heli-agri/lib/interaction/Extent.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/Extent
 */
import Event from '../events/Event.js';
import Feature from '../Feature.js';
import MapBrowserEventType from '../MapBrowserEventType.js';
import Point from '../geom/Point.js';
import PointerInteraction from './Pointer.js';
import VectorLayer from '../layer/Vector.js';
import VectorSource from '../source/Vector.js';
import {always} from '../events/condition.js';
import {boundingExtent, getArea} from '../extent.js';
import {
  closestOnSegment,
  distance as coordinateDistance,
  squaredDistance as squaredCoordinateDistance,
  squaredDistanceToSegment,
} from '../coordinate.js';
import {createEditingStyle} from '../style/Style.js';
import {fromExtent as polygonFromExtent} from '../geom/Polygon.js';
import {toUserExtent} from '../proj.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.always}.
 * @property {import("../extent.js").Extent} [extent] Initial extent. Defaults to no
 * initial extent.
 * @property {import("../style/Style.js").StyleLike} [boxStyle]
 * Style for the drawn extent box. Defaults to the `Polygon` editing style
 * documented in {@link module:ol/style/Style~Style}
 * @property {number} [pixelTolerance=10] Pixel tolerance for considering the
 * pointer close enough to a segment or vertex for editing.
 * @property {import("../style/Style.js").StyleLike} [pointerStyle]
 * Style for the cursor used to draw the extent. Defaults to the `Point` editing style
 * documented in {@link module:ol/style/Style~Style}
 * @property {boolean} [wrapX=false] Wrap the drawn extent across multiple maps
 * in the X direction? Only affects visuals, not functionality.
 */

/**
 * @enum {string}
 */
const ExtentEventType = {
  /**
   * Triggered after the extent is changed
   * @event ExtentEvent#extentchanged
   * @api
   */
  EXTENTCHANGED: 'extentchanged',
};

/**
 * @classdesc
 * Events emitted by {@link module:ol/interaction/Extent~Extent} instances are
 * instances of this type.
 */
export class ExtentEvent extends Event {
  /**
   * @param {import("../extent.js").Extent} extent the new extent
   */
  constructor(extent) {
    super(ExtentEventType.EXTENTCHANGED);

    /**
     * The current extent.
     * @type {import("../extent.js").Extent}
     * @api
     */
    this.extent = extent;
  }
}

/***
 * @template Return
 * @typedef {import("../Observable").OnSignature<import("../Observable").EventTypes, import("../events/Event.js").default, Return> &
 *   import("../Observable").OnSignature<import("../ObjectEventType").Types|
 *     'change:active', import("../Object").ObjectEvent, Return> &
 *   import("../Observable").OnSignature<'extentchanged', ExtentEvent, Return> &
 *   import("../Observable").CombinedOnSignature<import("../Observable").EventTypes|import("../ObjectEventType").Types|
 *     'change:active'|'extentchanged', Return>} ExtentOnSignature
 */

/**
 * @classdesc
 * Allows the user to draw a vector box by clicking and dragging on the map.
 * Once drawn, the vector box can be modified by dragging its vertices or edges.
 * This interaction is only supported for mouse devices.
 *
 * @fires ExtentEvent
 * @api
 */
class Extent extends PointerInteraction {
  /**
   * @param {Options} [options] Options.
   */
  constructor(options) {
    options = options || {};

    super(/** @type {import("./Pointer.js").Options} */ (options));

    /***
     * @type {ExtentOnSignature<import("../events").EventsKey>}
     */
    this.on;

    /***
     * @type {ExtentOnSignature<import("../events").EventsKey>}
     */
    this.once;

    /***
     * @type {ExtentOnSignature<void>}
     */
    this.un;

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

    /**
     * Extent of the drawn box
     * @type {import("../extent.js").Extent}
     * @private
     */
    this.extent_ = null;

    /**
     * Handler for pointer move events
     * @type {function (import("../coordinate.js").Coordinate): import("../extent.js").Extent|null}
     * @private
     */
    this.pointerHandler_ = null;

    /**
     * Pixel threshold to snap to extent
     * @type {number}
     * @private
     */
    this.pixelTolerance_ =
      options.pixelTolerance !== undefined ? options.pixelTolerance : 10;

    /**
     * Is the pointer snapped to an extent vertex
     * @type {boolean}
     * @private
     */
    this.snappedToVertex_ = false;

    /**
     * Feature for displaying the visible extent
     * @type {Feature}
     * @private
     */
    this.extentFeature_ = null;

    /**
     * Feature for displaying the visible pointer
     * @type {Feature<Point>}
     * @private
     */
    this.vertexFeature_ = null;

    if (!options) {
      options = {};
    }

    /**
     * Layer for the extentFeature
     * @type {VectorLayer}
     * @private
     */
    this.extentOverlay_ = new VectorLayer({
      source: new VectorSource({
        useSpatialIndex: false,
        wrapX: !!options.wrapX,
      }),
      style: options.boxStyle
        ? options.boxStyle
        : getDefaultExtentStyleFunction(),
      updateWhileAnimating: true,
      updateWhileInteracting: true,
    });

    /**
     * Layer for the vertexFeature
     * @type {VectorLayer}
     * @private
     */
    this.vertexOverlay_ = new VectorLayer({
      source: new VectorSource({
        useSpatialIndex: false,
        wrapX: !!options.wrapX,
      }),
      style: options.pointerStyle
        ? options.pointerStyle
        : getDefaultPointerStyleFunction(),
      updateWhileAnimating: true,
      updateWhileInteracting: true,
    });

    if (options.extent) {
      this.setExtent(options.extent);
    }
  }

  /**
   * @param {import("../pixel.js").Pixel} pixel cursor location
   * @param {import("../Map.js").default} map map
   * @return {import("../coordinate.js").Coordinate|null} snapped vertex on extent
   * @private
   */
  snapToVertex_(pixel, map) {
    const pixelCoordinate = map.getCoordinateFromPixelInternal(pixel);
    const sortByDistance = function (a, b) {
      return (
        squaredDistanceToSegment(pixelCoordinate, a) -
        squaredDistanceToSegment(pixelCoordinate, b)
      );
    };
    const extent = this.getExtentInternal();
    if (extent) {
      //convert extents to line segments and find the segment closest to pixelCoordinate
      const segments = getSegments(extent);
      segments.sort(sortByDistance);
      const closestSegment = segments[0];

      let vertex = closestOnSegment(pixelCoordinate, closestSegment);
      const vertexPixel = map.getPixelFromCoordinateInternal(vertex);

      //if the distance is within tolerance, snap to the segment
      if (coordinateDistance(pixel, vertexPixel) <= this.pixelTolerance_) {
        //test if we should further snap to a vertex
        const pixel1 = map.getPixelFromCoordinateInternal(closestSegment[0]);
        const pixel2 = map.getPixelFromCoordinateInternal(closestSegment[1]);
        const squaredDist1 = squaredCoordinateDistance(vertexPixel, pixel1);
        const squaredDist2 = squaredCoordinateDistance(vertexPixel, pixel2);
        const dist = Math.sqrt(Math.min(squaredDist1, squaredDist2));
        this.snappedToVertex_ = dist <= this.pixelTolerance_;
        if (this.snappedToVertex_) {
          vertex =
            squaredDist1 > squaredDist2 ? closestSegment[1] : closestSegment[0];
        }
        return vertex;
      }
    }
    return null;
  }

  /**
   * @param {import("../MapBrowserEvent.js").default} mapBrowserEvent pointer move event
   * @private
   */
  handlePointerMove_(mapBrowserEvent) {
    const pixel = mapBrowserEvent.pixel;
    const map = mapBrowserEvent.map;

    let vertex = this.snapToVertex_(pixel, map);
    if (!vertex) {
      vertex = map.getCoordinateFromPixelInternal(pixel);
    }
    this.createOrUpdatePointerFeature_(vertex);
  }

  /**
   * @param {import("../extent.js").Extent} extent extent
   * @return {Feature} extent as featrue
   * @private
   */
  createOrUpdateExtentFeature_(extent) {
    let extentFeature = this.extentFeature_;

    if (!extentFeature) {
      if (!extent) {
        extentFeature = new Feature({});
      } else {
        extentFeature = new Feature(polygonFromExtent(extent));
      }
      this.extentFeature_ = extentFeature;
      this.extentOverlay_.getSource().addFeature(extentFeature);
    } else {
      if (!extent) {
        extentFeature.setGeometry(undefined);
      } else {
        extentFeature.setGeometry(polygonFromExtent(extent));
      }
    }
    return extentFeature;
  }

  /**
   * @param {import("../coordinate.js").Coordinate} vertex location of feature
   * @return {Feature} vertex as feature
   * @private
   */
  createOrUpdatePointerFeature_(vertex) {
    let vertexFeature = this.vertexFeature_;
    if (!vertexFeature) {
      vertexFeature = new Feature(new Point(vertex));
      this.vertexFeature_ = vertexFeature;
      this.vertexOverlay_.getSource().addFeature(vertexFeature);
    } else {
      const geometry = vertexFeature.getGeometry();
      geometry.setCoordinates(vertex);
    }
    return vertexFeature;
  }

  /**
   * @param {import("../MapBrowserEvent.js").default} mapBrowserEvent Map browser event.
   * @return {boolean} `false` to stop event propagation.
   */
  handleEvent(mapBrowserEvent) {
    if (!mapBrowserEvent.originalEvent || !this.condition_(mapBrowserEvent)) {
      return true;
    }
    //display pointer (if not dragging)
    if (
      mapBrowserEvent.type == MapBrowserEventType.POINTERMOVE &&
      !this.handlingDownUpSequence
    ) {
      this.handlePointerMove_(mapBrowserEvent);
    }
    //call pointer to determine up/down/drag
    super.handleEvent(mapBrowserEvent);
    //return false to stop propagation
    return false;
  }

  /**
   * Handle pointer down events.
   * @param {import("../MapBrowserEvent.js").default} mapBrowserEvent Event.
   * @return {boolean} If the event was consumed.
   */
  handleDownEvent(mapBrowserEvent) {
    const pixel = mapBrowserEvent.pixel;
    const map = mapBrowserEvent.map;

    const extent = this.getExtentInternal();
    let vertex = this.snapToVertex_(pixel, map);

    //find the extent corner opposite the passed corner
    const getOpposingPoint = function (point) {
      let x_ = null;
      let y_ = null;
      if (point[0] == extent[0]) {
        x_ = extent[2];
      } else if (point[0] == extent[2]) {
        x_ = extent[0];
      }
      if (point[1] == extent[1]) {
        y_ = extent[3];
      } else if (point[1] == extent[3]) {
        y_ = extent[1];
      }
      if (x_ !== null && y_ !== null) {
        return [x_, y_];
      }
      return null;
    };
    if (vertex && extent) {
      const x =
        vertex[0] == extent[0] || vertex[0] == extent[2] ? vertex[0] : null;
      const y =
        vertex[1] == extent[1] || vertex[1] == extent[3] ? vertex[1] : null;

      //snap to point
      if (x !== null && y !== null) {
        this.pointerHandler_ = getPointHandler(getOpposingPoint(vertex));
        //snap to edge
      } else if (x !== null) {
        this.pointerHandler_ = getEdgeHandler(
          getOpposingPoint([x, extent[1]]),
          getOpposingPoint([x, extent[3]])
        );
      } else if (y !== null) {
        this.pointerHandler_ = getEdgeHandler(
          getOpposingPoint([extent[0], y]),
          getOpposingPoint([extent[2], y])
        );
      }
      //no snap - new bbox
    } else {
      vertex = map.getCoordinateFromPixelInternal(pixel);
      this.setExtent([vertex[0], vertex[1], vertex[0], vertex[1]]);
      this.pointerHandler_ = getPointHandler(vertex);
    }
    return true; //event handled; start downup sequence
  }

  /**
   * Handle pointer drag events.
   * @param {import("../MapBrowserEvent.js").default} mapBrowserEvent Event.
   */
  handleDragEvent(mapBrowserEvent) {
    if (this.pointerHandler_) {
      const pixelCoordinate = mapBrowserEvent.coordinate;
      this.setExtent(this.pointerHandler_(pixelCoordinate));
      this.createOrUpdatePointerFeature_(pixelCoordinate);
    }
  }

  /**
   * Handle pointer up events.
   * @param {import("../MapBrowserEvent.js").default} mapBrowserEvent Event.
   * @return {boolean} If the event was consumed.
   */
  handleUpEvent(mapBrowserEvent) {
    this.pointerHandler_ = null;
    //If bbox is zero area, set to null;
    const extent = this.getExtentInternal();
    if (!extent || getArea(extent) === 0) {
      this.setExtent(null);
    }
    return false; //Stop handling downup sequence
  }

  /**
   * Remove the interaction from its current map and attach it to the new map.
   * Subclasses may set up event handlers to get notified about changes to
   * the map here.
   * @param {import("../Map.js").default} map Map.
   */
  setMap(map) {
    this.extentOverlay_.setMap(map);
    this.vertexOverlay_.setMap(map);
    super.setMap(map);
  }

  /**
   * Returns the current drawn extent in the view projection (or user projection if set)
   *
   * @return {import("../extent.js").Extent} Drawn extent in the view projection.
   * @api
   */
  getExtent() {
    return toUserExtent(
      this.getExtentInternal(),
      this.getMap().getView().getProjection()
    );
  }

  /**
   * Returns the current drawn extent in the view projection
   *
   * @return {import("../extent.js").Extent} Drawn extent in the view projection.
   * @api
   */
  getExtentInternal() {
    return this.extent_;
  }

  /**
   * Manually sets the drawn extent, using the view projection.
   *
   * @param {import("../extent.js").Extent} extent Extent
   * @api
   */
  setExtent(extent) {
    //Null extent means no bbox
    this.extent_ = extent ? extent : null;
    this.createOrUpdateExtentFeature_(extent);
    this.dispatchEvent(new ExtentEvent(this.extent_));
  }
}

/**
 * Returns the default style for the drawn bbox
 *
 * @return {import("../style/Style.js").StyleFunction} Default Extent style
 */
function getDefaultExtentStyleFunction() {
  const style = createEditingStyle();
  return function (feature, resolution) {
    return style['Polygon'];
  };
}

/**
 * Returns the default style for the pointer
 *
 * @return {import("../style/Style.js").StyleFunction} Default pointer style
 */
function getDefaultPointerStyleFunction() {
  const style = createEditingStyle();
  return function (feature, resolution) {
    return style['Point'];
  };
}

/**
 * @param {import("../coordinate.js").Coordinate} fixedPoint corner that will be unchanged in the new extent
 * @return {function (import("../coordinate.js").Coordinate): import("../extent.js").Extent} event handler
 */
function getPointHandler(fixedPoint) {
  return function (point) {
    return boundingExtent([fixedPoint, point]);
  };
}

/**
 * @param {import("../coordinate.js").Coordinate} fixedP1 first corner that will be unchanged in the new extent
 * @param {import("../coordinate.js").Coordinate} fixedP2 second corner that will be unchanged in the new extent
 * @return {function (import("../coordinate.js").Coordinate): import("../extent.js").Extent|null} event handler
 */
function getEdgeHandler(fixedP1, fixedP2) {
  if (fixedP1[0] == fixedP2[0]) {
    return function (point) {
      return boundingExtent([fixedP1, [point[0], fixedP2[1]]]);
    };
  }
  if (fixedP1[1] == fixedP2[1]) {
    return function (point) {
      return boundingExtent([fixedP1, [fixedP2[0], point[1]]]);
    };
  }
  return null;
}

/**
 * @param {import("../extent.js").Extent} extent extent
 * @return {Array<Array<import("../coordinate.js").Coordinate>>} extent line segments
 */
function getSegments(extent) {
  return [
    [
      [extent[0], extent[1]],
      [extent[0], extent[3]],
    ],
    [
      [extent[0], extent[3]],
      [extent[2], extent[3]],
    ],
    [
      [extent[2], extent[3]],
      [extent[2], extent[1]],
    ],
    [
      [extent[2], extent[1]],
      [extent[0], extent[1]],
    ],
  ];
}

export default Extent;