Implement interactive move

Cargo.toml

@@ -109,7 +109,7 @@ features = [
 approx = "0.5.1"
 k9.workspace = true
 proptest = "1.5.0"
-proptest-derive = "0.5.0"
+proptest-derive = { version = "0.5.0", features = ["boxed_union"] }
 xshell = "0.2.6"
 
 [features]

niri-config/src/lib.rs

@@ -391,6 +391,8 @@ pub struct Layout {
     pub focus_ring: FocusRing,
     #[knuffel(child, default)]
     pub border: Border,
+    #[knuffel(child, default)]
+    pub insert_hint: InsertHint,
     #[knuffel(child, unwrap(children), default)]
     pub preset_column_widths: Vec<PresetSize>,
     #[knuffel(child)]
@@ -412,6 +414,7 @@ impl Default for Layout {
         Self {
             focus_ring: Default::default(),
             border: Default::default(),
+            insert_hint: Default::default(),
             preset_column_widths: Default::default(),
             default_column_width: Default::default(),
             center_focused_column: Default::default(),
@@ -558,6 +561,23 @@ impl From<FocusRing> for Border {
     }
 }
 
+#[derive(knuffel::Decode, Debug, Clone, Copy, PartialEq)]
+pub struct InsertHint {
+    #[knuffel(child)]
+    pub off: bool,
+    #[knuffel(child, default = Self::default().color)]
+    pub color: Color,
+}
+
+impl Default for InsertHint {
+    fn default() -> Self {
+        Self {
+            off: false,
+            color: Color::from_rgba8_unpremul(127, 200, 255, 128),
+        }
+    }
+}
+
 /// RGB color in [0, 1] with unpremultiplied alpha.
 #[derive(Debug, Default, Clone, Copy, PartialEq)]
 pub struct Color {
@@ -2966,6 +2986,10 @@ mod tests {
                 }
 
                 center-focused-column "on-overflow"
+
+                insert-hint {
+                    color "rgb(255, 200, 127)"
+                }
             }
 
             spawn-at-startup "alacritty" "-e" "fish"
@@ -3146,6 +3170,10 @@ mod tests {
                         active_gradient: None,
                         inactive_gradient: None,
                     },
+                    insert_hint: InsertHint {
+                        off: false,
+                        color: Color::from_rgba8_unpremul(255, 200, 127, 255),
+                    },
                     preset_column_widths: vec![
                         PresetSize::Proportion(0.25),
                         PresetSize::Proportion(0.5),

src/handlers/xdg_shell.rs

@@ -6,7 +6,7 @@ use smithay::desktop::{
     PopupKeyboardGrab, PopupKind, PopupManager, PopupPointerGrab, PopupUngrabStrategy, Window,
     WindowSurfaceType,
 };
-use smithay::input::pointer::Focus;
+use smithay::input::pointer::{Focus, PointerGrab};
 use smithay::output::Output;
 use smithay::reexports::wayland_protocols::xdg::decoration::zv1::server::zxdg_toplevel_decoration_v1;
 use smithay::reexports::wayland_protocols::xdg::shell::server::xdg_positioner::ConstraintAdjustment;
@@ -36,6 +36,7 @@ use smithay::{
 };
 use tracing::field::Empty;
 
+use crate::input::move_grab::MoveGrab;
 use crate::input::resize_grab::ResizeGrab;
 use crate::input::DOUBLE_CLICK_TIME;
 use crate::layout::workspace::ColumnWidth;
@@ -65,8 +66,44 @@ impl XdgShellHandler for State {
         }
     }
 
-    fn move_request(&mut self, _surface: ToplevelSurface, _seat: WlSeat, _serial: Serial) {
-        // FIXME
+    fn move_request(&mut self, surface: ToplevelSurface, _seat: WlSeat, serial: Serial) {
+        let pointer = self.niri.seat.get_pointer().unwrap();
+        if !pointer.has_grab(serial) {
+            return;
+        }
+
+        let Some(start_data) = pointer.grab_start_data() else {
+            return;
+        };
+
+        let Some((focus, _)) = &start_data.focus else {
+            return;
+        };
+
+        let wl_surface = surface.wl_surface();
+        if !focus.id().same_client_as(&wl_surface.id()) {
+            return;
+        }
+
+        let Some((mapped, output)) = self.niri.layout.find_window_and_output(wl_surface) else {
+            return;
+        };
+
+        let window = mapped.window.clone();
+        let output = output.clone();
+
+        let grab = MoveGrab::new(start_data, window.clone());
+
+        if !self
+            .niri
+            .layout
+            .interactive_move_begin(window, output, grab.start_data().location)
+        {
+            return;
+        }
+
+        pointer.set_grab(self, grab, serial, Focus::Clear);
+        self.niri.pointer_grab_ongoing = true;
     }
 
     fn resize_request(

src/input/mod.rs

@@ -28,13 +28,15 @@ use smithay::utils::{Logical, Point, Rectangle, SERIAL_COUNTER};
 use smithay::wayland::pointer_constraints::{with_pointer_constraint, PointerConstraint};
 use smithay::wayland::tablet_manager::{TabletDescriptor, TabletSeatTrait};
 
+use self::move_grab::MoveGrab;
 use self::resize_grab::ResizeGrab;
 use self::spatial_movement_grab::SpatialMovementGrab;
 use crate::niri::State;
 use crate::ui::screenshot_ui::ScreenshotUi;
 use crate::utils::spawning::spawn;
 use crate::utils::{center, get_monotonic_time, ResizeEdge};
 
+pub mod move_grab;
 pub mod resize_grab;
 pub mod scroll_tracker;
 pub mod spatial_movement_grab;
@@ -1528,8 +1530,41 @@ impl State {
             if let Some(mapped) = self.niri.window_under_cursor() {
                 let window = mapped.window.clone();
 
+                // Check if we need to start an interactive move.
+                if event.button() == Some(MouseButton::Left) && !pointer.is_grabbed() {
+                    let mods = self.niri.seat.get_keyboard().unwrap().modifier_state();
+                    let mod_down = match self.backend.mod_key() {
+                        CompositorMod::Super => mods.logo,
+                        CompositorMod::Alt => mods.alt,
+                    };
+                    if mod_down {
+                        let location = pointer.current_location();
+                        let (output, _) = self.niri.output_under(location).unwrap();
+                        let output = output.clone();
+
+                        self.niri.layout.activate_window(&window);
+
+                        if self
+                            .niri
+                            .layout
+                            .interactive_move_begin(window.clone(), output, location)
+                        {
+                            let start_data = PointerGrabStartData {
+                                focus: None,
+                                button: event.button_code(),
+                                location,
+                            };
+                            let grab = MoveGrab::new(start_data, window.clone());
+                            pointer.set_grab(self, grab, serial, Focus::Clear);
+                            self.niri.pointer_grab_ongoing = true;
+                            self.niri
+                                .cursor_manager
+                                .set_cursor_image(CursorImageStatus::Named(CursorIcon::Move));
+                        }
+                    }
+                }
                 // Check if we need to start an interactive resize.
-                if event.button() == Some(MouseButton::Right) && !pointer.is_grabbed() {
+                else if event.button() == Some(MouseButton::Right) && !pointer.is_grabbed() {
                     let mods = self.niri.seat.get_keyboard().unwrap().modifier_state();
                     let mod_down = match self.backend.mod_key() {
                         CompositorMod::Super => mods.logo,