lisn.js/dist/esm/utils/gesture-pointer.js

Simply handle user gestures and actions. Includes widgets.

/**
 * @module Utils
 */

import * as MC from "../globals/minification-constants.js";
import * as MH from "../globals/minification-helpers.js";
import { getVectorDirection } from "./directions.js";
import { getBrowserSupport } from "./event.js";
/**
 * Returns a {@link GestureFragment} for the given events. If the browser
 * supports Pointer events, then only "pointermove" events will be considered.
 * Otherwise, only "mousemove" events will be considered.
 *
 * If there are less than 2 such events in the given list of events, returns
 * `false`.
 *
 * If the gesture is to be considered terminated, e.g. because there is
 * "pointercancel" in the list or buttons other than the primary are pressed,
 * returns `null`.
 *
 * Pointer gestures always require the primary button to be pressed and the
 * resulting intent is always "drag", and `deltaZ` is always 1.
 *
 * @param [options.angleDiffThreshold] See {@link getVectorDirection}
 *
 * @returns `false` if there are less than 2 "pointermove"/"mousemove" events
 * in the list, `null` if the gesture is terminated, otherwise a
 * {@link GestureFragment}.
 *
 * @category Gestures
 */
export const getPointerGestureFragment = (events, options) => {
  if (!MH.isIterableObject(events)) {
    events = [events];
  }
  let isCancelled = false;
  const supports = getBrowserSupport();

  // If the browser supports pointer events, then only take those; otherwise
  // take the mouse events
  const pointerEventClass = supports._pointer ? PointerEvent : MouseEvent;
  const pointerUpType = supports._pointer ? MC.S_POINTERUP : MC.S_MOUSEUP;
  const filteredEvents = MH.filter(events, event => {
    const eType = event.type;
    isCancelled = isCancelled || eType === MC.S_POINTERCANCEL;
    if (eType !== MC.S_CLICK && MH.isInstanceOf(event, pointerEventClass)) {
      // Only events where the primary button is pressed (unless it's a
      // pointerup event, in which case no buttons should be pressed) are
      // considered, otherwise consider it terminated
      isCancelled = isCancelled || eType === pointerUpType && event.buttons !== 0 || eType !== pointerUpType && event.buttons !== 1;
      // we don't handle touch pointer events
      return !MH.isTouchPointerEvent(event);
    }
    return false;
  });
  const numEvents = MH.lengthOf(filteredEvents);
  if (numEvents < 2) {
    return false; // no enough events
  }
  if (isCancelled) {
    return null; // terminated
  }
  const firstEvent = filteredEvents[0];
  const lastEvent = filteredEvents[numEvents - 1];
  if (MH.getPointerType(firstEvent) !== MH.getPointerType(lastEvent)) {
    return null; // different devices, consider it terminated
  }
  const deltaX = lastEvent.clientX - firstEvent.clientX;
  const deltaY = lastEvent.clientY - firstEvent.clientY;
  const direction = getVectorDirection([deltaX, deltaY], options === null || options === void 0 ? void 0 : options.angleDiffThreshold);
  return direction === MC.S_NONE ? false : {
    device: MC.S_POINTER,
    direction,
    intent: MC.S_DRAG,
    deltaX,
    deltaY,
    deltaZ: 1
  };
};
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