heli-agri/lib/loadingstrategy.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/loadingstrategy
 */

import {fromUserExtent, fromUserResolution, toUserExtent} from './proj.js';

/**
 * Strategy function for loading all features with a single request.
 * @param {import("./extent.js").Extent} extent Extent.
 * @param {number} resolution Resolution.
 * @return {Array<import("./extent.js").Extent>} Extents.
 * @api
 */
export function all(extent, resolution) {
  return [[-Infinity, -Infinity, Infinity, Infinity]];
}

/**
 * Strategy function for loading features based on the view's extent and
 * resolution.
 * @param {import("./extent.js").Extent} extent Extent.
 * @param {number} resolution Resolution.
 * @return {Array<import("./extent.js").Extent>} Extents.
 * @api
 */
export function bbox(extent, resolution) {
  return [extent];
}

/**
 * Creates a strategy function for loading features based on a tile grid.
 * @param {import("./tilegrid/TileGrid.js").default} tileGrid Tile grid.
 * @return {function(import("./extent.js").Extent, number, import("./proj.js").Projection): Array<import("./extent.js").Extent>} Loading strategy.
 * @api
 */
export function tile(tileGrid) {
  return (
    /**
     * @param {import("./extent.js").Extent} extent Extent.
     * @param {number} resolution Resolution.
     * @param {import("./proj.js").Projection} projection Projection.
     * @return {Array<import("./extent.js").Extent>} Extents.
     */
    function (extent, resolution, projection) {
      const z = tileGrid.getZForResolution(
        fromUserResolution(resolution, projection)
      );
      const tileRange = tileGrid.getTileRangeForExtentAndZ(
        fromUserExtent(extent, projection),
        z
      );
      /** @type {Array<import("./extent.js").Extent>} */
      const extents = [];
      /** @type {import("./tilecoord.js").TileCoord} */
      const tileCoord = [z, 0, 0];
      for (
        tileCoord[1] = tileRange.minX;
        tileCoord[1] <= tileRange.maxX;
        ++tileCoord[1]
      ) {
        for (
          tileCoord[2] = tileRange.minY;
          tileCoord[2] <= tileRange.maxY;
          ++tileCoord[2]
        ) {
          extents.push(
            toUserExtent(tileGrid.getTileCoordExtent(tileCoord), projection)
          );
        }
      }
      return extents;
    }
  );
}