend extcopy-dmabuf
error: mirror-extcopy::init(): missing ext_image_copy_capture protocol
warning: mirror::auto_backend_fallback(): falling back to backend screencopy-dmabuf
debug: main::main(): entering event loop
debug: wayland::on_xdg_toplevel_configure(): window resized to 1050x1680
debug: egl::resize_window(): resizing EGL window to 1050x1680
debug: egl::resize_viewport(): resizing viewport
debug: egl::resize_viewport(): win_width = 1050, win_height = 1680
debug: egl::resize_viewport(): view_width = 1050, view_height = 1050
debug: egl::resize_viewport(): viewport 0, 315, 1050, 1050
debug: wayland::on_surface_configure_finished(): window configured
debug: wayland::dmabuf::on_feedback_main_device(): opening main device
debug: wayland::dmabuf::open_device(): opening gbm device
debug: mirror-screencopy::on_dmabuf_device_opened(): dmabuf device opened, ready for capture
debug: wayland::on_surface_enter(): updating window scale
debug: mirror-screencopy::on_linux_dmabuf(): received buffer offer for 1920x1080 frame
debug: wayland::dmabuf::alloc(): allocated dmabuf with format=34325258, size=1920x1080, modifier=300000000e08014, planes=1
debug: wayland::dmabuf::alloc(): plane[0]: fd=41, offset=0, stride=1e00
debug: mirror-screencopy::on_buffer_done(): received buffer done event
debug: mirror-screencopy::on_buffer_done(): waiting on dmabuf allocation
debug: wayland::dmabuf::on_linux_buffer_params_created(): allocation succeeded
debug: mirror-screencopy::on_dmabuf_allocated(): dmabuf allocated
debug: mirror-screencopy::on_flags(): received flags event: flags=0
debug: mirror-screencopy::on_ready(): received ready event with width: 1920, height: 1080, stride: 0, format: 42RX
debug: egl::resize_viewport(): resizing viewport
debug: egl::resize_viewport(): win_width = 1050, win_height = 1680
debug: egl::resize_viewport(): view_width = 1050, view_height = 590
debug: egl::resize_viewport(): viewport 0, 545, 1050, 590
debug: mirror-screencopy::on_linux_dmabuf(): received buffer offer for 1920x1080 frame
debug: mirror-screencopy::on_buffer_done(): received buffer done event
debug: mirror-screencopy::on_flags(): received flags event: flags=0
debug: mirror-screencopy::on_ready(): received ready event with width: 1920, height: 1080, stride: 0, format: 42RX
debug: mirror-screencopy::on_linux_dmabuf(): received buffer offer for 1920x1080 frame
debug: mirror-screencopy::on_buffer_done(): received buffer done event
debug: mirror-screencopy::on_flags(): received flags event: flags=0
debug: mirror-screencopy::on_ready(): received ready event with width: 1920, height: 1080, stride: 0, format: 42RX
debug: mirror-screencopy::on_linux_dmabuf(): received buffer offer for 1920x1080 frame
debug: mirror-screencopy::on_buffer_done(): received buffer done event
debug: mirror-screencopy::on_flags(): received flags event: flags=0
debug: mirror-screencopy::on_ready(): received ready event with width: 1920, height: 1080, stride: 0, format: 42RX
debug: mirror-screencopy::on_linux_dmabuf(): received buffer offer for 1920x1080 frame
debug: mirror-screencopy::on_buffer_done(): received buffer done event
debug: mirror-screencopy::on_flags(): received flags event: flags=0
debug: mirror-screencopy::on_ready(): received ready event with width: 1920, height: 1080, stride: 0, format: 42RX
debug: mirror-screencopy::on_linux_dmabuf(): received buffer offer for 1920x1080 frame
debug: mirror-screencopy::on_buffer_done(): received buffer done event
debug: mirror-screencopy::on_flags(): received flags event: flags=0
debug: mirror-screencopy::on_ready(): received ready event with width: 1920, height: 1080, stride: 0, format: 42RX
debug: mirror-screencopy::on_linux_dmabuf(): received buffer offer for 1920x1080 frame
debug: mirror-screencopy::on_buffer_done(): received buffer done event
debug: mirror-screencopy::on_flags(): received flags event: flags=0
debug: mirror-screencopy::on_ready(): received ready event with width: 1920, height: 1080, stride: 0, format: 42RX
debug: mirror-screencopy::on_linux_dmabuf(): received buffer offer for 1920x1080 frame
debug: mirror-screencopy::on_buffer_done(): received buffer done event
debug: mirror-screencopy::on_flags(): received flags event: flags=0
debug: mirror-screencopy::on_ready(): received ready event with width: 1920, height: 1080, stride: 0, format: 42RX
debug: mirror-screencopy::on_linux_dmabuf(): received buffer offer for 1920x1080 frame
debug: mirror-screencopy::on_buffer_done(): received buffer done event
debug: mirror-screencopy::on_flags(): received flags event: flags=0
debug: mirror-screencopy::on_ready(): received ready event with width: 1920, height: 1080, stride: 0, format: 42RX
debug: mirror-screencopy::on_linux_dmabuf(): received buffer offer for 1920x1080 frame
debug: mirror-screencopy::on_buffer_done(): received buffer done event
debug: mirror-screencopy::on_flags(): received flags event: flags=0
debug: mirror-screencopy::on_ready(): received ready event with width: 1920, height: 1080, stride: 0, format: 42RX
debug: mirror-screencopy::on_linux_dmabuf(): received buffer offer for 1920x1080 frame
debug: mirror-screencopy::on_buffer_done(): received buffer done event
debug: mirror-screencopy::on_flags(): received flags event: flags=0
debug: mirror-screencopy::on_ready(): received ready event with width: 1920, height: 1080, stride: 0, format: 42RX
debug: mirror-screencopy::on_linux_dmabuf(): received buffer offer for 1920x1080 frame
debug: mirror-screencopy::on_buffer_done(): received buffer done event
debug: mirror-screencopy::on_flags(): received flags event: flags=0
debug: mirror-screencopy::on_ready(): received ready event with width: 1920, height: 1080, stride: 0, format: 42RX
// ... this continues ...

The window stays open but only updates occasionally, for maybe a second or two. I think updates only happen when focus is shuffled around between the wl-mirror and windows on the screen that is captured. Sometimes an update does not capture visible windows, only my sway-bg image.

my niri config.kdl

// This config is in the KDL format: https://kdl.dev
// "/-" comments out the following node.
// Check the wiki for a full description of the configuration:
// https://github.com/YaLTeR/niri/wiki/Configuration:-Overview

// Input device configuration.
// Find the full list of options on the wiki:
// https://github.com/YaLTeR/niri/wiki/Configuration:-Input
input {
    // workspace-auto-back-and-forth
    keyboard {
        track-layout "global"
        xkb {
            // You can set rules, model, layout, variant and options.
            // For more information, see xkeyboard-config(7).

            // For example:
            // layout "us,ru"
            // options "grp:win_space_toggle,compose:ralt,ctrl:nocaps"
            layout "dk"
            options "caps:escape"
        }
    }

    // Next sections include libinput settings.
    // Omitting settings disables them, or leaves them at their default values.
    // touchpad {
    //     // off
    //     tap
    //     dwt
    //     // dwtp
    //     // drag false
    //     // drag-lock
    //     natural-scroll
    //     // accel-speed 0.05
    //     // accel-profile "flat"
    //     // scroll-method "two-finger"
    //     scroll-factor 0.75
    //     disabled-on-external-mouse
    //     middle-emulation
    // }

    mouse {
        // off
        // natural-scroll
        // accel-speed 0.1
        accel-profile "flat"
        // scroll-method "no-scroll"
    }

    // trackpoint {
    //     // off
    //     // natural-scroll
    //     // accel-speed 0.2
    //     // accel-profile "flat"
    //     // scroll-method "on-button-down"
    //     // scroll-button 273
    //     // middle-emulation
    // }

    // Uncomment this to make the mouse warp to the center of newly focused windows.
    // warp-mouse-to-focus

    // Focus windows and outputs automatically when moving the mouse into them.
    // Setting max-scroll-amount="0%" makes it work only on windows already fully on screen.
    // focus-follows-mouse max-scroll-amount="0%"
}

/// SCREENS/MONITORS
// imagine every point is the upper left corner of the screen. scaling matters for positioning.

// BOTTOM GIGABYTE
output "DP-2" {
    mode "2560x1440@239.998"
    position x=0 y=0
    variable-refresh-rate on-demand=true
    focus-at-startup
}

// TOP AOC
output "DP-3" {
    mode "1920x1080@144.001"
    position x=640 y=-1080
    // scale 0.9
    // position x=426 y=-1200
    variable-refresh-rate on-demand=true
}

// RIGHT OLD SAMSUNG
output "DP-1" {
    mode "1680x1050@59.954" // could be 59.954 or 59.883, or 75.025 at 1280x1024
    transform "270"
    position x=2560 y=-240 //(1680-1440)=240, this makes bottom screens connect
}

layer-rule {
    // make wallpapers stationary: https://github.com/YaLTeR/niri/wiki/Overview#backdrop-customization
    match namespace="^wallpaper$"
    place-within-backdrop true
}

// Settings that influence how windows are positioned and sized.
// Find more information on the wiki:
// https://github.com/YaLTeR/niri/wiki/Configuration:-Layout
layout {
    background-color "transparent"
    
    // Set gaps around windows in logical pixels.
    gaps 8

    // When to center a column when changing focus, options are:
    // - "never", default behavior, focusing an off-screen column will keep at the left
    //   or right edge of the screen.
    // - "always", the focused column will always be centered.
    // - "on-overflow", focusing a column will center it if it doesn't fit
    //   together with the previously focused column.
    center-focused-column "never"

    // You can customize the widths that "switch-preset-column-width" (Mod+R) toggles between.
    preset-column-widths {
        // Proportion sets the width as a fraction of the output width, taking gaps into account.
        // For example, you can perfectly fit four windows sized "proportion 0.25" on an output.
        // The default preset widths are 1/3, 1/2 and 2/3 of the output.
        proportion 0.33333
        proportion 0.5
        proportion 0.66667

        // Fixed sets the width in logical pixels exactly.
        // fixed 1920
    }

    // You can also customize the heights that "switch-preset-window-height" (Mod+Shift+R) toggles between.
    // preset-window-heights { }

    // You can change the default width of the new windows.
    default-column-width { proportion 0.5; }
    // If you leave the brackets empty, the windows themselves will decide their initial width.
    // default-column-width {}

    // By default focus ring and border are rendered as a solid background rectangle
    // behind windows. That is, they will show up through semitransparent windows.
    // This is because windows using client-side decorations can have an arbitrary shape.
    //
    // If you don't like that, you should uncomment `prefer-no-csd` below.
    // Niri will draw focus ring and border *around* windows that agree to omit their
    // client-side decorations.
    //
    // Alternatively, you can override it with a window rule called
    // `draw-border-with-background`.

    // You can change how the focus ring looks.
    focus-ring {
        // Uncomment this line to disable the focus ring.
        off

        // How many logical pixels the ring extends out from the windows.
        width 4

        // Colors can be set in a variety of ways:
        // - CSS named colors: "red"
        // - RGB hex: "#rgb", "#rgba", "#rrggbb", "#rrggbbaa"
        // - CSS-like notation: "rgb(255, 127, 0)", rgba(), hsl() and a few others.

        // Color of the ring on the active monitor.
        active-color "#7fc8ff"

        // Color of the ring on inactive monitors.
        inactive-color "#505050"

        // You can also use gradients. They take precedence over solid colors.
        // Gradients are rendered the same as CSS linear-gradient(angle, from, to).
        // The angle is the same as in linear-gradient, and is optional,
        // defaulting to 180 (top-to-bottom gradient).
        // You can use any CSS linear-gradient tool on the web to set these up.
        // Changing the color space is also supported, check the wiki for more info.
        //
        // active-gradient from="#80c8ff" to="#bbddff" angle=45

        // You can also color the gradient relative to the entire view
        // of the workspace, rather than relative to just the window itself.
        // To do that, set relative-to="workspace-view".
        //
        // inactive-gradient from="#505050" to="#808080" angle=45 relative-to="workspace-view"
    }

    // You can also add a border. It's similar to the focus ring, but always visible.
    border {
        // The settings are the same as for the focus ring.
        // If you enable the border, you probably want to disable the focus ring.
        //off

        width 4
        // active-color "#ffc87f"
        // active-color "#7fc8ff"
        
        active-color "#89b4fa"
        inactive-color "#505050"
        urgent-color "#ffc87f"

        // active-gradient from="#ffbb66" to="#ffc880" angle=45
        // active-gradient from="#ffbb66" to="#ffc880" angle=45 relative-to="workspace-view"
        // inactive-gradient from="#505050" to="#808080" angle=45 relative-to="workspace-view"
    }

    // You can enable drop shadows for windows.
    shadow {
        // Uncomment the next line to enable shadows.
        on

        // By default, the shadow draws only around its window, and not behind it.
        // Uncomment this setting to make the shadow draw behind its window.
        //
        // Note that niri has no way of knowing about the CSD window corner
        // radius. It has to assume that windows have square corners, leading to
        // shadow artifacts inside the CSD rounded corners. This setting fixes
        // those artifacts.
        // 
        // However, instead you may want to set prefer-no-csd and/or
        // geometry-corner-radius. Then, niri will know the corner radius and
        // draw the shadow correctly, without having to draw it behind the
        // window. These will also remove client-side shadows if the window
        // draws any.
        // 
        // draw-behind-window true

        // You can change how shadows look. The values below are in logical
        // pixels and match the CSS box-shadow properties.

        // Softness controls the shadow blur radius.
        softness 28

        // Spread expands the shadow.
        spread 2

        // Offset moves the shadow relative to the window.
        offset x=6 y=8

        // You can also change the shadow color and opacity.
        color "#000C"
    }

    // Struts shrink the area occupied by windows, similarly to layer-shell panels.
    // You can think of them as a kind of outer gaps. They are set in logical pixels.
    // Left and right struts will cause the next window to the side to always be visible.
    // Top and bottom struts will simply add outer gaps in addition to the area occupied by
    // layer-shell panels and regular gaps.
    struts {
        left 12
        right 12
        top 4
        bottom 4
    }
}

// Add lines like this to spawn processes at startup.
// Note that running niri as a session supports xdg-desktop-autostart,
// which may be more convenient to use.
// See the binds section below for more spawn examples.
// spawn-at-startup "alacritty" "-e" "fish"

// Uncomment this line to ask the clients to omit their client-side decorations if possible.
// If the client will specifically ask for CSD, the request will be honored.
// Additionally, clients will be informed that they are tiled, removing some client-side rounded corners.
// This option will also fix border/focus ring drawing behind some semitransparent windows.
// After enabling or disabling this, you need to restart the apps for this to take effect.
// prefer-no-csd

// You can change the path where screenshots are saved.
// A ~ at the front will be expanded to the home directory.
// The path is formatted with strftime(3) to give you the screenshot date and time.
screenshot-path "~/Pictures/Screenshots/Screenshot from %Y-%m-%d %H-%M-%S.png"

// You can also set this to null to disable saving screenshots to disk.
// screenshot-path null

// Animation settings.
// The wiki explains how to configure individual animations:
// https://github.com/YaLTeR/niri/wiki/Configuration:-Animations
animations {
    // Uncomment to turn off all animations.
    // off

    // Slow down all animations by this factor. Values below 1 speed them up instead.
    slowdown 0.875
}

// Window rules let you adjust behavior for individual windows.
// Find more information on the wiki:
// https://github.com/YaLTeR/niri/wiki/Configuration:-Window-Rules

// Work around WezTerm's initial configure bug
// by setting an empty default-column-width.
window-rule {
    // This regular expression is intentionally made as specific as possible,
    // since this is the default config, and we want no false positives.
    // You can get away with just app-id="wezterm" if you want.
    match app-id=r#"^org\.wezfurlong\.wezterm$"#
    default-column-width {}
}

// Open the Firefox picture-in-picture player as floating by default.
window-rule {
    // This app-id regular expression will work for both:
    // - host Firefox (app-id is "firefox")
    // - Flatpak Firefox (app-id is "org.mozilla.firefox")
    match app-id=r#"firefox$"# title="^Picture-in-Picture$"
    open-floating true
}

// Example: block out two password managers from screen capture.
// (This example rule is commented out with a "/-" in front.)
/-window-rule {
    match app-id=r#"^org\.keepassxc\.KeePassXC$"#
    match app-id=r#"^org\.gnome\.World\.Secrets$"#

    block-out-from "screen-capture"

    // Use this instead if you want them visible on third-party screenshot tools.
    // block-out-from "screencast"
}

// Example: enable rounded corners for all windows.
// (This example rule is commented out with a "/-" in front.)
window-rule {
    geometry-corner-radius 6
    clip-to-geometry true
}

binds {
    // ADDED: unicode emoji picker
    Mod+E { spawn "/usr/bin/wofi-emoji"; }
    Mod+S { spawn "/usr/bin/dolphin"; }

    // clipboard manager
    // NOTE: clipcat does not seems to work with wl-roots/niri?
    // Mod+Ctrl+V { spawn "clipcat-menu" "insert"; }
    // Mod+Ctrl+Alt+V { spawn "clipcat-menu" "edit"; }

    // Use `brightnessctl` to change backlight brightness gradually. Unfortunately there is a small delay when doing this.
    XF86MonBrightnessUp { spawn "brightnessctl" "set" "2+"; }
    Ctrl+XF86MonBrightnessUp { spawn "brightnessctl" "set" "10+"; }
    XF86MonBrightnessDown { spawn "brightnessctl" "set" "2-"; }
    Ctrl+XF86MonBrightnessDown { spawn "brightnessctl" "set" "10-"; }
    
    // Keys consist of modifiers separated by + signs, followed by an XKB key name
    // in the end. To find an XKB name for a particular key, you may use a program
    // like wev.
    //
    // "Mod" is a special modifier equal to Super when running on a TTY, and to Alt
    // when running as a winit window.
    //
    // Most actions that you can bind here can also be invoked programmatically with
    // `niri msg action do-something`.

    // Mod-Shift-/, which is usually the same as Mod-?,
    // shows a list of important hotkeys.
    Mod+Shift+7 { show-hotkey-overlay; }

    // Suggested binds for running programs: terminal, app launcher, screen locker.
    Mod+T { spawn "alacritty"; }
    Mod+D { spawn "fuzzel"; }
    Super+Alt+L { spawn "swaylock"; }

    // You can also use a shell. Do this if you need pipes, multiple commands, etc.
    // Note: the entire command goes as a single argument in the end.
    // Mod+T { spawn "bash" "-c" "notify-send hello && exec alacritty"; }

    // Example volume keys mappings for PipeWire & WirePlumber.
    // The allow-when-locked=true property makes them work even when the session is locked.
    XF86AudioRaiseVolume allow-when-locked=true { spawn "wpctl" "set-volume" "@DEFAULT_AUDIO_SINK@" "0.05+"; }
    XF86AudioLowerVolume allow-when-locked=true { spawn "wpctl" "set-volume" "@DEFAULT_AUDIO_SINK@" "0.05-"; }
    XF86AudioMute        allow-when-locked=true { spawn "wpctl" "set-mute" "@DEFAULT_AUDIO_SINK@" "toggle"; }
    XF86AudioMicMute     allow-when-locked=true { spawn "wpctl" "set-mute" "@DEFAULT_AUDIO_SOURCE@" "toggle"; }

    Mod+Q { close-window; }

    Mod+Left  { focus-column-left; }
    Mod+Down  { focus-window-down; }
    Mod+Up    { focus-window-up; }
    Mod+Right { focus-column-right; }
    Mod+H     { focus-column-left; }
    // Mod+J     { focus-window-down; }
    // Mod+K     { focus-window-up; }
    Mod+L     { focus-column-right; }

    Mod+Ctrl+Left  { move-column-left; }
    Mod+Ctrl+Down  { move-window-down; }
    Mod+Ctrl+Up    { move-window-up; }
    Mod+Ctrl+Right { move-column-right; }
    Mod+Ctrl+H     { move-column-left; }
    // Mod+Ctrl+J     { move-window-down; }
    // Mod+Ctrl+K     { move-window-up; }
    Mod+Ctrl+L     { move-column-right; }

    // Alternative commands that move across workspaces when reaching
    // the first or last window in a column.
    Mod+J     { focus-window-or-workspace-down; }
    Mod+K     { focus-window-or-workspace-up; }
    Mod+Ctrl+J     { move-window-down-or-to-workspace-down; }
    Mod+Ctrl+K     { move-window-up-or-to-workspace-up; }

    Mod+Home { focus-column-first; }
    Mod+End  { focus-column-last; }
    Mod+Ctrl+Home { move-column-to-first; }
    Mod+Ctrl+End  { move-column-to-last; }

    Mod+Shift+Left  { focus-monitor-left; }
    Mod+Shift+Down  { focus-monitor-down; }
    Mod+Shift+Up    { focus-monitor-up; }
    Mod+Shift+Right { focus-monitor-right; }
    Mod+Shift+H     { focus-monitor-left; }
    Mod+Shift+J     { focus-monitor-down; }
    Mod+Shift+K     { focus-monitor-up; }
    Mod+Shift+L     { focus-monitor-right; }

    Mod+Shift+Ctrl+Left  { move-column-to-monitor-left; }
    Mod+Shift+Ctrl+Down  { move-column-to-monitor-down; }
    Mod+Shift+Ctrl+Up    { move-column-to-monitor-up; }
    Mod+Shift+Ctrl+Right { move-column-to-monitor-right; }
    Mod+Shift+Ctrl+H     { move-column-to-monitor-left; }
    Mod+Shift+Ctrl+J     { move-column-to-monitor-down; }
    Mod+Shift+Ctrl+K     { move-column-to-monitor-up; }
    Mod+Shift+Ctrl+L     { move-column-to-monitor-right; }

    // Alternatively, there are commands to move just a single window:
    // Mod+Shift+Ctrl+Left  { move-window-to-monitor-left; }
    // ...

    // And you can also move a whole workspace to another monitor:
    // Mod+Shift+Ctrl+Left  { move-workspace-to-monitor-left; }
    // ...

    Mod+Page_Down      { focus-workspace-down; }
    Mod+Page_Up        { focus-workspace-up; }
    Mod+U              { focus-workspace-down; }
    Mod+I              { focus-workspace-up; }
    Mod+Ctrl+Page_Down { move-column-to-workspace-down; }
    Mod+Ctrl+Page_Up   { move-column-to-workspace-up; }
    Mod+Ctrl+U         { move-column-to-workspace-down; }
    Mod+Ctrl+I         { move-column-to-workspace-up; }

    // Alternatively, there are commands to move just a single window:
    // Mod+Ctrl+Page_Down { move-window-to-workspace-down; }
    // ...

    Mod+Shift+Page_Down { move-workspace-down; }
    Mod+Shift+Page_Up   { move-workspace-up; }
    Mod+Shift+U         { move-workspace-down; }
    Mod+Shift+I         { move-workspace-up; }

    // You can bind mouse wheel scroll ticks using the following syntax.
    // These binds will change direction based on the natural-scroll setting.
    //
    // To avoid scrolling through workspaces really fast, you can use
    // the cooldown-ms property. The bind will be rate-limited to this value.
    // You can set a cooldown on any bind, but it's most useful for the wheel.
    Mod+WheelScrollDown      cooldown-ms=200 { focus-workspace-down; }
    Mod+WheelScrollUp        cooldown-ms=200 { focus-workspace-up; }
    Mod+Ctrl+WheelScrollDown cooldown-ms=200 { move-column-to-workspace-down; }
    Mod+Ctrl+WheelScrollUp   cooldown-ms=200 { move-column-to-workspace-up; }

    Mod+WheelScrollRight      { focus-column-right; }
    Mod+WheelScrollLeft       { focus-column-left; }
    Mod+Ctrl+WheelScrollRight { move-column-right; }
    Mod+Ctrl+WheelScrollLeft  { move-column-left; }

    // Usually scrolling up and down with Shift in applications results in
    // horizontal scrolling; these binds replicate that.
    Mod+Shift+WheelScrollDown      { focus-column-right; }
    Mod+Shift+WheelScrollUp        { focus-column-left; }
    Mod+Ctrl+Shift+WheelScrollDown { move-column-right; }
    Mod+Ctrl+Shift+WheelScrollUp   { move-column-left; }

    // Similarly, you can bind touchpad scroll "ticks".
    // Touchpad scrolling is continuous, so for these binds it is split into
    // discrete intervals.
    // These binds are also affected by touchpad's natural-scroll, so these
    // example binds are "inverted", since we have natural-scroll enabled for
    // touchpads by default.
    // Mod+TouchpadScrollDown { spawn "wpctl" "set-volume" "@DEFAULT_AUDIO_SINK@" "0.02+"; }
    // Mod+TouchpadScrollUp   { spawn "wpctl" "set-volume" "@DEFAULT_AUDIO_SINK@" "0.02-"; }

    // You can refer to workspaces by index. However, keep in mind that
    // niri is a dynamic workspace system, so these commands are kind of
    // "best effort". Trying to refer to a workspace index bigger than
    // the current workspace count will instead refer to the bottommost
    // (empty) workspace.
    //
    // For example, with 2 workspaces + 1 empty, indices 3, 4, 5 and so on
    // will all refer to the 3rd workspace.
    Mod+1 { focus-workspace 1; }
    Mod+2 { focus-workspace 2; }
    Mod+3 { focus-workspace 3; }
    Mod+4 { focus-workspace 4; }
    Mod+5 { focus-workspace 5; }
    Mod+6 { focus-workspace 6; }
    Mod+7 { focus-workspace 7; }
    Mod+8 { focus-workspace 8; }
    Mod+9 { focus-workspace 9; }
    Mod+Ctrl+1 { move-column-to-workspace 1; }
    Mod+Ctrl+2 { move-column-to-workspace 2; }
    Mod+Ctrl+3 { move-column-to-workspace 3; }
    Mod+Ctrl+4 { move-column-to-workspace 4; }
    Mod+Ctrl+5 { move-column-to-workspace 5; }
    Mod+Ctrl+6 { move-column-to-workspace 6; }
    Mod+Ctrl+7 { move-column-to-workspace 7; }
    Mod+Ctrl+8 { move-column-to-workspace 8; }
    Mod+Ctrl+9 { move-column-to-workspace 9; }

    // Alternatively, there are commands to move just a single window:
    // Mod+Ctrl+1 { move-window-to-workspace 1; }

    // Switches focus between the current and the previous workspace.
    // Mod+Tab { focus-workspace-previous; }

    // The following binds move the focused window in and out of a column.
    // If the window is alone, they will consume it into the nearby column to the side.
    // If the window is already in a column, they will expel it out.
    Mod+BracketLeft  { consume-or-expel-window-left; } // this is comma
    Mod+BracketRight { consume-or-expel-window-right; } // this is dot

    // Consume one window from the right to the bottom of the focused column.
    Mod+Comma  { consume-window-into-column; }
    // Expel the bottom window from the focused column to the right.
    Mod+Period { expel-window-from-column; }

    Mod+R { switch-preset-column-width; }
    Mod+Shift+R { switch-preset-window-height; }
    Mod+Ctrl+R { reset-window-height; }
    Mod+F { maximize-column; }
    Mod+Shift+F { fullscreen-window; }

    // Expand the focused column to space not taken up by other fully visible columns.
    // Makes the column "fill the rest of the space".
    Mod+Ctrl+F { expand-column-to-available-width; }

    Mod+C { center-column; }

    // Finer width adjustments.
    // This command can also:
    // * set width in pixels: "1000"
    // * adjust width in pixels: "-5" or "+5"
    // * set width as a percentage of screen width: "25%"
    // * adjust width as a percentage of screen width: "-10%" or "+10%"
    // Pixel sizes use logical, or scaled, pixels. I.e. on an output with scale 2.0,
    // set-column-width "100" will make the column occupy 200 physical screen pixels.
    Mod+Minus { set-column-width "-10%"; }
    Mod+Plus { set-column-width "+10%"; }

    // Finer height adjustments when in column with other windows.
    Mod+Shift+Minus { set-window-height "-10%"; }
    Mod+Shift+Plus { set-window-height "+10%"; }

    // Move the focused window between the floating and the tiling layout.
    Mod+V       { toggle-window-floating; }
    Mod+Shift+V { switch-focus-between-floating-and-tiling; }

    // Toggle tabbed column display mode.
    // Windows in this column will appear as vertical tabs,
    // rather than stacked on top of each other.
    Mod+W { toggle-column-tabbed-display; }

    // Actions to switch layouts.
    // Note: if you uncomment these, make sure you do NOT have
    // a matching layout switch hotkey configured in xkb options above.
    // Having both at once on the same hotkey will break the switching,
    // since it will switch twice upon pressing the hotkey (once by xkb, once by niri).
    // Mod+Space       { switch-layout "next"; }
    // Mod+Shift+Space { switch-layout "prev"; }

    Print { screenshot; }
    Ctrl+Print { screenshot-screen; }
    Alt+Print { screenshot-window; }
    
    Mod+P { screenshot; }
    Mod+Ctrl+P { screenshot-screen; }
    Mod+Alt+P { screenshot-window; }

    // Applications such as remote-desktop clients and software KVM switches may
    // request that niri stops processing the keyboard shortcuts defined here
    // so they may, for example, forward the key presses as-is to a remote machine.
    // It's a good idea to bind an escape hatch to toggle the inhibitor,
    // so a buggy application can't hold your session hostage.
    //
    // The allow-inhibiting=false property can be applied to other binds as well,
    // which ensures niri always processes them, even when an inhibitor is active.
    Mod+Escape allow-inhibiting=false { toggle-keyboard-shortcuts-inhibit; }

    // The quit action will show a confirmation dialog to avoid accidental exits.
    Mod+Shift+E { quit; }
    Ctrl+Alt+Delete { quit; }

    // Powers off the monitors. To turn them back on, do any input like
    // moving the mouse or pressing any other key.
    Mod+Ctrl+Shift+Alt+P { power-off-monitors; }
}

// NOTE: consider refactoring to instead use niri settings for this?
// https://github.com/YaLTeR/niri/wiki/Configuration:-Miscellaneous#xwayland-satellite
spawn-at-startup "xwayland-satellite" // let X11 windows be opened with xwayland

spawn-at-startup

// spawn-at-startup "gammastep -l 55.6761:12.5683" // start gammastep
// spawn-at-startup "gammastep -l geoclue2" // start gammastep with auto location

// NOTE: should be spawned by systemd instead: https://github.com/xrelkd/clipcat#integration
//spawn-at-startup "clipcatd" // clipboard manager

// spawn-at-startup "wluma"

spawn-at-startup "nm-applet" // system tray app that interacts with NetworkManager

environment {
    // for xwayland
    DISPLAY ":0"
    
    // enable nvidia gpu stuff
    LIBVA_DRIVER_NAME "nvidia"
    __GLX_VENDOR_LIBRARY_NAME "nvidia"
    NVD_BACKEND "direct"

    QT_QPA_PLATFORM "wayland"
    _JAVA_AWT_WM_NONREPARENTING "1" // fix java apps?

    // use native electron wayland support (electron >28)
    ELECTRON_OZONE_PLATFORM_HINT "auto"
}

[Ferdi265]

@selvmaya Thanks for the report!

The related wl-mirror bug report is wl-mirror#59. From all of the reports over the last year, it appears this issue is specific to the nvidia drivers, and not tied to any particular wl-mirror backend (the issue happens with both shm and dmabuf).

The issue is that parts of wl-mirror seem to hang in some spots (still not exactly sure which spots); I'll see if I can find a user-friendly way of enabling profiling so that I can figure out what exactly hangs here.

I don't have an nvidia GPU I can test this with, so all changes are on a guess-and-check basis; sorry that it's taking so long.

[selvmaya]

No bother, thank you for your work!
My temporary solution - using OBS Studio screen capture scene preview on the target monitor - isn't the greatest though :^)

[Ferdi265]

It'd be interesting to see what OBS does differently; I think I'll look into that! Maybe something stands out that I can try :)

OBS preview is also what I used before I wrote wl-mirror.

[0xsam1r]

I agree it would be useful, but display mirroring is somewhat complicated. Also would require thinking how to configure it.

I've tried to use wl-mirror to put it on the other display, but when that window loses focus, it stops updating.

Maybe there's a way to make it work? It sounds like it should work for that case.

it will be a nice improvement you can share what is the complix part and may some one can help with the algorithm wl-mirror is bad in use i have the same issue i hope i could help to solve this

[crispy-caesus]

I'd really like this feature!
It can for instance be especially useful when presenting something on a big screen/projector in front of a class or big group. That way you can look at your computer screen while being at the front (looking at the big screen so close and next to it would be hard) and others can see what you're doing on your screen.

(I don't wanna go like implement X and Y Hyprland feature, but as a reference this could be configured in Hyprland like this

[selvmaya]

While wl-mirror still has problems on niri (at least for my computers with nvidia graphics cards), if you find a better temporary workaround than my solution of using/abusing OBS' monitor source + preview-on-monitor feature, please let me know! c:

[axelkar]

I've been making a simple fuzzel+wl-mirror wrapper program to make this easier but I'm running into an issue: Niri's CPU usage gets increased by 30% for every visisble instance of wl-mirror, and OBS isn't any better. Should I try building Niri with debug symbols and profiling it using Tracy? Though I'm still on Niri 25.08 so I don't know if this has been fixed in 25.11.

[stites]

I am using wl-mirror with niri 25.11 now and am seeing a huge spike in CPU usage (7% by niri, 7% by wl-mirror).

[VoidAlone]

+1 for mirror monitor support. Categorically essential.

[Sempyos]

You can use wl-mirror