From 84d3d6e6098d9fb0468706ebafc714cd1f90cd96 Mon Sep 17 00:00:00 2001
From: Poly <marynczak.bartlomiej@gmail.com>
Date: Sat, 31 Jul 2021 03:51:35 +0200
Subject: [PATCH 1/4] wayland.shell: implement wlr_layer_shell

---
 src/wayland/shell/mod.rs                |   2 +
 src/wayland/shell/wlr_layer/handlers.rs | 298 ++++++++++++++++
 src/wayland/shell/wlr_layer/mod.rs      | 454 ++++++++++++++++++++++++
 src/wayland/shell/wlr_layer/types.rs    | 231 ++++++++++++
 src/wayland/shell/xdg/mod.rs            |   2 +-
 5 files changed, 986 insertions(+), 1 deletion(-)
 create mode 100644 src/wayland/shell/wlr_layer/handlers.rs
 create mode 100644 src/wayland/shell/wlr_layer/mod.rs
 create mode 100644 src/wayland/shell/wlr_layer/types.rs

diff --git a/src/wayland/shell/mod.rs b/src/wayland/shell/mod.rs
index 470bf67..03a9dd5 100644
--- a/src/wayland/shell/mod.rs
+++ b/src/wayland/shell/mod.rs
@@ -22,6 +22,8 @@ use wayland_server::protocol::wl_surface::WlSurface;
 pub mod legacy;
 pub mod xdg;
 
+pub mod wlr_layer;
+
 /// Represents the possible errors returned from
 /// a surface ping
 #[derive(Debug, Error)]
diff --git a/src/wayland/shell/wlr_layer/handlers.rs b/src/wayland/shell/wlr_layer/handlers.rs
new file mode 100644
index 0000000..3e97e78
--- /dev/null
+++ b/src/wayland/shell/wlr_layer/handlers.rs
@@ -0,0 +1,298 @@
+use std::{convert::TryFrom, ops::Deref, sync::Mutex};
+
+use wayland_protocols::wlr::unstable::layer_shell::v1::server::{zwlr_layer_shell_v1, zwlr_layer_surface_v1};
+use wayland_server::{protocol::wl_surface, DispatchData, Filter, Main};
+
+use crate::wayland::{compositor, shell::wlr_layer::Layer, Serial};
+
+use super::{
+    Anchor, KeyboardInteractivity, LayerShellRequest, LayerSurfaceAttributes, LayerSurfaceCachedState,
+    Margins, ShellUserData,
+};
+
+use super::LAYER_SURFACE_ROLE;
+
+pub(super) fn layer_shell_implementation(
+    shell: Main<zwlr_layer_shell_v1::ZwlrLayerShellV1>,
+    request: zwlr_layer_shell_v1::Request,
+    dispatch_data: DispatchData<'_>,
+) {
+    let data = shell.as_ref().user_data().get::<ShellUserData>().unwrap();
+    match request {
+        zwlr_layer_shell_v1::Request::GetLayerSurface {
+            id,
+            surface,
+            output,
+            layer,
+            namespace,
+        } => {
+            let layer = match Layer::try_from(layer) {
+                Ok(layer) => layer,
+                Err((err, msg)) => {
+                    id.as_ref().post_error(err as u32, msg);
+                    return;
+                }
+            };
+
+            if compositor::give_role(&surface, LAYER_SURFACE_ROLE).is_err() {
+                shell.as_ref().post_error(
+                    zwlr_layer_shell_v1::Error::Role as u32,
+                    "Surface already has a role.".into(),
+                );
+                return;
+            }
+
+            compositor::with_states(&surface, |states| {
+                states.data_map.insert_if_missing_threadsafe(|| {
+                    Mutex::new(LayerSurfaceAttributes::new(id.deref().clone()))
+                });
+
+                states.cached_state.pending::<LayerSurfaceCachedState>().layer = layer;
+            })
+            .unwrap();
+
+            compositor::add_commit_hook(&surface, |surface| {
+                compositor::with_states(surface, |states| {
+                    let mut guard = states
+                        .data_map
+                        .get::<Mutex<LayerSurfaceAttributes>>()
+                        .unwrap()
+                        .lock()
+                        .unwrap();
+
+                    let pending = states.cached_state.pending::<LayerSurfaceCachedState>();
+
+                    if pending.size.w == 0 && !pending.anchor.anchored_horizontally() {
+                        guard.surface.as_ref().post_error(
+                            zwlr_layer_surface_v1::Error::InvalidSize as u32,
+                            "width 0 requested without setting left and right anchors".into(),
+                        );
+                        return;
+                    }
+
+                    if pending.size.h == 0 && !pending.anchor.anchored_vertically() {
+                        guard.surface.as_ref().post_error(
+                            zwlr_layer_surface_v1::Error::InvalidSize as u32,
+                            "height 0 requested without setting top and bottom anchors".into(),
+                        );
+                        return;
+                    }
+
+                    if let Some(state) = guard.last_acked.clone() {
+                        guard.current = state;
+                    }
+                })
+                .unwrap();
+            });
+
+            id.quick_assign(|surface, req, dispatch_data| {
+                layer_surface_implementation(surface.deref().clone(), req, dispatch_data)
+            });
+
+            id.assign_destructor(Filter::new(
+                |layer_surface: zwlr_layer_surface_v1::ZwlrLayerSurfaceV1, _, _| {
+                    let data = layer_surface
+                        .as_ref()
+                        .user_data()
+                        .get::<LayerSurfaceUserData>()
+                        .unwrap();
+
+                    // remove this surface from the known ones (as well as any leftover dead surface)
+                    data.shell_data
+                        .shell_state
+                        .lock()
+                        .unwrap()
+                        .known_layers
+                        .retain(|other| other.alive());
+                },
+            ));
+
+            id.as_ref().user_data().set(|| LayerSurfaceUserData {
+                shell_data: data.clone(),
+                wl_surface: surface.clone(),
+            });
+
+            let handle = super::LayerSurface {
+                wl_surface: surface,
+                shell_surface: id.deref().clone(),
+            };
+
+            data.shell_state.lock().unwrap().known_layers.push(handle.clone());
+
+            let mut user_impl = data.user_impl.borrow_mut();
+            (&mut *user_impl)(
+                LayerShellRequest::NewLayerSurface {
+                    surface: handle,
+                    output,
+                    layer,
+                    namespace,
+                },
+                dispatch_data,
+            );
+        }
+        zwlr_layer_shell_v1::Request::Destroy => {
+            // Handled by destructor
+        }
+        _ => {}
+    }
+}
+
+fn layer_surface_implementation(
+    layer_surface: zwlr_layer_surface_v1::ZwlrLayerSurfaceV1,
+    request: zwlr_layer_surface_v1::Request,
+    dispatch_data: DispatchData<'_>,
+) {
+    match request {
+        zwlr_layer_surface_v1::Request::SetSize { width, height } => {
+            with_surface_pending_state(&layer_surface, |data| {
+                data.size = (width as i32, height as i32).into();
+            });
+        }
+        zwlr_layer_surface_v1::Request::SetAnchor { anchor } => {
+            match Anchor::try_from(anchor) {
+                Ok(anchor) => {
+                    with_surface_pending_state(&layer_surface, |data| {
+                        data.anchor = Anchor::from_bits(anchor.bits()).unwrap_or_default();
+                    });
+                }
+                Err((err, msg)) => {
+                    layer_surface.as_ref().post_error(err as u32, msg);
+                }
+            };
+        }
+        zwlr_layer_surface_v1::Request::SetExclusiveZone { zone } => {
+            with_surface_pending_state(&layer_surface, |data| {
+                data.exclusive_zone = zone.into();
+            });
+        }
+        zwlr_layer_surface_v1::Request::SetMargin {
+            top,
+            right,
+            bottom,
+            left,
+        } => {
+            with_surface_pending_state(&layer_surface, |data| {
+                data.margin = Margins {
+                    top,
+                    right,
+                    bottom,
+                    left,
+                };
+            });
+        }
+        zwlr_layer_surface_v1::Request::SetKeyboardInteractivity {
+            keyboard_interactivity,
+        } => {
+            match KeyboardInteractivity::try_from(keyboard_interactivity) {
+                Ok(keyboard_interactivity) => {
+                    with_surface_pending_state(&layer_surface, |data| {
+                        data.keyboard_interactivity = keyboard_interactivity;
+                    });
+                }
+                Err((err, msg)) => {
+                    layer_surface.as_ref().post_error(err as u32, msg);
+                }
+            };
+        }
+        zwlr_layer_surface_v1::Request::SetLayer { layer } => {
+            match Layer::try_from(layer) {
+                Ok(layer) => {
+                    with_surface_pending_state(&layer_surface, |data| {
+                        data.layer = layer;
+                    });
+                }
+                Err((err, msg)) => {
+                    layer_surface.as_ref().post_error(err as u32, msg);
+                }
+            };
+        }
+        zwlr_layer_surface_v1::Request::GetPopup { popup } => {
+            let data = layer_surface
+                .as_ref()
+                .user_data()
+                .get::<LayerSurfaceUserData>()
+                .unwrap();
+
+            let parent_surface = data.wl_surface.clone();
+
+            let data = popup
+                .as_ref()
+                .user_data()
+                .get::<crate::wayland::shell::xdg::xdg_handlers::ShellSurfaceUserData>()
+                .unwrap();
+
+            compositor::with_states(&data.wl_surface, move |states| {
+                states
+                    .data_map
+                    .get::<Mutex<crate::wayland::shell::xdg::XdgPopupSurfaceRoleAttributes>>()
+                    .unwrap()
+                    .lock()
+                    .unwrap()
+                    .parent = Some(parent_surface);
+            })
+            .unwrap();
+        }
+        zwlr_layer_surface_v1::Request::AckConfigure { serial } => {
+            let data = layer_surface
+                .as_ref()
+                .user_data()
+                .get::<LayerSurfaceUserData>()
+                .unwrap();
+
+            let serial = Serial::from(serial);
+            let surface = &data.wl_surface;
+
+            let found_configure = compositor::with_states(surface, |states| {
+                states
+                    .data_map
+                    .get::<Mutex<LayerSurfaceAttributes>>()
+                    .unwrap()
+                    .lock()
+                    .unwrap()
+                    .ack_configure(serial)
+            })
+            .unwrap();
+
+            let configure = match found_configure {
+                Some(configure) => configure,
+                None => {
+                    layer_surface.as_ref().post_error(
+                        zwlr_layer_surface_v1::Error::InvalidSurfaceState as u32,
+                        format!("wrong configure serial: {}", <u32>::from(serial)),
+                    );
+                    return;
+                }
+            };
+
+            let mut user_impl = data.shell_data.user_impl.borrow_mut();
+            (&mut *user_impl)(
+                LayerShellRequest::AckConfigure {
+                    surface: data.wl_surface.clone(),
+                    configure,
+                },
+                dispatch_data,
+            );
+        }
+        _ => {}
+    }
+}
+
+struct LayerSurfaceUserData {
+    shell_data: ShellUserData,
+    wl_surface: wl_surface::WlSurface,
+}
+
+fn with_surface_pending_state<F, T>(layer_surface: &zwlr_layer_surface_v1::ZwlrLayerSurfaceV1, f: F) -> T
+where
+    F: FnOnce(&mut LayerSurfaceCachedState) -> T,
+{
+    let data = layer_surface
+        .as_ref()
+        .user_data()
+        .get::<LayerSurfaceUserData>()
+        .unwrap();
+    compositor::with_states(&data.wl_surface, |states| {
+        f(&mut *states.cached_state.pending::<LayerSurfaceCachedState>())
+    })
+    .unwrap()
+}
diff --git a/src/wayland/shell/wlr_layer/mod.rs b/src/wayland/shell/wlr_layer/mod.rs
new file mode 100644
index 0000000..f012dbd
--- /dev/null
+++ b/src/wayland/shell/wlr_layer/mod.rs
@@ -0,0 +1,454 @@
+//! Utilities for handling shell surfaces with the `wlr_layer_shell` protocol
+//!
+//! This interface should be suitable for the implementation of many desktop shell components,
+//! and a broad number of other applications that interact with the desktop.
+//!
+//! ### Initialization
+//!
+//! To initialize this handler, simple use the [`wlr_layer_shell_init`] function provided in this module.
+//! You need to provide a closure that will be invoked whenever some action is required from you,
+//! are represented by the [`LayerShellRequest`] enum.
+//!
+//! ```no_run
+//! # extern crate wayland_server;
+//! #
+//! use smithay::wayland::shell::wlr_layer::{wlr_layer_shell_init, LayerShellRequest};
+//!
+//! # let mut display = wayland_server::Display::new();
+//! let (shell_state, _) = wlr_layer_shell_init(
+//!     &mut display,
+//!     // your implementation
+//!     |event: LayerShellRequest, dispatch_data| { /* handle the shell requests here */ },
+//!     None  // put a logger if you want
+//! );
+//!
+//! // You're now ready to go!
+//! ```
+
+use std::{
+    cell::RefCell,
+    rc::Rc,
+    sync::{Arc, Mutex},
+};
+
+use wayland_protocols::wlr::unstable::layer_shell::v1::server::{zwlr_layer_shell_v1, zwlr_layer_surface_v1};
+use wayland_server::{
+    protocol::{wl_output::WlOutput, wl_surface},
+    DispatchData, Display, Filter, Global, Main,
+};
+
+use crate::{
+    utils::{DeadResource, Logical, Size},
+    wayland::{
+        compositor::{self, Cacheable},
+        Serial, SERIAL_COUNTER,
+    },
+};
+
+mod handlers;
+mod types;
+
+pub use types::{Anchor, ExclusiveZone, KeyboardInteractivity, Layer, Margins};
+
+/// The role of a wlr_layer_shell_surface
+pub static LAYER_SURFACE_ROLE: &str = "zwlr_layer_surface_v1";
+
+/// Attributes for layer surface
+#[derive(Debug)]
+pub struct LayerSurfaceAttributes {
+    surface: zwlr_layer_surface_v1::ZwlrLayerSurfaceV1,
+    /// Defines if the surface has received at least one
+    /// layer_surface.ack_configure from the client
+    pub configured: bool,
+    /// The serial of the last acked configure
+    pub configure_serial: Option<Serial>,
+    /// Holds the state if the surface has sent the initial
+    /// configure event to the client. It is expected that
+    /// during the first commit a initial
+    /// configure event is sent to the client
+    pub initial_configure_sent: bool,
+    /// Holds the configures the server has sent out
+    /// to the client waiting to be acknowledged by
+    /// the client. All pending configures that are older
+    /// than the acknowledged one will be discarded during
+    /// processing layer_surface.ack_configure.
+    pending_configures: Vec<LayerSurfaceConfigure>,
+    /// Holds the pending state as set by the server.
+    pub server_pending: Option<LayerSurfaceState>,
+    /// Holds the last server_pending state that has been acknowledged
+    /// by the client. This state should be cloned to the current
+    /// during a commit.
+    pub last_acked: Option<LayerSurfaceState>,
+    /// Holds the current state of the layer after a successful
+    /// commit.
+    pub current: LayerSurfaceState,
+}
+
+impl LayerSurfaceAttributes {
+    fn new(surface: zwlr_layer_surface_v1::ZwlrLayerSurfaceV1) -> Self {
+        Self {
+            surface,
+            configured: false,
+            configure_serial: None,
+            initial_configure_sent: false,
+            pending_configures: Vec::new(),
+            server_pending: None,
+            last_acked: None,
+            current: Default::default(),
+        }
+    }
+
+    fn ack_configure(&mut self, serial: Serial) -> Option<LayerSurfaceConfigure> {
+        let configure = self
+            .pending_configures
+            .iter()
+            .find(|configure| configure.serial == serial)
+            .cloned()?;
+
+        self.last_acked = Some(configure.state.clone());
+
+        self.configured = true;
+        self.configure_serial = Some(serial);
+        self.pending_configures.retain(|c| c.serial > serial);
+        Some(configure)
+    }
+}
+
+/// State of a layer surface
+#[derive(Debug, Default, Clone, PartialEq)]
+pub struct LayerSurfaceState {
+    /// The suggested size of the surface
+    pub size: Option<Size<i32, Logical>>,
+}
+
+/// Represents the client pending state
+#[derive(Debug, Default, Clone, Copy)]
+pub struct LayerSurfaceCachedState {
+    /// The size requested by the client
+    pub size: Size<i32, Logical>,
+    /// Anchor bitflags, describing how the layers surface should be positioned and sized
+    pub anchor: Anchor,
+    /// Descripton of exclusive zone
+    pub exclusive_zone: ExclusiveZone,
+    /// Describes distance from the anchor point of the output
+    pub margin: Margins,
+    /// Describes how keyboard events are delivered to this surface
+    pub keyboard_interactivity: KeyboardInteractivity,
+    /// The layer that the surface is rendered on
+    pub layer: Layer,
+}
+
+impl Cacheable for LayerSurfaceCachedState {
+    fn commit(&mut self) -> Self {
+        *self
+    }
+    fn merge_into(self, into: &mut Self) {
+        *into = self;
+    }
+}
+
+/// Shell global state
+///
+/// This state allows you to retrieve a list of surfaces
+/// currently known to the shell global.
+#[derive(Debug)]
+pub struct LayerShellState {
+    known_layers: Vec<LayerSurface>,
+}
+
+impl LayerShellState {
+    /// Access all the shell surfaces known by this handler
+    pub fn layer_surfaces(&self) -> &[LayerSurface] {
+        &self.known_layers[..]
+    }
+}
+
+#[derive(Clone)]
+struct ShellUserData {
+    log: ::slog::Logger,
+    user_impl: Rc<RefCell<dyn FnMut(LayerShellRequest, DispatchData<'_>)>>,
+    shell_state: Arc<Mutex<LayerShellState>>,
+}
+
+/// Create a new `wlr_layer_shell` globals
+pub fn wlr_layer_shell_init<L, Impl>(
+    display: &mut Display,
+    implementation: Impl,
+    logger: L,
+) -> (
+    Arc<Mutex<LayerShellState>>,
+    Global<zwlr_layer_shell_v1::ZwlrLayerShellV1>,
+)
+where
+    L: Into<Option<::slog::Logger>>,
+    Impl: FnMut(LayerShellRequest, DispatchData<'_>) + 'static,
+{
+    let log = crate::slog_or_fallback(logger);
+    let shell_state = Arc::new(Mutex::new(LayerShellState {
+        known_layers: Vec::new(),
+    }));
+
+    let shell_data = ShellUserData {
+        log: log.new(slog::o!("smithay_module" => "layer_shell_handler")),
+        user_impl: Rc::new(RefCell::new(implementation)),
+        shell_state: shell_state.clone(),
+    };
+
+    let layer_shell_global = display.create_global(
+        4,
+        Filter::new(
+            move |(shell, _version): (Main<zwlr_layer_shell_v1::ZwlrLayerShellV1>, _), _, _ddata| {
+                shell.quick_assign(self::handlers::layer_shell_implementation);
+                shell.as_ref().user_data().set({
+                    let shell_data = shell_data.clone();
+                    move || shell_data
+                });
+            },
+        ),
+    );
+
+    (shell_state, layer_shell_global)
+}
+
+/// A handle to a layer surface
+#[derive(Debug, Clone)]
+pub struct LayerSurface {
+    wl_surface: wl_surface::WlSurface,
+    shell_surface: zwlr_layer_surface_v1::ZwlrLayerSurfaceV1,
+}
+
+impl std::cmp::PartialEq for LayerSurface {
+    fn eq(&self, other: &Self) -> bool {
+        self.alive() && other.alive() && self.wl_surface == other.wl_surface
+    }
+}
+
+impl LayerSurface {
+    /// Is the layer surface referred by this handle still alive?
+    pub fn alive(&self) -> bool {
+        self.shell_surface.as_ref().is_alive() && self.wl_surface.as_ref().is_alive()
+    }
+
+    /// Gets the current pending state for a configure
+    ///
+    /// Returns `Some` if either no initial configure has been sent or
+    /// the `server_pending` is `Some` and different from the last pending
+    /// configure or `last_acked` if there is no pending
+    ///
+    /// Returns `None` if either no `server_pending` or the pending
+    /// has already been sent to the client or the pending is equal
+    /// to the `last_acked`
+    fn get_pending_state(&self, attributes: &mut LayerSurfaceAttributes) -> Option<LayerSurfaceState> {
+        if !attributes.initial_configure_sent {
+            return Some(attributes.server_pending.take().unwrap_or_default());
+        }
+
+        let server_pending = match attributes.server_pending.take() {
+            Some(state) => state,
+            None => {
+                return None;
+            }
+        };
+
+        let last_state = attributes
+            .pending_configures
+            .last()
+            .map(|c| &c.state)
+            .or_else(|| attributes.last_acked.as_ref());
+
+        if let Some(state) = last_state {
+            if state == &server_pending {
+                return None;
+            }
+        }
+
+        Some(server_pending)
+    }
+
+    /// Send a configure event to this layer surface to suggest it a new configuration
+    ///
+    /// The serial of this configure will be tracked waiting for the client to ACK it.
+    ///
+    /// You can manipulate the state that will be sent to the client with the [`with_pending_state`](#method.with_pending_state)
+    /// method.
+    pub fn send_configure(&self) {
+        if let Some(surface) = self.get_surface() {
+            let configure = compositor::with_states(surface, |states| {
+                let mut attributes = states
+                    .data_map
+                    .get::<Mutex<LayerSurfaceAttributes>>()
+                    .unwrap()
+                    .lock()
+                    .unwrap();
+                if let Some(pending) = self.get_pending_state(&mut *attributes) {
+                    let configure = LayerSurfaceConfigure {
+                        serial: SERIAL_COUNTER.next_serial(),
+                        state: pending,
+                    };
+
+                    attributes.pending_configures.push(configure.clone());
+                    attributes.initial_configure_sent = true;
+
+                    Some(configure)
+                } else {
+                    None
+                }
+            })
+            .unwrap_or(None);
+
+            // send surface configure
+            if let Some(configure) = configure {
+                let (width, height) = configure.state.size.unwrap_or_default().into();
+                let serial = configure.serial;
+                self.shell_surface
+                    .configure(serial.into(), width as u32, height as u32);
+            }
+        }
+    }
+
+    /// Make sure this surface was configured
+    ///
+    /// Returns `true` if it was, if not, returns `false` and raise
+    /// a protocol error to the associated layer surface. Also returns `false`
+    /// if the surface is already destroyed.
+    pub fn ensure_configured(&self) -> bool {
+        if !self.alive() {
+            return false;
+        }
+        let configured = compositor::with_states(&self.wl_surface, |states| {
+            states
+                .data_map
+                .get::<Mutex<LayerSurfaceAttributes>>()
+                .unwrap()
+                .lock()
+                .unwrap()
+                .configured
+        })
+        .unwrap();
+        if !configured {
+            self.shell_surface.as_ref().post_error(
+                zwlr_layer_shell_v1::Error::AlreadyConstructed as u32,
+                "layer_surface has never been configured".into(),
+            );
+        }
+        configured
+    }
+
+    /// Send a "close" event to the client
+    pub fn send_close(&self) {
+        self.shell_surface.closed()
+    }
+
+    /// Access the underlying `wl_surface` of this layer surface
+    ///
+    /// Returns `None` if the layer surface actually no longer exists.
+    pub fn get_surface(&self) -> Option<&wl_surface::WlSurface> {
+        if self.alive() {
+            Some(&self.wl_surface)
+        } else {
+            None
+        }
+    }
+
+    /// Allows the pending state of this layer to
+    /// be manipulated.
+    ///
+    /// This should be used to inform the client about size and state changes,
+    /// for example after a resize request from the client.
+    ///
+    /// The state will be sent to the client when calling [`send_configure`](#method.send_configure).
+    pub fn with_pending_state<F, T>(&self, f: F) -> Result<T, DeadResource>
+    where
+        F: FnOnce(&mut LayerSurfaceState) -> T,
+    {
+        if !self.alive() {
+            return Err(DeadResource);
+        }
+
+        Ok(compositor::with_states(&self.wl_surface, |states| {
+            let mut attributes = states
+                .data_map
+                .get::<Mutex<LayerSurfaceAttributes>>()
+                .unwrap()
+                .lock()
+                .unwrap();
+            if attributes.server_pending.is_none() {
+                attributes.server_pending = Some(attributes.current.clone());
+            }
+
+            let server_pending = attributes.server_pending.as_mut().unwrap();
+            f(server_pending)
+        })
+        .unwrap())
+    }
+
+    /// Gets a copy of the current state of this layer
+    ///
+    /// Returns `None` if the underlying surface has been
+    /// destroyed
+    pub fn current_state(&self) -> Option<LayerSurfaceState> {
+        if !self.alive() {
+            return None;
+        }
+
+        Some(
+            compositor::with_states(&self.wl_surface, |states| {
+                let attributes = states
+                    .data_map
+                    .get::<Mutex<LayerSurfaceAttributes>>()
+                    .unwrap()
+                    .lock()
+                    .unwrap();
+
+                attributes.current.clone()
+            })
+            .unwrap(),
+        )
+    }
+}
+
+/// A configure message for layer surfaces
+#[derive(Debug, Clone)]
+pub struct LayerSurfaceConfigure {
+    /// The state associated with this configure
+    pub state: LayerSurfaceState,
+
+    /// A serial number to track ACK from the client
+    ///
+    /// This should be an ever increasing number, as the ACK-ing
+    /// from a client for a serial will validate all pending lower
+    /// serials.
+    pub serial: Serial,
+}
+
+/// Events generated by layer shell surfaces
+///
+/// Depending on what you want to do, you might ignore some of them
+#[derive(Debug)]
+pub enum LayerShellRequest {
+    /// A new layer surface was created
+    ///
+    /// You likely need to send a [`LayerSurfaceConfigure`] to the surface, to hint the
+    /// client as to how its layer surface should be sized.
+    NewLayerSurface {
+        /// the surface
+        surface: LayerSurface,
+        /// The output that the layer will be displayed on
+        ///
+        /// None means that the compositor should decide which output to use,
+        /// Generally this will be the one that the user most recently interacted with
+        output: Option<WlOutput>,
+        /// This values indicate on which layer a surface should be rendered on
+        layer: Layer,
+        /// namespace that defines the purpose of the layer surface
+        namespace: String,
+    },
+
+    /// A surface has acknowledged a configure serial.
+    AckConfigure {
+        /// The surface.
+        surface: wl_surface::WlSurface,
+        /// The configure serial.
+        configure: LayerSurfaceConfigure,
+    },
+}
diff --git a/src/wayland/shell/wlr_layer/types.rs b/src/wayland/shell/wlr_layer/types.rs
new file mode 100644
index 0000000..2fe383c
--- /dev/null
+++ b/src/wayland/shell/wlr_layer/types.rs
@@ -0,0 +1,231 @@
+use std::{cmp::Ordering, convert::TryFrom};
+
+use wayland_protocols::wlr::unstable::layer_shell::v1::server::{zwlr_layer_shell_v1, zwlr_layer_surface_v1};
+
+/// Available layers for surfaces
+///
+/// These values indicate which layers a surface can be rendered in.
+/// They are ordered by z depth, bottom-most first.
+/// Traditional shell surfaces will typically be rendered between the bottom and top layers.
+/// Fullscreen shell surfaces are typically rendered at the top layer.
+/// Multiple surfaces can share a single layer, and ordering within a single layer is undefined.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Layer {
+    /// The lowest layer, used usualy for wallpapers
+    Background,
+    /// The layer bellow the windows and above the wallpaper
+    Bottom,
+    /// The layer above the windows and bellow overlay
+    Top,
+    /// The top layer above all other layers
+    Overlay,
+}
+
+impl TryFrom<zwlr_layer_shell_v1::Layer> for Layer {
+    type Error = (zwlr_layer_shell_v1::Error, String);
+
+    fn try_from(layer: zwlr_layer_shell_v1::Layer) -> Result<Self, Self::Error> {
+        match layer {
+            zwlr_layer_shell_v1::Layer::Background => Ok(Self::Background),
+            zwlr_layer_shell_v1::Layer::Bottom => Ok(Self::Bottom),
+            zwlr_layer_shell_v1::Layer::Top => Ok(Self::Top),
+            zwlr_layer_shell_v1::Layer::Overlay => Ok(Self::Overlay),
+            _ => Err((
+                zwlr_layer_shell_v1::Error::InvalidLayer,
+                format!("invalid layer: {:?}", layer),
+            )),
+        }
+    }
+}
+
+impl Default for Layer {
+    fn default() -> Self {
+        Self::Background
+    }
+}
+
+/// Types of keyboard interaction possible for a layer shell surface
+///
+/// The rationale for this is twofold:
+/// - some applications are not interested in keyboard events
+///   and not allowing them to be focused can improve the desktop experience
+/// - some applications will want to take exclusive keyboard focus.
+#[derive(Debug, Clone, Copy)]
+pub enum KeyboardInteractivity {
+    /// This value indicates that this surface is not interested in keyboard events
+    /// and the compositor should never assign it the keyboard focus.
+    ///
+    /// This is the default value, set for newly created layer shell surfaces.
+    ///
+    /// This is useful for e.g. desktop widgets that display information
+    /// or only have interaction with non-keyboard input devices.
+    None,
+    /// Request exclusive keyboard focus if this surface is above the shell surface layer.
+    ///
+    /// For the top and overlay layers, the seat will always give exclusive keyboard focus
+    /// to the top-most layer which has keyboard interactivity set to exclusive.
+    /// If this layer contains multiple surfaces with keyboard interactivity set to exclusive,
+    /// the compositor determines the one receiving keyboard events in an implementation- defined manner.
+    /// In this case, no guarantee is made when this surface will receive keyboard focus (if ever).
+    ///
+    /// For the bottom and background layers, the compositor is allowed to use normal focus semantics.
+    ///
+    /// This setting is mainly intended for applications that need to
+    /// ensure they receive all keyboard events, such as a lock screen or a password prompt.
+    Exclusive,
+    /// This requests the compositor to allow this surface
+    /// to be focused and unfocused by the user in an implementation-defined manner.
+    /// The user should be able to unfocus this surface even regardless of the layer it is on.
+    ///
+    /// Typically, the compositor will want to use its normal mechanism
+    /// to manage keyboard focus between layer shell surfaces
+    /// with this setting and regular toplevels on the desktop layer (e.g. click to focus).
+    /// Nevertheless, it is possible for a compositor to require a special interaction
+    /// to focus or unfocus layer shell surfaces
+    ///
+    /// This setting is mainly intended for desktop shell components that allow keyboard interaction.
+    /// Using this option can allow implementing a desktop shell that can be fully usable without the mouse.
+    OnDemand,
+}
+
+impl Default for KeyboardInteractivity {
+    fn default() -> Self {
+        Self::None
+    }
+}
+
+impl TryFrom<zwlr_layer_surface_v1::KeyboardInteractivity> for KeyboardInteractivity {
+    type Error = (zwlr_layer_surface_v1::Error, String);
+
+    fn try_from(ki: zwlr_layer_surface_v1::KeyboardInteractivity) -> Result<Self, Self::Error> {
+        match ki {
+            zwlr_layer_surface_v1::KeyboardInteractivity::None => Ok(Self::None),
+            zwlr_layer_surface_v1::KeyboardInteractivity::Exclusive => Ok(Self::Exclusive),
+            zwlr_layer_surface_v1::KeyboardInteractivity::OnDemand => Ok(Self::OnDemand),
+            _ => Err((
+                zwlr_layer_surface_v1::Error::InvalidKeyboardInteractivity,
+                format!("wrong keyboard interactivity value: {:?}", ki),
+            )),
+        }
+    }
+}
+
+bitflags::bitflags! {
+    /// Anchor bitflags, describing how the layers surface should be positioned and sized
+    pub struct Anchor: u32 {
+        /// The top edge of the anchor rectangle
+        const TOP = 1;
+        /// The bottom edge of the anchor rectangle
+        const BOTTOM = 2;
+        /// The left edge of the anchor rectangle
+        const LEFT = 4;
+        /// The right edge of the anchor rectangle
+        const RIGHT = 8;
+    }
+}
+
+impl Anchor {
+    /// Check if anchored horizontally
+    ///
+    /// If it is anchored to `left` and `right` anchor at the same time
+    /// it returns `true`
+    pub fn anchored_horizontally(&self) -> bool {
+        self.contains(Self::LEFT) && self.contains(Self::RIGHT)
+    }
+    /// Check if anchored vertically
+    ///
+    /// If it is anchored to `top` and `bottom` anchor at the same time
+    /// it returns `true`
+    pub fn anchored_vertically(&self) -> bool {
+        self.contains(Self::TOP) && self.contains(Self::BOTTOM)
+    }
+}
+
+impl Default for Anchor {
+    fn default() -> Self {
+        Self::empty()
+    }
+}
+
+impl TryFrom<zwlr_layer_surface_v1::Anchor> for Anchor {
+    type Error = (zwlr_layer_surface_v1::Error, String);
+
+    fn try_from(anchor: zwlr_layer_surface_v1::Anchor) -> Result<Self, Self::Error> {
+        match Anchor::from_bits(anchor.bits()) {
+            Some(a) => Ok(a),
+            _ => Err((
+                zwlr_layer_surface_v1::Error::InvalidAnchor,
+                format!("invalid anchor {:?}", anchor),
+            )),
+        }
+    }
+}
+
+/// Exclusive zone descriptor
+#[derive(Debug, Clone, Copy)]
+pub enum ExclusiveZone {
+    /// Requests that the compositor avoids occluding an area with other surfaces.
+    ///
+    /// A exclusive zone value is the distance from the edge in surface-local coordinates to consider exclusive.
+    ///
+    /// A exclusive value is only meaningful if the surface is
+    /// anchored to one edge or an edge and both perpendicular edges.
+    ///
+    /// If the surface is:
+    /// - not anchored
+    /// - anchored to only two perpendicular edges (a corner),
+    /// - anchored to only two parallel edges or anchored to all edges,
+    ///
+    /// The exclusive value should be treated the same as [`ExclusiveZone::Neutral`].
+    Exclusive(u32),
+    /// If set to Neutral,
+    /// the surface indicates that it would like to be moved to avoid occluding surfaces with a exclusive zone.
+    Neutral,
+    /// If set to DontCare,
+    /// the surface indicates that it would not like to be moved to accommodate for other surfaces,
+    /// and the compositor should extend it all the way to the edges it is anchored to.
+    DontCare,
+}
+
+impl Default for ExclusiveZone {
+    fn default() -> Self {
+        Self::Neutral
+    }
+}
+
+impl From<i32> for ExclusiveZone {
+    fn from(v: i32) -> Self {
+        match v.cmp(&0) {
+            Ordering::Greater => Self::Exclusive(v as u32),
+            Ordering::Equal => Self::Neutral,
+            Ordering::Less => Self::DontCare,
+        }
+    }
+}
+
+impl From<ExclusiveZone> for i32 {
+    fn from(z: ExclusiveZone) -> i32 {
+        match z {
+            ExclusiveZone::Exclusive(v) => v as i32,
+            ExclusiveZone::Neutral => 0,
+            ExclusiveZone::DontCare => -1,
+        }
+    }
+}
+
+/// Describes distance from the anchor point of the output, in surface-local coordinates.
+///
+/// If surface did not anchor curtain edge, margin for that edge should be ignored.
+///
+/// The exclusive zone should includes the margins.
+#[derive(Debug, Default, Clone, Copy)]
+pub struct Margins {
+    /// Distance from [`Anchor::TOP`]
+    pub top: i32,
+    /// Distance from [`Anchor::TOP`]
+    pub right: i32,
+    /// Distance from [`Anchor::BOTTOM`]
+    pub bottom: i32,
+    /// Distance from [`Anchor::LEFT`]
+    pub left: i32,
+}
diff --git a/src/wayland/shell/xdg/mod.rs b/src/wayland/shell/xdg/mod.rs
index b5e2bd0..6ddc174 100644
--- a/src/wayland/shell/xdg/mod.rs
+++ b/src/wayland/shell/xdg/mod.rs
@@ -89,7 +89,7 @@ use wayland_server::{
 use super::PingError;
 
 // handlers for the xdg_shell protocol
-mod xdg_handlers;
+pub(super) mod xdg_handlers;
 // compatibility handlers for the zxdg_shell_v6 protocol, its earlier version
 mod zxdgv6_handlers;
 

From 115403633b2f0cc1bd8c4ddd5cd5d62a9ac27efc Mon Sep 17 00:00:00 2001
From: Poly <marynczak.bartlomiej@gmail.com>
Date: Fri, 30 Jul 2021 18:15:15 +0200
Subject: [PATCH 2/4] anvil: Implement wlr_layer_shell

---
 anvil/src/drawing.rs              |  54 +++++++
 anvil/src/input_handler.rs        |   5 +
 anvil/src/output_map.rs           |  38 ++++-
 anvil/src/shell.rs                |  63 +++++++-
 anvil/src/udev.rs                 |  26 +++
 anvil/src/window_map.rs           |  23 +++
 anvil/src/window_map/layer_map.rs | 253 ++++++++++++++++++++++++++++++
 anvil/src/winit.rs                |  36 ++++-
 8 files changed, 484 insertions(+), 14 deletions(-)
 create mode 100644 anvil/src/window_map/layer_map.rs

diff --git a/anvil/src/drawing.rs b/anvil/src/drawing.rs
index 4d386c7..53e9807 100644
--- a/anvil/src/drawing.rs
+++ b/anvil/src/drawing.rs
@@ -20,6 +20,7 @@ use smithay::{
             SurfaceAttributes, TraversalAction,
         },
         seat::CursorImageAttributes,
+        shell::wlr_layer::Layer,
     },
 };
 
@@ -241,6 +242,59 @@ where
     result
 }
 
+pub fn draw_layers<R, E, F, T>(
+    renderer: &mut R,
+    frame: &mut F,
+    window_map: &WindowMap,
+    layer: Layer,
+    output_rect: Rectangle<i32, Logical>,
+    output_scale: f32,
+    log: &::slog::Logger,
+) -> Result<(), SwapBuffersError>
+where
+    R: Renderer<Error = E, TextureId = T, Frame = F> + ImportAll,
+    F: Frame<Error = E, TextureId = T>,
+    E: std::error::Error + Into<SwapBuffersError>,
+    T: Texture + 'static,
+{
+    let mut result = Ok(());
+
+    window_map
+        .layers
+        .with_layers_from_bottom_to_top(&layer, |layer_surface| {
+            // skip layers that do not overlap with a given output
+            if !output_rect.overlaps(layer_surface.bbox) {
+                return;
+            }
+
+            let mut initial_place: Point<i32, Logical> = layer_surface.location;
+            initial_place.x -= output_rect.loc.x;
+
+            if let Some(wl_surface) = layer_surface.surface.get_surface() {
+                // this surface is a root of a subsurface tree that needs to be drawn
+                if let Err(err) =
+                    draw_surface_tree(renderer, frame, wl_surface, initial_place, output_scale, log)
+                {
+                    result = Err(err);
+                }
+
+                window_map.with_child_popups(wl_surface, |popup| {
+                    let location = popup.location();
+                    let draw_location = initial_place + location;
+                    if let Some(wl_surface) = popup.get_surface() {
+                        if let Err(err) =
+                            draw_surface_tree(renderer, frame, wl_surface, draw_location, output_scale, log)
+                        {
+                            result = Err(err);
+                        }
+                    }
+                });
+            }
+        });
+
+    result
+}
+
 pub fn draw_dnd_icon<R, E, F, T>(
     renderer: &mut R,
     frame: &mut F,
diff --git a/anvil/src/input_handler.rs b/anvil/src/input_handler.rs
index 2985793..e2f06d2 100644
--- a/anvil/src/input_handler.rs
+++ b/anvil/src/input_handler.rs
@@ -211,6 +211,11 @@ impl AnvilState<WinitData> {
                     },
                     crate::winit::OUTPUT_NAME,
                 );
+
+                let output_mut = self.output_map.borrow();
+                let output = output_mut.find_by_name(crate::winit::OUTPUT_NAME).unwrap();
+
+                self.window_map.borrow_mut().layers.arange_layers(output);
             }
             _ => {
                 // other events are not handled in anvil (yet)
diff --git a/anvil/src/output_map.rs b/anvil/src/output_map.rs
index 98583b8..df367bf 100644
--- a/anvil/src/output_map.rs
+++ b/anvil/src/output_map.rs
@@ -4,7 +4,10 @@ use smithay::{
     reexports::{
         wayland_protocols::xdg_shell::server::xdg_toplevel,
         wayland_server::{
-            protocol::{wl_output, wl_surface::WlSurface},
+            protocol::{
+                wl_output,
+                wl_surface::{self, WlSurface},
+            },
             Display, Global, UserDataMap,
         },
     },
@@ -22,6 +25,7 @@ pub struct Output {
     output: output::Output,
     global: Option<Global<wl_output::WlOutput>>,
     surfaces: Vec<WlSurface>,
+    layer_surfaces: RefCell<Vec<wl_surface::WlSurface>>,
     current_mode: Mode,
     scale: f32,
     output_scale: i32,
@@ -60,6 +64,7 @@ impl Output {
             output,
             location,
             surfaces: Vec::new(),
+            layer_surfaces: Default::default(),
             current_mode: mode,
             scale,
             output_scale,
@@ -101,6 +106,16 @@ impl Output {
     pub fn current_mode(&self) -> Mode {
         self.current_mode
     }
+
+    /// Add a layer surface to this output
+    pub fn add_layer_surface(&self, layer: wl_surface::WlSurface) {
+        self.layer_surfaces.borrow_mut().push(layer);
+    }
+
+    /// Get all layer surfaces assigned to this output
+    pub fn layer_surfaces(&self) -> Vec<wl_surface::WlSurface> {
+        self.layer_surfaces.borrow().iter().cloned().collect()
+    }
 }
 
 impl Drop for Output {
@@ -171,6 +186,7 @@ impl OutputMap {
         // and move them to the primary output
         let primary_output_location = self.with_primary().map(|o| o.location()).unwrap_or_default();
         let mut window_map = self.window_map.borrow_mut();
+
         // TODO: This is a bit unfortunate, we save the windows in a temp vector
         // cause we can not call window_map.set_location within the closure.
         let mut windows_to_move = Vec::new();
@@ -218,6 +234,10 @@ impl OutputMap {
         for (window, location) in windows_to_move.drain(..) {
             window_map.set_location(&window, location);
         }
+
+        for output in self.outputs.iter() {
+            window_map.layers.arange_layers(output);
+        }
     }
 
     pub fn add<N>(&mut self, name: N, physical: PhysicalProperties, mode: Mode) -> &Output
@@ -293,6 +313,15 @@ impl OutputMap {
         self.find(|o| o.output.owns(output))
     }
 
+    pub fn find_by_layer_surface(&self, surface: &wl_surface::WlSurface) -> Option<&Output> {
+        self.find(|o| {
+            o.layer_surfaces
+                .borrow()
+                .iter()
+                .any(|s| s.as_ref().equals(surface.as_ref()))
+        })
+    }
+
     pub fn find_by_name<N>(&self, name: N) -> Option<&Output>
     where
         N: AsRef<str>,
@@ -388,9 +417,10 @@ impl OutputMap {
 
     pub fn refresh(&mut self) {
         // Clean-up dead surfaces
-        self.outputs
-            .iter_mut()
-            .for_each(|o| o.surfaces.retain(|s| s.as_ref().is_alive()));
+        self.outputs.iter_mut().for_each(|o| {
+            o.surfaces.retain(|s| s.as_ref().is_alive());
+            o.layer_surfaces.borrow_mut().retain(|s| s.as_ref().is_alive());
+        });
 
         let window_map = self.window_map.clone();
 
diff --git a/anvil/src/shell.rs b/anvil/src/shell.rs
index 7509ccb..73320bd 100644
--- a/anvil/src/shell.rs
+++ b/anvil/src/shell.rs
@@ -22,6 +22,7 @@ use smithay::{
         seat::{AxisFrame, GrabStartData, PointerGrab, PointerInnerHandle, Seat},
         shell::{
             legacy::{wl_shell_init, ShellRequest, ShellState as WlShellState, ShellSurfaceKind},
+            wlr_layer::{LayerShellRequest, LayerSurfaceAttributes},
             xdg::{
                 xdg_shell_init, Configure, ShellState as XdgShellState, SurfaceCachedState,
                 XdgPopupSurfaceRoleAttributes, XdgRequest, XdgToplevelSurfaceRoleAttributes,
@@ -329,7 +330,8 @@ pub fn init_shell<BackendData: 'static>(display: Rc<RefCell<Display>>, log: ::sl
         move |surface, mut ddata| {
             let anvil_state = ddata.get::<AnvilState<BackendData>>().unwrap();
             let window_map = anvil_state.window_map.as_ref();
-            surface_commit(&surface, &*window_map)
+            let output_map = anvil_state.output_map.as_ref();
+            surface_commit(&surface, &*window_map, &*output_map)
         },
         log.clone(),
     );
@@ -822,6 +824,38 @@ pub fn init_shell<BackendData: 'static>(display: Rc<RefCell<Display>>, log: ::sl
         log.clone(),
     );
 
+    let layer_window_map = window_map.clone();
+    let layer_output_map = output_map.clone();
+    smithay::wayland::shell::wlr_layer::wlr_layer_shell_init(
+        &mut *display.borrow_mut(),
+        move |event, mut ddata| match event {
+            LayerShellRequest::NewLayerSurface {
+                surface,
+                output,
+                layer,
+                ..
+            } => {
+                let output_map = layer_output_map.borrow();
+                let anvil_state = ddata.get::<AnvilState<BackendData>>().unwrap();
+
+                let output = output.and_then(|output| output_map.find_by_output(&output));
+                let output = output.unwrap_or_else(|| {
+                    output_map
+                        .find_by_position(anvil_state.pointer_location.to_i32_round())
+                        .unwrap_or_else(|| output_map.with_primary().unwrap())
+                });
+
+                if let Some(wl_surface) = surface.get_surface() {
+                    output.add_layer_surface(wl_surface.clone());
+
+                    layer_window_map.borrow_mut().layers.insert(surface, layer);
+                }
+            }
+            LayerShellRequest::AckConfigure { .. } => {}
+        },
+        log.clone(),
+    );
+
     ShellHandles {
         xdg_state: xdg_shell_state,
         wl_state: wl_shell_state,
@@ -937,7 +971,11 @@ impl SurfaceData {
     }
 }
 
-fn surface_commit(surface: &wl_surface::WlSurface, window_map: &RefCell<WindowMap>) {
+fn surface_commit(
+    surface: &wl_surface::WlSurface,
+    window_map: &RefCell<WindowMap>,
+    output_map: &RefCell<OutputMap>,
+) {
     #[cfg(feature = "xwayland")]
     super::xwayland::commit_hook(surface);
 
@@ -1055,4 +1093,25 @@ fn surface_commit(surface: &wl_surface::WlSurface, window_map: &RefCell<WindowMa
             popup.send_configure();
         }
     }
+
+    if let Some(layer) = window_map.layers.find(surface) {
+        // send the initial configure if relevant
+        let initial_configure_sent = with_states(surface, |states| {
+            states
+                .data_map
+                .get::<Mutex<LayerSurfaceAttributes>>()
+                .unwrap()
+                .lock()
+                .unwrap()
+                .initial_configure_sent
+        })
+        .unwrap();
+        if !initial_configure_sent {
+            layer.surface.send_configure();
+        }
+
+        if let Some(output) = output_map.borrow().find_by_layer_surface(surface) {
+            window_map.layers.arange_layers(output);
+        }
+    }
 }
diff --git a/anvil/src/udev.rs b/anvil/src/udev.rs
index 30d2533..8811df2 100644
--- a/anvil/src/udev.rs
+++ b/anvil/src/udev.rs
@@ -55,6 +55,7 @@ use smithay::{
     wayland::{
         output::{Mode, PhysicalProperties},
         seat::CursorImageStatus,
+        shell::wlr_layer::Layer,
     },
 };
 #[cfg(feature = "egl")]
@@ -744,9 +745,34 @@ fn render_surface(
             Transform::Flipped180, // Scanout is rotated
             |renderer, frame| {
                 frame.clear([0.8, 0.8, 0.9, 1.0])?;
+
+                for layer in [Layer::Background, Layer::Bottom] {
+                    draw_layers(
+                        renderer,
+                        frame,
+                        window_map,
+                        layer,
+                        output_geometry,
+                        output_scale,
+                        logger,
+                    )?;
+                }
+
                 // draw the surfaces
                 draw_windows(renderer, frame, window_map, output_geometry, output_scale, logger)?;
 
+                for layer in [Layer::Top, Layer::Overlay] {
+                    draw_layers(
+                        renderer,
+                        frame,
+                        window_map,
+                        layer,
+                        output_geometry,
+                        output_scale,
+                        logger,
+                    )?;
+                }
+
                 // set cursor
                 if output_geometry.to_f64().contains(pointer_location) {
                     let (ptr_x, ptr_y) = pointer_location.into();
diff --git a/anvil/src/window_map.rs b/anvil/src/window_map.rs
index 0ca4b4c..b96e334 100644
--- a/anvil/src/window_map.rs
+++ b/anvil/src/window_map.rs
@@ -8,6 +8,7 @@ use smithay::{
         compositor::{with_states, with_surface_tree_downward, SubsurfaceCachedState, TraversalAction},
         shell::{
             legacy::ShellSurface,
+            wlr_layer::Layer,
             xdg::{PopupSurface, SurfaceCachedState, ToplevelSurface, XdgPopupSurfaceRoleAttributes},
         },
     },
@@ -17,6 +18,9 @@ use crate::shell::SurfaceData;
 #[cfg(feature = "xwayland")]
 use crate::xwayland::X11Surface;
 
+mod layer_map;
+pub use layer_map::{LayerMap, LayerSurface};
+
 #[derive(Clone, PartialEq)]
 pub enum Kind {
     Xdg(ToplevelSurface),
@@ -242,6 +246,8 @@ pub struct Popup {
 pub struct WindowMap {
     windows: Vec<Window>,
     popups: Vec<Popup>,
+
+    pub layers: LayerMap,
 }
 
 impl WindowMap {
@@ -268,11 +274,26 @@ impl WindowMap {
         &self,
         point: Point<f64, Logical>,
     ) -> Option<(wl_surface::WlSurface, Point<i32, Logical>)> {
+        if let Some(res) = self.layers.get_surface_under(&Layer::Overlay, point) {
+            return Some(res);
+        }
+        if let Some(res) = self.layers.get_surface_under(&Layer::Top, point) {
+            return Some(res);
+        }
+
         for w in &self.windows {
             if let Some(surface) = w.matching(point) {
                 return Some(surface);
             }
         }
+
+        if let Some(res) = self.layers.get_surface_under(&Layer::Bottom, point) {
+            return Some(res);
+        }
+        if let Some(res) = self.layers.get_surface_under(&Layer::Background, point) {
+            return Some(res);
+        }
+
         None
     }
 
@@ -330,6 +351,7 @@ impl WindowMap {
     pub fn refresh(&mut self) {
         self.windows.retain(|w| w.toplevel.alive());
         self.popups.retain(|p| p.popup.alive());
+        self.layers.refresh();
         for w in &mut self.windows {
             w.self_update();
         }
@@ -404,5 +426,6 @@ impl WindowMap {
         for window in &self.windows {
             window.send_frame(time);
         }
+        self.layers.send_frames(time);
     }
 }
diff --git a/anvil/src/window_map/layer_map.rs b/anvil/src/window_map/layer_map.rs
new file mode 100644
index 0000000..52a28a3
--- /dev/null
+++ b/anvil/src/window_map/layer_map.rs
@@ -0,0 +1,253 @@
+use std::cell::RefCell;
+
+use smithay::{
+    reexports::wayland_server::protocol::wl_surface,
+    utils::{Logical, Point, Rectangle},
+    wayland::{
+        compositor::{with_states, with_surface_tree_downward, SubsurfaceCachedState, TraversalAction},
+        shell::wlr_layer::{self, Anchor, LayerSurfaceCachedState},
+    },
+};
+
+use crate::{output_map::Output, shell::SurfaceData};
+
+pub struct LayerSurface {
+    pub surface: wlr_layer::LayerSurface,
+    pub location: Point<i32, Logical>,
+    pub bbox: Rectangle<i32, Logical>,
+    pub layer: wlr_layer::Layer,
+}
+
+impl LayerSurface {
+    /// Finds the topmost surface under this point if any and returns it together with the location of this
+    /// surface.
+    fn matching(&self, point: Point<f64, Logical>) -> Option<(wl_surface::WlSurface, Point<i32, Logical>)> {
+        if !self.bbox.to_f64().contains(point) {
+            return None;
+        }
+        // need to check more carefully
+        let found = RefCell::new(None);
+        if let Some(wl_surface) = self.surface.get_surface() {
+            with_surface_tree_downward(
+                wl_surface,
+                self.location,
+                |wl_surface, states, location| {
+                    let mut location = *location;
+                    let data = states.data_map.get::<RefCell<SurfaceData>>();
+
+                    if states.role == Some("subsurface") {
+                        let current = states.cached_state.current::<SubsurfaceCachedState>();
+                        location += current.location;
+                    }
+
+                    let contains_the_point = data
+                        .map(|data| {
+                            data.borrow()
+                                .contains_point(&*states.cached_state.current(), point - location.to_f64())
+                        })
+                        .unwrap_or(false);
+                    if contains_the_point {
+                        *found.borrow_mut() = Some((wl_surface.clone(), location));
+                    }
+
+                    TraversalAction::DoChildren(location)
+                },
+                |_, _, _| {},
+                |_, _, _| {
+                    // only continue if the point is not found
+                    found.borrow().is_none()
+                },
+            );
+        }
+        found.into_inner()
+    }
+
+    fn self_update(&mut self) {
+        let mut bounding_box = Rectangle::from_loc_and_size(self.location, (0, 0));
+        if let Some(wl_surface) = self.surface.get_surface() {
+            with_surface_tree_downward(
+                wl_surface,
+                self.location,
+                |_, states, &loc| {
+                    let mut loc = loc;
+                    let data = states.data_map.get::<RefCell<SurfaceData>>();
+
+                    if let Some(size) = data.and_then(|d| d.borrow().size()) {
+                        if states.role == Some("subsurface") {
+                            let current = states.cached_state.current::<SubsurfaceCachedState>();
+                            loc += current.location;
+                        }
+
+                        // Update the bounding box.
+                        bounding_box = bounding_box.merge(Rectangle::from_loc_and_size(loc, size));
+
+                        TraversalAction::DoChildren(loc)
+                    } else {
+                        // If the parent surface is unmapped, then the child surfaces are hidden as
+                        // well, no need to consider them here.
+                        TraversalAction::SkipChildren
+                    }
+                },
+                |_, _, _| {},
+                |_, _, _| true,
+            );
+        }
+        self.bbox = bounding_box;
+
+        if let Some(surface) = self.surface.get_surface() {
+            self.layer = with_states(surface, |states| {
+                let current = states.cached_state.current::<LayerSurfaceCachedState>();
+                current.layer
+            })
+            .unwrap();
+        }
+    }
+
+    /// Sends the frame callback to all the subsurfaces in this
+    /// window that requested it
+    fn send_frame(&self, time: u32) {
+        if let Some(wl_surface) = self.surface.get_surface() {
+            with_surface_tree_downward(
+                wl_surface,
+                (),
+                |_, _, &()| TraversalAction::DoChildren(()),
+                |_, states, &()| {
+                    // the surface may not have any user_data if it is a subsurface and has not
+                    // yet been commited
+                    SurfaceData::send_frame(&mut *states.cached_state.current(), time)
+                },
+                |_, _, &()| true,
+            );
+        }
+    }
+}
+
+#[derive(Default)]
+pub struct LayerMap {
+    surfaces: Vec<LayerSurface>,
+}
+
+impl LayerMap {
+    pub fn insert(&mut self, surface: wlr_layer::LayerSurface, layer: wlr_layer::Layer) {
+        let mut layer = LayerSurface {
+            location: Default::default(),
+            bbox: Rectangle::default(),
+            surface,
+            layer,
+        };
+        layer.self_update();
+        self.surfaces.insert(0, layer);
+    }
+
+    pub fn get_surface_under(
+        &self,
+        layer: &wlr_layer::Layer,
+        point: Point<f64, Logical>,
+    ) -> Option<(wl_surface::WlSurface, Point<i32, Logical>)> {
+        for l in self.surfaces.iter().filter(|s| &s.layer == layer) {
+            if let Some(surface) = l.matching(point) {
+                return Some(surface);
+            }
+        }
+        None
+    }
+
+    pub fn with_layers_from_bottom_to_top<Func>(&self, layer: &wlr_layer::Layer, mut f: Func)
+    where
+        Func: FnMut(&LayerSurface),
+    {
+        for l in self.surfaces.iter().filter(|s| &s.layer == layer).rev() {
+            f(l)
+        }
+    }
+
+    pub fn refresh(&mut self) {
+        self.surfaces.retain(|l| l.surface.alive());
+
+        for l in self.surfaces.iter_mut() {
+            l.self_update();
+        }
+    }
+
+    /// Finds the layer corresponding to the given `WlSurface`.
+    pub fn find(&self, surface: &wl_surface::WlSurface) -> Option<&LayerSurface> {
+        self.surfaces.iter().find_map(|l| {
+            if l.surface
+                .get_surface()
+                .map(|s| s.as_ref().equals(surface.as_ref()))
+                .unwrap_or(false)
+            {
+                Some(l)
+            } else {
+                None
+            }
+        })
+    }
+
+    pub fn arange_layers(&mut self, output: &Output) {
+        let output_rect = output.geometry();
+
+        // Get all layer surfaces assigned to this output
+        let surfaces: Vec<_> = output
+            .layer_surfaces()
+            .into_iter()
+            .map(|s| s.as_ref().clone())
+            .collect();
+
+        // Find layers for this output
+        let filtered_layers = self.surfaces.iter_mut().filter(|l| {
+            l.surface
+                .get_surface()
+                .map(|s| surfaces.contains(s.as_ref()))
+                .unwrap_or(false)
+        });
+
+        for layer in filtered_layers {
+            let surface = if let Some(surface) = layer.surface.get_surface() {
+                surface
+            } else {
+                continue;
+            };
+
+            let data = with_states(surface, |states| {
+                *states.cached_state.current::<LayerSurfaceCachedState>()
+            })
+            .unwrap();
+
+            let x = if data.size.w == 0 || data.anchor.contains(Anchor::LEFT) {
+                output_rect.loc.x
+            } else if data.anchor.contains(Anchor::RIGHT) {
+                output_rect.loc.x + (output_rect.size.w - data.size.w)
+            } else {
+                output_rect.loc.x + ((output_rect.size.w / 2) - (data.size.w / 2))
+            };
+
+            let y = if data.size.h == 0 || data.anchor.contains(Anchor::TOP) {
+                output_rect.loc.y
+            } else if data.anchor.contains(Anchor::BOTTOM) {
+                output_rect.loc.y + (output_rect.size.h - data.size.h)
+            } else {
+                output_rect.loc.y + ((output_rect.size.h / 2) - (data.size.h / 2))
+            };
+
+            let location: Point<i32, Logical> = (x, y).into();
+
+            layer
+                .surface
+                .with_pending_state(|state| {
+                    state.size = Some(output_rect.size);
+                })
+                .unwrap();
+
+            layer.surface.send_configure();
+
+            layer.location = location;
+        }
+    }
+
+    pub fn send_frames(&self, time: u32) {
+        for layer in &self.surfaces {
+            layer.send_frame(time);
+        }
+    }
+}
diff --git a/anvil/src/winit.rs b/anvil/src/winit.rs
index e1b9f09..8e3e87c 100644
--- a/anvil/src/winit.rs
+++ b/anvil/src/winit.rs
@@ -16,6 +16,7 @@ use smithay::{
     wayland::{
         output::{Mode, PhysicalProperties},
         seat::CursorImageStatus,
+        shell::wlr_layer::Layer,
     },
 };
 
@@ -144,15 +145,34 @@ pub fn run_winit(log: Logger) {
                 .render(|renderer, frame| {
                     frame.clear([0.8, 0.8, 0.9, 1.0])?;
 
+                    let window_map = &*state.window_map.borrow();
+
+                    for layer in [Layer::Background, Layer::Bottom] {
+                        draw_layers(
+                            renderer,
+                            frame,
+                            window_map,
+                            layer,
+                            output_geometry,
+                            output_scale,
+                            &log,
+                        )?;
+                    }
+
                     // draw the windows
-                    draw_windows(
-                        renderer,
-                        frame,
-                        &*state.window_map.borrow(),
-                        output_geometry,
-                        output_scale,
-                        &log,
-                    )?;
+                    draw_windows(renderer, frame, window_map, output_geometry, output_scale, &log)?;
+
+                    for layer in [Layer::Top, Layer::Overlay] {
+                        draw_layers(
+                            renderer,
+                            frame,
+                            window_map,
+                            layer,
+                            output_geometry,
+                            output_scale,
+                            &log,
+                        )?;
+                    }
 
                     let (x, y) = state.pointer_location.into();
                     // draw the dnd icon if any

From e4c7822476d40a32359fbc2dc3fd4c94df747933 Mon Sep 17 00:00:00 2001
From: Poly <marynczak.bartlomiej@gmail.com>
Date: Sat, 31 Jul 2021 13:45:38 +0200
Subject: [PATCH 3/4] Update CHANGELOG

---
 CHANGELOG.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index aa5d823..efd4866 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,9 +6,10 @@
 
 #### Clients & Protocols
 
+- `wlr-layer-shell-unstable-v1` support
 - Added public api constants for the roles of `wl_shell_surface`, `zxdg_toplevel` and `xdg_toplevel`. See the
   `shell::legacy` and `shell::xdg` modules for these constants.
-- Whether a surface is toplevel equivalent can be determined with the new function `shell::is_toplevel_equivalent`. 
+- Whether a surface is toplevel equivalent can be determined with the new function `shell::is_toplevel_equivalent`.
 - Setting the parent of a toplevel surface is now possible with the `xdg::ToplevelSurface::set_parent` function.
 - Add support for the zxdg-foreign-v2 protocol.
 

From 1c6db1e7eed284f85aa192e811b98ef553187c85 Mon Sep 17 00:00:00 2001
From: Poly <marynczak.bartlomiej@gmail.com>
Date: Sat, 31 Jul 2021 05:54:08 +0200
Subject: [PATCH 4/4] wayland.shell.layer: change role static to constant

---
 src/wayland/shell/wlr_layer/mod.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/wayland/shell/wlr_layer/mod.rs b/src/wayland/shell/wlr_layer/mod.rs
index f012dbd..6ac7a30 100644
--- a/src/wayland/shell/wlr_layer/mod.rs
+++ b/src/wayland/shell/wlr_layer/mod.rs
@@ -51,7 +51,7 @@ mod types;
 pub use types::{Anchor, ExclusiveZone, KeyboardInteractivity, Layer, Margins};
 
 /// The role of a wlr_layer_shell_surface
-pub static LAYER_SURFACE_ROLE: &str = "zwlr_layer_surface_v1";
+pub const LAYER_SURFACE_ROLE: &str = "zwlr_layer_surface_v1";
 
 /// Attributes for layer surface
 #[derive(Debug)]