Upgrade compositor to v6 with output-aware surface preferences

compositor/src/handlers/compositor.rs

@@ -49,7 +49,16 @@ impl CompositorHandler for Ferese {
             .compositor_state
     }
 
+    fn new_surface(&mut self, surface: &WlSurface) {
+        self.update_surface_preferences(surface);
+    }
+
+    fn new_subsurface(&mut self, surface: &WlSurface, _parent: &WlSurface) {
+        self.update_surface_preferences(surface);
+    }
+
     fn commit(&mut self, surface: &WlSurface) {
+        self.update_surface_preferences(surface);
         self.capture_resize_before_commit(surface);
         if self.surface_affects_backdrop(surface) {
             self.backdrop_generation = self.backdrop_generation.wrapping_add(1);

compositor/src/handlers/layer_shell.rs

@@ -31,20 +31,19 @@ impl WlrLayerShellHandler for Ferese {
         }
 
         tracing::debug!(%namespace, output = %output.name(), "mapped layer surface");
-        super::set_surface_tree_scale(layer.wl_surface(), output.current_scale().fractional_scale());
+        super::set_surface_tree_output(layer.wl_surface(), &output);
         self.relayout();
         crate::backends::direct::render_all(self);
     }
 
     fn new_popup(&mut self, parent: LayerSurface, popup: PopupSurface) {
-        let scale = self.space.outputs().find_map(|output| {
+        let output = self.space.outputs().find(|output| {
             layer_map_for_output(output)
                 .layers()
                 .any(|layer| layer.wl_surface() == parent.wl_surface())
-                .then(|| output.current_scale().fractional_scale())
         });
-        if let Some(scale) = scale {
-            super::set_surface_tree_scale(popup.wl_surface(), scale);
+        if let Some(output) = output {
+            super::set_surface_tree_output(popup.wl_surface(), output);
         }
         self.unconstrain_popup(&popup);
         if let Err(error) = self.popups.track_popup(PopupKind::Xdg(popup)) {

compositor/src/handlers/mod.rs

@@ -79,18 +79,7 @@ impl OutputHandler for Ferese {}
 
 impl FractionalScaleHandler for Ferese {
     fn new_fractional_scale(&mut self, surface: WlSurface) {
-        let scale = self
-            .space
-            .outputs()
-            .next()
-            .map(|output| output.current_scale().fractional_scale())
-            .unwrap_or(1.0);
-
-        with_states(&surface, |states| {
-            with_fractional_scale(states, |surface_scale| {
-                surface_scale.set_preferred_scale(scale);
-            });
-        });
+        self.update_surface_preferences(&surface);
     }
 }
 
@@ -140,43 +129,69 @@ impl KeyboardShortcutsInhibitHandler for Ferese {
 }
 
 impl Ferese {
-    pub fn update_fractional_scale(&self, scale: f64) {
-        for window in self.space.elements() {
-            let Some(toplevel) = window.toplevel() else {
-                continue;
-            };
+    pub(crate) fn update_surface_preferences(&self, surface: &WlSurface) {
+        use smithay::desktop::{WindowSurfaceType, find_popup_root_surface};
+        use smithay::wayland::compositor::get_parent;
 
-            set_surface_tree_scale(toplevel.wl_surface(), scale);
+        let mut root = surface.clone();
+        while let Some(parent) = get_parent(&root) {
+            root = parent;
         }
-
-        // Layer surfaces are not Space elements. Use their own output's scale,
-        // rather than broadcasting one output's density to every bar.
-        for output in self.space.outputs() {
-            let scale = output.current_scale().fractional_scale();
-            let layers: Vec<_> = layer_map_for_output(output).layers().cloned().collect();
-            for layer in layers {
-                set_surface_tree_scale(layer.wl_surface(), scale);
+        if let Some(popup) = self.popups.find_popup(&root)
+            && let Ok(parent) = find_popup_root_surface(&popup)
+        {
+            root = parent;
         }
+        let window = self.window_ids.iter().find_map(|(window, id)| {
+            window
+                .toplevel()
+                .is_some_and(|toplevel| toplevel.wl_surface() == &root)
+                .then_some(*id)
+        });
+        let output = self.space.outputs().find(|output| {
+            window.is_some_and(|id| self.window_belongs_to_output(id, output))
+                || layer_map_for_output(output)
+                    .layer_for_surface(&root, WindowSurfaceType::ALL)
+                    .is_some()
+                || self
+                    .session_lock
+                    .surfaces
+                    .get(output)
+                    .is_some_and(|lock| lock.wl_surface() == &root)
+        });
+        // Hidden workspaces retain their last output preferences until presented again.
+        if window.is_some() && output.is_none() {
+            return;
         }
+        let output = output
+            .or_else(|| self.focused_output())
+            .or_else(|| self.space.outputs().next());
+        with_states(surface, |states| set_surface_preferences(surface, states, output));
     }
 }
 
-pub(crate) fn set_surface_tree_scale(surface: &WlSurface, scale: f64) {
+fn set_surface_preferences(
+    surface: &WlSurface,
+    states: &smithay::wayland::compositor::SurfaceData,
+    output: Option<&smithay::output::Output>,
+) {
+    let scale = output.map_or(1.0, |output| output.current_scale().fractional_scale());
+    let transform = output.map_or(smithay::utils::Transform::Normal, |output| output.current_transform());
+    smithay::wayland::compositor::send_surface_state(surface, states, scale.ceil() as i32, transform);
+    with_fractional_scale(states, |surface_scale| surface_scale.set_preferred_scale(scale));
+}
+
+pub(crate) fn set_surface_tree_output(surface: &WlSurface, output: &smithay::output::Output) {
     let update_tree = |root: &WlSurface| {
         with_surface_tree_downward(
             root,
             (),
             |_, _, &()| TraversalAction::DoChildren(()),
-            |_, states, &()| {
-                with_fractional_scale(states, |surface_scale| {
-                    surface_scale.set_preferred_scale(scale);
-                });
-            },
+            |surface, states, &()| set_surface_preferences(surface, states, Some(output)),
             |_, _, &()| true,
         );
     };
     update_tree(surface);
-    // XDG popups are separate surface trees, not wl_subsurfaces.
     for (popup, _) in PopupManager::popups_for_surface(surface) {
         update_tree(popup.wl_surface());
     }

compositor/src/session_lock.rs

@@ -202,6 +202,7 @@ impl Ferese {
 
     pub(crate) fn configure_lock_surfaces(&mut self) {
         for (output, surface) in &self.session_lock.surfaces {
+            crate::handlers::set_surface_tree_output(surface.wl_surface(), output);
             if let Some(geometry) = self.space.output_geometry(output) {
                 surface.with_pending_state(|state| {
                     state.size = Some((geometry.size.w as u32, geometry.size.h as u32).into())
@@ -316,6 +317,7 @@ impl SessionLockHandler for Ferese {
         {
             surface
                 .with_pending_state(|state| state.size = Some((geometry.size.w as u32, geometry.size.h as u32).into()));
+            crate::handlers::set_surface_tree_output(surface.wl_surface(), &output);
             self.session_lock.surfaces.insert(output, surface);
             self.focus_lock_surface();
         }

compositor/src/state.rs

@@ -473,7 +473,7 @@ impl Ferese {
         crate::shell_control::init_global(&display_handle);
 
         let alpha_modifier_state = AlphaModifierState::new::<Self>(&display_handle);
-        let compositor_state = CompositorState::new::<Self>(&display_handle);
+        let compositor_state = CompositorState::new_v6::<Self>(&display_handle);
         let cursor_shape_state = CursorShapeManagerState::new::<Self>(&display_handle);
         let xdg_shell_state = XdgShellState::new::<Self>(&display_handle);
         let decoration_state = XdgDecorationState::new::<Self>(&display_handle);

compositor/src/state/layout.rs

@@ -81,9 +81,8 @@ impl Ferese {
                 continue;
             };
             let fullscreen_bounds = self.full_output_bounds_for(&output).unwrap_or(bounds);
-            let scale = output.current_scale().fractional_scale();
             for layer in layer_map_for_output(&output).layers() {
-                crate::handlers::set_surface_tree_scale(layer.wl_surface(), scale);
+                crate::handlers::set_surface_tree_output(layer.wl_surface(), &output);
             }
             let Some(workspace) = self.workspaces.workspace(workspace_id) else {
                 continue;
@@ -140,7 +139,7 @@ impl Ferese {
                     continue;
                 }
                 if let Some(toplevel) = window.toplevel() {
-                    crate::handlers::set_surface_tree_scale(toplevel.wl_surface(), scale);
+                    crate::handlers::set_surface_tree_output(toplevel.wl_surface(), &output);
                 }
 
                 let is_maximized = self.maximized_windows.contains(id) && workspace_fullscreen != Some(*id);

compositor/src/winit.rs

@@ -70,7 +70,6 @@ pub fn init(event_loop: &mut EventLoop<Ferese>, state: &mut Ferese) -> Result<()
     let clock = Clock::<Monotonic>::new();
     let mut sequence = 0_u64;
     let mut missed_deadlines = 0_u64;
-    let mut output_scale = initial_scale;
     let mut render_metrics = RenderMetrics::from_environment(output.name());
 
     // Do not request a redraw recursively: a no-damage redraw has no EGL
@@ -112,11 +111,6 @@ pub fn init(event_loop: &mut EventLoop<Ferese>, state: &mut Ferese) -> Result<()
                         None,
                     );
 
-                    if scale != output_scale {
-                        output_scale = scale;
-                        state.update_fractional_scale(scale);
-                    }
-
                     state.relayout();
                     if let Err(error) = state.display_handle.flush_clients() {
                         tracing::debug!(%error, "failed to flush output-resize configure");

scripts/tests/fixtures/surface-preferences.c

@@ -0,0 +1,89 @@
+#include <assert.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wayland-client.h>
+#include "fractional-scale-client-protocol.h"
+
+static struct wl_compositor *compositor;
+static struct wp_fractional_scale_manager_v1 *manager;
+static uint32_t version, fractional, fractional_events;
+static int32_t integer_scale = 1, transform;
+static unsigned scale_events, transform_events;
+
+static void global(void *data, struct wl_registry *registry, uint32_t name,
+                   const char *interface, uint32_t advertised) {
+    (void)data;
+    if (!strcmp(interface, "wl_compositor")) {
+        assert(advertised >= 6);
+        compositor = wl_registry_bind(registry, name, &wl_compositor_interface, version);
+    } else if (!strcmp(interface, "wp_fractional_scale_manager_v1")) {
+        manager = wl_registry_bind(registry, name, &wp_fractional_scale_manager_v1_interface, 1);
+    }
+}
+
+static void removed(void *data, struct wl_registry *registry, uint32_t name) {
+    (void)data; (void)registry; (void)name;
+}
+
+static void scale(void *data, struct wl_surface *surface, int32_t value) {
+    (void)data; (void)surface;
+    integer_scale = value;
+    scale_events++;
+}
+
+static void transformed(void *data, struct wl_surface *surface, uint32_t value) {
+    (void)data; (void)surface;
+    transform = (int32_t)value;
+    transform_events++;
+}
+
+static void preferred(void *data, struct wp_fractional_scale_v1 *object, uint32_t value) {
+    (void)data; (void)object;
+    fractional = value;
+    fractional_events++;
+}
+
+int main(int argc, char **argv) {
+    assert(argc == 2);
+    version = (uint32_t)atoi(argv[1]);
+    struct wl_display *display = wl_display_connect(NULL);
+    assert(display);
+    struct wl_registry *registry = wl_display_get_registry(display);
+    const struct wl_registry_listener registry_listener = {global, removed};
+    wl_registry_add_listener(registry, &registry_listener, NULL);
+    assert(wl_display_roundtrip(display) >= 0 && compositor && manager);
+    struct wl_surface *surface = wl_compositor_create_surface(compositor);
+    const struct wl_surface_listener listener = {
+        .preferred_buffer_scale = scale,
+        .preferred_buffer_transform = transformed,
+    };
+    wl_surface_add_listener(surface, &listener, NULL);
+    assert(wl_display_roundtrip(display) >= 0);
+    // Create the fractional object after the compositor cached its preference.
+    struct wp_fractional_scale_v1 *object =
+        wp_fractional_scale_manager_v1_get_fractional_scale(manager, surface);
+    const struct wp_fractional_scale_v1_listener fractional_listener = {preferred};
+    wp_fractional_scale_v1_add_listener(object, &fractional_listener, NULL);
+    assert(wl_display_roundtrip(display) >= 0);
+    assert(fractional > 0 && fractional_events == 1);
+    if (version >= 6) {
+        assert(integer_scale == (int32_t)((fractional + 119) / 120));
+        assert(scale_events == (integer_scale != 1 ? 1u : 0u));
+        assert(transform_events == (transform != 0 ? 1u : 0u));
+    } else {
+        assert(scale_events == 0 && transform_events == 0);
+    }
+    for (int i = 0; i < 3; i++) {
+        wl_surface_commit(surface);
+        assert(wl_display_roundtrip(display) >= 0);
+    }
+    assert(fractional_events == 1);
+    assert(scale_events == (version >= 6 && integer_scale != 1 ? 1u : 0u));
+    assert(transform_events == (version >= 6 && transform != 0 ? 1u : 0u));
+    wp_fractional_scale_v1_destroy(object);
+    wl_surface_destroy(surface);
+    wl_display_roundtrip(display);
+    wl_display_disconnect(display);
+    return 0;
+}

scripts/tests/test_surface_preferences_isolated.py

@@ -0,0 +1,69 @@
+"""FERESE_TEST_SURFACE_PREFERENCES=1 python3 scripts/tests/test_surface_preferences_isolated.py"""
+
+import os
+from pathlib import Path
+import subprocess
+import tempfile
+import time
+import unittest
+
+
+@unittest.skipUnless(os.environ.get("FERESE_TEST_SURFACE_PREFERENCES") == "1", "opt-in nested test")
+class SurfacePreferencesTest(unittest.TestCase):
+    def test_v6_preferences_and_v5_compatibility(self):
+        repo = Path(__file__).resolve().parents[2]
+        with tempfile.TemporaryDirectory(prefix="ferese-surface-preferences-") as temporary:
+            root = Path(temporary)
+            protocols = subprocess.check_output(
+                ["pkg-config", "--variable=pkgdatadir", "wayland-protocols"], text=True
+            ).strip()
+            xml = str(Path(protocols) / "staging/fractional-scale/fractional-scale-v1.xml")
+            for kind, name in [("client-header", "fractional-scale-client-protocol.h"),
+                               ("private-code", "fractional-scale.c")]:
+                subprocess.run(["wayland-scanner", kind, xml, str(root / name)], check=True)
+            flags = subprocess.check_output(
+                ["pkg-config", "--cflags", "--libs", "wayland-client"], text=True
+            ).split()
+            subprocess.run([
+                "cc", "-Wall", "-Wextra", "-Werror", "-I", str(root),
+                str(repo / "scripts/tests/fixtures/surface-preferences.c"),
+                str(root / "fractional-scale.c"), "-o", str(root / "client"), *flags,
+            ], check=True)
+            runtime = root / "runtime"
+            runtime.mkdir(mode=0o700)
+            config = root / "config/ferese"
+            config.mkdir(parents=True)
+            (config / "config.kdl").write_text("\n")
+            display = Path(os.environ["WAYLAND_DISPLAY"])
+            if not display.is_absolute():
+                display = Path(os.environ["XDG_RUNTIME_DIR"]) / display
+            env = dict(os.environ, WAYLAND_DISPLAY=str(display), XDG_RUNTIME_DIR=str(runtime),
+                       XDG_CONFIG_HOME=str(root / "config"))
+            binary = repo / os.environ.get("FERESE_TEST_BINARY", "target/debug/ferese")
+            with (root / "compositor.log").open("w") as log:
+                compositor = subprocess.Popen([str(binary), "--backend", "nested"],
+                                              env=env, stdout=log, stderr=log)
+                try:
+                    sockets = []
+                    for _ in range(100):
+                        if compositor.poll() is not None:
+                            self.fail((root / "compositor.log").read_text())
+                        sockets = [p for p in runtime.glob("wayland-*") if p.is_socket()]
+                        if sockets:
+                            break
+                        time.sleep(0.1)
+                    self.assertTrue(sockets, "nested compositor did not create a socket")
+                    for version in [5, 6]:
+                        subprocess.run([str(root / "client"), str(version)], check=True, timeout=10,
+                                       env=dict(env, WAYLAND_DISPLAY=str(sockets[0])))
+                finally:
+                    compositor.terminate()
+                    try:
+                        compositor.wait(timeout=5)
+                    except subprocess.TimeoutExpired:
+                        compositor.kill()
+                        compositor.wait()
+
+
+if __name__ == "__main__":
+    unittest.main()