Adding upstream version 43.9.upstream/43.9upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 841 insertions, 0 deletions

diff --git a/js/ui/dnd.js b/js/ui/dnd.js
new file mode 100644
index 0000000..613402d
--- /dev/null
+++ b/js/ui/dnd.js
@@ -0,0 +1,841 @@
+// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
+/* exported addDragMonitor, removeDragMonitor, makeDraggable */
+
+const { Clutter, GLib, Meta, Shell, St } = imports.gi;
+const Signals = imports.misc.signals;
+
+const Main = imports.ui.main;
+const Params = imports.misc.params;
+
+// Time to scale down to maxDragActorSize
+var SCALE_ANIMATION_TIME = 250;
+// Time to animate to original position on cancel
+var SNAP_BACK_ANIMATION_TIME = 250;
+// Time to animate to original position on success
+var REVERT_ANIMATION_TIME = 750;
+
+var DragMotionResult = {
+    NO_DROP:   0,
+    COPY_DROP: 1,
+    MOVE_DROP: 2,
+    CONTINUE:  3,
+};
+
+var DragState = {
+    INIT:      0,
+    DRAGGING:  1,
+    CANCELLED: 2,
+};
+
+var DRAG_CURSOR_MAP = {
+    0: Meta.Cursor.DND_UNSUPPORTED_TARGET,
+    1: Meta.Cursor.DND_COPY,
+    2: Meta.Cursor.DND_MOVE,
+};
+
+var DragDropResult = {
+    FAILURE:  0,
+    SUCCESS:  1,
+    CONTINUE: 2,
+};
+var dragMonitors = [];
+
+let eventHandlerActor = null;
+let currentDraggable = null;
+
+function _getEventHandlerActor() {
+    if (!eventHandlerActor) {
+        eventHandlerActor = new Clutter.Actor({ width: 0, height: 0, reactive: true });
+        Main.uiGroup.add_actor(eventHandlerActor);
+        // We connect to 'event' rather than 'captured-event' because the capturing phase doesn't happen
+        // when you've grabbed the pointer.
+        eventHandlerActor.connect('event', (actor, event) => {
+            return currentDraggable._onEvent(actor, event);
+        });
+    }
+    return eventHandlerActor;
+}
+
+function _getRealActorScale(actor) {
+    let scale = 1.0;
+    while (actor) {
+        scale *= actor.scale_x;
+        actor = actor.get_parent();
+    }
+    return scale;
+}
+
+function addDragMonitor(monitor) {
+    dragMonitors.push(monitor);
+}
+
+function removeDragMonitor(monitor) {
+    for (let i = 0; i < dragMonitors.length; i++) {
+        if (dragMonitors[i] == monitor) {
+            dragMonitors.splice(i, 1);
+            return;
+        }
+    }
+}
+
+var _Draggable = class _Draggable extends Signals.EventEmitter {
+    constructor(actor, params) {
+        super();
+
+        params = Params.parse(params, {
+            manualMode: false,
+            timeoutThreshold: 0,
+            restoreOnSuccess: false,
+            dragActorMaxSize: undefined,
+            dragActorOpacity: undefined,
+        });
+
+        this.actor = actor;
+        this._dragState = DragState.INIT;
+
+        if (!params.manualMode) {
+            this.actor.connect('button-press-event',
+                               this._onButtonPress.bind(this));
+            this.actor.connect('touch-event',
+                               this._onTouchEvent.bind(this));
+        }
+
+        this.actor.connect('destroy', () => {
+            this._actorDestroyed = true;
+
+            if (this._dragState == DragState.DRAGGING && this._dragCancellable)
+                this._cancelDrag(global.get_current_time());
+            this.disconnectAll();
+        });
+        this._onEventId = null;
+        this._touchSequence = null;
+
+        this._restoreOnSuccess = params.restoreOnSuccess;
+        this._dragActorMaxSize = params.dragActorMaxSize;
+        this._dragActorOpacity = params.dragActorOpacity;
+        this._dragTimeoutThreshold = params.timeoutThreshold;
+
+        this._buttonDown = false; // The mouse button has been pressed and has not yet been released.
+        this._animationInProgress = false; // The drag is over and the item is in the process of animating to its original position (snapping back or reverting).
+        this._dragCancellable = true;
+    }
+
+    _onButtonPress(actor, event) {
+        if (event.get_button() != 1)
+            return Clutter.EVENT_PROPAGATE;
+
+        this._buttonDown = true;
+        this._grabActor(event.get_device());
+
+        let [stageX, stageY] = event.get_coords();
+        this._dragStartX = stageX;
+        this._dragStartY = stageY;
+        this._dragStartTime = event.get_time();
+        this._dragThresholdIgnored = false;
+
+        return Clutter.EVENT_PROPAGATE;
+    }
+
+    _onTouchEvent(actor, event) {
+        // We only handle touch events here on wayland. On X11
+        // we do get emulated pointer events, which already works
+        // for single-touch cases. Besides, the X11 passive touch grab
+        // set up by Mutter will make us see first the touch events
+        // and later the pointer events, so it will look like two
+        // unrelated series of events, we want to avoid double handling
+        // in these cases.
+        if (!Meta.is_wayland_compositor())
+            return Clutter.EVENT_PROPAGATE;
+
+        if (event.type() != Clutter.EventType.TOUCH_BEGIN ||
+            !global.display.is_pointer_emulating_sequence(event.get_event_sequence()))
+            return Clutter.EVENT_PROPAGATE;
+
+        this._buttonDown = true;
+        this._grabActor(event.get_device(), event.get_event_sequence());
+        this._dragStartTime = event.get_time();
+        this._dragThresholdIgnored = false;
+
+        let [stageX, stageY] = event.get_coords();
+        this._dragStartX = stageX;
+        this._dragStartY = stageY;
+
+        return Clutter.EVENT_PROPAGATE;
+    }
+
+    _grabDevice(actor, pointer, touchSequence) {
+        this._grab = global.stage.grab(actor);
+        this._grabbedDevice = pointer;
+        this._touchSequence = touchSequence;
+    }
+
+    _ungrabDevice() {
+        if (this._grab) {
+            this._grab.dismiss();
+            this._grab = null;
+        }
+        this._touchSequence = null;
+        this._grabbedDevice = null;
+    }
+
+    _grabActor(device, touchSequence) {
+        this._grabDevice(this.actor, device, touchSequence);
+        this._onEventId = this.actor.connect('event',
+                                             this._onEvent.bind(this));
+    }
+
+    _ungrabActor() {
+        if (!this._onEventId)
+            return;
+
+        this._ungrabDevice();
+        this.actor.disconnect(this._onEventId);
+        this._onEventId = null;
+    }
+
+    _grabEvents(device, touchSequence) {
+        if (!this._eventsGrab) {
+            let grab = Main.pushModal(_getEventHandlerActor());
+            if ((grab.get_seat_state() & Clutter.GrabState.POINTER) !== 0) {
+                this._grabDevice(_getEventHandlerActor(), device, touchSequence);
+                this._eventsGrab = grab;
+            } else {
+                Main.popModal(grab);
+            }
+        }
+    }
+
+    _ungrabEvents() {
+        if (this._eventsGrab) {
+            this._ungrabDevice();
+            Main.popModal(this._eventsGrab);
+            this._eventsGrab = null;
+        }
+    }
+
+    _eventIsRelease(event) {
+        if (event.type() == Clutter.EventType.BUTTON_RELEASE) {
+            let buttonMask = Clutter.ModifierType.BUTTON1_MASK |
+                              Clutter.ModifierType.BUTTON2_MASK |
+                              Clutter.ModifierType.BUTTON3_MASK;
+            /* We only obey the last button release from the device,
+             * other buttons may get pressed/released during the DnD op.
+             */
+            return (event.get_state() & buttonMask) == 0;
+        } else if (event.type() == Clutter.EventType.TOUCH_END) {
+            /* For touch, we only obey the pointer emulating sequence */
+            return global.display.is_pointer_emulating_sequence(event.get_event_sequence());
+        }
+
+        return false;
+    }
+
+    _onEvent(actor, event) {
+        let device = event.get_device();
+
+        if (this._grabbedDevice &&
+            device != this._grabbedDevice &&
+            device.get_device_type() != Clutter.InputDeviceType.KEYBOARD_DEVICE)
+            return Clutter.EVENT_PROPAGATE;
+
+        // We intercept BUTTON_RELEASE event to know that the button was released in case we
+        // didn't start the drag, to drop the draggable in case the drag was in progress, and
+        // to complete the drag and ensure that whatever happens to be under the pointer does
+        // not get triggered if the drag was cancelled with Esc.
+        if (this._eventIsRelease(event)) {
+            this._buttonDown = false;
+            if (this._dragState == DragState.DRAGGING) {
+                return this._dragActorDropped(event);
+            } else if ((this._dragActor != null || this._dragState == DragState.CANCELLED) &&
+                       !this._animationInProgress) {
+                // Drag must have been cancelled with Esc.
+                this._dragComplete();
+                return Clutter.EVENT_STOP;
+            } else {
+                // Drag has never started.
+                this._ungrabActor();
+                return Clutter.EVENT_PROPAGATE;
+            }
+        // We intercept MOTION event to figure out if the drag has started and to draw
+        // this._dragActor under the pointer when dragging is in progress
+        } else if (event.type() == Clutter.EventType.MOTION ||
+                   (event.type() == Clutter.EventType.TOUCH_UPDATE &&
+                    global.display.is_pointer_emulating_sequence(event.get_event_sequence()))) {
+            if (this._dragActor && this._dragState == DragState.DRAGGING)
+                return this._updateDragPosition(event);
+            else if (this._dragActor == null && this._dragState != DragState.CANCELLED)
+                return this._maybeStartDrag(event);
+
+        // We intercept KEY_PRESS event so that we can process Esc key press to cancel
+        // dragging and ignore all other key presses.
+        } else if (event.type() == Clutter.EventType.KEY_PRESS && this._dragState == DragState.DRAGGING) {
+            let symbol = event.get_key_symbol();
+            if (symbol == Clutter.KEY_Escape) {
+                this._cancelDrag(event.get_time());
+                return Clutter.EVENT_STOP;
+            }
+        }
+
+        return Clutter.EVENT_PROPAGATE;
+    }
+
+    /**
+     * fakeRelease:
+     *
+     * Fake a release event.
+     * Must be called if you want to intercept release events on draggable
+     * actors for other purposes (for example if you're using
+     * PopupMenu.ignoreRelease())
+     */
+    fakeRelease() {
+        this._buttonDown = false;
+        this._ungrabActor();
+    }
+
+    /**
+     * startDrag:
+     * @param {number} stageX: X coordinate of event
+     * @param {number} stageY: Y coordinate of event
+     * @param {number} time: Event timestamp
+     * @param {Clutter.EventSequence=} sequence: Event sequence
+     * @param {Clutter.InputDevice=} device: device that originated the event
+     *
+     * Directly initiate a drag and drop operation from the given actor.
+     * This function is useful to call if you've specified manualMode
+     * for the draggable.
+     */
+    startDrag(stageX, stageY, time, sequence, device) {
+        if (currentDraggable)
+            return;
+
+        if (device == undefined) {
+            let event = Clutter.get_current_event();
+
+            if (event)
+                device = event.get_device();
+
+            if (device == undefined) {
+                let seat = Clutter.get_default_backend().get_default_seat();
+                device = seat.get_pointer();
+            }
+        }
+
+        currentDraggable = this;
+        this._dragState = DragState.DRAGGING;
+
+        // Special-case St.Button: the pointer grab messes with the internal
+        // state, so force a reset to a reasonable state here
+        if (this.actor instanceof St.Button) {
+            this.actor.fake_release();
+            this.actor.hover = false;
+        }
+
+        this.emit('drag-begin', time);
+        if (this._onEventId)
+            this._ungrabActor();
+
+        this._grabEvents(device, sequence);
+        global.display.set_cursor(Meta.Cursor.DND_IN_DRAG);
+
+        this._dragX = this._dragStartX = stageX;
+        this._dragY = this._dragStartY = stageY;
+
+        let scaledWidth, scaledHeight;
+
+        if (this.actor._delegate && this.actor._delegate.getDragActor) {
+            this._dragActor = this.actor._delegate.getDragActor();
+            Main.uiGroup.add_child(this._dragActor);
+            Main.uiGroup.set_child_above_sibling(this._dragActor, null);
+            Shell.util_set_hidden_from_pick(this._dragActor, true);
+
+            // Drag actor does not always have to be the same as actor. For example drag actor
+            // can be an image that's part of the actor. So to perform "snap back" correctly we need
+            // to know what was the drag actor source.
+            if (this.actor._delegate.getDragActorSource) {
+                this._dragActorSource = this.actor._delegate.getDragActorSource();
+                // If the user dragged from the source, then position
+                // the dragActor over it. Otherwise, center it
+                // around the pointer
+                let [sourceX, sourceY] = this._dragActorSource.get_transformed_position();
+                let x, y;
+                if (stageX > sourceX && stageX <= sourceX + this._dragActor.width &&
+                    stageY > sourceY && stageY <= sourceY + this._dragActor.height) {
+                    x = sourceX;
+                    y = sourceY;
+                } else {
+                    x = stageX - this._dragActor.width / 2;
+                    y = stageY - this._dragActor.height / 2;
+                }
+                this._dragActor.set_position(x, y);
+
+                this._dragActorSourceDestroyId = this._dragActorSource.connect('destroy', () => {
+                    this._dragActorSource = null;
+                });
+            } else {
+                this._dragActorSource = this.actor;
+            }
+            this._dragOrigParent = undefined;
+
+            this._dragOffsetX = this._dragActor.x - this._dragStartX;
+            this._dragOffsetY = this._dragActor.y - this._dragStartY;
+
+            [scaledWidth, scaledHeight] = this._dragActor.get_transformed_size();
+        } else {
+            this._dragActor = this.actor;
+
+            this._dragActorSource = undefined;
+            this._dragOrigParent = this.actor.get_parent();
+            this._dragActorHadFixedPos = this._dragActor.fixed_position_set;
+            this._dragOrigX = this._dragActor.allocation.x1;
+            this._dragOrigY = this._dragActor.allocation.y1;
+            this._dragActorHadNatWidth = this._dragActor.natural_width_set;
+            this._dragActorHadNatHeight = this._dragActor.natural_height_set;
+            this._dragOrigWidth = this._dragActor.allocation.get_width();
+            this._dragOrigHeight = this._dragActor.allocation.get_height();
+            this._dragOrigScale = this._dragActor.scale_x;
+
+            // Ensure actors with an allocation smaller than their natural size
+            // retain their size
+            this._dragActor.set_size(...this._dragActor.allocation.get_size());
+
+            const transformedExtents = this._dragActor.get_transformed_extents();
+
+            this._dragOffsetX = transformedExtents.origin.x - this._dragStartX;
+            this._dragOffsetY = transformedExtents.origin.y - this._dragStartY;
+
+            scaledWidth = transformedExtents.get_width();
+            scaledHeight = transformedExtents.get_height();
+
+            this._dragActor.scale_x = scaledWidth / this._dragOrigWidth;
+            this._dragActor.scale_y = scaledHeight / this._dragOrigHeight;
+
+            this._dragOrigParent.remove_actor(this._dragActor);
+            Main.uiGroup.add_child(this._dragActor);
+            Main.uiGroup.set_child_above_sibling(this._dragActor, null);
+            Shell.util_set_hidden_from_pick(this._dragActor, true);
+
+            this._dragOrigParentDestroyId = this._dragOrigParent.connect('destroy', () => {
+                this._dragOrigParent = null;
+            });
+        }
+
+        this._dragActorDestroyId = this._dragActor.connect('destroy', () => {
+            // Cancel ongoing animation (if any)
+            this._finishAnimation();
+
+            this._dragActor = null;
+            if (this._dragState == DragState.DRAGGING)
+                this._dragState = DragState.CANCELLED;
+        });
+        this._dragOrigOpacity = this._dragActor.opacity;
+        if (this._dragActorOpacity != undefined)
+            this._dragActor.opacity = this._dragActorOpacity;
+
+        this._snapBackX = this._dragStartX + this._dragOffsetX;
+        this._snapBackY = this._dragStartY + this._dragOffsetY;
+        this._snapBackScale = this._dragActor.scale_x;
+
+        let origDragOffsetX = this._dragOffsetX;
+        let origDragOffsetY = this._dragOffsetY;
+        let [transX, transY] = this._dragActor.get_translation();
+        this._dragOffsetX -= transX;
+        this._dragOffsetY -= transY;
+
+        this._dragActor.set_position(
+            this._dragX + this._dragOffsetX,
+            this._dragY + this._dragOffsetY);
+
+        if (this._dragActorMaxSize != undefined) {
+            let currentSize = Math.max(scaledWidth, scaledHeight);
+            if (currentSize > this._dragActorMaxSize) {
+                let scale = this._dragActorMaxSize / currentSize;
+                let origScale =  this._dragActor.scale_x;
+
+                // The position of the actor changes as we scale
+                // around the drag position, but we can't just tween
+                // to the final position because that tween would
+                // fight with updates as the user continues dragging
+                // the mouse; instead we do the position computations in
+                // a ::new-frame handler.
+                this._dragActor.ease({
+                    scale_x: scale * origScale,
+                    scale_y: scale * origScale,
+                    duration: SCALE_ANIMATION_TIME,
+                    mode: Clutter.AnimationMode.EASE_OUT_QUAD,
+                    onComplete: () => {
+                        this._updateActorPosition(origScale,
+                            origDragOffsetX, origDragOffsetY, transX, transY);
+                    },
+                });
+
+                this._dragActor.get_transition('scale-x').connect('new-frame', () => {
+                    this._updateActorPosition(origScale,
+                        origDragOffsetX, origDragOffsetY, transX, transY);
+                });
+            }
+        }
+    }
+
+    _updateActorPosition(origScale, origDragOffsetX, origDragOffsetY, transX, transY) {
+        const currentScale = this._dragActor.scale_x / origScale;
+        this._dragOffsetX = currentScale * origDragOffsetX - transX;
+        this._dragOffsetY = currentScale * origDragOffsetY - transY;
+        this._dragActor.set_position(
+            this._dragX + this._dragOffsetX,
+            this._dragY + this._dragOffsetY);
+    }
+
+    _maybeStartDrag(event) {
+        let [stageX, stageY] = event.get_coords();
+
+        if (this._dragThresholdIgnored)
+            return Clutter.EVENT_PROPAGATE;
+
+        // See if the user has moved the mouse enough to trigger a drag
+        let scaleFactor = St.ThemeContext.get_for_stage(global.stage).scale_factor;
+        let threshold = St.Settings.get().drag_threshold * scaleFactor;
+        if (!currentDraggable &&
+            (Math.abs(stageX - this._dragStartX) > threshold ||
+             Math.abs(stageY - this._dragStartY) > threshold)) {
+            const deviceType = event.get_source_device().get_device_type();
+            const isPointerOrTouchpad =
+                deviceType === Clutter.InputDeviceType.POINTER_DEVICE ||
+                deviceType === Clutter.InputDeviceType.TOUCHPAD_DEVICE;
+            const ellapsedTime = event.get_time() - this._dragStartTime;
+
+            // Pointer devices (e.g. mouse) start the drag immediately
+            if (isPointerOrTouchpad || ellapsedTime > this._dragTimeoutThreshold) {
+                this.startDrag(stageX, stageY, event.get_time(), this._touchSequence, event.get_device());
+                this._updateDragPosition(event);
+            } else {
+                this._dragThresholdIgnored = true;
+                this._ungrabActor();
+                return Clutter.EVENT_PROPAGATE;
+            }
+        }
+
+        return Clutter.EVENT_STOP;
+    }
+
+    _pickTargetActor() {
+        return this._dragActor.get_stage().get_actor_at_pos(Clutter.PickMode.ALL,
+                                                            this._dragX, this._dragY);
+    }
+
+    _updateDragHover() {
+        this._updateHoverId = 0;
+        let target = this._pickTargetActor();
+
+        let dragEvent = {
+            x: this._dragX,
+            y: this._dragY,
+            dragActor: this._dragActor,
+            source: this.actor._delegate,
+            targetActor: target,
+        };
+
+        let targetActorDestroyHandlerId;
+        let handleTargetActorDestroyClosure;
+        handleTargetActorDestroyClosure = () => {
+            target = this._pickTargetActor();
+            dragEvent.targetActor = target;
+            targetActorDestroyHandlerId =
+                target.connect('destroy', handleTargetActorDestroyClosure);
+        };
+        targetActorDestroyHandlerId =
+            target.connect('destroy', handleTargetActorDestroyClosure);
+
+        for (let i = 0; i < dragMonitors.length; i++) {
+            let motionFunc = dragMonitors[i].dragMotion;
+            if (motionFunc) {
+                let result = motionFunc(dragEvent);
+                if (result != DragMotionResult.CONTINUE) {
+                    global.display.set_cursor(DRAG_CURSOR_MAP[result]);
+                    dragEvent.targetActor.disconnect(targetActorDestroyHandlerId);
+                    return GLib.SOURCE_REMOVE;
+                }
+            }
+        }
+        dragEvent.targetActor.disconnect(targetActorDestroyHandlerId);
+
+        while (target) {
+            if (target._delegate && target._delegate.handleDragOver) {
+                let [r_, targX, targY] = target.transform_stage_point(this._dragX, this._dragY);
+                // We currently loop through all parents on drag-over even if one of the children has handled it.
+                // We can check the return value of the function and break the loop if it's true if we don't want
+                // to continue checking the parents.
+                let result = target._delegate.handleDragOver(this.actor._delegate,
+                                                             this._dragActor,
+                                                             targX,
+                                                             targY,
+                                                             0);
+                if (result != DragMotionResult.CONTINUE) {
+                    global.display.set_cursor(DRAG_CURSOR_MAP[result]);
+                    return GLib.SOURCE_REMOVE;
+                }
+            }
+            target = target.get_parent();
+        }
+        global.display.set_cursor(Meta.Cursor.DND_IN_DRAG);
+        return GLib.SOURCE_REMOVE;
+    }
+
+    _queueUpdateDragHover() {
+        if (this._updateHoverId)
+            return;
+
+        this._updateHoverId = GLib.idle_add(GLib.PRIORITY_DEFAULT,
+                                            this._updateDragHover.bind(this));
+        GLib.Source.set_name_by_id(this._updateHoverId, '[gnome-shell] this._updateDragHover');
+    }
+
+    _updateDragPosition(event) {
+        let [stageX, stageY] = event.get_coords();
+        this._dragX = stageX;
+        this._dragY = stageY;
+        this._dragActor.set_position(stageX + this._dragOffsetX,
+                                     stageY + this._dragOffsetY);
+
+        this._queueUpdateDragHover();
+        return true;
+    }
+
+    _dragActorDropped(event) {
+        let [dropX, dropY] = event.get_coords();
+        let target = this._dragActor.get_stage().get_actor_at_pos(Clutter.PickMode.ALL,
+                                                                  dropX, dropY);
+
+        // We call observers only once per motion with the innermost
+        // target actor. If necessary, the observer can walk the
+        // parent itself.
+        let dropEvent = {
+            dropActor: this._dragActor,
+            targetActor: target,
+            clutterEvent: event,
+        };
+        for (let i = 0; i < dragMonitors.length; i++) {
+            let dropFunc = dragMonitors[i].dragDrop;
+            if (dropFunc) {
+                switch (dropFunc(dropEvent)) {
+                case DragDropResult.FAILURE:
+                case DragDropResult.SUCCESS:
+                    return true;
+                case DragDropResult.CONTINUE:
+                    continue;
+                }
+            }
+        }
+
+        // At this point it is too late to cancel a drag by destroying
+        // the actor, the fate of which is decided by acceptDrop and its
+        // side-effects
+        this._dragCancellable = false;
+
+        while (target) {
+            if (target._delegate && target._delegate.acceptDrop) {
+                let [r_, targX, targY] = target.transform_stage_point(dropX, dropY);
+                let accepted = false;
+                try {
+                    accepted = target._delegate.acceptDrop(this.actor._delegate,
+                        this._dragActor, targX, targY, event.get_time());
+                } catch (e) {
+                    // On error, skip this target
+                    logError(e, "Skipping drag target");
+                }
+                if (accepted) {
+                    // If it accepted the drop without taking the actor,
+                    // handle it ourselves.
+                    if (this._dragActor && this._dragActor.get_parent() == Main.uiGroup) {
+                        if (this._restoreOnSuccess) {
+                            this._restoreDragActor(event.get_time());
+                            return true;
+                        } else {
+                            this._dragActor.destroy();
+                        }
+                    }
+
+                    this._dragState = DragState.INIT;
+                    global.display.set_cursor(Meta.Cursor.DEFAULT);
+                    this.emit('drag-end', event.get_time(), true);
+                    this._dragComplete();
+                    return true;
+                }
+            }
+            target = target.get_parent();
+        }
+
+        this._cancelDrag(event.get_time());
+
+        return true;
+    }
+
+    _getRestoreLocation() {
+        let x, y, scale;
+
+        if (this._dragActorSource && this._dragActorSource.visible) {
+            // Snap the clone back to its source
+            [x, y] = this._dragActorSource.get_transformed_position();
+            let [sourceScaledWidth] = this._dragActorSource.get_transformed_size();
+            scale = sourceScaledWidth ? sourceScaledWidth / this._dragActor.width : 0;
+        } else if (this._dragOrigParent) {
+            // Snap the actor back to its original position within
+            // its parent, adjusting for the fact that the parent
+            // may have been moved or scaled
+            let [parentX, parentY] = this._dragOrigParent.get_transformed_position();
+            let parentScale = _getRealActorScale(this._dragOrigParent);
+
+            x = parentX + parentScale * this._dragOrigX;
+            y = parentY + parentScale * this._dragOrigY;
+            scale = this._dragOrigScale * parentScale;
+        } else {
+            // Snap back actor to its original stage position
+            x = this._snapBackX;
+            y = this._snapBackY;
+            scale = this._snapBackScale;
+        }
+
+        return [x, y, scale];
+    }
+
+    _cancelDrag(eventTime) {
+        this.emit('drag-cancelled', eventTime);
+        let wasCancelled = this._dragState == DragState.CANCELLED;
+        this._dragState = DragState.CANCELLED;
+
+        if (this._actorDestroyed || wasCancelled) {
+            global.display.set_cursor(Meta.Cursor.DEFAULT);
+            if (!this._buttonDown)
+                this._dragComplete();
+            this.emit('drag-end', eventTime, false);
+            if (!this._dragOrigParent && this._dragActor)
+                this._dragActor.destroy();
+
+            return;
+        }
+
+        let [snapBackX, snapBackY, snapBackScale] = this._getRestoreLocation();
+
+        this._animateDragEnd(eventTime, {
+            x: snapBackX,
+            y: snapBackY,
+            scale_x: snapBackScale,
+            scale_y: snapBackScale,
+            duration: SNAP_BACK_ANIMATION_TIME,
+        });
+    }
+
+    _restoreDragActor(eventTime) {
+        this._dragState = DragState.INIT;
+        let [restoreX, restoreY, restoreScale] = this._getRestoreLocation();
+
+        // fade the actor back in at its original location
+        this._dragActor.set_position(restoreX, restoreY);
+        this._dragActor.set_scale(restoreScale, restoreScale);
+        this._dragActor.opacity = 0;
+
+        this._animateDragEnd(eventTime, {
+            duration: REVERT_ANIMATION_TIME,
+        });
+    }
+
+    _animateDragEnd(eventTime, params) {
+        this._animationInProgress = true;
+
+        // start the animation
+        this._dragActor.ease(Object.assign(params, {
+            opacity: this._dragOrigOpacity,
+            mode: Clutter.AnimationMode.EASE_OUT_QUAD,
+            onComplete: () => {
+                this._onAnimationComplete(this._dragActor, eventTime);
+            },
+        }));
+    }
+
+    _finishAnimation() {
+        if (!this._animationInProgress)
+            return;
+
+        this._animationInProgress = false;
+        if (!this._buttonDown)
+            this._dragComplete();
+
+        global.display.set_cursor(Meta.Cursor.DEFAULT);
+    }
+
+    _onAnimationComplete(dragActor, eventTime) {
+        if (this._dragOrigParent) {
+            Main.uiGroup.remove_child(this._dragActor);
+            this._dragOrigParent.add_actor(this._dragActor);
+            dragActor.set_scale(this._dragOrigScale, this._dragOrigScale);
+            if (this._dragActorHadFixedPos)
+                dragActor.set_position(this._dragOrigX, this._dragOrigY);
+            else
+                dragActor.fixed_position_set = false;
+            if (this._dragActorHadNatWidth)
+                this._dragActor.set_width(-1);
+            if (this._dragActorHadNatHeight)
+                this._dragActor.set_height(-1);
+        } else {
+            dragActor.destroy();
+        }
+
+        this.emit('drag-end', eventTime, false);
+        this._finishAnimation();
+    }
+
+    _dragComplete() {
+        if (!this._actorDestroyed && this._dragActor)
+            Shell.util_set_hidden_from_pick(this._dragActor, false);
+
+        this._ungrabEvents();
+
+        if (this._updateHoverId) {
+            GLib.source_remove(this._updateHoverId);
+            this._updateHoverId = 0;
+        }
+
+        if (this._dragActor) {
+            this._dragActor.disconnect(this._dragActorDestroyId);
+            this._dragActor = null;
+        }
+
+        if (this._dragOrigParent) {
+            this._dragOrigParent.disconnect(this._dragOrigParentDestroyId);
+            this._dragOrigParent = null;
+        }
+
+        if (this._dragActorSource) {
+            this._dragActorSource.disconnect(this._dragActorSourceDestroyId);
+            this._dragActorSource = null;
+        }
+
+        this._dragState = DragState.INIT;
+        currentDraggable = null;
+    }
+};
+
+/**
+ * makeDraggable:
+ * @param {Clutter.Actor} actor: Source actor
+ * @param {Object=} params: Additional parameters
+ * @returns {Object} a new Draggable
+ *
+ * Create an object which controls drag and drop for the given actor.
+ *
+ * If %manualMode is %true in @params, do not automatically start
+ * drag and drop on click
+ *
+ * If %dragActorMaxSize is present in @params, the drag actor will
+ * be scaled down to be no larger than that size in pixels.
+ *
+ * If %dragActorOpacity is present in @params, the drag actor will
+ * will be set to have that opacity during the drag.
+ *
+ * Note that when the drag actor is the source actor and the drop
+ * succeeds, the actor scale and opacity aren't reset; if the drop
+ * target wants to reuse the actor, it's up to the drop target to
+ * reset these values.
+ */
+function makeDraggable(actor, params) {
+    return new _Draggable(actor, params);
+}