Add "Switch windows" gesture (#1802)

data/gala.gschema.xml

@@ -355,6 +355,7 @@
     <value nick="none" value="0" />
     <value nick="switch-to-workspace" value="1" />
     <value nick="move-to-workspace" value="2" />
+    <value nick="switch-windows" value="3" />
   </enum>
   <enum id="GestureSwipeUp">
     <value nick="none" value="0" />

src/Widgets/WindowSwitcher/WindowSwitcher.vala

@@ -10,15 +10,20 @@
 public class Gala.WindowSwitcher : Clutter.Actor {
     public const int ICON_SIZE = 64;
     public const int WRAPPER_PADDING = 12;
+
     private const string CAPTION_FONT_NAME = "Inter";
     private const int MIN_OFFSET = 64;
     private const int ANIMATION_DURATION = 200;
-
+    // https://github.com/elementary/gala/issues/1317#issuecomment-982484415
-    public bool opened { get; private set; default = false; }
+    private const int GESTURE_RANGE_LIMIT = 10;
 
     public Gala.WindowManager? wm { get; construct; }
-    private Gala.ModalProxy modal_proxy = null;
+    public GestureTracker gesture_tracker { get; construct; }
+    public bool opened { get; private set; default = false; }
 
+    private bool handling_gesture = false;
+    private int modifier_mask;
+    private Gala.ModalProxy modal_proxy = null;
     private Granite.Settings granite_settings;
     private Clutter.Canvas canvas;
     private Clutter.Actor container;
@@ -28,8 +33,6 @@ public class Gala.WindowSwitcher : Clutter.Actor {
     private Gtk.StyleContext style_context;
     private unowned Gtk.CssProvider? dark_style_provider = null;
 
-    private int modifier_mask;
-
     private WindowSwitcherIcon? _current_icon = null;
     private WindowSwitcherIcon? current_icon {
         get {
@@ -51,8 +54,11 @@ public class Gala.WindowSwitcher : Clutter.Actor {
 
     private float scaling_factor = 1.0f;
 
-    public WindowSwitcher (Gala.WindowManager wm) {
+    public WindowSwitcher (Gala.WindowManager wm, GestureTracker gesture_tracker) {
-        Object (wm: wm);
+        Object (
+            wm: wm,
+            gesture_tracker: gesture_tracker
+        );
     }
 
     construct {
@@ -184,6 +190,10 @@ public class Gala.WindowSwitcher : Clutter.Actor {
         Meta.Display display, Meta.Window? window,
         Clutter.KeyEvent event, Meta.KeyBinding binding
     ) {
+        if (handling_gesture) {
+            return;
+        }
+
         var workspace = display.get_workspace_manager ().get_active_workspace ();
 
         // copied from gnome-shell, finds the primary modifier in the mask
@@ -219,6 +229,49 @@ public class Gala.WindowSwitcher : Clutter.Actor {
         next_window (backward);
     }
 
+    public void handle_gesture (GestureDirection direction) {
+        handling_gesture = true;
+
+        unowned var display = wm.get_display ();
+        unowned var workspace_manager = display.get_workspace_manager ();
+        unowned var active_workspace = workspace_manager.get_active_workspace ();
+
+        var windows_exist = collect_all_windows (display, active_workspace);
+        if (!windows_exist) {
+            return;
+        }
+        open_switcher ();
+
+        // if direction == LEFT we need to move to the end of the list first, thats why last_window_index is set to -1
+        var last_window_index = direction == RIGHT ? 0 : -1;
+        GestureTracker.OnUpdate on_animation_update = (percentage) => {
+            var window_index = GestureTracker.animation_value (0, GESTURE_RANGE_LIMIT, percentage, true);
+
+            if (window_index >= container.get_n_children ()) {
+                return;
+            }
+
+            if (window_index > last_window_index) {
+                while (last_window_index < window_index) {
+                    next_window (direction == LEFT);
+                    last_window_index++;
+                }
+            } else if (window_index < last_window_index) {
+                while (last_window_index > window_index) {
+                    next_window (direction == RIGHT);
+                    last_window_index--;
+                }
+            }
+        };
+
+        GestureTracker.OnEnd on_animation_end = (percentage, cancel_action, calculated_duration) => {
+            handling_gesture = false;
+            close_switcher (wm.get_display ().get_current_time ());
+        };
+
+        gesture_tracker.connect_handlers (null, (owned) on_animation_update, (owned) on_animation_end);
+    }
+
     private bool collect_all_windows (Meta.Display display, Meta.Workspace? workspace) {
         var windows = display.get_tab_list (Meta.TabList.NORMAL, workspace);
         if (windows == null) {
@@ -319,11 +372,6 @@ public class Gala.WindowSwitcher : Clutter.Actor {
         );
 
         toggle_display (true);
-
-        // if we did not have the grab before the key was released, close immediately
-        if ((get_current_modifiers () & modifier_mask) == 0) {
-            close_switcher (wm.get_display ().get_current_time ());
-        }
     }
 
     private void toggle_display (bool show) {
@@ -381,7 +429,7 @@ public class Gala.WindowSwitcher : Clutter.Actor {
         }
 
         if (!cancel) {
-            var workspace = window.get_workspace ();
+            unowned var workspace = window.get_workspace ();
             if (workspace != wm.get_display ().get_workspace_manager ().get_active_workspace ()) {
                 workspace.activate_with_focus (window, time);
             } else {
@@ -431,7 +479,9 @@ public class Gala.WindowSwitcher : Clutter.Actor {
     }
 
     public override void key_focus_out () {
-        close_switcher (wm.get_display ().get_current_time ());
+        if (!handling_gesture) {
+            close_switcher (wm.get_display ().get_current_time ());
+        }
     }
 
 #if HAS_MUTTER45
@@ -439,16 +489,20 @@ public class Gala.WindowSwitcher : Clutter.Actor {
 #else
     private bool container_motion_event (Clutter.MotionEvent event) {
 #endif
+        if (handling_gesture) {
+            return Clutter.EVENT_STOP;
+        }
+
         float x, y;
         event.get_coords (out x, out y);
         var actor = container.get_stage ().get_actor_at_pos (Clutter.PickMode.ALL, (int)x, (int)y);
         if (actor == null) {
-            return true;
+            return Clutter.EVENT_STOP;
         }
 
         var selected = actor as WindowSwitcherIcon;
         if (selected == null) {
-            return true;
+            return Clutter.EVENT_STOP;
         }
 
         if (current_icon != selected) {
@@ -463,7 +517,7 @@ public class Gala.WindowSwitcher : Clutter.Actor {
 #else
     private bool container_mouse_release (Clutter.ButtonEvent event) {
 #endif
-        if (opened && event.get_button () == Clutter.Button.PRIMARY) {
+        if (opened && event.get_button () == Clutter.Button.PRIMARY && !handling_gesture) {
             close_switcher (event.get_time ());
         }
 
@@ -475,7 +529,7 @@ public class Gala.WindowSwitcher : Clutter.Actor {
 #else
     public override bool key_release_event (Clutter.KeyEvent event) {
 #endif
-        if ((get_current_modifiers () & modifier_mask) == 0) {
+        if ((get_current_modifiers () & modifier_mask) == 0 && !handling_gesture) {
             close_switcher (event.get_time ());
         }
 
@@ -489,10 +543,14 @@ public class Gala.WindowSwitcher : Clutter.Actor {
 #endif
         switch (event.get_key_symbol ()) {
             case Clutter.Key.Right:
-                next_window (false);
+                if (!handling_gesture) {
+                    next_window (false);
+                }
                 return Clutter.EVENT_STOP;
             case Clutter.Key.Left:
-                next_window (true);
+                if (!handling_gesture) {
+                    next_window (true);
+                }
                 return Clutter.EVENT_STOP;
             case Clutter.Key.Escape:
                 close_switcher (event.get_time (), true);

src/WindowManager.vala

@@ -71,7 +71,7 @@ namespace Gala {
 
         private Meta.PluginInfo info;
 
-        private WindowSwitcher? winswitcher = null;
+        private WindowSwitcher? window_switcher = null;
         private ActivatableComponent? window_overview = null;
 
         public ScreenSaverManager? screensaver { get; private set; }
@@ -332,15 +332,15 @@ namespace Gala {
                 });
 
                 if (plugin_manager.window_switcher_provider == null) {
-                    winswitcher = new WindowSwitcher (this);
+                    window_switcher = new WindowSwitcher (this, gesture_tracker);
-                    ui_group.add_child (winswitcher);
+                    ui_group.add_child (window_switcher);
 
-                    Meta.KeyBinding.set_custom_handler ("switch-applications", (Meta.KeyHandlerFunc) winswitcher.handle_switch_windows);
+                    Meta.KeyBinding.set_custom_handler ("switch-applications", (Meta.KeyHandlerFunc) window_switcher.handle_switch_windows);
-                    Meta.KeyBinding.set_custom_handler ("switch-applications-backward", (Meta.KeyHandlerFunc) winswitcher.handle_switch_windows);
+                    Meta.KeyBinding.set_custom_handler ("switch-applications-backward", (Meta.KeyHandlerFunc) window_switcher.handle_switch_windows);
-                    Meta.KeyBinding.set_custom_handler ("switch-windows", (Meta.KeyHandlerFunc) winswitcher.handle_switch_windows);
+                    Meta.KeyBinding.set_custom_handler ("switch-windows", (Meta.KeyHandlerFunc) window_switcher.handle_switch_windows);
-                    Meta.KeyBinding.set_custom_handler ("switch-windows-backward", (Meta.KeyHandlerFunc) winswitcher.handle_switch_windows);
+                    Meta.KeyBinding.set_custom_handler ("switch-windows-backward", (Meta.KeyHandlerFunc) window_switcher.handle_switch_windows);
-                    Meta.KeyBinding.set_custom_handler ("switch-group", (Meta.KeyHandlerFunc) winswitcher.handle_switch_windows);
+                    Meta.KeyBinding.set_custom_handler ("switch-group", (Meta.KeyHandlerFunc) window_switcher.handle_switch_windows);
-                    Meta.KeyBinding.set_custom_handler ("switch-group-backward", (Meta.KeyHandlerFunc) winswitcher.handle_switch_windows);
+                    Meta.KeyBinding.set_custom_handler ("switch-group-backward", (Meta.KeyHandlerFunc) window_switcher.handle_switch_windows);
                 }
 
                 if (plugin_manager.window_overview_provider == null
@@ -530,12 +530,8 @@ namespace Gala {
                 return;
             }
 
-            var can_handle_swipe = (
+            if (gesture.type != Clutter.EventType.TOUCHPAD_SWIPE ||
-                gesture.type == Clutter.EventType.TOUCHPAD_SWIPE &&
+                (gesture.direction != GestureDirection.LEFT && gesture.direction != GestureDirection.RIGHT)) {
-                (gesture.direction == GestureDirection.LEFT || gesture.direction == GestureDirection.RIGHT)
-            );
-
-            if (!can_handle_swipe) {
                 return;
             }
 
@@ -550,6 +546,9 @@ namespace Gala {
             var three_fingers_move_to_workspace = fingers == 3 && three_finger_swipe_horizontal == "move-to-workspace";
             var four_fingers_move_to_workspace = fingers == 4 && four_finger_swipe_horizontal == "move-to-workspace";
 
+            var three_fingers_switch_windows = fingers == 3 && three_finger_swipe_horizontal == "switch-windows";
+            var four_fingers_switch_windows = fingers == 4 && four_finger_swipe_horizontal == "switch-windows";
+
             switch_workspace_with_gesture = three_fingers_switch_to_workspace || four_fingers_switch_to_workspace;
             if (switch_workspace_with_gesture) {
                 var direction = gesture_tracker.settings.get_natural_scroll_direction (gesture);
@@ -572,6 +571,11 @@ namespace Gala {
                 switch_to_next_workspace (direction);
                 return;
             }
+
+            var switch_windows = three_fingers_switch_windows || four_fingers_switch_windows;
+            if (switch_windows && !window_switcher.opened) {
+                window_switcher.handle_gesture (gesture.direction);
+            }
         }
 
         /**