Adding a distanceTo for pixels. p=bbinet, r=me (closes #3119)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@11491 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/BaseTypes/Pixel.js

@@ -85,6 +85,24 @@ OpenLayers.Pixel = OpenLayers.Class({
         return equals;
     },
 
+    /**
+     * APIMethod: distanceTo
+     * Returns the distance to the pixel point passed in as a parameter.
+     *
+     * Parameters:
+     * px - {<OpenLayers.Pixel>}
+     *
+     * Returns:
+     * {Float} The pixel point passed in as parameter to calculate the
+     *     distance to.
+     */
+    distanceTo:function(px) {
+        return Math.sqrt(
+            Math.pow(this.x - px.x, 2) +
+            Math.pow(this.y - px.y, 2)
+        );
+    },
+
     /**
      * APIMethod: add
      *