3 files changed, 134 insertions, 0 deletions

diff --git a/js/js-resources.gresource.xml b/js/js-resources.gresource.xml
index c99189cfe..4206f4cbd 100644
--- a/js/js-resources.gresource.xml
+++ b/js/js-resources.gresource.xml
@@ -90,6 +90,7 @@
     <file>ui/windowAttentionHandler.js</file>
     <file>ui/windowMenu.js</file>
     <file>ui/windowManager.js</file>
+    <file>ui/wobbly.js</file>
     <file>ui/workspace.js</file>
     <file>ui/workspaceSwitcherPopup.js</file>
     <file>ui/workspaceThumbnail.js</file>
diff --git a/js/ui/windowManager.js b/js/ui/windowManager.js
index 101f9a8d7..397af8958 100644
--- a/js/ui/windowManager.js
+++ b/js/ui/windowManager.js
@@ -17,6 +17,7 @@ const Main = imports.ui.main;
 const ModalDialog = imports.ui.modalDialog;
 const Tweener = imports.ui.tweener;
 const WindowMenu = imports.ui.windowMenu;
+const Wobbly = imports.ui.wobbly;
 
 const SHELL_KEYBINDINGS_SCHEMA = 'org.gnome.shell.keybindings';
 const MAXIMIZE_WINDOW_ANIMATION_TIME = 0.15;
@@ -811,6 +812,8 @@ const WindowManager = new Lang.Class({
         gesture = new AppSwitchAction();
         gesture.connect('activated', Lang.bind(this, this._switchApp));
         global.stage.add_action(gesture);
+
+        this._wobblyWindows = new Wobbly.WobblyWindowManager();
     },
 
     _lookupIndex: function (windows, metaWindow) {
diff --git a/js/ui/wobbly.js b/js/ui/wobbly.js
new file mode 100644
index 000000000..ad53fc66f
--- /dev/null
+++ b/js/ui/wobbly.js
@@ -0,0 +1,130 @@
+// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
+
+const Clutter = imports.gi.Clutter;
+const Lang = imports.lang;
+const Meta = imports.gi.Meta;
+const Shell = imports.gi.Shell;
+
+function clampAbs(v, cap) {
+    if (v > cap)
+        v = cap;
+    if (v < -cap)
+        v = -cap;
+    return v;
+}
+
+const ActorWobbler = new Lang.Class({
+    Name: 'ActorWobbler',
+
+    _init: function(actor) {
+        this._actor = actor;
+        this._effect = new Shell.WobblyEffect();
+        this._actor.add_effect(this._effect);
+        this._actor._wobbler = this;
+
+        this._currentBend = 0;
+        this._currentHeightOffset = 0;
+        this._running = false;
+
+        this._allocationChangedId = this._actor.connect('allocation-changed', Lang.bind(this, this._allocationChanged));
+
+        this._timeline = new Clutter.Timeline({ duration: 100, repeat_count: -1 });
+        this._timeline.connect('new-frame', Lang.bind(this, this._newFrame));
+        this._timeline.start();
+    },
+
+    start: function() {
+        this._running = true;
+    },
+
+    stop: function() {
+        this._running = false;
+    },
+
+    _destroy: function() {
+        this._timeline.run_dispose();
+        this._timeline = null;
+
+        this._actor.disconnect(this._allocationChangedId);
+        this._actor.scale_y = 1.0;
+        this._actor.remove_effect(this._effect);
+        this._actor._wobbler = null;
+    },
+
+    _newFrame: function() {
+        this._step();
+    },
+
+    _step: function() {
+        const DAMPEN = 0.8;
+        this._currentBend *= DAMPEN;
+        if (Math.abs(this._currentBend) < 1)
+            this._currentBend = 0;
+        this._currentHeightOffset *= DAMPEN;
+        if (Math.abs(this._currentHeightOffset) < 1)
+            this._currentHeightOffset = 0;
+
+        // Cap the bend to a 100px shift.
+        const BEND_CAP = 50;
+        this._currentBend = clampAbs(this._currentBend, BEND_CAP);
+        this._effect.set_bend_x(this._currentBend);
+
+        // Cap the height change to 25px in either direction.
+        const HEIGHT_OFFSET_CAP = 25;
+        this._currentHeightOffset = clampAbs(this._currentHeightOffset, HEIGHT_OFFSET_CAP);
+        let [minHeight, natHeight] = this._actor.get_preferred_height(-1);
+        let scale = (natHeight + this._currentHeightOffset) / natHeight;
+        this._actor.scale_y = scale;
+
+        if (!this._running && this._currentBend == 0 && this._currentHeightOffset == 0)
+            this._destroy();
+    },
+
+    _allocationChanged: function(actor, box, flags) {
+        if (!this._running)
+            return;
+
+        if (this._oldX) {
+            let deltaX = box.x1 - this._oldX;
+            // Every 2px the user moves the window, we bend it by 1px.
+            this._currentBend -= deltaX / 2;
+        }
+
+        if (this._oldY) {
+            let deltaY = box.y1 - this._oldY;
+            // Every 2px the user moves the window, we scale it by 1px.
+            this._currentHeightOffset -= deltaY / 2;
+        }
+
+        this._oldX = box.x1;
+        this._oldY = box.y1;
+    },
+});
+
+const WobblyWindowManager = new Lang.Class({
+    Name: 'WobblyWindowManager',
+
+    _init: function() {
+        global.display.connect('grab-op-begin', Lang.bind(this, this._grabOpBegin));
+        global.display.connect('grab-op-end', Lang.bind(this, this._grabOpEnd));
+    },
+
+    _grabOpBegin: function(display, screen, window, op) {
+        if (op != Meta.GrabOp.MOVING)
+            return;
+
+        let actor = window.get_compositor_private();
+        if (!actor._wobbler)
+            new ActorWobbler(actor);
+        actor._wobbler.start();
+    },
+
+    _grabOpEnd: function(display, screen, window, op) {
+        if (!window)
+            return;
+
+        let actor = window.get_compositor_private();
+        if (actor._wobbler)
+            actor._wobbler.stop();
+    },
+});