NativeScript/nativescript-core/ui/gestures/gestures.android.ts

// Definitions.
import { GestureEventData, SwipeGestureEventData, PanGestureEventData, RotationGestureEventData } from ".";
import { View, EventData } from "../core/view";

// Types.
import {
    GesturesObserverBase, toString, TouchAction, GestureStateTypes, GestureTypes, SwipeDirection
} from "./gestures-common";

// Import layout from utils directly to avoid circular references
import { layout } from "../../utils/utils";

import * as timer from "../../timer";

export * from "./gestures-common";

interface TapAndDoubleTapGestureListener {
    new(observer: GesturesObserver, target: View, type: number): android.view.GestureDetector.SimpleOnGestureListener;
}

let TapAndDoubleTapGestureListener: TapAndDoubleTapGestureListener;
function initializeTapAndDoubleTapGestureListener() {
    if (TapAndDoubleTapGestureListener) {
        return;
    }

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

        private _lastUpTime: number = 0;
        private _tapTimeoutId: number;

        private static DoubleTapTimeout = android.view.ViewConfiguration.getDoubleTapTimeout();

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

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

            return global.__native(this);
        }

        public onSingleTapUp(motionEvent: android.view.MotionEvent): boolean {
            this._handleSingleTap(motionEvent);
            this._lastUpTime = Date.now();

            return true;
        }

        public onDown(motionEvent: android.view.MotionEvent): boolean {
            const tapTime = Date.now();
            if ((tapTime - this._lastUpTime) <= TapAndDoubleTapGestureListenerImpl.DoubleTapTimeout) {
                this._handleDoubleTap(motionEvent);
            }

            return true;
        }

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

        private _handleSingleTap(motionEvent: android.view.MotionEvent): void {
            if (this._target.getGestureObservers(GestureTypes.doubleTap)) {
                this._tapTimeoutId = timer.setTimeout(() => {
                    if (this._type & GestureTypes.tap) {
                        const args = _getArgs(GestureTypes.tap, this._target, motionEvent);
                        _executeCallback(this._observer, args);
                    }
                    timer.clearTimeout(this._tapTimeoutId);
                }, TapAndDoubleTapGestureListenerImpl.DoubleTapTimeout);
            } else {
                if (this._type & GestureTypes.tap) {
                    const args = _getArgs(GestureTypes.tap, this._target, motionEvent);
                    _executeCallback(this._observer, args);
                }
            }
        }

        private _handleDoubleTap(motionEvent: android.view.MotionEvent): void {
            if (this._tapTimeoutId) {
                timer.clearTimeout(this._tapTimeoutId);
            }
            if (this._type & GestureTypes.doubleTap) {
                const args = _getArgs(GestureTypes.doubleTap, this._target, motionEvent);
                _executeCallback(this._observer, args);
            }
        }
    }

    TapAndDoubleTapGestureListener = TapAndDoubleTapGestureListenerImpl;
}

interface PinchGestureListener {
    new(observer: GesturesObserver, target: View): android.view.ScaleGestureDetector.SimpleOnScaleGestureListener;
}

let PinchGestureListener: PinchGestureListener;
function initializePinchGestureListener() {
    if (PinchGestureListener) {
        return;
    }

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

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

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

            return global.__native(this);
        }

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

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

            _executeCallback(this._observer, args);

            return true;
        }

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

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

            _executeCallback(this._observer, args);

            return true;
        }

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

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

            _executeCallback(this._observer, args);
        }
    }

    PinchGestureListener = PinchGestureListenerImpl;
}

interface SwipeGestureListener {
    new(observer: GesturesObserver, target: View): android.view.GestureDetector.SimpleOnGestureListener;
}

let SwipeGestureListener: SwipeGestureListener;
function initializeSwipeGestureListener() {
    if (SwipeGestureListener) {
        return;
    }

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

        constructor(observer: GesturesObserver, target: 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 {
            let result = false;
            let args: SwipeGestureEventData;
            try {
                let deltaY = currentEvent.getY() - initialEvent.getY();
                let 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(SwipeDirection.right, this._target, initialEvent, currentEvent);
                            _executeCallback(this._observer, args);
                            result = true;
                        } else {
                            args = _getSwipeArgs(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(SwipeDirection.down, this._target, initialEvent, currentEvent);
                            _executeCallback(this._observer, args);
                            result = true;
                        } else {
                            args = _getSwipeArgs(SwipeDirection.up, this._target, initialEvent, currentEvent);
                            _executeCallback(this._observer, args);
                            result = true;
                        }
                    }
                }
            } catch (ex) {
                //
            }

            return result;
        }
    }

    SwipeGestureListener = SwipeGestureListenerImpl;
}

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

export function observe(target: View, type: GestureTypes, callback: (args: GestureEventData) => void, context?: any): GesturesObserver {
    const observer = new GesturesObserver(target, callback, context);
    observer.observe(type);

    return observer;
}

export class GesturesObserver extends GesturesObserverBase {
    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: EventData) => void;
    private _onTargetUnloaded: (data: EventData) => void;

    public observe(type: GestureTypes) {
        if (this.target) {
            this.type = type;
            this._onTargetLoaded = args => {
                this._attach(this.target, type);
            };
            this._onTargetUnloaded = args => {
                this._detach();
            };

            this.target.on("loaded", this._onTargetLoaded);
            this.target.on("unloaded", this._onTargetUnloaded);

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

    public disconnect() {
        this._detach();

        if (this.target) {
            this.target.off("loaded", this._onTargetLoaded);
            this.target.off("unloaded", this._onTargetUnloaded);

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

    private _detach() {
        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, type: GestureTypes) {
        this._detach();

        if ((type & GestureTypes.tap) || (type & GestureTypes.doubleTap) || (type & GestureTypes.longPress)) {
            initializeTapAndDoubleTapGestureListener();
            this._simpleGestureDetector = new androidx.core.view.GestureDetectorCompat(target._context, new TapAndDoubleTapGestureListener(this, this.target, type));
        }

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

        if (type & GestureTypes.swipe) {
            initializeSwipeGestureListener();
            this._swipeGestureDetector = new androidx.core.view.GestureDetectorCompat(target._context, new SwipeGestureListener(this, this.target));
        }

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

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

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

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

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

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

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

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

    }

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

class CustomPanGestureDetector {
    private observer: GesturesObserver;
    private target: 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) {
        this.observer = observer;
        this.target = target;
        this.isTracking = false;

        this.density = 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, cacheEvent: boolean) {
        if (this.isTracking) {
            let args = _getPanArgs(this.deltaX, this.deltaY, this.target, GestureStateTypes.ended, null, currentEvent);
            _executeCallback(this.observer, args);

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

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

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

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

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

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

    private getEventCoordinates(event: android.view.MotionEvent): { x: number, y: number } {
        const count = event.getPointerCount();
        if (count === 1) {
            return {
                x: event.getRawX() / this.density,
                y: event.getRawY() / this.density
            };
        } else {
            const offX = event.getRawX() - event.getX();
            const offY = event.getRawY() - event.getY();
            let res = { x: 0, y: 0 };

            for (let i = 0; i < count; i++) {
                res.x += event.getX(i) + offX;
                res.y += event.getY(i) + offY;
            }

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

            return res;
        }
    }
}

class CustomRotateGestureDetector {
    private observer: GesturesObserver;
    private target: 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) {
        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, GestureStateTypes.began);
                }
                break;

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

                    this.executeCallback(event, 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, GestureStateTypes.ended);
                }
                break;

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

        return true;
    }

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

        _executeCallback(this.observer, args);
    }

    private updateAngle(event: android.view.MotionEvent) {
        let newPointersAngle = this.getPointersAngle(event);
        let 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 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) / layout.getDisplayDensity();
    }

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

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

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

    public prepare(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 (let 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 TouchAction.down;

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

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

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

        return "";
    }
}