Added optional coordinateConversion method

src/converter.js

@@ -1,12 +1,20 @@
 //converter.js
 var multi = require('multigeojson');
-function getCoordString(coords,res,origin) {
+
+function getCoordString(coords,res,origin,opt) {
   //origin - svg image origin 
   var coordStr = coords.map(function(coord) {
+          if (opt.coordinateConversion) {
+           //CONVERT coords into meters
+           var newCoord = opt.coordinateConversion(coord[1], coord[0]);
+           var newOrigin = opt.coordinateConversion(origin.y, origin.x);
+           return (newCoord[0] - newOrigin[0])/res + ',' + (newOrigin[1] - newCoord[1])/res;
+       }
     return (coord[0] - origin.x)/res + ',' + (origin.y - coord[1])/res;
   });
   return coordStr.join(' ');
 }
+
 function addAttributes(ele,attributes) {
   var part = ele.split('/>')[0];
   for(var key in attributes) {
@@ -19,25 +27,27 @@ function addAttributes(ele,attributes) {
 
 function point(geom,res,origin,opt) {
   var r = opt && opt.r ? opt.r : 1;
-  var path = 'M' + getCoordString([geom.coordinates],res,origin)
+  var path = 'M' + getCoordString([geom.coordinates],res,origin,opt)
     +' m'+ -r+ ',0'+ ' a'+r+','+ r + ' 0 1,1 '+ 2*r + ','+0
     +' a'+r+','+ r + ' 0 1,1 '+ -2*r + ','+0;
   return [path];
 }
+
 function multiPoint(geom,res,origin,opt) {
   var explode = opt && opt.hasOwnProperty('explode') ? opt.explode : false;
   var paths = multi.explode(geom).map(function(single) {
     return point(single,res,origin,opt)[0];
   });
   if(!explode) return [paths.join(' ')];
   return paths;
-
 }
-function lineString(geom,res,origin,otp) {
-  var coords = getCoordString(geom.coordinates,res,origin);
+
+function lineString(geom,res,origin,opt) {
+  var coords = getCoordString(geom.coordinates,res,origin,opt);
   var path = 'M'+ coords;  
   return [path];
 }
+
 function multiLineString(geom,res,origin,opt) {
   var explode = opt && opt.hasOwnProperty('explode') ? opt.explode : false;
   var paths = multi.explode(geom).map(function(single) {
@@ -46,21 +56,23 @@ function multiLineString(geom,res,origin,opt) {
   if(!explode) return [paths.join(' ')];
   return paths;
 }
+
 function polygon(geom,res,origin,opt) {
   var mainStr,holes,holeStr;
-  mainStr = getCoordString(geom.coordinates[0],res,origin);
+  mainStr = getCoordString(geom.coordinates[0],res,origin, opt);
   if (geom.coordinates.length > 1) {
     holes = geom.coordinates.slice(1,geom.coordinates.length);
   }
   var path = 'M'+ mainStr;
   if(holes) {
     for(var i=0;i<holes.length; i++) {
-      path += ' M' +  getCoordString(holes[i],res,origin);
+      path += ' M' +  getCoordString(holes[i],res,origin, opt);
     }
   }
   path += 'Z';
   return [path];
 }
+
 function multiPolygon(geom,res,origin,opt) {
   var explode = opt.hasOwnProperty('explode') ? opt.explode : false;
   var paths = multi.explode(geom).map(function(single) {
@@ -69,6 +81,7 @@ function multiPolygon(geom,res,origin,opt) {
   if(!explode) return [paths.join(' ').replace(/Z/g,'') + 'Z'];
   return paths;
 }
+
 module.exports = {
   Point: point,
   MultiPoint: multiPoint,

src/instance.js

@@ -1,24 +1,31 @@
 var extend = require('xtend'),
 	converter = require('./converter.js');
 
+
+
 //g2svg as geojson2svg (shorthand)
 var g2svg = function(viewportSize,options) {
   if(!viewportSize) return;
   this.viewportSize = viewportSize;
   this.options = options || {};
-  this.mapExtent = this.options.mapExtent ||
-    {
-      left: -20037508.342789244,
-      right: 20037508.342789244,
-      bottom: -20037508.342789244,
-      top: 20037508.342789244
-    };
+  this.mapExtent = this.options.mapExtent 
+    || {'left':-180,'bottom':-90,'right':180,'top':90}; 
   this.res = this.calResolution(this.mapExtent,this.viewportSize);
 };
 g2svg.prototype.calResolution = function(extent,size) {
-  var xres = (extent.right - extent.left)/size.width;
-  var yres = (extent.top - extent.bottom)/size.height;
-  return Math.max(xres,yres);
+    if(this.options.coordinateConversion)  {
+        var newExtentNE = this.options.coordinateConversion(extent.top, extent.right);
+        var newExtentSW = this.options.coordinateConversion(extent.bottom, extent.left);
+        var xres = (newExtentNE[0] - newExtentSW[0])/size.width;
+        var yres = (newExtentNE[1] - newExtentSW[1])/size.height;
+        return Math.max(xres,yres);
+    } else{
+        var xres = (extent.right - extent.left)/size.width;
+         var yres = (extent.top - extent.bottom)/size.height;
+         return Math.max(xres,yres);
+    }
+
+
 };
 g2svg.prototype.convert = function(geojson,options)  {
   var opt = extend(extend({},this.options), options || {});
@@ -55,24 +62,23 @@ g2svg.prototype.convertFeature = function(feature,options) {
 g2svg.prototype.convertGeometry = function(geom,options) {
   if(converter[geom.type]) {
     var opt = extend(extend({},this.options), options || {});
-    var output = opt.output || 'svg';
+    //var explode = opt.hasOwnProperty('explode') ? opt.explode : false;
     var paths = converter[geom.type].call(this,geom,
       this.res,
       {x:this.mapExtent.left,y:this.mapExtent.top},
       opt
     );
     var svgJsons,svgEles;
-    if (output.toLowerCase() == 'svg') {
+    if(opt.output && opt.output.toLowerCase() == 'svg') {
       svgJsons = paths.map(function(path) {
         return pathToSvgJson(path,geom.type,opt.attributes,opt);
       });
       svgEles = svgJsons.map(function(json) {
         return jsonToSvgElement(json,geom.type);
       });
       return svgEles;
-    } else {
-      return paths;
     }
+    return paths;
   } else {
     return;
   }