[gnome-shell/wip/exalm/gestures: 7/16] swipeTracker: Introduce swipe tracker

[Alexander Mikhaylenko <alexm src gnome org>]

commit 6b1f6cbbfd7a8f92fb9321e13a3cea95a4330caf
Author: Alexander Mikhaylenko <exalm7659 gmail com>
Date:   Sun Jun 30 17:11:27 2019 +0500

    swipeTracker: Introduce swipe tracker
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/605

 js/js-resources.gresource.xml |   1 +
 js/ui/swipeTracker.js         | 420 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 421 insertions(+)
---
diff --git a/js/js-resources.gresource.xml b/js/js-resources.gresource.xml
index b5348ddcb..aec3427e0 100644
--- a/js/js-resources.gresource.xml
+++ b/js/js-resources.gresource.xml
@@ -98,6 +98,7 @@
     <file>ui/shellEntry.js</file>
     <file>ui/shellMountOperation.js</file>
     <file>ui/slider.js</file>
+    <file>ui/swipeTracker.js</file>
     <file>ui/switcherPopup.js</file>
     <file>ui/switchMonitor.js</file>
     <file>ui/tweener.js</file>
diff --git a/js/ui/swipeTracker.js b/js/ui/swipeTracker.js
new file mode 100644
index 000000000..5d57c90ce
--- /dev/null
+++ b/js/ui/swipeTracker.js
@@ -0,0 +1,420 @@
+// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
+
+const { Clutter, Gio, GObject, Meta, Shell } = imports.gi;
+
+const Signals = imports.signals;
+
+const Main = imports.ui.main;
+
+const TOUCHPAD_BASE_DISTANCE = 400;
+const SCROLL_MULTIPLIER = 20;
+
+const MIN_ANIMATION_DURATION = 0.1;
+const MAX_ANIMATION_DURATION = 0.4;
+const CANCEL_AREA = 0.5;
+const VELOCITY_THRESHOLD = 0.001;
+const DURATION_MULTIPLIER = 3;
+const ANIMATION_BASE_VELOCITY = 0.002;
+
+var State = {
+    NONE: 0,
+    SCROLLING: 1,
+};
+
+function clamp(value, min, max) {
+    return Math.max(min, Math.min(max, value));
+}
+
+// TODO: support horizontal
+// TODO: swap back and forward, this doesn't make sense
+
+var TouchpadSwipeGesture = class TouchpadSwipeGesture {
+    constructor(shouldSkip) {
+        this._shouldSkip = shouldSkip;
+        this._touchpadSettings = new Gio.Settings({ schema_id: 'org.gnome.desktop.peripherals.touchpad' });
+
+        global.stage.connect('captured-event', this._handleEvent.bind(this));
+    }
+
+    _handleEvent(actor, event) {
+        if (event.type() != Clutter.EventType.TOUCHPAD_SWIPE)
+            return Clutter.EVENT_PROPAGATE;
+
+        if (event.get_touchpad_gesture_finger_count() != 4)
+            return Clutter.EVENT_PROPAGATE;
+
+        if (this._shouldSkip())
+            return Clutter.EVENT_PROPAGATE;
+
+        let time = event.get_time();
+
+        switch (event.get_gesture_phase()) {
+        case Clutter.TouchpadGesturePhase.BEGIN:
+            let [x, y] = event.get_coords();
+            this.emit('begin', time, x, y);
+            break;
+
+        case Clutter.TouchpadGesturePhase.UPDATE:
+            let [dx, dy] = event.get_gesture_motion_delta();
+
+            if(!(this._touchpadSettings.get_boolean('natural-scroll'))) {
+                dx = -dx;
+                dy = -dy;
+            }
+
+            this.emit('update', time, -dy / TOUCHPAD_BASE_DISTANCE);
+            break;
+
+        case Clutter.TouchpadGesturePhase.END:
+        case Clutter.TouchpadGesturePhase.CANCEL:
+            this.emit('end', time);
+            break;
+        }
+
+        return Clutter.EVENT_STOP;
+    }
+};
+Signals.addSignalMethods(TouchpadSwipeGesture.prototype);
+
+var TouchSwipeGesture = GObject.registerClass({
+    Signals: { 'begin':  { param_types: [GObject.TYPE_UINT, GObject.TYPE_DOUBLE, GObject.TYPE_DOUBLE] },
+               'update': { param_types: [GObject.TYPE_UINT, GObject.TYPE_DOUBLE] },
+               'end':    { param_types: [GObject.TYPE_UINT] },
+               'cancel': { param_types: [GObject.TYPE_UINT] } },
+}, class TouchSwipeGesture extends Clutter.TriggerAction {
+    _init(shouldSkip, n_touch_points, trigger_edge = Clutter.TriggerEdge.NONE) {
+        super._init();
+        this.set_n_touch_points(n_touch_points);
+        this.set_trigger_edge(trigger_edge);
+
+        this._shouldSkip = shouldSkip;
+        this._distance = global.screen_height;
+    }
+
+    vfunc_gesture_begin(actor, point) {
+        if (!super.vfunc_gesture_begin(actor, point))
+            return false;
+
+        if (this._shouldSkip())
+            return false;
+
+        let time = this.get_last_event(point).get_time();
+        let [x, y] = this.get_press_coords(point);
+
+        this.emit('begin', time, x, y);
+        return true;
+    }
+
+    // TODO: track center of the fingers instead of the first one
+    vfunc_gesture_progress(actor, point) {
+        if (point != 0)
+            return;
+
+        let [distance, dx, dy] = this.get_motion_delta(0);
+        let time = this.get_last_event(point).get_time();
+
+        this.emit('update', time, -dy / this._distance);
+    }
+
+    vfunc_gesture_end(actor, point) {
+        let time = this.get_last_event(point).get_time();
+
+        this.emit('end', time);
+    }
+
+    vfunc_gesture_cancel(actor) {
+        let time = Clutter.get_current_event_time();
+
+        this.emit('cancel', time);
+    }
+
+    setDistance(distance) {
+        this._distance = distance;
+    }
+});
+
+var ScrollGesture = class ScrollGesture {
+    constructor(actor, shouldSkip) {
+        this._shouldSkip = shouldSkip;
+        this._began = false;
+
+        actor.connect('scroll-event', this._handleEvent.bind(this));
+    }
+
+    _handleEvent(actor, event) {
+        if (event.type() != Clutter.EventType.SCROLL)
+            return Clutter.EVENT_PROPAGATE;
+
+        if (event.get_scroll_direction() != Clutter.ScrollDirection.SMOOTH)
+            return Clutter.EVENT_PROPAGATE;
+
+        if (event.get_scroll_source() != Clutter.ScrollSource.FINGER && 
event.get_source_device().get_device_type() != Clutter.InputDeviceType.TOUCHPAD_DEVICE)
+            return Clutter.EVENT_PROPAGATE;
+
+        if (this._shouldSkip())
+            return Clutter.EVENT_PROPAGATE;
+
+        let time = event.get_time();
+        let [dx, dy] = event.get_scroll_delta();
+        if (dx == 0 && dy == 0) {
+            this.emit('end', time);
+            this._began = false;
+            return;
+        }
+
+        if (!this._began) {
+            let [x, y] = event.get_coords();
+            this.emit('begin', time, x, y);
+            this._began = true;
+        }
+
+        this.emit('update', time, dy * SCROLL_MULTIPLIER / TOUCHPAD_BASE_DISTANCE);
+
+        return Clutter.EVENT_STOP;
+    }
+};
+Signals.addSignalMethods(ScrollGesture.prototype);
+
+// USAGE:
+//
+// To correctly implement the gesture, the implementer must implement handlers for the
+// following four signals with the following behavior:
+//
+// begin(tracker, monitor)
+//   The handler should check whether a deceleration animation is currently
+//   running. If it is, it should stop the animation (without resetting progress)
+//   and call tracker.continueSwipe(progress). Otherwise it should initialize the gesture
+//   and call tracker.confirmSwipe(canSwipeBack, canSwipeForward, distance, backExtent, forwardExtent).
+//   If nothing is called, the swipe would be ignored.
+//   The parameters are:
+//    * canSwipeBack: whether the tracker should allow to swipe back;
+//    * canSwipeForward: whether the tracker should allow to swipe forward;
+//    * distance: the page size;
+//    * backExtent: can be used to make "back" page longer. Normally this is 0;
+//    * forwardExtent: can be used to make "forward" page longer. Normally this is 0.
+//   Extents should be used for extending one or both page in some cases (such as switching to a
+//   workspace with a fullscreen window). Speed of touchpad swipe and scrolling only depend on
+//   distance, so the speed is consistent with or without extents.
+//   Internally it means progress range is not [-1, 1], but [-(1 + forwardExtent/distance), 1 + 
(backExtent/distance)],
+//   but progress and duration in update() and end() will be normalized.
+//
+// update(tracker, progress)
+//   The handler should set the progress to the given value.
+//
+// end(tracker, duration, isBack)
+//   The handler should animate the progress to 1 if isBack is true, or to -1 otherwise.
+//   When the animation ends, it should change the state, e.g. change the current page
+//   or switch workspace.
+//
+// cancel(tracker, duration)
+//   The tracker should animate the progress back to 0 and forget about the gesture
+//   NOTE: duration can be 0 in some cases, in this case it should reset instantly.
+//
+// ======================================================================================
+//
+// 'enabled'
+//   This property can be used to enable or disable the swipe tracker temporarily.
+
+var SwipeTracker = class {
+    constructor(actor, allowedModes, allowDrag = true, allowScroll = true) {
+        this._allowedModes = allowedModes;
+        this._enabled = true;
+
+        this._reset();
+
+        this._canSwipeBack = true;
+        this._canSwipeForward = true;
+        this._distance = 0;
+        this._backExtent = 0;
+        this._forwardExtent = 0;
+
+        let shouldSkip = () => {
+            ((this._allowedModes & Main.actionMode) == 0 || !this._enabled)
+        };
+
+        let touchpadGesture = new TouchpadSwipeGesture(shouldSkip);
+        touchpadGesture.connect('begin', this._beginGesture.bind(this));
+        touchpadGesture.connect('update', this._updateGesture.bind(this));
+        touchpadGesture.connect('end', this._endGesture.bind(this));
+//        touchpadGesture.connect('cancel', this._cancelGesture.bind(this)); // End the gesture normally for 
touchpads
+
+        let touchGesture = new TouchSwipeGesture(shouldSkip, 4, Clutter.TriggerEdge.NONE);
+        touchGesture.connect('begin', this._beginGesture.bind(this));
+        touchGesture.connect('update', this._updateGesture.bind(this));
+        touchGesture.connect('end', this._endGesture.bind(this));
+        touchGesture.connect('cancel', this._cancelGesture.bind(this));
+        global.stage.add_action(touchGesture);
+        this._touchGesture = touchGesture;
+
+        if (allowDrag) {
+            let dragGesture = new TouchSwipeGesture(shouldSkip, 1, Clutter.TriggerEdge.AFTER);
+            dragGesture.connect('begin', this._beginGesture.bind(this));
+            dragGesture.connect('update', this._updateGesture.bind(this));
+            dragGesture.connect('end', this._endGesture.bind(this));
+            dragGesture.connect('cancel', this._cancelGesture.bind(this));
+            try {
+                actor.add_action(dragGesture);
+            } catch (e) {
+                actor.addAction(dragGesture); // FIXME: wtf is this
+            }
+            this._dragGesture = dragGesture;
+        } else
+            this._dragGesture = null;
+
+        if (allowScroll) {
+            let scrollGesture = new ScrollGesture(actor, shouldSkip);
+            scrollGesture.connect('begin', this._beginGesture.bind(this));
+            scrollGesture.connect('update', this._updateGesture.bind(this));
+            scrollGesture.connect('end', this._endGesture.bind(this));
+        }
+    }
+
+    get enabled() {
+        return this._enabled;
+    }
+
+    set enabled(enabled) {
+        if (this._enabled == enabled)
+            return;
+
+        this._enabled = enabled;
+        if (!enabled && this._state == State.SCROLLING)
+            this._cancel();
+    }
+
+    _reset() {
+        this._state = State.NONE;
+
+        this._prevOffset = 0;
+
+        this._progress = 0;
+
+        this._prevTime = 0;
+        this._velocity = 0;
+
+        this._cancelled = false;
+    }
+
+    _cancel() {
+        this.emit('cancel', 0);
+        this._reset();
+    }
+
+    _beginGesture(gesture, time, x, y) {
+        if (this._state == State.SCROLLING)
+            return;
+
+        this._prevTime = time;
+
+        let rect = new Meta.Rectangle({ x: x, y: y, width: 1, height: 1 });
+        let monitor = global.display.get_monitor_index_for_rect(rect);
+
+        this.emit('begin', monitor);
+    }
+
+    _updateGesture(gesture, time, delta) {
+        if ((this._allowedModes & Main.actionMode) == 0 || !this._enabled)
+            return;
+
+        if (this._state != State.SCROLLING)
+            return;
+
+        this._progress += delta;
+
+        if (time != this._prevTime)
+            this._velocity = delta / (time - this._prevTime);
+
+        if (this._progress > 0 && !this._canSwipeBack)
+            this._progress = 0;
+        if (this._progress < 0 && !this._canSwipeForward)
+            this._progress = 0;
+
+        let maxProgress = (this._progress > 0) ? (1 + this._backExtent / this._distance) : 0;
+        let minProgress = (this._progress < 0) ? -(1 + this._forwardExtent / this._distance) : 0;
+        this._progress = clamp(this._progress, minProgress, maxProgress);
+
+        // Clamp progress to [0,1]
+        let progress = this._progress / (1 + (this._progress > 0 ? this._backExtent : this._forwardExtent) / 
this._distance);
+        this.emit('update', progress);
+
+        this._prevTime = time;
+    }
+
+    _shouldCancel() {
+        if (this._cancelled)
+            return true;
+
+        if (this._progress == 0)
+            return true;
+
+        if (this._progress > 0 && !this._canSwipeBack)
+            return true;
+
+        if (this._progress < 0 && !this._canSwipeForward)
+            return true;
+
+        if (Math.abs(this._velocity) < VELOCITY_THRESHOLD)
+            return Math.abs(this._progress) < CANCEL_AREA;
+
+        return (this._velocity * this._progress < 0);
+    }
+
+    _endGesture(gesture, time) {
+        if ((this._allowedModes & Main.actionMode) == 0 || !this._enabled) {
+//            this._cancel();
+            return;
+        }
+
+        if (this._state != State.SCROLLING)
+            return;
+
+        let cancelled = this._shouldCancel();
+
+        let endProgress = 0;
+        if (!cancelled)
+            endProgress = (this._progress > 0) ? (1 + this._backExtent / this._distance) : -(1 + 
this._forwardExtent / this._distance);
+
+        let velocity = ANIMATION_BASE_VELOCITY;
+        if ((endProgress - this._progress) * this._velocity > 0)
+            velocity = this._velocity;
+
+        let duration = Math.abs((this._progress - endProgress) / velocity * DURATION_MULTIPLIER) / 1000;
+        duration = clamp(duration, MIN_ANIMATION_DURATION, MAX_ANIMATION_DURATION);
+
+        if (cancelled)
+            this.emit('cancel', duration);
+        else
+            this.emit('end', duration, this._progress > 0);
+        this._reset();
+    }
+
+    _cancelGesture(gesture, time) {
+        if (this._state != State.SCROLLING)
+            return;
+
+        this._cancelled = true;
+        this._endGesture(gesture, time);
+    }
+
+    confirmSwipe(canSwipeBack, canSwipeForward, distance, backExtent, forwardExtent) {
+        this._canSwipeBack = canSwipeBack;
+        this._canSwipeForward = canSwipeForward;
+        this._distance = distance;
+        this._backExtent = backExtent;
+        this._forwardExtent = forwardExtent;
+
+        this._touchGesture.setDistance(distance);
+        if (this._dragGesture)
+            this._dragGesture.setDistance(distance);
+
+        this._state = State.SCROLLING;
+    }
+
+    continueSwipe(progress) {
+        this._progress = progress;
+        this._velocity = 0;
+        this._state = State.SCROLLING;
+    }
+
+};
+Signals.addSignalMethods(SwipeTracker.prototype);