Top bar: the title-bar drag uses craft-window's title_bar, and a panel over the bar keeps the window still on macOS

Cargo.lock

@@ -1095,6 +1095,17 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "craft-window"
+version = "0.1.0"
+source = "git+https://github.com/storytold/craft-libs?rev=8177bad411b577f3204deb0a0e074516d76a0b93#8177bad411b577f3204deb0a0e074516d76a0b93"
+dependencies = [
+ "egui",
+ "objc2 0.6.4",
+ "objc2-app-kit 0.3.2",
+ "wayland-client",
+]
+
 [[package]]
 name = "crc32fast"
 version = "1.5.2"
@@ -3522,6 +3533,7 @@ name = "lightcraft-ui-egui"
 version = "0.13.0"
 dependencies = [
  "craft-ui",
+ "craft-window",
  "egui",
  "egui_kittest",
  "lightcraft-catalog",

Cargo.toml

@@ -12,6 +12,7 @@ repository = "https://github.com/storytold/lightcraft"
 [workspace.dependencies]
 craft-ui = { git = "https://github.com/storytold/craft-libs", rev = "5c874d51eeb3de70e735c8ce87a59a7dedd47675", features = ["serde"] }
 craft-docpath = { version = "0.1.0", git = "https://github.com/storytold/craft-libs", rev = "82a24b006eefa036b43c09a67fb9a3fbd17ffe63" }
+craft-window = { git = "https://github.com/storytold/craft-libs", rev = "8177bad411b577f3204deb0a0e074516d76a0b93", features = ["egui"] }
 # internal
 lightcraft-denoise-core = { path = "crates/denoise-core" }
 lightcraft-denoise = { path = "crates/denoise", default-features = false }

crates/ui-egui/Cargo.toml

@@ -11,6 +11,7 @@ workspace = true
 
 [dependencies]
 craft-ui = { workspace = true }
+craft-window = { workspace = true }
 lightcraft-geom = { workspace = true }
 lightcraft-meta = { workspace = true }
 lightcraft-color = { workspace = true }

crates/ui-egui/src/lib.rs

@@ -49,7 +49,6 @@ pub mod sync;
 pub mod tasks;
 pub mod text_field;
 pub mod theme;
-pub mod titlebar;
 pub mod widgets;
 pub mod window_place;
 
@@ -388,6 +387,8 @@ pub struct LightcraftApp {
     pub perf: Perf,
     /// macOS: the host draws the traffic lights over our top bar.
     pub integrated_titlebar: bool,
+    /// The `movable` flag last given to the window (macOS, `craft_window::title_bar::sync_movable`).
+    pub window_movable: Option<bool>,
     /// The host installed a native menu bar (no in-window menus then).
     pub native_menu: bool,
     /// Shortcuts the native menu bar currently handles (`Cmd+Z`, `G`…): the egui shortcut handler
@@ -545,6 +546,7 @@ impl LightcraftApp {
             perf: Perf::default(),
             caches: Caches::default(),
             integrated_titlebar: false,
+            window_movable: None,
             native_menu: false,
             native_shortcuts: Default::default(),
             recording_shortcut: None,
@@ -1624,6 +1626,10 @@ impl LightcraftApp {
         panels::keyword_list::drag_feedback(self, &ctx);
         panels::toast(self, &ctx);
         drop_overlay::show(self, &ctx);
+        // AppKit moves the window on a drag anywhere in the title-bar band unless the window isn't
+        // movable: it stops being movable while the pointer is on a bar control or a panel over it
+        #[cfg(target_os = "macos")]
+        craft_window::title_bar::sync_movable(&ctx, &mut self.window_movable);
         self.widgets = widgets::take_registry(&ctx);
         self.text_focus = ctx.egui_wants_keyboard_input();
         self.end_frame(&ctx, t0);

crates/ui-egui/src/panels/topbar.rs

@@ -9,39 +9,13 @@ use crate::theme::Tokens;
 use crate::widgets::{icon_button, register};
 
 /// The bar doubles as the window's title bar: dragging its empty space moves the window and a
-/// double-click zooms or restores it. Registered before the bar's widgets so they win the click.
-fn window_handle(app: &LightcraftApp, ui: &mut egui::Ui, bar: Rect, search_rect: Rect) {
-    use crate::titlebar::{Gesture, WindowState, command_for};
+/// double-click acts as the system setting says. Made before the bar's widgets so they win the click.
+fn window_handle(ui: &mut egui::Ui, bar: Rect) {
     register(ui.ctx(), "region:titlebar", bar);
-    let handle = egui::Id::new("titlebar-handle");
-    let resp = ui.interact(bar, handle, Sense::click_and_drag());
-    crate::widgets::announce(&resp, crate::i18n::tr("Title bar"));
-    // a press that began on a button or the search field is theirs: dragging off it must not move the window
-    // (while pressing, egui hovers every widget under the pointer; once the drag starts, only the dragged one)
-    let ctx = ui.ctx().clone();
-    let memo = egui::Id::new("titlebar-press-on-widget");
-    if resp.is_pointer_button_down_on() && ctx.input(|i| i.pointer.primary_pressed()) {
-        let hovered = ctx.interaction_snapshot(|s| s.hovered.clone());
-        let on_widget =
-            hovered.iter().any(|id| *id != handle && ctx.read_response(*id).is_some_and(|r| r.sense.senses_click() || r.sense.senses_drag()));
-        ctx.data_mut(|d| d.insert_temp(memo, on_widget));
-    }
-    let on_widget = ctx.data(|d| d.get_temp::<bool>(memo)).unwrap_or(false);
-    // The search field is drawn after this handle. Its hit-test response may not exist
-    // yet when the press is recorded; the press origin still identifies text selection.
-    let on_search = ui.input(|i| i.pointer.press_origin().is_some_and(|p| search_rect.contains(p)));
-    let gesture = if resp.double_clicked_by(egui::PointerButton::Primary) && !on_search {
-        Some(Gesture::DoubleClicked)
-    } else if resp.drag_started_by(egui::PointerButton::Primary) && !on_widget && !on_search {
-        Some(Gesture::DragStarted)
-    } else {
-        None
-    };
-    if let Some(g) = gesture {
-        let window = WindowState { maximized: ui.input(|i| i.viewport().maximized).unwrap_or(false), fullscreen: app.window_is_fullscreen };
-        if let Some(cmd) = command_for(g, window) {
-            ui.ctx().send_viewport_cmd(cmd);
-        }
+    craft_window::title_bar::empty_area(ui, bar);
+    // (the empty area is the widget `empty_area` makes under this id)
+    if let Some(resp) = ui.ctx().read_response(ui.id().with("title_bar_empty")) {
+        crate::widgets::announce(&resp, crate::i18n::tr("Title bar"));
     }
 }
 
@@ -75,7 +49,7 @@ pub fn show(app: &mut LightcraftApp, ui: &mut egui::Ui) {
             let search_left = bar.center().x - sw / 2.0;
             let sr = Rect::from_center_size(pos2(bar.center().x, full.center().y), vec2(sw, 28.0));
             if app.integrated_titlebar {
-                window_handle(app, ui, bar, sr);
+                window_handle(ui, bar);
             }
             ui.horizontal_centered(|ui| {
                 ui.spacing_mut().item_spacing.x = 4.0;

crates/ui-egui/src/tests_titlebar.rs

@@ -169,3 +169,25 @@ fn full_screen_moves_the_left_buttons_into_the_traffic_lights_space() {
     assert!(!h.app.window_is_fullscreen);
     assert_eq!(widget(&h, "icon:sidebar").left(), windowed, "leaving full screen restores the room for the traffic lights");
 }
+
+// Scenario: a panel floating over the bar keeps a drag on it from moving the window (macOS's
+// title-bar band would otherwise take the drag); a bar control does too
+#[test]
+fn a_panel_floating_over_the_bar_keeps_the_window_from_moving() {
+    let mut h = integrated();
+    let bar = widget(&h, "region:titlebar");
+    let empty = empty_spot(&h);
+    let hover = |h: &mut Headless, p: egui::Pos2| {
+        h.events.push(egui::Event::PointerMoved(p));
+        play(h);
+        craft_window::title_bar::window_movable(&h.view.ctx)
+    };
+    assert!(hover(&mut h, empty), "the empty bar moves the window");
+    let help = widget(&h, "icon:help").center();
+    assert!(!hover(&mut h, help), "a bar control");
+    let params = json!({"operation": "float", "panel": "tools", "rect": [bar.left(), bar.top() + 4.0, 330.0, 500.0]});
+    let r = h.request("engine.execute", json!({"command": "ui.dock", "params": params}), T);
+    assert_eq!(r["ok"], true, "{r}");
+    play(&mut h);
+    assert!(!hover(&mut h, empty), "the floating panel covers the empty bar there");
+}

crates/ui-egui/src/titlebar.rs

@@ -1,76 +0,0 @@
-//! The integrated title bar's window gestures (macOS: the native title bar is hidden and the top
-//! bar takes its place, so dragging and double-click-to-zoom have to be done here).
-//!
-//! Pure policy, no egui widgets: [`command_for`] maps a gesture on the bar's empty space and the
-//! window's current state to the viewport command the host should run.
-
-use egui::ViewportCommand;
-
-/// What the user did on the bar's empty space.
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub enum Gesture {
-    /// A primary-button drag began: the window follows the pointer.
-    DragStarted,
-    /// A primary-button double-click: zoom the window, or restore it when already zoomed.
-    DoubleClicked,
-}
-
-/// The window as the host reports it.
-#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
-pub struct WindowState {
-    /// Zoomed (macOS) / maximized (elsewhere).
-    pub maximized: bool,
-    /// In the OS's full-screen mode.
-    pub fullscreen: bool,
-}
-
-/// The viewport command for `gesture`, if any. Full screen has no title bar to drag or zoom.
-pub fn command_for(gesture: Gesture, window: WindowState) -> Option<ViewportCommand> {
-    if window.fullscreen {
-        return None;
-    }
-    match gesture {
-        Gesture::DragStarted => Some(ViewportCommand::StartDrag),
-        Gesture::DoubleClicked => Some(ViewportCommand::Maximized(!window.maximized)),
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    const NORMAL: WindowState = WindowState { maximized: false, fullscreen: false };
-    const ZOOMED: WindowState = WindowState { maximized: true, fullscreen: false };
-    const FULL: WindowState = WindowState { maximized: false, fullscreen: true };
-
-    // Scenario: dragging the title bar moves the window
-    #[test]
-    fn given_a_normal_window_when_dragging_then_the_window_follows_the_pointer() {
-        assert_eq!(command_for(Gesture::DragStarted, NORMAL), Some(ViewportCommand::StartDrag));
-    }
-
-    // Scenario: a zoomed window can still be dragged (macOS lets you pull it free)
-    #[test]
-    fn given_a_zoomed_window_when_dragging_then_the_window_follows_the_pointer() {
-        assert_eq!(command_for(Gesture::DragStarted, ZOOMED), Some(ViewportCommand::StartDrag));
-    }
-
-    // Scenario: double-click zooms
-    #[test]
-    fn given_a_normal_window_when_double_clicking_then_it_zooms() {
-        assert_eq!(command_for(Gesture::DoubleClicked, NORMAL), Some(ViewportCommand::Maximized(true)));
-    }
-
-    // Scenario: double-click again restores
-    #[test]
-    fn given_a_zoomed_window_when_double_clicking_then_it_is_restored() {
-        assert_eq!(command_for(Gesture::DoubleClicked, ZOOMED), Some(ViewportCommand::Maximized(false)));
-    }
-
-    // Scenario: full screen ignores both
-    #[test]
-    fn given_a_full_screen_window_then_neither_gesture_does_anything() {
-        assert_eq!(command_for(Gesture::DragStarted, FULL), None);
-        assert_eq!(command_for(Gesture::DoubleClicked, FULL), None);
-    }
-}