package/LICENSE.md000644 000765 000024 00000002717 11616254573 014651 0ustar00kkaeferstaff000000 000000 Copyright (c) 2011, Development Seed All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: - Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. - Neither the name "Development Seed" nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. package/package.json000644 000765 000024 00000000322 11616254573 015521 0ustar00kkaeferstaff000000 000000 { "name": "sphericalmercator", "version": "1.0.1", "author": { "name": "MapBox", "url": "http://mapbox.com/", "email": "info@mapbox.com" }, "main": "./sphericalmercator" } package/sphericalmercator.js000644 000765 000024 00000013104 11616254573 017302 0ustar00kkaeferstaff000000 000000 var SphericalMercator = (function(){ // Closures including constants and other precalculated values. var cache = {}, EPSLN = 1.0e-10, D2R = Math.PI / 180, R2D = 180 / Math.PI, // 900913 properties. A = 6378137, MAXEXTENT = 20037508.34; // SphericalMercator constructor: precaches calculations // for fast tile lookups. function SphericalMercator(options) { options = options || {}; this.size = options.size || 256; if (!cache[this.size]) { var size = this.size; var c = cache[this.size] = {}; c.Bc = []; c.Cc = []; c.zc = []; c.Ac = []; for (var d = 0; d < 30; d++) { c.Bc.push(size / 360); c.Cc.push(size / (2 * Math.PI)); c.zc.push(size / 2); c.Ac.push(size); size *= 2; } } this.Bc = cache[this.size].Bc; this.Cc = cache[this.size].Cc; this.zc = cache[this.size].zc; this.Ac = cache[this.size].Ac; }; // Convert lon lat to screen pixel value // // - `ll` {Array} `[lon, lat]` array of geographic coordinates. // - `zoom` {Number} zoom level. SphericalMercator.prototype.px = function(ll, zoom) { var d = this.zc[zoom]; var f = Math.min(Math.max(Math.sin(D2R * ll[1]), -0.9999), 0.9999); var x = Math.round(d + ll[0] * this.Bc[zoom]); var y = Math.round(d + 0.5 * Math.log((1 + f) / (1 - f)) * (-this.Cc[zoom])); (x > this.Ac[zoom]) && (x = this.Ac[zoom]); (y > this.Ac[zoom]) && (y = this.Ac[zoom]); //(x < 0) && (x = 0); //(y < 0) && (y = 0); return [x, y]; }; // Convert screen pixel value to lon lat // // - `px` {Array} `[x, y]` array of geographic coordinates. // - `zoom` {Number} zoom level. SphericalMercator.prototype.ll = function(px, zoom) { var g = (px[1] - this.zc[zoom]) / (-this.Cc[zoom]); var lon = (px[0] - this.zc[zoom]) / this.Bc[zoom]; var lat = R2D * (2 * Math.atan(Math.exp(g)) - 0.5 * Math.PI); return [lon, lat]; }; // Convert tile xyz value to bbox of the form `[w, s, e, n]` // // - `x` {Number} x (longitude) number. // - `y` {Number} y (latitude) number. // - `zoom` {Number} zoom. // - `tms_style` {Boolean} whether to compute using tms-style. // - `srs` {String} projection for resulting bbox (WGS84|900913). // - `return` {Array} bbox array of values in form `[w, s, e, n]`. SphericalMercator.prototype.bbox = function(x, y, zoom, tms_style, srs) { // Convert xyz into bbox with srs WGS84 if (tms_style) { y = (Math.pow(2, zoom) - 1) - y; } // Use +y to make sure it's a number to avoid inadvertent concatenation. var ll = [x * this.size, (+y + 1) * this.size]; // lower left // Use +x to make sure it's a number to avoid inadvertent concatenation. var ur = [(+x + 1) * this.size, y * this.size]; // upper right var bbox = this.ll(ll, zoom).concat(this.ll(ur, zoom)); // If web mercator requested reproject to 900913. if (srs === '900913') { return this.convert(bbox, '900913'); } else { return bbox; } }; // Convert bbox to xyx bounds // // - `bbox` {Number} bbox in the form `[w, s, e, n]`. // - `zoom` {Number} zoom. // - `tms_style` {Boolean} whether to compute using tms-style. // - `srs` {String} projection of input bbox (WGS84|900913). // - `@return` {Object} XYZ bounds containing minX, maxX, minY, maxY properties. SphericalMercator.prototype.xyz = function(bbox, zoom, tms_style, srs) { // If web mercator provided reproject to WGS84. if (srs === '900913') { bbox = this.convert(bbox, 'WGS84'); } var ll = [bbox[0], bbox[1]]; // lower left var ur = [bbox[2], bbox[3]]; // upper right var px_ll = this.px(ll, zoom); var px_ur = this.px(ur, zoom); // Y = 0 for XYZ is the top hence minY uses px_ur[1]. var bounds = { minX: Math.floor(px_ll[0] / this.size), minY: Math.floor(px_ur[1] / this.size), maxX: Math.floor((px_ur[0] - 1) / this.size), maxY: Math.floor((px_ll[1] - 1) / this.size) }; if (tms_style) { var tms = { minY: (Math.pow(2, zoom) - 1) - bounds.maxY, maxY: (Math.pow(2, zoom) - 1) - bounds.minY }; bounds.minY = tms.minY; bounds.maxY = tms.maxY; } return bounds; }; // Convert projection of given bbox. // // - `bbox` {Number} bbox in the form `[w, s, e, n]`. // - `to` {String} projection of output bbox (WGS84|900913). Input bbox // assumed to be the "other" projection. // - `@return` {Object} bbox with reprojected coordinates. SphericalMercator.prototype.convert = function(bbox, to) { if (to === '900913') { return this.forward(bbox.slice(0, 2)).concat(this.forward(bbox.slice(2,4))); } else { return this.inverse(bbox.slice(0, 2)).concat(this.inverse(bbox.slice(2,4))); } }; // Convert lon/lat values to 900913 x/y. SphericalMercator.prototype.forward = function(ll) { var xy = [ A * ll[0] * D2R, A * Math.log(Math.tan((Math.PI*0.25) + (0.5 * ll[1] * D2R))) ]; // if xy value is beyond maxextent (e.g. poles), return maxextent. (xy[0] > MAXEXTENT) && (xy[0] = MAXEXTENT); (xy[0] < -MAXEXTENT) && (xy[0] = -MAXEXTENT); (xy[1] > MAXEXTENT) && (xy[1] = MAXEXTENT); (xy[1] < -MAXEXTENT) && (xy[1] = -MAXEXTENT); return xy; }; // Convert 900913 x/y values to lon/lat. SphericalMercator.prototype.inverse = function(xy) { return [ (xy[0] * R2D / A), ((Math.PI*0.5) - 2.0 * Math.atan(Math.exp(-xy[1] / A))) * R2D ]; }; return SphericalMercator; })(); if (typeof module !== 'undefined' && typeof exports !== 'undefined') { module.exports = exports = SphericalMercator; } package/test/sphericalmercator.test.js000644 000765 000024 00000003276 11616254573 021250 0ustar00kkaeferstaff000000 000000 var sm = new (require('..')), assert = require('assert'); exports['bbox'] = function() { assert.deepEqual( sm.bbox(0,0,0,true,'WGS84'), [-180,-85.05112877980659,180,85.0511287798066], '[0,0,0] converted to proper bbox.' ); assert.deepEqual( sm.bbox(0,0,1,true,'WGS84'), [-180,-85.05112877980659,0,0], '[0,0,1] converted to proper bbox.' ); }; exports['xyz'] = function() { assert.deepEqual( sm.xyz([-180,-85.05112877980659,180,85.0511287798066],0,true,'WGS84'), {minX:0,minY:0,maxX:0, maxY:0}, 'World extents converted to proper tile ranges.' ); assert.deepEqual( sm.xyz([-180,-85.05112877980659,0,0],1,true,'WGS84'), {minX:0,minY:0,maxX:0, maxY:0}, 'SW converted to proper tile ranges.' ); }; exports['convert'] = function() { assert.deepEqual( sm.convert([-180,-85.05112877980659,180,85.0511287798066],'900913'), [-20037508.34,-20037508.34,20037508.34,20037508.34], 'WGS84 converted to 900913.' ); assert.deepEqual( sm.convert([-20037508.34,-20037508.34,20037508.34,20037508.34],'WGS84'), [-179.99999997494382,-85.05112877764509,179.99999997494382,85.05112877764508], '900913 converted to WGS84.' ); }; exports['extents'] = function() { assert.deepEqual( sm.convert([-240,-90,240,90],'900913'), [-20037508.34,-20037508.34,20037508.34,20037508.34], 'Maximum extents enforced on conversion to 900913.' ); assert.deepEqual( sm.xyz([-240,-90,240,90],4,true,'WGS84'), {minX:0,minY:0,maxX:15, maxY:15}, 'Maximum extents enforced on conversion to tile ranges.' ); };