react-native-gesture-handler/lib/module/web/tools/PointerEventManager.js

Experimental implementation of a new declarative API for gesture handling in react-native

function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }

import { EventTypes, MouseButtons, PointerType } from '../interfaces';
import EventManager from './EventManager';
import { isPointerInBounds } from '../utils';
export default class PointerEventManager extends EventManager {
  constructor(...args) {
    super(...args);

    _defineProperty(this, "trackedPointers", new Set());
  }

  setListeners() {
    this.view.addEventListener('pointerdown', event => {
      if (event.pointerType === PointerType.TOUCH) {
        return;
      }

      if (!isPointerInBounds(this.view, {
        x: event.clientX,
        y: event.clientY
      })) {
        return;
      }

      const adaptedEvent = this.mapEvent(event, EventTypes.DOWN);
      const target = event.target;
      target.setPointerCapture(adaptedEvent.pointerId);
      this.markAsInBounds(adaptedEvent.pointerId);
      this.trackedPointers.add(adaptedEvent.pointerId);

      if (++this.activePointersCounter > 1) {
        adaptedEvent.eventType = EventTypes.ADDITIONAL_POINTER_DOWN;
        this.onPointerAdd(adaptedEvent);
      } else {
        this.onPointerDown(adaptedEvent);
      }
    });
    this.view.addEventListener('pointerup', event => {
      if (event.pointerType === PointerType.TOUCH) {
        return;
      } // When we call reset on gesture handlers, it also resets their event managers
      // In some handlers (like RotationGestureHandler) reset is called before all pointers leave view
      // This means, that activePointersCounter will be set to 0, while there are still remaining pointers on view
      // Removing them will end in activePointersCounter going below 0, therefore handlers won't behave properly


      if (this.activePointersCounter === 0) {
        return;
      }

      const adaptedEvent = this.mapEvent(event, EventTypes.UP);
      const target = event.target;
      target.releasePointerCapture(adaptedEvent.pointerId);
      this.markAsOutOfBounds(adaptedEvent.pointerId);
      this.trackedPointers.delete(adaptedEvent.pointerId);

      if (--this.activePointersCounter > 0) {
        adaptedEvent.eventType = EventTypes.ADDITIONAL_POINTER_UP;
        this.onPointerRemove(adaptedEvent);
      } else {
        this.onPointerUp(adaptedEvent);
      }
    });
    this.view.addEventListener('pointermove', event => {
      if (event.pointerType === PointerType.TOUCH) {
        return;
      }

      if (event.pointerType === PointerType.MOUSE && event.buttons !== MouseButtons.LEFT) {
        return;
      }

      const adaptedEvent = this.mapEvent(event, EventTypes.MOVE);
      const inBounds = isPointerInBounds(this.view, {
        x: adaptedEvent.x,
        y: adaptedEvent.y
      });
      const pointerIndex = this.pointersInBounds.indexOf(adaptedEvent.pointerId);

      if (inBounds) {
        if (pointerIndex < 0) {
          adaptedEvent.eventType = EventTypes.ENTER;
          this.onPointerEnter(adaptedEvent);
          this.markAsInBounds(adaptedEvent.pointerId);
        } else {
          this.onPointerMove(adaptedEvent);
        }
      } else {
        if (pointerIndex >= 0) {
          adaptedEvent.eventType = EventTypes.OUT;
          this.onPointerOut(adaptedEvent);
          this.markAsOutOfBounds(adaptedEvent.pointerId);
        } else {
          this.onPointerOutOfBounds(adaptedEvent);
        }
      }
    });
    this.view.addEventListener('pointercancel', event => {
      if (event.pointerType === PointerType.TOUCH) {
        return;
      }

      const adaptedEvent = this.mapEvent(event, EventTypes.CANCEL);
      this.onPointerCancel(adaptedEvent);
      this.markAsOutOfBounds(adaptedEvent.pointerId);
      this.activePointersCounter = 0;
      this.trackedPointers.clear();
    });
    this.view.addEventListener('lostpointercapture', event => {
      const adaptedEvent = this.mapEvent(event, EventTypes.CANCEL);

      if (this.trackedPointers.has(adaptedEvent.pointerId)) {
        // in some cases the `pointerup` event is not fired, but `lostpointercapture` is
        // we simulate the `pointercancel` event here to make sure the gesture handler stops tracking it
        this.onPointerCancel(adaptedEvent);
        this.activePointersCounter = 0;
        this.trackedPointers.clear();
      }
    });
  }

  mapEvent(event, eventType) {
    return {
      x: event.clientX,
      y: event.clientY,
      offsetX: event.offsetX,
      offsetY: event.offsetY,
      pointerId: event.pointerId,
      eventType: eventType,
      pointerType: event.pointerType,
      buttons: event.buttons,
      time: event.timeStamp
    };
  }

  resetManager() {
    super.resetManager();
    this.trackedPointers.clear();
  }

}
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