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Modify "China" boundary for offset fix plugin #1188

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Modify "China" boundary for offset fix plugin #1188

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665bccf
Modify "China" boundary for offset fix plugin
Artoria2e5 Feb 13, 2017
6dab495
(squash this change) add "classified" line back
Artoria2e5 Feb 14, 2017
75a517b
(squash me) pnpoly-related corrections
Artoria2e5 Feb 14, 2017
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239 changes: 179 additions & 60 deletions plugins/fix-googlemap-china-offset.user.js
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Original file line number Diff line number Diff line change
Expand Up @@ -66,70 +66,189 @@ window.plugin.fixChinaOffset = {};
// The algorithm of transforming WGS-84 to GCJ-02 comes from:
// https://on4wp7.codeplex.com/SourceControl/changeset/view/21483#353936
// There is no official algorithm because it is classified information.

/////////// begin WGS84 to GCJ-02 transformer /////////
var WGS84transformer = window.plugin.fixChinaOffset.WGS84transformer = function() {};
// Krasovsky 1940
//
// a = 6378245.0, 1/f = 298.3
// b = a * (1 - f)
// ee = (a^2 - b^2) / a^2;
WGS84transformer.prototype.a = 6378245.0;
WGS84transformer.prototype.ee = 0.00669342162296594323;

WGS84transformer.prototype.transform = function(wgLat, wgLng) {

if(this.isOutOfChina(wgLat, wgLng))
return {lat: wgLat, lng: wgLng};

dLat = this.transformLat(wgLng - 105.0, wgLat - 35.0);
dLng = this.transformLng(wgLng - 105.0, wgLat - 35.0);
radLat = wgLat / 180.0 * Math.PI;
magic = Math.sin(radLat);
magic = 1 - this.ee * magic * magic;
sqrtMagic = Math.sqrt(magic);
dLat = (dLat * 180.0) / ((this.a * (1 - this.ee)) / (magic * sqrtMagic) * Math.PI);
dLng = (dLng * 180.0) / (this.a / sqrtMagic * Math.cos(radLat) * Math.PI);
mgLat = wgLat + dLat;
mgLng = wgLng + dLng;

return {lat: mgLat, lng: mgLng};

};

WGS84transformer.prototype.isOutOfChina = function(lat, lng) {

if(lng < 72.004 || lng > 137.8347) return true;
if(lat < 0.8293 || lat > 55.8271) return true;
//
// Here we use the PRCoords implementation of this algorithm, which contains
// a more careful yet still rough "China area" check in "insane_is_in_china.js".
// Comments and code style have been adapted, mainly to remove profanity.
// https://github.com/Artoria2e5/PRCoords

/////////// begin WGS84 to GCJ-02 obfuscator /////////
var PRCoords = window.plugin.fixChinaOffset.PRCoords = (function(){
// This set of points roughly illustrates the scope of Google's
// distortion. It has nothing to do with national borders etc.
// Points around Hong Kong/Shenzhen are mapped with a little more precision,
// in hope that it will make agents work a bit more smoothly there.
//
// Edits around these points are welcome.
var POINTS = [
// start hkmo
114.433722, 22.064310,
114.009458, 22.182105,
113.599275, 22.121763,
113.583463, 22.176002,
113.530900, 22.175318,
113.529542, 22.210608,
113.613377, 22.227435,
113.938514, 22.483714,
114.043449, 22.500274,
114.138506, 22.550640,
114.222984, 22.550960,
114.366803, 22.524255,
// end hkmo
115.254019, 20.235733,
121.456316, 26.504442,
123.417261, 30.355685,
124.289197, 39.761103,
126.880509, 41.774504,
127.887261, 41.370015,
128.214602, 41.965359,
129.698745, 42.452788,
130.766139, 42.668534,
131.282487, 45.037051,
133.142361, 44.842986,
134.882453, 48.370596,
132.235531, 47.785403,
130.980075, 47.804860,
130.659026, 48.968383,
127.860252, 50.043973,
125.284310, 53.667091,
120.619316, 53.100485,
119.403751, 50.105903,
117.070862, 49.690388,
115.586019, 47.995542,
118.599613, 47.927785,
118.260771, 46.707335,
113.534759, 44.735134,
112.093739, 45.001999,
111.431259, 43.489381,
105.206324, 41.809510,
96.485703, 42.778692,
94.167961, 44.991668,
91.130430, 45.192938,
90.694601, 47.754437,
87.356293, 49.232005,
85.375791, 48.263928,
85.876055, 47.109272,
82.935423, 47.285727,
81.929808, 45.506317,
79.919457, 45.108122,
79.841455, 42.178752,
73.334917, 40.076332,
73.241805, 39.062331,
79.031902, 34.206413,
78.738395, 31.578004,
80.715812, 30.453822,
81.821692, 30.585965,
85.501663, 28.208463,
92.096061, 27.754241,
94.699781, 29.357171,
96.079442, 29.429559,
98.910308, 27.140660,
97.404057, 24.494701,
99.400021, 23.168966,
100.697449, 21.475914,
102.976870, 22.616482,
105.476997, 23.244292,
108.565621, 20.907735,
107.730505, 18.193406,
110.669856, 17.754550,
]
var HK_LENGTH = 12 // for future use (e.g. with Baidu)
var lats = POINTS.filter(function (_, idx) { return idx % 2 == 1; })
var lngs = POINTS.filter(function (_, idx) { return idx % 2 == 0; })
POINTS = null // not needed anyway...

return false;

};

WGS84transformer.prototype.transformLat = function(x, y) {

var ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
ret += (20.0 * Math.sin(6.0 * x * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0 / 3.0;
ret += (20.0 * Math.sin(y * Math.PI) + 40.0 * Math.sin(y / 3.0 * Math.PI)) * 2.0 / 3.0;
ret += (160.0 * Math.sin(y / 12.0 * Math.PI) + 320 * Math.sin(y * Math.PI / 30.0)) * 2.0 / 3.0;
/// *** pnpoly *** ///
// Wm. Franklin's 8-line point-in-polygon C program
// Copyright (c) 1970-2003, Wm. Randolph Franklin
// Copyright (c) 2017, Mingye Wang (js translation)
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimers.
// 2. Redistributions in binary form must reproduce the above
// copyright notice in the documentation and/or other materials
// provided with the distribution.
// 3. The name of W. Randolph Franklin may not be used to endorse or
// promote products derived from this Software without specific
// prior written permission.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
var pnpoly = function(xs, ys, x, y) {
if (! (xs.length === ys.length))
throw new Error('pnpoly: assert(xs.length === ys.length)')
var inside = 0
for (let i = 0, j = xs.length - 1; i < xs.length; j = i++)
inside ^= (((ys[i] > y) !== (ys[j] > y)) &&
(x < (xs[j] - xs[i]) * (y - ys[i]) / (ys[j] - ys[i]) + xs[i]))
return !!inside
}
/// ^^^ pnpoly ^^^ ///

return ret;

};

WGS84transformer.prototype.transformLng = function(x, y) {
var isInGoogle = function(coords) {
// Yank out South China Sea as it's not distorted.
return coords.lat >= 17.754 && coords.lat <= 55.8271 &&
coords.lng >= 72.004 && coords.lng <= 137.8347 &&
pnpoly(lats, lngs, coords.lat, coords.lng)
}

var ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
ret += (20.0 * Math.sin(6.0 * x * Math.PI) + 20.0 * Math.sin(2.0 * x * Math.PI)) * 2.0 / 3.0;
ret += (20.0 * Math.sin(x * Math.PI) + 40.0 * Math.sin(x / 3.0 * Math.PI)) * 2.0 / 3.0;
ret += (150.0 * Math.sin(x / 12.0 * Math.PI) + 300.0 * Math.sin(x / 30.0 * Math.PI)) * 2.0 / 3.0;
/// Krasovsky 1940 ellipsoid
/// @const
var GCJ_A = 6378245
var GCJ_EE = 0.00669342162296594323 // f = 1/298.3; e^2 = 2*f - f**2

var gcjObfs = function(wgs) {
if(!isInGoogle(wgs)) {
return wgs
}

var x = wgs.lng - 105, y = wgs.lat - 35
// These distortion functions accept (x = lon - 105, y = lat - 35).
// They return distortions in terms of arc lengths, in meters.
var dLat_m = -100 + 2 * x + 3 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x)) +
20 / 3 * (
2 * Math.sin(x * 6 * Math.PI) + 2 * Math.sin(x * 2 * Math.PI) +
2 * Math.sin(y * Math.PI) + 4 * Math.sin(y / 3 * Math.PI) +
16 * Math.sin(y / 12 * Math.PI) + 32 * Math.sin(y / 30 * Math.PI))
var dLon_m = 300 + x + 2 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x)) +
20 / 3 * (
2 * Math.sin(x * 6 * Math.PI) + 2 * Math.sin(x * 2 * Math.PI) +
2 * Math.sin(x * Math.PI) + 4 * Math.sin(x / 3 * Math.PI) +
15 * Math.sin(x / 12 * Math.PI) + 30 * Math.sin(x / 30 * Math.PI))

var radLat = wgs.lat / 180 * Math.PI
var magic = 1 - GCJ_EE * Math.pow(Math.sin(radLat), 2) // just a common expr

// Arc lengths per degree, on the wrong ellipsoid
var lat_deg_arclen = (Math.PI / 180) * (GCJ_A * (1 - GCJ_EE)) * Math.pow(magic, 1.5)
var lon_deg_arclen = (Math.PI / 180) * (GCJ_A * Math.cos(radLat) / Math.sqrt(magic))

return {
lat: wgs.lat + (dLat_m / lat_deg_arclen),
lng: wgs.lng + (dLon_m / lon_deg_arclen),
}
}

return ret;

};
/////////// end WGS84 to GCJ-02 transformer /////////
return {
gcjObfs: gcjObfs,
isInGoogle: isInGoogle,
}
})();

var WGS84toGCJ02 = new WGS84transformer();
/////////// end WGS84 to GCJ-02 obfuscator /////////

/////////// begin overwrited L.Google /////////
window.plugin.fixChinaOffset.L = {};
Expand Down Expand Up @@ -173,7 +292,7 @@ window.plugin.fixChinaOffset.getLatLng = function(pos, type) {

// No offsets in satellite and hybrid maps
if(type !== 'SATELLITE' && type !== 'HYBRID') {
var newPos = WGS84toGCJ02.transform(pos.lat, pos.lng);
var newPos = PRCoords.gcjObfs(pos);
return new google.maps.LatLng(newPos.lat, newPos.lng);
} else {
return new google.maps.LatLng(pos.lat, pos.lng);
Expand Down