Fixed ScaleLine when geodesic option is set to true and the map center is beyond the poles. Also added geodesic option to the Scale control. r=tschaub (closes #2600)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@10657 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Control/Scale.js

@@ -23,6 +23,15 @@ OpenLayers.Control.Scale = OpenLayers.Class(OpenLayers.Control, {
      */
     element: null,
     
+    /**
+     * APIProperty: geodesic
+     * {Boolean} Use geodesic measurement. Default is false. The recommended
+     * setting for maps in EPSG:4326 is false, and true EPSG:900913. If set to
+     * true, the scale will be calculated based on the horizontal size of the
+     * pixel in the center of the map viewport.
+     */
+    geodesic: false,
+
     /**
      * Constructor: OpenLayers.Control.Scale
      * 
@@ -56,7 +65,19 @@ OpenLayers.Control.Scale = OpenLayers.Class(OpenLayers.Control, {
      * Method: updateScale
      */
     updateScale: function() {
-        var scale = this.map.getScale();
+        var scale;
+        if(this.geodesic === true) {
+            var units = this.map.getUnits();
+            if(!units) {
+                return;
+            }
+            var inches = OpenLayers.INCHES_PER_UNIT;
+            scale = (this.map.getGeodesicPixelSize().w || 0.000001) *
+                    inches["km"] * OpenLayers.DOTS_PER_INCH;
+        } else {
+            scale = this.map.getScale();
+        }
+            
         if (!scale) {
             return;
         }

lib/OpenLayers/Control/ScaleLine.js

@@ -64,7 +64,10 @@ OpenLayers.Control.ScaleLine = OpenLayers.Class(OpenLayers.Control, {
     
     /**
      * APIProperty: geodesic
-     * {Boolean} Use geodesic measurement. Default is false.
+     * {Boolean} Use geodesic measurement. Default is false. The recommended
+     * setting for maps in EPSG:4326 is false, and true EPSG:900913. If set to
+     * true, the scale will be calculated based on the horizontal size of the
+     * pixel in the center of the map viewport.
      */
     geodesic: false,
 
@@ -165,7 +168,8 @@ OpenLayers.Control.ScaleLine = OpenLayers.Class(OpenLayers.Control, {
         var maxSizeData = this.maxWidth * res * inches[curMapUnits];
         var geodesicRatio = 1;
         if(this.geodesic === true) {
-            var maxSizeGeodesic = this.getGeodesicLength(this.maxWidth);
+            var maxSizeGeodesic = (this.map.getGeodesicPixelSize().w ||
+                0.000001) * this.maxWidth;
             var maxSizeKilometers = maxSizeData / inches["km"];
             geodesicRatio = maxSizeGeodesic / maxSizeKilometers;
             maxSizeData *= geodesicRatio;
@@ -213,26 +217,6 @@ OpenLayers.Control.ScaleLine = OpenLayers.Class(OpenLayers.Control, {
         
     }, 
 
-    /**
-     * Method: getGeodesicLength
-     * 
-     * Parameters:
-     * pixels - {Number} the pixels to get the geodesic length in meters for.
-     */
-    getGeodesicLength: function(pixels) {
-        var map = this.map;
-        var centerPx = map.getPixelFromLonLat(map.getCenter());
-        var bottom = map.getLonLatFromPixel(centerPx.add(0, -pixels / 2));
-        var top = map.getLonLatFromPixel(centerPx.add(0, pixels / 2));
-        var source = map.getProjectionObject();
-        var dest = new OpenLayers.Projection("EPSG:4326");
-        if(!source.equals(dest)) {
-            bottom.transform(source, dest);
-            top.transform(source, dest);
-        }
-        return OpenLayers.Util.distVincenty(bottom, top);
-    },
-
     CLASS_NAME: "OpenLayers.Control.ScaleLine"
 });
 

lib/OpenLayers/Map.js

@@ -2288,6 +2288,39 @@ OpenLayers.Map = OpenLayers.Class({
         px.y = Math.round(px.y);
         return px;
     },
+    
+    /**
+     * Method: getGeodesicPixelSize
+     * 
+     * Parameters:
+     * px - {<OpenLayers.Pixel>} The pixel to get the geodesic length for. If
+     *     not provided, the center pixel of the map viewport will be used.
+     * 
+     * Returns:
+     * {<OpenLayers.Size>} The geodesic size of the pixel in kilometers.
+     */
+    getGeodesicPixelSize: function(px) {
+        var lonlat = px ? this.getLonLatFromPixel(px) : (this.getCenter() ||
+            new OpenLayers.LonLat(0, 0));
+        var res = this.getResolution();
+        var left = lonlat.add(-res / 2, 0);
+        var right = lonlat.add(res / 2, 0);
+        var bottom = lonlat.add(0, -res / 2);
+        var top = lonlat.add(0, res / 2);
+        var dest = new OpenLayers.Projection("EPSG:4326");
+        var source = this.getProjectionObject() || dest;
+        if(!source.equals(dest)) {
+            left.transform(source, dest);
+            right.transform(source, dest);
+            bottom.transform(source, dest);
+            top.transform(source, dest);
+        }
+        
+        return new OpenLayers.Size(
+            OpenLayers.Util.distVincenty(left, right),
+            OpenLayers.Util.distVincenty(bottom, top)
+        );
+    },