@deck.gl/experimental-layers/dist/es6/tile-layer/utils/viewport-util.js

Experimental layers for deck.gl

function _slicedToArray(arr, i) { return _arrayWithHoles(arr) || _iterableToArrayLimit(arr, i) || _nonIterableRest(); }

function _nonIterableRest() { throw new TypeError("Invalid attempt to destructure non-iterable instance"); }

function _iterableToArrayLimit(arr, i) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"] != null) _i["return"](); } finally { if (_d) throw _e; } } return _arr; }

function _arrayWithHoles(arr) { if (Array.isArray(arr)) return arr; }

function _objectSpread(target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i] != null ? arguments[i] : {}; var ownKeys = Object.keys(source); if (typeof Object.getOwnPropertySymbols === 'function') { ownKeys = ownKeys.concat(Object.getOwnPropertySymbols(source).filter(function (sym) { return Object.getOwnPropertyDescriptor(source, sym).enumerable; })); } ownKeys.forEach(function (key) { _defineProperty(target, key, source[key]); }); } return target; }

function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }

import { lngLatToWorld } from 'viewport-mercator-project';
const TILE_SIZE = 512;

function getBoundingBox(viewport) {
  const corners = [viewport.unproject([0, 0]), viewport.unproject([viewport.width, 0]), viewport.unproject([0, viewport.height]), viewport.unproject([viewport.width, viewport.height])];
  return [corners.reduce((minLng, p) => minLng < p[0] ? minLng : p[0], 180), corners.reduce((minLat, p) => minLat < p[1] ? minLat : p[1], 90), corners.reduce((maxLng, p) => maxLng > p[0] ? maxLng : p[0], -180), corners.reduce((maxLat, p) => maxLat > p[1] ? maxLat : p[1], -90)];
}

function pixelsToTileIndex(a) {
  return Math.floor(a / TILE_SIZE);
}
/**
 * Returns all tile indices in the current viewport. If the current zoom level is smaller
 * than minZoom, return an empty array. If the current zoom level is greater than maxZoom,
 * return tiles that are on maxZoom.
 */


export function getTileIndices(viewport, maxZoom, minZoom) {
  const z = Math.floor(viewport.zoom);

  if (minZoom && z < minZoom) {
    return [];
  }

  viewport = new viewport.constructor(_objectSpread({}, viewport, {
    zoom: z
  }));
  const bbox = getBoundingBox(viewport);

  const _lngLatToWorld$map = lngLatToWorld([bbox[0], bbox[3]], viewport.scale).map(pixelsToTileIndex),
        _lngLatToWorld$map2 = _slicedToArray(_lngLatToWorld$map, 2),
        minX = _lngLatToWorld$map2[0],
        minY = _lngLatToWorld$map2[1];

  const _lngLatToWorld$map3 = lngLatToWorld([bbox[2], bbox[1]], viewport.scale).map(pixelsToTileIndex),
        _lngLatToWorld$map4 = _slicedToArray(_lngLatToWorld$map3, 2),
        maxX = _lngLatToWorld$map4[0],
        maxY = _lngLatToWorld$map4[1];

  const indices = [];

  for (let x = minX; x <= maxX; x++) {
    for (let y = minY; y <= maxY; y++) {
      if (maxZoom && z > maxZoom) {
        indices.push(getAdjustedTileIndex({
          x,
          y,
          z
        }, maxZoom));
      } else {
        indices.push({
          x,
          y,
          z
        });
      }
    }
  }

  return indices;
}
/**
 * Calculates and returns a new tile index {x, y, z}, with z being the given adjustedZ.
 */

function getAdjustedTileIndex(_ref, adjustedZ) {
  let x = _ref.x,
      y = _ref.y,
      z = _ref.z;
  const m = Math.pow(2, z - adjustedZ);
  return {
    x: Math.floor(x / m),
    y: Math.floor(y / m),
    z: adjustedZ
  };
}
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