feat: render named cursor images

Cargo.lock

@@ -423,6 +423,7 @@ dependencies = [
  "smithay",
  "tracing",
  "tracing-subscriber",
+ "xcursor",
 ]
 
 [[package]]

Cargo.toml

@@ -28,3 +28,4 @@ smithay = { version = "0.7.0", default-features = false, features = [
 ] }
 tracing = "0.1.41"
 tracing-subscriber = { version = "0.3.20", features = ["env-filter"] }
+xcursor = "0.3.11"

compositor/Cargo.toml

@@ -13,3 +13,4 @@ libc.workspace = true
 smithay.workspace = true
 tracing.workspace = true
 tracing-subscriber.workspace = true
+xcursor.workspace = true

compositor/src/cursor.rs

@@ -0,0 +1,146 @@
+use std::{fs, sync::OnceLock};
+
+use smithay::{
+    backend::{allocator::Fourcc, renderer::element::memory::MemoryRenderBuffer},
+    input::pointer::CursorIcon,
+    utils::{Buffer, Point, Size, Transform},
+};
+use xcursor::{CursorTheme, parser::Image};
+
+const DEFAULT_CURSOR_SIZE: u32 = 24;
+
+#[derive(Debug, Clone)]
+pub(crate) struct NamedCursor {
+    pub buffer: MemoryRenderBuffer,
+    pub hotspot: Point<i32, Buffer>,
+}
+
+pub(crate) fn cursor_theme() -> CursorTheme {
+    let name = std::env::var("XCURSOR_THEME").unwrap_or_else(|_| "default".into());
+
+    CursorTheme::load(&name)
+}
+
+pub(crate) fn load_named_cursor(theme: &CursorTheme, icon: CursorIcon) -> NamedCursor {
+    let requested_size = cursor_size();
+    let image = cursor_names(icon)
+        .iter()
+        .find_map(|name| load_image(theme, name, requested_size));
+
+    match image {
+        Some(image) => cursor_from_image(image),
+        None => fallback_cursor(),
+    }
+}
+
+fn cursor_size() -> u32 {
+    static SIZE: OnceLock<u32> = OnceLock::new();
+
+    *SIZE.get_or_init(|| {
+        std::env::var("XCURSOR_SIZE")
+            .ok()
+            .and_then(|value| value.parse().ok())
+            .filter(|size| *size > 0)
+            .unwrap_or(DEFAULT_CURSOR_SIZE)
+    })
+}
+
+fn cursor_names(icon: CursorIcon) -> [&'static str; 3] {
+    match icon {
+        CursorIcon::Default => ["default", "left_ptr", "arrow"],
+        CursorIcon::Pointer => ["pointer", "hand2", "left_ptr"],
+        CursorIcon::Text => ["text", "xterm", "left_ptr"],
+        _ => [icon.name(), "default", "left_ptr"],
+    }
+}
+
+fn load_image(theme: &CursorTheme, name: &str, requested_size: u32) -> Option<Image> {
+    let path = theme.load_icon(name)?;
+    let bytes = fs::read(path).ok()?;
+
+    xcursor::parser::parse_xcursor(&bytes)?
+        .into_iter()
+        .min_by_key(|image| {
+            (
+                image.size.abs_diff(requested_size),
+                image.width.abs_diff(requested_size),
+            )
+        })
+}
+
+fn cursor_from_image(image: Image) -> NamedCursor {
+    let size = Size::<i32, Buffer>::from((image.width as i32, image.height as i32));
+    let buffer = MemoryRenderBuffer::from_slice(
+        &image.pixels_rgba,
+        Fourcc::Abgr8888,
+        size,
+        1,
+        Transform::Normal,
+        None,
+    );
+
+    NamedCursor {
+        buffer,
+        hotspot: Point::from((image.xhot as i32, image.yhot as i32)),
+    }
+}
+
+fn fallback_cursor() -> NamedCursor {
+    const WIDTH: usize = 12;
+    const HEIGHT: usize = 18;
+    let mut pixels = vec![0_u8; WIDTH * HEIGHT * 4];
+
+    for y in 0..HEIGHT {
+        let body_width = (y / 2 + 1).min(8);
+
+        for x in 0..body_width {
+            let edge = x == 0 || x + 1 == body_width || y == 0;
+            let offset = (y * WIDTH + x) * 4;
+            let color = if edge { 0 } else { 255 };
+            pixels[offset..offset + 4].copy_from_slice(&[color, color, color, 255]);
+        }
+    }
+
+    NamedCursor {
+        buffer: MemoryRenderBuffer::from_slice(
+            &pixels,
+            Fourcc::Abgr8888,
+            Size::<i32, Buffer>::from((WIDTH as i32, HEIGHT as i32)),
+            1,
+            Transform::Normal,
+            None,
+        ),
+        hotspot: Point::default(),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use smithay::input::pointer::CursorIcon;
+
+    use super::cursor_names;
+
+    #[test]
+    fn supplies_legacy_fallback_names_for_common_cursors() {
+        assert_eq!(
+            cursor_names(CursorIcon::Default),
+            ["default", "left_ptr", "arrow"]
+        );
+        assert_eq!(
+            cursor_names(CursorIcon::Pointer),
+            ["pointer", "hand2", "left_ptr"]
+        );
+        assert_eq!(
+            cursor_names(CursorIcon::Text),
+            ["text", "xterm", "left_ptr"]
+        );
+    }
+
+    #[test]
+    fn falls_back_to_default_for_other_named_cursors() {
+        assert_eq!(
+            cursor_names(CursorIcon::Crosshair),
+            ["crosshair", "default", "left_ptr"]
+        );
+    }
+}

compositor/src/handlers/mod.rs

@@ -45,6 +45,11 @@ impl SeatHandler for Ferese {
     }
 
     fn cursor_image(&mut self, _seat: &Seat<Self>, image: CursorImageStatus) {
+        if let CursorImageStatus::Named(icon) = &image {
+            self.named_cursors
+                .entry(*icon)
+                .or_insert_with(|| crate::cursor::load_named_cursor(&self.cursor_theme, *icon));
+        }
         self.cursor_status = image;
         crate::backends::direct::render_all(self);
     }

compositor/src/main.rs

@@ -1,6 +1,7 @@
 #![allow(irrefutable_let_patterns)]
 
 mod backends;
+mod cursor;
 mod grabs;
 mod handlers;
 mod input;

compositor/src/state.rs

@@ -16,7 +16,10 @@ use smithay::{
         LayerSurface, PopupManager, Space, Window, WindowSurfaceType, layer_map_for_output,
         utils::send_frames_surface_tree,
     },
-    input::{Seat, SeatState, pointer::CursorImageStatus},
+    input::{
+        Seat, SeatState,
+        pointer::{CursorIcon, CursorImageStatus},
+    },
     output::Output,
     reexports::{
         calloop::{EventLoop, Interest, LoopSignal, Mode, PostAction, generic::Generic},
@@ -62,6 +65,8 @@ pub struct Ferese {
     pub window_geometry: HashMap<WindowId, WindowGeometry>,
     pub focused_window: Option<WindowId>,
     pub cursor_status: CursorImageStatus,
+    pub(crate) cursor_theme: xcursor::CursorTheme,
+    pub(crate) named_cursors: HashMap<CursorIcon, crate::cursor::NamedCursor>,
     pub intercepted_keys: HashSet<smithay::input::keyboard::Keycode>,
     pub idle_inhibitors: HashMap<WlSurface, usize>,
     pub direct_backend: Option<crate::backends::direct::DirectBackendState>,
@@ -122,6 +127,9 @@ impl Ferese {
         let socket_name = Self::init_wayland_listener(display, event_loop)?;
 
         let start_time = Instant::now();
+        let cursor_theme = crate::cursor::cursor_theme();
+        let default_cursor = crate::cursor::load_named_cursor(&cursor_theme, CursorIcon::Default);
+        let named_cursors = HashMap::from([(CursorIcon::Default, default_cursor)]);
 
         Ok(Self {
             start_time,
@@ -134,6 +142,8 @@ impl Ferese {
             window_geometry: HashMap::new(),
             focused_window: None,
             cursor_status: CursorImageStatus::default_named(),
+            cursor_theme,
+            named_cursors,
             intercepted_keys: HashSet::new(),
             idle_inhibitors: HashMap::new(),
             direct_backend: None,

compositor/src/winit.rs

@@ -9,6 +9,8 @@ use smithay::{
             damage::OutputDamageTracker,
             element::{
                 AsRenderElements, Kind as RenderElementKind,
+                memory::MemoryRenderBufferRenderElement,
+                render_elements,
                 surface::{WaylandSurfaceRenderElement, render_elements_from_surface_tree},
                 utils::{
                     ConstrainAlign, ConstrainScaleBehavior, CropRenderElement, Relocate,
@@ -35,10 +37,20 @@ use smithay::{
 
 use crate::Ferese;
 
-pub(crate) type AnimatedWindowRenderElement = CropRenderElement<
+type SurfaceRenderElement = CropRenderElement<
     RelocateRenderElement<RescaleRenderElement<WaylandSurfaceRenderElement<GlesRenderer>>>,
 >;
 
+type MemoryRenderElement = CropRenderElement<
+    RelocateRenderElement<RescaleRenderElement<MemoryRenderBufferRenderElement<GlesRenderer>>>,
+>;
+
+render_elements! {
+    pub(crate) AnimatedWindowRenderElement<=GlesRenderer>;
+    Surface=SurfaceRenderElement,
+    Memory=MemoryRenderElement,
+}
+
 pub fn init(event_loop: &mut EventLoop<Ferese>, state: &mut Ferese) -> Result<(), Box<dyn Error>> {
     let (mut backend, event_source) = winit::init()?;
     let initial_scale = normalized_scale(backend.scale_factor());
@@ -281,7 +293,7 @@ fn layer_elements(
             let element = RescaleRenderElement::from_element(element, origin, 1.0);
             let element = RelocateRenderElement::from_element(element, origin, Relocate::Relative);
 
-            CropRenderElement::from_element(element, scale, output_crop)
+            CropRenderElement::from_element(element, scale, output_crop).map(Into::into)
         })
         .collect()
 }
@@ -292,42 +304,73 @@ fn cursor_elements(
     output_geometry: Rectangle<i32, Logical>,
     scale: f64,
 ) -> Vec<AnimatedWindowRenderElement> {
-    let CursorImageStatus::Surface(surface) = &state.cursor_status else {
-        return Vec::new();
-    };
     let Some(pointer) = state.seat.get_pointer() else {
         return Vec::new();
     };
-    let hotspot = with_states(surface, |states| {
-        states
-            .data_map
-            .get::<CursorImageSurfaceData>()
-            .map(|attributes| attributes.lock().unwrap().hotspot)
-            .unwrap_or_default()
-    });
-    let logical_location =
-        pointer.current_location() - output_geometry.loc.to_f64() - hotspot.to_f64();
-    let physical_location = logical_location.to_physical_precise_round(scale);
     let output_crop =
         Rectangle::<i32, Logical>::from_size(output_geometry.size).to_physical_precise_round(scale);
     let origin = Point::<i32, Physical>::default();
+    let pointer_location = pointer.current_location() - output_geometry.loc.to_f64();
+    match &state.cursor_status {
+        CursorImageStatus::Surface(surface) => {
+            let hotspot = with_states(surface, |states| {
+                states
+                    .data_map
+                    .get::<CursorImageSurfaceData>()
+                    .map(|attributes| attributes.lock().unwrap().hotspot)
+                    .unwrap_or_default()
+            });
+            let physical_location =
+                (pointer_location - hotspot.to_f64()).to_physical_precise_round(scale);
 
-    render_elements_from_surface_tree::<GlesRenderer, WaylandSurfaceRenderElement<GlesRenderer>>(
-        renderer,
-        surface,
-        physical_location,
-        scale,
-        1.0,
-        RenderElementKind::Cursor,
-    )
-    .into_iter()
-    .filter_map(|element| {
-        let element = RescaleRenderElement::from_element(element, origin, 1.0);
-        let element = RelocateRenderElement::from_element(element, origin, Relocate::Relative);
+            render_elements_from_surface_tree::<
+                GlesRenderer,
+                WaylandSurfaceRenderElement<GlesRenderer>,
+            >(
+                renderer,
+                surface,
+                physical_location,
+                scale,
+                1.0,
+                RenderElementKind::Cursor,
+            )
+            .into_iter()
+            .filter_map(|element| {
+                let element = RescaleRenderElement::from_element(element, origin, 1.0);
+                let element =
+                    RelocateRenderElement::from_element(element, origin, Relocate::Relative);
 
-        CropRenderElement::from_element(element, scale, output_crop)
-    })
-    .collect()
+                CropRenderElement::from_element(element, scale, output_crop).map(Into::into)
+            })
+            .collect()
+        }
+        CursorImageStatus::Named(icon) => {
+            let Some(cursor) = state.named_cursors.get(icon) else {
+                return Vec::new();
+            };
+            let hotspot = Point::<i32, Physical>::from((cursor.hotspot.x, cursor.hotspot.y));
+            let physical_location = pointer_location.to_physical_precise_round(scale) - hotspot;
+            let Ok(element) = MemoryRenderBufferRenderElement::from_buffer(
+                renderer,
+                physical_location.to_f64(),
+                &cursor.buffer,
+                None,
+                None,
+                None,
+                RenderElementKind::Cursor,
+            ) else {
+                return Vec::new();
+            };
+
+            let element = RescaleRenderElement::from_element(element, origin, 1.0);
+            let element = RelocateRenderElement::from_element(element, origin, Relocate::Relative);
+
+            CropRenderElement::from_element(element, scale, output_crop)
+                .map(|element| vec![element.into()])
+                .unwrap_or_default()
+        }
+        CursorImageStatus::Hidden => Vec::new(),
+    }
 }
 
 fn normalized_scale(scale: f64) -> f64 {