NativeScript/ui/gestures/gestures.android.ts

import common = require("./gestures-common");
import definition = require("ui/gestures");
import observable = require("data/observable");
import view = require("ui/core/view");
import trace = require("trace");
import utils = require("utils/utils");

global.moduleMerge(common, exports);

const SWIPE_THRESHOLD = 100;
const SWIPE_VELOCITY_THRESHOLD = 100;
const INVALID_POINTER_ID = -1;
const TO_DEGREES = (180 / Math.PI);

export class GesturesObserver extends common.GesturesObserver {
    private _notifyTouch: boolean;
    private _simpleGestureDetector: android.view.GestureDetector;
    private _scaleGestureDetector: android.view.ScaleGestureDetector;
    private _swipeGestureDetector: android.view.GestureDetector;
    private _panGestureDetector: CustomPanGestureDetector;
    private _rotateGestureDetector: CustomRotateGestureDetector;

    private _eventData: TouchGestureEventData;

    private _onTargetLoaded: (data: observable.EventData) => void;
    private _onTargetUnloaded: (data: observable.EventData) => void;

    public observe(type: definition.GestureTypes) {
        if (this.target) {
            this.type = type;
            this._onTargetLoaded = args => {
                if (trace.enabled) {
                    trace.write(this.target + ".target loaded. android:" + this.target._nativeView, "gestures");
                }
                this._attach(this.target, type);
            };
            this._onTargetUnloaded = args => {
                if (trace.enabled) {
                    trace.write(this.target + ".target unloaded. android:" + this.target._nativeView, "gestures");
                }
                this._detach();
            };

            this.target.on(view.View.loadedEvent, this._onTargetLoaded);
            this.target.on(view.View.unloadedEvent, this._onTargetUnloaded);

            if (this.target.isLoaded) {
                this._attach(this.target, type);
            }
        }
    }

    public disconnect() {
        this._detach();

        if (this.target) {
            this.target.off(view.View.loadedEvent, this._onTargetLoaded);
            this.target.off(view.View.unloadedEvent, this._onTargetUnloaded);

            this._onTargetLoaded = null;
            this._onTargetUnloaded = null;
        }
        // clears target, context and callback references
        super.disconnect();
    }

    private _detach() {
        if (trace.enabled) {
            trace.write(this.target + "._detach() android:" + this.target._nativeView, "gestures");
        }

        this._notifyTouch = false
        this._simpleGestureDetector = null;
        this._scaleGestureDetector = null;
        this._swipeGestureDetector = null;
        this._panGestureDetector = null;
        this._rotateGestureDetector = null;
        this._eventData = null;
    }

    private _attach(target: view.View, type: definition.GestureTypes) {
        if (trace.enabled) {
            trace.write(this.target + "._attach() android:" + this.target._nativeView, "gestures");
        }
        this._detach();

        if (type & definition.GestureTypes.tap || type & definition.GestureTypes.doubleTap || type & definition.GestureTypes.longPress) {
            ensureTapAndDoubleTapGestureListenerClass();
            this._simpleGestureDetector = new android.support.v4.view.GestureDetectorCompat(target._context, new TapAndDoubleTapGestureListenerClass(this, this.target, type));
        }

        if (type & definition.GestureTypes.pinch) {
            ensurePinchGestureListenerClass();
            this._scaleGestureDetector = new android.view.ScaleGestureDetector(target._context, new PinchGestureListenerClass(this, this.target));
        }

        if (type & definition.GestureTypes.swipe) {
            ensureSwipeGestureListenerClass();
            this._swipeGestureDetector = new android.support.v4.view.GestureDetectorCompat(target._context, new SwipeGestureListenerClass(this, this.target));
        }

        if (type & definition.GestureTypes.pan) {
            this._panGestureDetector = new CustomPanGestureDetector(this, this.target);
        }

        if (type & definition.GestureTypes.rotation) {
            this._rotateGestureDetector = new CustomRotateGestureDetector(this, this.target);
        }

        if (type & definition.GestureTypes.touch) {
            this._notifyTouch = true;
        }
    }

    public androidOnTouchEvent(motionEvent: android.view.MotionEvent) {
        if (this._notifyTouch) {
            if (!this._eventData) {
                this._eventData = new TouchGestureEventData();
            }

            this._eventData.prepare(this.target, motionEvent);          
            _executeCallback(this, this._eventData);
        }

        if (this._simpleGestureDetector) {
            this._simpleGestureDetector.onTouchEvent(motionEvent);
        }

        if (this._scaleGestureDetector) {
            this._scaleGestureDetector.onTouchEvent(motionEvent);
        }

        if (this._swipeGestureDetector) {
            this._swipeGestureDetector.onTouchEvent(motionEvent);
        }

        if (this._panGestureDetector) {
            this._panGestureDetector.onTouchEvent(motionEvent);
        }

        if (this._rotateGestureDetector) {
            this._rotateGestureDetector.onTouchEvent(motionEvent);
        }
    }
}

function _getArgs(type: definition.GestureTypes, view: view.View, e: android.view.MotionEvent): definition.GestureEventData {
    return <definition.GestureEventData>{
        type: type,
        view: view,
        android: e,
        ios: undefined,
        object: view,
        eventName: definition.toString(type),
    };
}

function _getSwipeArgs(direction: definition.SwipeDirection, view: view.View,
    initialEvent: android.view.MotionEvent, currentEvent: android.view.MotionEvent): definition.SwipeGestureEventData {
    return <definition.SwipeGestureEventData>{
        type: definition.GestureTypes.swipe,
        view: view,
        android: { initial: initialEvent, current: currentEvent },
        direction: direction,
        ios: undefined,
        object: view,
        eventName: definition.toString(definition.GestureTypes.swipe),
    };
}

function _getPanArgs(deltaX: number, deltaY: number, view: view.View, state: common.GestureStateTypes,
    initialEvent: android.view.MotionEvent, currentEvent: android.view.MotionEvent): definition.PanGestureEventData {
    return <definition.PanGestureEventData>{
        type: definition.GestureTypes.pan,
        view: view,
        android: { initial: initialEvent, current: currentEvent },
        deltaX: deltaX,
        deltaY: deltaY,
        ios: undefined,
        object: view,
        eventName: definition.toString(definition.GestureTypes.pan),
        state: state
    };
}

function _executeCallback(observer: GesturesObserver, args: definition.GestureEventData) {
    if (observer && observer.callback) {
        observer.callback.call((<any>observer)._context, args);
    }
}

var TapAndDoubleTapGestureListenerClass;
function ensureTapAndDoubleTapGestureListenerClass() {
    if (TapAndDoubleTapGestureListenerClass) {
        return;
    }

    class TapAndDoubleTapGestureListener extends android.view.GestureDetector.SimpleOnGestureListener {
        private _observer: GesturesObserver;
        private _target: view.View;
        private _type: number;

        constructor(observer: GesturesObserver, target: view.View, type: number) {
            super();

            this._observer = observer;
            this._target = target;
            this._type = type;
            return global.__native(this);
        }

        public onSingleTapUp(motionEvent: android.view.MotionEvent): boolean {
            if (this._type & definition.GestureTypes.tap) {
                var args = _getArgs(definition.GestureTypes.tap, this._target, motionEvent);
                _executeCallback(this._observer, args);
            }
            return true;
        }

        public onDoubleTap(motionEvent: android.view.MotionEvent): boolean {
            if (this._type & definition.GestureTypes.doubleTap) {
                var args = _getArgs(definition.GestureTypes.doubleTap, this._target, motionEvent);
                _executeCallback(this._observer, args);
            }
            return true;
        }

        public onDown(motionEvent: android.view.MotionEvent): boolean {
            return true;
        }

        public onLongPress(motionEvent: android.view.MotionEvent): void {
            if (this._type & definition.GestureTypes.longPress) {
                var args = _getArgs(definition.GestureTypes.longPress, this._target, motionEvent);
                _executeCallback(this._observer, args);
            }
        }
    }

    TapAndDoubleTapGestureListenerClass = TapAndDoubleTapGestureListener;
}

class PinchGestureEventData implements definition.PinchGestureEventData {
    public type = definition.GestureTypes.pinch;
    public eventName = definition.toString(definition.GestureTypes.pinch);
    public ios;

    constructor(
        public view: view.View,
        public android: android.view.ScaleGestureDetector,
        public scale: number,
        public object: any,
        public state: common.GestureStateTypes) {

    }

    getFocusX(): number {
        return this.android.getFocusX() / utils.layout.getDisplayDensity();
    }
    getFocusY(): number {
        return this.android.getFocusY() / utils.layout.getDisplayDensity();
    }
}

var PinchGestureListenerClass;
function ensurePinchGestureListenerClass() {
    if (PinchGestureListenerClass) {
        return;
    }

    class PinchGestureListener extends android.view.ScaleGestureDetector.SimpleOnScaleGestureListener {
        private _observer: GesturesObserver;
        private _target: view.View;
        private _scale: number;
        private _density: number;

        constructor(observer: GesturesObserver, target: view.View) {
            super();

            this._observer = observer;
            this._target = target;
            this._density = utils.layout.getDisplayDensity();

            return global.__native(this);
        }

        public onScaleBegin(detector: android.view.ScaleGestureDetector): boolean {
            this._scale = detector.getScaleFactor();

            var args = new PinchGestureEventData(
                this._target,
                detector,
                this._scale,
                this._target,
                common.GestureStateTypes.began);

            _executeCallback(this._observer, args);

            return true;
        }

        public onScale(detector: android.view.ScaleGestureDetector): boolean {
            this._scale *= detector.getScaleFactor();

            var args = new PinchGestureEventData(
                this._target,
                detector,
                this._scale,
                this._target,
                common.GestureStateTypes.changed);

            _executeCallback(this._observer, args);
            return true;
        }

        public onScaleEnd(detector: android.view.ScaleGestureDetector): void {
            this._scale *= detector.getScaleFactor();

            var args = new PinchGestureEventData(
                this._target,
                detector,
                this._scale,
                this._target,
                common.GestureStateTypes.ended);

            _executeCallback(this._observer, args);
        }
    }

    PinchGestureListenerClass = PinchGestureListener;
}

var SwipeGestureListenerClass;
function ensureSwipeGestureListenerClass() {
    if (SwipeGestureListenerClass) {
        return;
    }

    class SwipeGestureListener extends android.view.GestureDetector.SimpleOnGestureListener {
        private _observer: GesturesObserver;
        private _target: view.View;

        constructor(observer: GesturesObserver, target: view.View) {
            super();

            this._observer = observer;
            this._target = target;

            return global.__native(this);
        }

        public onDown(motionEvent: android.view.MotionEvent): boolean {
            return true;
        }

        public onFling(initialEvent: android.view.MotionEvent, currentEvent: android.view.MotionEvent, velocityX: number, velocityY: number): boolean {
            var result = false;
            var args: definition.SwipeGestureEventData;
            try {
                var deltaY = currentEvent.getY() - initialEvent.getY();
                var deltaX = currentEvent.getX() - initialEvent.getX();

                if (Math.abs(deltaX) > Math.abs(deltaY)) {

                    if (Math.abs(deltaX) > SWIPE_THRESHOLD
                        && Math.abs(velocityX) > SWIPE_VELOCITY_THRESHOLD) {

                        if (deltaX > 0) {

                            args = _getSwipeArgs(definition.SwipeDirection.right, this._target, initialEvent, currentEvent);
                            _executeCallback(this._observer, args);

                            result = true;
                        } else {

                            args = _getSwipeArgs(definition.SwipeDirection.left, this._target, initialEvent, currentEvent);
                            _executeCallback(this._observer, args);

                            result = true;
                        }
                    }

                } else {

                    if (Math.abs(deltaY) > SWIPE_THRESHOLD
                        && Math.abs(velocityY) > SWIPE_VELOCITY_THRESHOLD) {

                        if (deltaY > 0) {

                            args = _getSwipeArgs(definition.SwipeDirection.down, this._target, initialEvent, currentEvent);
                            _executeCallback(this._observer, args);

                            result = true;
                        } else {

                            args = _getSwipeArgs(definition.SwipeDirection.up, this._target, initialEvent, currentEvent);
                            _executeCallback(this._observer, args);

                            result = true;
                        }
                    }
                }
            } catch (ex) {
                //
            }

            return result;
        }
    }

    SwipeGestureListenerClass = SwipeGestureListener;
}

class CustomPanGestureDetector {
    private observer: GesturesObserver;
    private target: view.View;

    private density: number;

    private isTracking: boolean;
    private deltaX: number;
    private deltaY: number;
    private initialX: number;
    private initialY: number;

    private lastEventCache: android.view.MotionEvent;

    constructor(observer: GesturesObserver, target: view.View) {
        this.observer = observer;
        this.target = target;
        this.isTracking = false;

        this.density = utils.layout.getDisplayDensity();
    }

    public onTouchEvent(event: android.view.MotionEvent) {
        switch (event.getActionMasked()) {
            case android.view.MotionEvent.ACTION_UP:
            case android.view.MotionEvent.ACTION_CANCEL:
                this.trackStop(event, false);
                break;

            case android.view.MotionEvent.ACTION_DOWN:
            case android.view.MotionEvent.ACTION_POINTER_DOWN:
            case android.view.MotionEvent.ACTION_POINTER_UP:
                this.trackStop(event, true);
                break;

            case android.view.MotionEvent.ACTION_MOVE:
                if (!this.isTracking) {
                    this.trackStart(event)
                }

                this.trackChange(event);
                break;
        }
        return true;
    }

    private trackStop(currentEvent: android.view.MotionEvent, cahceEvent: boolean) {
        if (this.isTracking) {
            let args = _getPanArgs(this.deltaX, this.deltaY, this.target, common.GestureStateTypes.ended, null, currentEvent);
            _executeCallback(this.observer, args);

            this.deltaX = undefined;
            this.deltaY = undefined;
            this.isTracking = false;
        }

        if (cahceEvent) {
            this.lastEventCache = currentEvent;
        }
        else {
            this.lastEventCache = undefined;
        }
    }

    private trackStart(currentEvent: android.view.MotionEvent) {
        let inital = this.getMotionEventCenter(this.lastEventCache ? this.lastEventCache : currentEvent);
        this.initialX = inital.x;
        this.initialY = inital.y;
        this.isTracking = true;

        let args = _getPanArgs(0, 0, this.target, common.GestureStateTypes.began, null, currentEvent);
        _executeCallback(this.observer, args);
    }

    private trackChange(currentEvent: android.view.MotionEvent) {
        let current = this.getMotionEventCenter(currentEvent);
        this.deltaX = current.x - this.initialX;
        this.deltaY = current.y - this.initialY;

        let args = _getPanArgs(this.deltaX, this.deltaY, this.target, common.GestureStateTypes.changed, null, currentEvent);
        _executeCallback(this.observer, args);
    }

    private getMotionEventCenter(event: android.view.MotionEvent): { x: number, y: number } {
        let count = event.getPointerCount();
        let res = { x: 0, y: 0 };
        for (var i = 0; i < count; i++) {
            res.x += event.getX(i);
            res.y += event.getY(i);
        }

        res.x /= (count * this.density);
        res.y /= (count * this.density);

        return res;
    }
}

class CustomRotateGestureDetector {
    private observer: GesturesObserver;
    private target: view.View;
    private trackedPtrId1: number;
    private trackedPtrId2: number;

    private initalPointersAngle: number;
    private angle: number;

    private get isTracking(): boolean {
        return this.trackedPtrId1 !== INVALID_POINTER_ID && this.trackedPtrId2 !== INVALID_POINTER_ID;
    }

    constructor(observer: GesturesObserver, target: view.View) {
        this.observer = observer;
        this.target = target;

        this.trackedPtrId1 = INVALID_POINTER_ID;
        this.trackedPtrId2 = INVALID_POINTER_ID;
    }

    public onTouchEvent(event: android.view.MotionEvent) {
        let pointerID = event.getPointerId(event.getActionIndex());
        let wasTracking = this.isTracking;

        switch (event.getActionMasked()) {
            case android.view.MotionEvent.ACTION_DOWN:
            case android.view.MotionEvent.ACTION_POINTER_DOWN:
                let assigned = false;
                if (this.trackedPtrId1 === INVALID_POINTER_ID && pointerID !== this.trackedPtrId2) {
                    this.trackedPtrId1 = pointerID;
                    assigned = true;
                }
                else if (this.trackedPtrId2 === INVALID_POINTER_ID && pointerID !== this.trackedPtrId1) {
                    this.trackedPtrId2 = pointerID;
                    assigned = true;
                }

                if (assigned && this.isTracking) {
                    // We have started tracking 2 pointers
                    this.angle = 0;
                    this.initalPointersAngle = this.getPointersAngle(event);
                    this.executeCallback(event, common.GestureStateTypes.began);
                }
                break;

            case android.view.MotionEvent.ACTION_MOVE:
                if (this.isTracking) {
                    this.updateAngle(event);

                    this.executeCallback(event, common.GestureStateTypes.changed);
                }
                break;

            case android.view.MotionEvent.ACTION_UP:
            case android.view.MotionEvent.ACTION_POINTER_UP:
                if (pointerID === this.trackedPtrId1) {
                    this.trackedPtrId1 = INVALID_POINTER_ID;
                }
                else if (pointerID === this.trackedPtrId2) {
                    this.trackedPtrId2 = INVALID_POINTER_ID;
                }

                if (wasTracking && !this.isTracking) {
                    this.executeCallback(event, common.GestureStateTypes.ended);
                }
                break;

            case android.view.MotionEvent.ACTION_CANCEL:
                this.trackedPtrId1 = INVALID_POINTER_ID;
                this.trackedPtrId2 = INVALID_POINTER_ID;
                if (wasTracking) {
                    this.executeCallback(event, common.GestureStateTypes.cancelled);
                }
                break;
        }
        return true;
    }

    private executeCallback(event: android.view.MotionEvent, state: common.GestureStateTypes) {
        var args = <definition.RotationGestureEventData>{
            type: definition.GestureTypes.rotation,
            view: this.target,
            android: event,
            rotation: this.angle,
            ios: undefined,
            object: this.target,
            eventName: definition.toString(definition.GestureTypes.rotation),
            state: state
        }

        _executeCallback(this.observer, args);
    }

    private updateAngle(event: android.view.MotionEvent) {
        var newPointersAngle = this.getPointersAngle(event);
        var result = ((newPointersAngle - this.initalPointersAngle) * TO_DEGREES) % 360;

        if (result < -180) {
            result += 360;
        }
        if (result > 180) {
            result -= 360;
        }

        this.angle = result;
    }

    private getPointersAngle(event: android.view.MotionEvent) {
        let firstX = event.getX(event.findPointerIndex(this.trackedPtrId1));
        let firstY = event.getY(event.findPointerIndex(this.trackedPtrId1));
        let secondX = event.getX(event.findPointerIndex(this.trackedPtrId2));
        let secondY = event.getY(event.findPointerIndex(this.trackedPtrId2));

        return Math.atan2((secondY - firstY), (secondX - firstX));
    }
}

class Pointer implements definition.Pointer {
    public android: number;
    public ios: any = undefined;

    constructor(id: number, private event: android.view.MotionEvent) {
        this.android = id;
    }

    getX(): number {
        return this.event.getX(this.android) / utils.layout.getDisplayDensity();
    }

    getY(): number {
        return this.event.getY(this.android) / utils.layout.getDisplayDensity();
    }
}

class TouchGestureEventData implements definition.TouchGestureEventData {
    eventName: string = definition.toString(definition.GestureTypes.touch);
    type: definition.GestureTypes = definition.GestureTypes.touch;
    ios: any = undefined;
    action: string;
    view: view.View;
    android: android.view.MotionEvent;
    object: any;

    private _activePointers: Array<Pointer>;
    private _allPointers: Array<Pointer>;

    public prepare(view: view.View, e: android.view.MotionEvent) {
        this.view = view;
        this.object = view;
        this.android = e;
        this.action = this.getActionType(e);

        this._activePointers = undefined;
        this._allPointers = undefined;
    }

    getPointerCount(): number {
        return this.android.getPointerCount();
    }

    getActivePointers(): Array<Pointer> {
        // Only one active pointer in Android
        if (!this._activePointers) {
            this._activePointers = [new Pointer(this.android.getActionIndex(), this.android)];
        }
        return this._activePointers;
    }

    getAllPointers(): Array<Pointer> {
        if (!this._allPointers) {
            this._allPointers = [];
            for (var i = 0; i < this.getPointerCount(); i++) {
                this._allPointers.push(new Pointer(i, this.android));
            }
        }

        return this._allPointers;
    }

    getX(): number {
        return this.getActivePointers()[0].getX();
    }

    getY(): number {
        return this.getActivePointers()[0].getY();
    }

    private getActionType(e: android.view.MotionEvent): string {
        switch (e.getActionMasked()) {
            case android.view.MotionEvent.ACTION_DOWN:
            case android.view.MotionEvent.ACTION_POINTER_DOWN:
                return common.TouchAction.down;

            case android.view.MotionEvent.ACTION_MOVE:
                return common.TouchAction.move;

            case android.view.MotionEvent.ACTION_UP:
            case android.view.MotionEvent.ACTION_POINTER_UP:
                return common.TouchAction.up;

            case android.view.MotionEvent.ACTION_CANCEL:
                return common.TouchAction.cancel;
        }

        return "";
    }
}