NativeScript/packages/core/ui/gestures/gestures-common.ts

import type { GesturesObserver as GesturesObserverDefinition } from '.';
import type { View } from '../core/view';
import type { EventData } from '../../data/observable';

export * from './touch-manager';

/**
 * Events emitted during gesture lifecycle
 */
export enum GestureEvents {
	/**
	 * When the gesture is attached to the view
	 * Provides access to the native gesture recognizer for further customization
	 */
	gestureAttached = 'gestureAttached',
	/**
	 * When a touch down was detected
	 */
	touchDown = 'touchDown',
	/**
	 * When a touch up was detected
	 */
	touchUp = 'touchUp',
}

/**
 * Defines an enum with supported gesture types.
 */
export enum GestureTypes {
	/**
	 * Denotes tap (click) gesture.
	 */
	tap = 1 << 0,
	/**
	 * Denotes double tap gesture.
	 */
	doubleTap = 1 << 1,
	/**
	 * Denotes pinch gesture.
	 */
	pinch = 1 << 2,
	/**
	 * Denotes pan gesture.
	 */
	pan = 1 << 3,
	/**
	 * Denotes swipe gesture.
	 */
	swipe = 1 << 4,
	/**
	 * Denotes rotation gesture.
	 */
	rotation = 1 << 5,
	/**
	 * Denotes long press gesture.
	 */
	longPress = 1 << 6,
	/**
	 * Denotes touch action.
	 */
	touch = 1 << 7,
}

/**
 * Defines an enum with supported gesture states.
 */
export enum GestureStateTypes {
	/**
	 * Gesture canceled.
	 */
	cancelled,
	/**
	 * Gesture began.
	 */
	began,
	/**
	 * Gesture changed.
	 */
	changed,
	/**
	 * Gesture ended.
	 */
	ended,
}

/**
 * Defines an enum for swipe gesture direction.
 */
export enum SwipeDirection {
	/**
	 * Denotes right direction for swipe gesture.
	 */
	right = 1 << 0,
	/**
	 * Denotes left direction for swipe gesture.
	 */
	left = 1 << 1,
	/**
	 * Denotes up direction for swipe gesture.
	 */
	up = 1 << 2,
	/**
	 * Denotes down direction for swipe gesture.
	 */
	down = 1 << 3,
}

/**
 * Defines a touch action
 */
export enum TouchAction {
	/**
	 * Down action.
	 */
	down = 'down',

	/**
	 * Up action.
	 */
	up = 'up',

	/**
	 * Move action.
	 */
	move = 'move',

	/**
	 * Cancel action.
	 */
	cancel = 'cancel',
}

/**
 * Provides gesture event data.
 */
export interface GestureEventData extends EventData {
	/**
	 * Gets the type of the gesture.
	 */
	type: GestureTypes;
	/**
	 * Gets the view which originates the gesture.
	 */
	view: View;
	/**
	 * Gets the underlying native iOS specific [UIGestureRecognizer](https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIGestureRecognizer_Class/).
	 */
	ios: any /* UIGestureRecognizer */;
	/**
	 * Gets the underlying native android specific [gesture detector](http://developer.android.com/reference/android/view/GestureDetector.html).
	 */
	android: any;
}

/**
 * Provides gesture event data.
 */
export interface TapGestureEventData extends GestureEventData {
	/**
	 * Gets the number of pointers in the event.
	 */
	getPointerCount(): number;
	/**
	 * Gets the X coordinate of this event inside the view that triggered the event
	 */
	getX(): number;
	/**
	 * Gets the Y coordinate of the event inside the view that triggered the event.
	 */
	getY(): number;
}

/**
 * Provides gesture event data.
 */
export interface TouchGestureEventData extends TapGestureEventData {
	/**
	 * Gets action of the touch. Possible values: 'up', 'move', 'down', 'cancel'
	 */
	action: 'up' | 'move' | 'down' | 'cancel';
	/**
	 * Gets the pointers that triggered the event.
	 * Note: In Android there is aways only one active pointer.
	 */
	getActivePointers(): Array<Pointer>;

	/**
	 * Gets all pointers.
	 */
	getAllPointers(): Array<Pointer>;
}

/**
 * Pointer is an object representing a finger (or other object) that is touching the screen.
 */
export interface Pointer {
	/**
	 * The id of the pointer.
	 */
	android: any;

	/**
	 * The UITouch object associated to the touch
	 */
	ios: any;

	/**
	 * Gets the X coordinate of the pointer inside the view that triggered the event.
	 */
	getX(): number;

	/**
	 * Gets the Y coordinate of the pointer inside the view that triggered the event.
	 */
	getY(): number;

	/**
	 * Gests the X coordinate of the pointer inside the view that triggered the event.
	 * @returns The X coordinate in _Device Pixels_.
	 */
	getXPixels(): number;

	/**
	 * Gets the X coordinate of the pointer inside the view that triggered the event.
	 * @returns The X coordinate in _Device Independent Pixels_.
	 */
	getXDIP(): number;

	/**
	 * Gests the Y coordinate of the pointer inside the view that triggered the event.
	 * @returns The Y coordinate in _Device Pixels_.
	 */
	getYPixels(): number;

	/**
	 * Gets the Y coordinate of the pointer inside the view that triggered the event.
	 * @returns The Y coordinate in _Device Independent Pixels_.
	 */
	getYDIP(): number;
}

/**
 * Provides gesture event data.
 */
export interface GestureEventDataWithState extends GestureEventData {
	state: number;
}

/**
 * Provides gesture event data for pinch gesture.
 */
export interface PinchGestureEventData extends GestureEventDataWithState {
	scale: number;

	getFocusX(): number;
	getFocusY(): number;
}

/**
 * Provides gesture event data for swipe gesture.
 */
export interface SwipeGestureEventData extends GestureEventData {
	direction: SwipeDirection;
}

/**
 * Provides gesture event data for pan gesture.
 */
export interface PanGestureEventData extends GestureEventDataWithState {
	deltaX: number;
	deltaY: number;
}

/**
 * Provides gesture event data for rotation gesture.
 */
export interface RotationGestureEventData extends GestureEventDataWithState {
	rotation: number;
}

/**
 * Returns a string representation of a gesture type.
 * @param type - The singular type of the gesture. Looks for an exact match, so
 *   passing plural types like `GestureTypes.tap & GestureTypes.doubleTap` will
 *   simply return undefined.
 */
export function toString(type: GestureTypes): (typeof GestureTypes)[GestureTypes] | undefined {
	switch (type) {
		case GestureTypes.tap:
			return GestureTypes[GestureTypes.tap];

		case GestureTypes.doubleTap:
			return GestureTypes[GestureTypes.doubleTap];

		case GestureTypes.pinch:
			return GestureTypes[GestureTypes.pinch];

		case GestureTypes.pan:
			return GestureTypes[GestureTypes.pan];

		case GestureTypes.swipe:
			return GestureTypes[GestureTypes.swipe];

		case GestureTypes.rotation:
			return GestureTypes[GestureTypes.rotation];

		case GestureTypes.longPress:
			return GestureTypes[GestureTypes.longPress];

		case GestureTypes.touch:
			return GestureTypes[GestureTypes.touch];
	}
}

/**
 * Returns a gesture type enum value from a string (case insensitive).
 *
 * @param type - A string representation of a single gesture type (e.g. "tap").
 */
export function fromString(type: (typeof GestureTypes)[GestureTypes]): GestureTypes | undefined {
	const t = type.trim().toLowerCase();

	switch (t) {
		case 'tap':
			return GestureTypes.tap;
		case 'doubletap':
			return GestureTypes.doubleTap;
		case 'pinch':
			return GestureTypes.pinch;
		case 'pan':
			return GestureTypes.pan;
		case 'swipe':
			return GestureTypes.swipe;
		case 'rotation':
			return GestureTypes.rotation;
		case 'longpress':
			return GestureTypes.longPress;
		case 'touch':
			return GestureTypes.touch;
	}

	return undefined;
}

export abstract class GesturesObserverBase implements GesturesObserverDefinition {
	private _callback: (args: GestureEventData) => void;
	private _target: View;
	private _context?: any;

	/** This is populated on the first call to observe(). */
	type: GestureTypes;

	public get callback(): (args: GestureEventData) => void {
		return this._callback;
	}

	public get target(): View {
		return this._target;
	}

	public get context() {
		return this._context;
	}

	constructor(target: View, callback: (args: GestureEventData) => void, context?: any) {
		this._target = target;
		this._callback = callback;
		this._context = context;
	}

	public abstract androidOnTouchEvent(motionEvent: android.view.MotionEvent);
	public abstract observe(type: GestureTypes);

	public disconnect() {
		this._target = null;
		this._callback = null;
		this._context = null;
	}
}