allow an uninitialized Bounds object to be functional (and extendable). thanks for the extra docs cr5 (Closes #929)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@4049 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/BaseTypes/Bounds.js

@@ -5,7 +5,14 @@
 /**
  * Class: OpenLayers.Bounds
  * Instances of this class represent bounding boxes.  Data stored as left,
- * bottom, right, top floats
+ * bottom, right, top floats. All values are initialized to null, however,
+ * you should make sure you set them before using the bounds for anything.
+ * Possible use case:
+ *
+ * > bounds = new OpenLayers.Bounds();
+ * > bounds.extend(new OpenLayers.LonLat(4,5));
+ * > bounds.extend(new OpenLayers.LonLat(5,6));
+ * > bounds.toBBOX() // returns 4,5,5,6
  */
 OpenLayers.Bounds = OpenLayers.Class({
 
@@ -13,25 +20,25 @@ OpenLayers.Bounds = OpenLayers.Class({
      * Property: left
      * {Number}
      */
-    left: 0.0,
+    left: null,
 
     /**
      * Property: bottom
      * {Number}
      */
-    bottom: 0.0,
+    bottom: null,
 
     /**
      * Property: right
      * {Number}
      */
-    right: 0.0,
+    right: null,
 
     /**
      * Property: top
      * {Number}
      */
-    top: 0.0,    
+    top: null,    
 
     /**
      * Constructor: OpenLayers.Bounds
@@ -46,10 +53,18 @@ OpenLayers.Bounds = OpenLayers.Class({
      * top - {Number} The top bounds.
      */
     initialize: function(left, bottom, right, top) {
-        this.left = parseFloat(left);
+        if (left != null) {
-        this.bottom = parseFloat(bottom);
+            this.left = parseFloat(left);
-        this.right = parseFloat(right);
+        }
-        this.top = parseFloat(top);
+        if (bottom != null) {
+            this.bottom = parseFloat(bottom);
+        }
+        if (right != null) {
+            this.right = parseFloat(right);
+        }
+        if (top != null) {
+            this.top = parseFloat(top);
+        }
     },
 
     /**
@@ -237,14 +252,18 @@ OpenLayers.Bounds = OpenLayers.Class({
             }
     
             if (bounds) {
-               this.left = (bounds.left < this.left) ? bounds.left 
+                if ( (this.left == null) || (bounds.left < this.left)) {
-                                                     : this.left;
+                    this.left = bounds.left;
-               this.bottom = (bounds.bottom < this.bottom) ? bounds.bottom 
+                }
-                                                           : this.bottom;
+                if ( (this.bottom == null) || (bounds.bottom < this.bottom) ) {
-               this.right = (bounds.right > this.right) ? bounds.right 
+                    this.bottom = bounds.bottom;
-                                                        : this.right;
+                } 
-               this.top = (bounds.top > this.top) ? bounds.top 
+                if ( (this.right == null) || (bounds.right > this.right) ) {
-                                                  : this.top;
+                    this.right = bounds.right;
+                }
+                if ( (this.top == null) || (bounds.top > this.top) ) { 
+                    this.top = bounds.top;
+                }
             }
         }
     },

tests/BaseTypes/test_Bounds.html

@@ -4,7 +4,17 @@
   <script type="text/javascript"><!--
     var bounds; 
     function test_01_Bounds_constructor (t) {
-        t.plan( 11 );
+        t.plan( 17 );
+        
+        bounds = new OpenLayers.Bounds();
+        t.ok( bounds instanceof OpenLayers.Bounds, "new OpenLayers.Bounds returns Bounds object" );
+        t.eq( bounds.CLASS_NAME, "OpenLayers.Bounds", "bounds.CLASS_NAME is set correctly" );
+        t.eq( bounds.left, null, "bounds.left is initialized to null" );
+        t.eq( bounds.bottom, null, "bounds.bottom is initialized to null" );
+        t.eq( bounds.right, null, "bounds.right is initialized to null" );
+        t.eq( bounds.top, null, "bounds.top is initialized to null" );
+
+
         bounds = new OpenLayers.Bounds(0,2,10,4);
         t.ok( bounds instanceof OpenLayers.Bounds, "new OpenLayers.Bounds returns Bounds object" );
         t.eq( bounds.CLASS_NAME, "OpenLayers.Bounds", "bounds.CLASS_NAME is set correctly" );
@@ -298,11 +308,19 @@
 
 
      function test_16_Bounds_extend(t) {
-        t.plan( 8 );
+        t.plan( 9 );
-
-        var originalBounds = new OpenLayers.Bounds(10,20,50,80);
 
+        var originalBounds = new OpenLayers.Bounds();
         var bounds = originalBounds.clone();
+      //null bounds to start
+        bounds.extend(new OpenLayers.LonLat(4,5));        
+        t.ok(bounds.equals(new OpenLayers.Bounds(4,5,4,5)), "uninitialized bounds can be safely extended");
+
+
+
+        originalBounds = new OpenLayers.Bounds(10,20,50,80);
+
+        bounds = originalBounds.clone();
         
       //null obj
         bounds.extend(null);