openlayers/src/ol/render/Feature.js

/**
 * @module ol/render/Feature
 */
import GeometryType from '../geom/GeometryType.js';
import {
  compose as composeTransform,
  create as createTransform,
} from '../transform.js';
import {
  createOrUpdateFromCoordinate,
  createOrUpdateFromFlatCoordinates,
  getCenter,
  getHeight,
} from '../extent.js';
import {extend} from '../array.js';
import {
  getInteriorPointOfArray,
  getInteriorPointsOfMultiArray,
} from '../geom/flat/interiorpoint.js';
import {get as getProjection} from '../proj.js';
import {interpolatePoint} from '../geom/flat/interpolate.js';
import {linearRingss as linearRingssCenter} from '../geom/flat/center.js';
import {transform2D} from '../geom/flat/transform.js';

/**
 * @type {import("../transform.js").Transform}
 */
const tmpTransform = createTransform();

/**
 * Lightweight, read-only, {@link module:ol/Feature~Feature} and {@link module:ol/geom/Geometry~Geometry} like
 * structure, optimized for vector tile rendering and styling. Geometry access
 * through the API is limited to getting the type and extent of the geometry.
 */
class RenderFeature {
  /**
   * @param {import("../geom/GeometryType.js").default} type Geometry type.
   * @param {Array<number>} flatCoordinates Flat coordinates. These always need
   *     to be right-handed for polygons.
   * @param {Array<number>|Array<Array<number>>} ends Ends or Endss.
   * @param {Object<string, *>} properties Properties.
   * @param {number|string|undefined} id Feature id.
   */
  constructor(type, flatCoordinates, ends, properties, id) {
    /**
     * @private
     * @type {import("../extent.js").Extent|undefined}
     */
    this.extent_;

    /**
     * @private
     * @type {number|string|undefined}
     */
    this.id_ = id;

    /**
     * @private
     * @type {import("../geom/GeometryType.js").default}
     */
    this.type_ = type;

    /**
     * @private
     * @type {Array<number>}
     */
    this.flatCoordinates_ = flatCoordinates;

    /**
     * @private
     * @type {Array<number>}
     */
    this.flatInteriorPoints_ = null;

    /**
     * @private
     * @type {Array<number>}
     */
    this.flatMidpoints_ = null;

    /**
     * @private
     * @type {Array<number>|Array<Array<number>>}
     */
    this.ends_ = ends;

    /**
     * @private
     * @type {Object<string, *>}
     */
    this.properties_ = properties;
  }

  /**
   * Get a feature property by its key.
   * @param {string} key Key
   * @return {*} Value for the requested key.
   * @api
   */
  get(key) {
    return this.properties_[key];
  }

  /**
   * Get the extent of this feature's geometry.
   * @return {import("../extent.js").Extent} Extent.
   * @api
   */
  getExtent() {
    if (!this.extent_) {
      this.extent_ =
        this.type_ === GeometryType.POINT
          ? createOrUpdateFromCoordinate(this.flatCoordinates_)
          : createOrUpdateFromFlatCoordinates(
              this.flatCoordinates_,
              0,
              this.flatCoordinates_.length,
              2
            );
    }
    return this.extent_;
  }

  /**
   * @return {Array<number>} Flat interior points.
   */
  getFlatInteriorPoint() {
    if (!this.flatInteriorPoints_) {
      const flatCenter = getCenter(this.getExtent());
      this.flatInteriorPoints_ = getInteriorPointOfArray(
        this.flatCoordinates_,
        0,
        /** @type {Array<number>} */ (this.ends_),
        2,
        flatCenter,
        0
      );
    }
    return this.flatInteriorPoints_;
  }

  /**
   * @return {Array<number>} Flat interior points.
   */
  getFlatInteriorPoints() {
    if (!this.flatInteriorPoints_) {
      const flatCenters = linearRingssCenter(
        this.flatCoordinates_,
        0,
        /** @type {Array<Array<number>>} */ (this.ends_),
        2
      );
      this.flatInteriorPoints_ = getInteriorPointsOfMultiArray(
        this.flatCoordinates_,
        0,
        /** @type {Array<Array<number>>} */ (this.ends_),
        2,
        flatCenters
      );
    }
    return this.flatInteriorPoints_;
  }

  /**
   * @return {Array<number>} Flat midpoint.
   */
  getFlatMidpoint() {
    if (!this.flatMidpoints_) {
      this.flatMidpoints_ = interpolatePoint(
        this.flatCoordinates_,
        0,
        this.flatCoordinates_.length,
        2,
        0.5
      );
    }
    return this.flatMidpoints_;
  }

  /**
   * @return {Array<number>} Flat midpoints.
   */
  getFlatMidpoints() {
    if (!this.flatMidpoints_) {
      this.flatMidpoints_ = [];
      const flatCoordinates = this.flatCoordinates_;
      let offset = 0;
      const ends = /** @type {Array<number>} */ (this.ends_);
      for (let i = 0, ii = ends.length; i < ii; ++i) {
        const end = ends[i];
        const midpoint = interpolatePoint(flatCoordinates, offset, end, 2, 0.5);
        extend(this.flatMidpoints_, midpoint);
        offset = end;
      }
    }
    return this.flatMidpoints_;
  }

  /**
   * Get the feature identifier.  This is a stable identifier for the feature and
   * is set when reading data from a remote source.
   * @return {number|string|undefined} Id.
   * @api
   */
  getId() {
    return this.id_;
  }

  /**
   * @return {Array<number>} Flat coordinates.
   */
  getOrientedFlatCoordinates() {
    return this.flatCoordinates_;
  }

  /**
   * For API compatibility with {@link module:ol/Feature~Feature}, this method is useful when
   * determining the geometry type in style function (see {@link #getType}).
   * @return {RenderFeature} Feature.
   * @api
   */
  getGeometry() {
    return this;
  }

  /**
   * @param {number} squaredTolerance Squared tolerance.
   * @return {RenderFeature} Simplified geometry.
   */
  getSimplifiedGeometry(squaredTolerance) {
    return this;
  }

  /**
   * Get a transformed and simplified version of the geometry.
   * @abstract
   * @param {number} squaredTolerance Squared tolerance.
   * @param {import("../proj.js").TransformFunction} [opt_transform] Optional transform function.
   * @return {RenderFeature} Simplified geometry.
   */
  simplifyTransformed(squaredTolerance, opt_transform) {
    return this;
  }

  /**
   * Get the feature properties.
   * @return {Object<string, *>} Feature properties.
   * @api
   */
  getProperties() {
    return this.properties_;
  }

  /**
   * @return {number} Stride.
   */
  getStride() {
    return 2;
  }

  /**
   * @return {undefined}
   */
  getStyleFunction() {
    return undefined;
  }

  /**
   * Get the type of this feature's geometry.
   * @return {import("../geom/GeometryType.js").default} Geometry type.
   * @api
   */
  getType() {
    return this.type_;
  }

  /**
   * Transform geometry coordinates from tile pixel space to projected.
   *
   * @param {import("../proj.js").ProjectionLike} projection The data projection
   */
  transform(projection) {
    projection = getProjection(projection);
    const pixelExtent = projection.getExtent();
    const projectedExtent = projection.getWorldExtent();
    if (pixelExtent && projectedExtent) {
      const scale = getHeight(projectedExtent) / getHeight(pixelExtent);
      composeTransform(
        tmpTransform,
        projectedExtent[0],
        projectedExtent[3],
        scale,
        -scale,
        0,
        0,
        0
      );
      transform2D(
        this.flatCoordinates_,
        0,
        this.flatCoordinates_.length,
        2,
        tmpTransform,
        this.flatCoordinates_
      );
    }
  }
  /**
   * @return {Array<number>|Array<Array<number>>} Ends or endss.
   */
  getEnds() {
    return this.ends_;
  }
}

RenderFeature.prototype.getEndss = RenderFeature.prototype.getEnds;

/**
 * @return {Array<number>} Flat coordinates.
 */
RenderFeature.prototype.getFlatCoordinates =
  RenderFeature.prototype.getOrientedFlatCoordinates;

export default RenderFeature;