Improve dock reveal animation when switching workspaces

lib/Gestures/Gesture.vala

@@ -41,6 +41,7 @@ namespace Gala {
         MULTITASKING_VIEW,
         ZOOM,
         CUSTOM,
+        CUSTOM_2,
         N_ACTIONS
     }
 

lib/Gestures/WorkspaceHideTracker.vala

@@ -0,0 +1,134 @@
+/*
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ * SPDX-FileCopyrightText: 2025 elementary, Inc. (https://elementary.io)
+ */
+
+public class Gala.WorkspaceHideTracker : Object, GestureTarget {
+    public signal double compute_progress (Meta.Workspace workspace);
+    public signal void switching_workspace_progress_updated (double new_progress);
+    public signal void window_state_changed_progress_updated (double new_progress);
+
+    //we don't want to hold a strong reference to the actor because we might've been added to it which would form a reference cycle
+    private weak Clutter.Actor? _actor;
+    public Clutter.Actor? actor { get { return _actor; }}
+    public Meta.Display display { private get; construct; }
+
+    private double switch_workspace_progress = 0.0;
+    private double[] workspace_hide_progress_cache = {};
+
+    public WorkspaceHideTracker (Meta.Display display, Clutter.Actor actor) {
+        Object (display: display);
+        _actor = actor;
+    }
+
+    construct {
+        display.list_all_windows ().foreach (setup_window);
+        display.window_created.connect (setup_window);
+
+        unowned var monitor_manager = display.get_context ().get_backend ().get_monitor_manager ();
+        monitor_manager.monitors_changed.connect (recalculate_all_workspaces);
+
+        unowned var workspace_manager = display.get_workspace_manager ();
+        workspace_manager.workspace_added.connect (recalculate_all_workspaces);
+        workspace_manager.workspace_removed.connect (recalculate_all_workspaces);
+
+        recalculate_all_workspaces ();
+    }
+
+    private void setup_window (Meta.Window window) {
+        window.notify["window-type"].connect (on_window_type_changed);
+
+        if (!Utils.get_window_is_normal (window)) {
+            return;
+        }
+
+        if (window.on_all_workspaces) {
+            recalculate_all_workspaces ();
+        } else {
+            recalculate_workspace (window);
+        }
+
+        window.position_changed.connect (recalculate_workspace);
+        window.size_changed.connect (recalculate_workspace);
+        window.workspace_changed.connect (recalculate_all_workspaces);
+        window.focused.connect (recalculate_workspace);
+        window.notify["on-all-workspaces"].connect (recalculate_all_workspaces);
+        window.notify["fullscreen"].connect (recalculate_workspace_pspec);
+        window.notify["minimized"].connect (recalculate_workspace_pspec);
+        window.notify["above"].connect (recalculate_workspace_pspec);
+        window.unmanaged.connect (recalculate_workspace);
+    }
+
+    private void on_window_type_changed (Object obj, ParamSpec pspec) {
+        var window = (Meta.Window) obj;
+
+        window.notify["window-type"].disconnect (on_window_type_changed);
+        window.position_changed.disconnect (recalculate_workspace);
+        window.size_changed.disconnect (recalculate_workspace);
+        window.workspace_changed.disconnect (recalculate_all_workspaces);
+        window.focused.disconnect (recalculate_workspace);
+        window.notify["on-all-workspaces"].disconnect (recalculate_all_workspaces);
+        window.notify["fullscreen"].disconnect (recalculate_workspace_pspec);
+        window.notify["minimized"].disconnect (recalculate_workspace_pspec);
+        window.notify["above"].disconnect (recalculate_workspace_pspec);
+        window.unmanaged.disconnect (recalculate_workspace);
+
+        setup_window (window);
+    }
+
+    public override void propagate (UpdateType update_type, GestureAction action, double progress) {
+        if (action != SWITCH_WORKSPACE || update_type == COMMIT) {
+            return;
+        }
+
+        switch_workspace_progress = progress.abs ();
+        switching_workspace_progress_updated (get_hidden_progress ());
+    }
+
+    private double get_hidden_progress () {
+        var n_workspaces = workspace_hide_progress_cache.length;
+
+        var left_workspace = int.max ((int) Math.floor (switch_workspace_progress), 0);
+        var right_workspace = int.min ((int) Math.ceil (switch_workspace_progress), n_workspaces - 1);
+
+        var relative_progress = switch_workspace_progress - left_workspace;
+
+        return (
+            workspace_hide_progress_cache[left_workspace] * (1 - relative_progress) +
+            workspace_hide_progress_cache[right_workspace] * relative_progress
+        );
+    }
+
+    /**
+     * Trigger recalculation of all workspaces
+     */
+    public void recalculate_all_workspaces () {
+        unowned var workspace_manager = display.get_workspace_manager ();
+        workspace_hide_progress_cache = new double[workspace_manager.n_workspaces];
+        foreach (unowned var workspace in workspace_manager.get_workspaces ()) {
+            internal_recalculate_workspace (workspace, false);
+        }
+
+        window_state_changed_progress_updated (get_hidden_progress ());
+    }
+
+    private void internal_recalculate_workspace (Meta.Workspace? workspace, bool send_signal) {
+        if (workspace == null || workspace.workspace_index >= workspace_hide_progress_cache.length) {
+            return;
+        }
+
+        workspace_hide_progress_cache[workspace.workspace_index] = compute_progress (workspace);
+
+        if (send_signal) {
+            window_state_changed_progress_updated (get_hidden_progress ());
+        }
+    }
+
+    private void recalculate_workspace (Meta.Window window) {
+        internal_recalculate_workspace (window.get_workspace (), true);
+    }
+
+    private void recalculate_workspace_pspec (Object obj, ParamSpec pspec) {
+        internal_recalculate_workspace (((Meta.Window) obj).get_workspace (), true);
+    }
+}

lib/meson.build

@@ -36,7 +36,8 @@ gala_lib_sources = files(
     'Gestures/ScrollBackend.vala',
     'Gestures/SpringTimeline.vala',
     'Gestures/ToucheggBackend.vala',
-    'Gestures/TouchpadBackend.vala'
+    'Gestures/TouchpadBackend.vala',
+    'Gestures/WorkspaceHideTracker.vala'
 ) + gala_common_enums
 
 gala_resources = gnome.compile_resources(