Add Super+Scroll action

data/gala.gschema.xml

@@ -14,6 +14,12 @@
     <value nick="switch-to-workspace-last" value="10" />
   </enum>
 
+  <enum id="SuperScrollAction">
+    <value nick="none" value="0" />
+    <value nick="switch-workspace" value="1" />
+    <value nick="zoom" value="2" />
+  </enum>
+
   <schema path="/io/elementary/desktop/screensaver/" id="io.elementary.desktop.screensaver">
     <key type="b" name="lock-on-suspend">
       <default>true</default>
@@ -96,6 +102,11 @@
       <summary>Whether hotcorners should be enabled when fullscreen window is opened</summary>
       <description></description>
     </key>
+    <key enum="SuperScrollAction" name="super-scroll-action">
+      <default>"none"</default>
+      <summary>What action should be performed on Super + Scroll</summary>
+      <description></description>
+    </key>
   </schema>
 
   <schema path="/io/elementary/desktop/wm/keybindings/" id="io.elementary.desktop.wm.keybindings">

src/SuperScrollAction.vala

@@ -0,0 +1,45 @@
+/*
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ * SPDX-FileCopyrightText: 2024 elementary, Inc. (https://elementary.io)
+ */
+
+public class Gala.SuperScrollAction : Clutter.Action {
+    public signal bool triggered (uint32 timestamp, double dx, double dy);
+
+    public Meta.Display display { private get; construct; }
+
+    public SuperScrollAction (Meta.Display display) {
+        Object (display: display);
+    }
+
+    public override bool handle_event (Clutter.Event event) {
+        if (
+            event.get_type () == SCROLL &&
+            (event.get_state () & display.compositor_modifiers) != 0
+        ) {
+            double dx = 0.0, dy = 0.0;
+            switch (event.get_scroll_direction ()) {
+                case LEFT:
+                    dx = -1.0;
+                    break;
+                case RIGHT:
+                    dx = 1.0;
+                    break;
+                case UP:
+                    dy = 1.0;
+                    break;
+                case DOWN:
+                    dy = -1.0;
+                    break;
+                default:
+                    break;
+            }
+
+            // TODO: support natural scroll settings
+
+            return triggered (event.get_time (), dx, dy);
+        }
+
+        return Clutter.EVENT_PROPAGATE;
+    }
+}

src/WindowManager.vala

@@ -383,6 +383,10 @@ namespace Gala {
 
             display.window_created.connect ((window) => window_created (window));
 
+            var scroll_action = new SuperScrollAction (display);
+            scroll_action.triggered.connect (handle_super_scroll);
+            stage.add_action_full ("wm-super-scroll-action", CAPTURE, scroll_action);
+
             stage.show ();
 
             plugin_manager.load_waiting_plugins ();
@@ -438,6 +442,23 @@ namespace Gala {
             }
         }
 
+
+        private bool handle_super_scroll (uint32 timestamp, double dx, double dy) {
+            if (behavior_settings.get_enum ("super-scroll-action") != 1) {
+                return Clutter.EVENT_PROPAGATE;
+            }
+
+            var d = dx.abs () > dy.abs () ? dx : dy;
+
+            if (d > 0) {
+                switch_to_next_workspace (Meta.MotionDirection.RIGHT, timestamp);
+            } else if (d < 0) {
+                switch_to_next_workspace (Meta.MotionDirection.LEFT, timestamp);
+            }
+
+            return Clutter.EVENT_STOP;
+        }
+
         [CCode (instance_pos = -1)]
         private void handle_cycle_workspaces (Meta.Display display, Meta.Window? window, Clutter.KeyEvent event,
             Meta.KeyBinding binding) {

src/Zoom.vala

@@ -19,6 +19,7 @@ public class Gala.Zoom : Object {
     private ulong wins_handler_id = 0UL;
 
     private GestureTracker gesture_tracker;
+    private GLib.Settings behavior_settings;
 
     public Zoom (WindowManager wm) {
         Object (wm: wm);
@@ -33,6 +34,12 @@ public class Gala.Zoom : Object {
         gesture_tracker.enable_touchpad ();
         gesture_tracker.on_gesture_detected.connect (on_gesture_detected);
         gesture_tracker.on_gesture_handled.connect ((gesture) => zoom_with_gesture (gesture.direction));
+
+        behavior_settings = new GLib.Settings ("io.elementary.desktop.wm.behavior");
+
+        var scroll_action = new SuperScrollAction (display);
+        scroll_action.triggered.connect (handle_super_scroll);
+        display.get_stage ().add_action_full ("zoom-super-scroll-action", CAPTURE, scroll_action);
     }
 
     ~Zoom () {
@@ -78,6 +85,22 @@ public class Gala.Zoom : Object {
         return false;
     }
 
+    private bool handle_super_scroll (uint32 timestamp, double dx, double dy) {
+        if (behavior_settings.get_enum ("super-scroll-action") != 2) {
+            return Clutter.EVENT_PROPAGATE;
+        }
+
+        var d = dx.abs () > dy.abs () ? dx : dy;
+
+        if (d > 0) {
+            zoom (SHORTCUT_DELTA, true, AnimationsSettings.get_enable_animations ());
+        } else if (d < 0) {
+            zoom (-SHORTCUT_DELTA, true, AnimationsSettings.get_enable_animations ());
+        }
+
+        return Clutter.EVENT_STOP;
+    }
+
     private void zoom_with_gesture (GestureDirection direction) {
         var initial_zoom = current_zoom;
         var target_zoom = (direction == GestureDirection.IN)

src/meson.build

@@ -14,6 +14,7 @@ gala_bin_sources = files(
     'ScreenSaverManager.vala',
     'ScreenshotManager.vala',
     'SessionManager.vala',
+    'SuperScrollAction.vala',
     'WindowAttentionTracker.vala',
     'WindowGrabTracker.vala',
     'WindowListener.vala',