heli-agri/lib/interaction/DragRotate.js

HeliAgri is a high-performance, feature-packed library for creating interactive maps on the web. It can display map tiles, vector data and markers loaded from any source on any web page. OpenLayers has been developed to further the use of geographic infor

/**
 * @module ol/interaction/DragRotate
 */
import PointerInteraction from './Pointer.js';
import {FALSE} from '../functions.js';
import {
  altShiftKeysOnly,
  mouseActionButton,
  mouseOnly,
} from '../events/condition.js';
import {disable} from '../rotationconstraint.js';

/**
 * @typedef {Object} Options
 * @property {import("../events/condition.js").Condition} [condition] A function that takes an
 * {@link module:ol/MapBrowserEvent~MapBrowserEvent} and returns a boolean
 * to indicate whether that event should be handled.
 * Default is {@link module:ol/events/condition.altShiftKeysOnly}.
 * @property {number} [duration=250] Animation duration in milliseconds.
 */

/**
 * @classdesc
 * Allows the user to rotate the map by clicking and dragging on the map,
 * normally combined with an {@link module:ol/events/condition} that limits
 * it to when the alt and shift keys are held down.
 *
 * This interaction is only supported for mouse devices.
 * @api
 */
class DragRotate extends PointerInteraction {
  /**
   * @param {Options} [options] Options.
   */
  constructor(options) {
    options = options ? options : {};

    super({
      stopDown: FALSE,
    });

    /**
     * @private
     * @type {import("../events/condition.js").Condition}
     */
    this.condition_ = options.condition ? options.condition : altShiftKeysOnly;

    /**
     * @private
     * @type {number|undefined}
     */
    this.lastAngle_ = undefined;

    /**
     * @private
     * @type {number}
     */
    this.duration_ = options.duration !== undefined ? options.duration : 250;
  }

  /**
   * Handle pointer drag events.
   * @param {import("../MapBrowserEvent.js").default} mapBrowserEvent Event.
   */
  handleDragEvent(mapBrowserEvent) {
    if (!mouseOnly(mapBrowserEvent)) {
      return;
    }

    const map = mapBrowserEvent.map;
    const view = map.getView();
    if (view.getConstraints().rotation === disable) {
      return;
    }
    const size = map.getSize();
    const offset = mapBrowserEvent.pixel;
    const theta = Math.atan2(size[1] / 2 - offset[1], offset[0] - size[0] / 2);
    if (this.lastAngle_ !== undefined) {
      const delta = theta - this.lastAngle_;
      view.adjustRotationInternal(-delta);
    }
    this.lastAngle_ = theta;
  }

  /**
   * Handle pointer up events.
   * @param {import("../MapBrowserEvent.js").default} mapBrowserEvent Event.
   * @return {boolean} If the event was consumed.
   */
  handleUpEvent(mapBrowserEvent) {
    if (!mouseOnly(mapBrowserEvent)) {
      return true;
    }

    const map = mapBrowserEvent.map;
    const view = map.getView();
    view.endInteraction(this.duration_);
    return false;
  }

  /**
   * Handle pointer down events.
   * @param {import("../MapBrowserEvent.js").default} mapBrowserEvent Event.
   * @return {boolean} If the event was consumed.
   */
  handleDownEvent(mapBrowserEvent) {
    if (!mouseOnly(mapBrowserEvent)) {
      return false;
    }

    if (
      mouseActionButton(mapBrowserEvent) &&
      this.condition_(mapBrowserEvent)
    ) {
      const map = mapBrowserEvent.map;
      map.getView().beginInteraction();
      this.lastAngle_ = undefined;
      return true;
    }
    return false;
  }
}

export default DragRotate;