add a static function to make a Bounds from a Size. test included.

git-svn-id: http://svn.openlayers.org/trunk/openlayers@531 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Util.js

@@ -490,6 +490,23 @@ OpenLayers.Bounds.fromArray = function(bbox) {
                                  parseFloat(bbox[3]));
 };
 
+/** Alternative constructor that builds a new OpenLayers.Bounds
+*    from an OpenLayers.Size
+* 
+* @constructor
+* 
+* @param {OpenLayers.Size} size
+*
+* @returns New OpenLayers.Bounds object built with top and left set to 0 and
+*           bottom right taken from the passed-in OpenLayers.Size.
+* @type OpenLayers.Bounds
+*/
+OpenLayers.Bounds.fromSize = function(size) {
+    return new OpenLayers.Bounds(0,
+                                 size.h,
+                                 size.w,
+                                 0);
+};
 /**
  * @param {String} quadrant 
  * 

tests/test_Bounds.html

@@ -209,6 +209,20 @@
         t.eq( bounds.top, 4, "bounds.top is set correctly" );
      }
 
+     function test_14_Bounds_fromSize(t) {
+        t.plan( 5 );
+        
+        var height = 15;
+        var width = 16;
+        var size = new OpenLayers.Size(width, height);
+        bounds = OpenLayers.Bounds.fromSize(size);
+        t.ok( bounds instanceof OpenLayers.Bounds, "new OpenLayers.Bounds returns Bounds object" );
+        t.eq( bounds.left, 0, "bounds.left is set correctly" );
+        t.eq( bounds.bottom, height, "bounds.bottom is set correctly" );
+        t.eq( bounds.right, width, "bounds.right is set correctly" );
+        t.eq( bounds.top, 0, "bounds.top is set correctly" );
+     }
+
   // -->
   </script>
 </head>