依赖文件

2025-03-20 17:35:53 +08:00
parent 634fe57349
commit 021ffc6052
1134 changed files with 137518 additions and 132 deletions
@@ -0,0 +1,139 @@
+/**
+#
+# Copyright 2010 Alexandre Gellibert
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+*/
+
+var LatLng = require('./LatLng'),
+  LatLngBounds = require('./LatLngBounds'),
+  GEOCELL_GRID_SIZE = 4,
+  GEOCELL_ALPHABET = '0123456789abcdef';
+
+function computeBox(geocell) {
+  var subcell_lng_span, subcell_lat_span;
+  var xy, x, y;
+  var bbox = _createBoundingBox(90.0, 180.0, -90.0, -180.0);
+  while(geocell.length > 0) {
+    //geoChar = geocell.charAt(i);
+    //pos = GEOCELL_ALPHABET.indexOf(geoChar);
+
+    subcell_lng_span = (bbox.getEast() - bbox.getWest()) / GEOCELL_GRID_SIZE;
+    subcell_lat_span = (bbox.getNorth() - bbox.getSouth()) / GEOCELL_GRID_SIZE;
+
+    xy = _subdiv_xy(geocell.charAt(0));
+    x = xy[0];
+    y = xy[1];
+
+    bbox = _createBoundingBox(bbox.getSouth() + subcell_lat_span * (y + 1),
+      bbox.getWest()  + subcell_lng_span * (x + 1),
+      bbox.getSouth() + subcell_lat_span * y,
+      bbox.getWest()  + subcell_lng_span * x);
+
+    geocell = geocell.substring(1);
+  }
+  var sw = new LatLng(bbox.getSouth(), bbox.getWest());
+  var ne = new LatLng(bbox.getNorth(), bbox.getEast());
+  var bounds = new LatLngBounds(sw, ne);
+  return bounds;
+}
+
+function _createBoundingBox(north, east, south, west) {
+  var north_,south_;
+
+  if(south > north) {
+    south_ = north;
+    north_ = south;
+  } else {
+    south_ = south;
+    north_ = north;
+  }
+  return {
+    northEast: {lat: north_, lng: east},
+    southWest: {lat: south_, lng: west},
+    getNorth: function() {
+      return this.northEast.lat;
+    },
+    getSouth: function() {
+      return this.southWest.lat;
+    },
+    getWest: function() {
+      return this.southWest.lng;
+    },
+    getEast: function() {
+      return this.northEast.lng;
+    }
+  };
+}
+
+
+/**
+ * https://code.google.com/p/geomodel/source/browse/trunk/geo/geocell.py#370
+ * @param latLng
+ * @param resolution
+ * @return
+ */
+function getGeocell(lat, lng, resolution) {
+  var cell = '';
+  var north = 90.0;
+  var south = -90.0;
+  var east = 180.0;
+  var west = -180.0;
+
+  var subcell_lng_span, subcell_lat_span;
+  var x, y;
+  while(cell.length < resolution + 1) {
+    subcell_lng_span = (east - west) / GEOCELL_GRID_SIZE;
+    subcell_lat_span = (north - south) / GEOCELL_GRID_SIZE;
+
+    x = Math.min(Math.floor(GEOCELL_GRID_SIZE * (lng - west) / (east - west)), GEOCELL_GRID_SIZE - 1);
+    y = Math.min(Math.floor(GEOCELL_GRID_SIZE * (lat - south) / (north - south)),GEOCELL_GRID_SIZE - 1);
+    cell += _subdiv_char(x, y);
+
+    south += subcell_lat_span * y;
+    north = south + subcell_lat_span;
+
+    west += subcell_lng_span * x;
+    east = west + subcell_lng_span;
+  }
+  return cell;
+}
+
+
+/*
+ * Returns the (x, y) of the geocell character in the 4x4 alphabet grid.
+ */
+function _subdiv_xy(char) {
+  // NOTE: This only works for grid size 4.
+  var charI = GEOCELL_ALPHABET.indexOf(char);
+  return [(charI & 4) >> 1 | (charI & 1) >> 0,
+    (charI & 8) >> 2 | (charI & 2) >> 1];
+}
+
+/**
+ * Returns the geocell character in the 4x4 alphabet grid at pos. (x, y).
+ * @return
+ */
+function _subdiv_char(posX, posY) {
+  // NOTE: This only works for grid size 4.
+  return GEOCELL_ALPHABET.charAt(
+    (posY & 2) << 2 |
+    (posX & 2) << 1 |
+    (posY & 1) << 1 |
+    (posX & 1) << 0);
+}
+
+module.exports = {
+  computeBox: computeBox,
+  getGeocell: getGeocell
+};