optional filter callback for getChildren function. close #313

src/Container.js

@@ -8,9 +8,29 @@
          * returns a {@link Kinetic.Collection} of direct descendant nodes
          * @method
          * @memberof Kinetic.Container.prototype
+         * @param {Function} [filterFunc] filter function
+         * @returns {Kinetic.Collection}
+         * @example
+         * // get all children<br>
+         * var children = layer.getChildren();<br><br>
+         *
+         * // get only circles<br>
+         * var circles = layer.getChildren(function(node){<br>
+         *    return node.getClassName() === 'Circle';<br>
+         * });
          */
-        getChildren: function() {
-            return this.children;
+        getChildren: function(predicate) {
+            if (!predicate) {
+                return this.children;
+            } else {
+                var results = new Kinetic.Collection();
+                this.children.each(function(child){
+                    if (predicate(child)) {
+                        results.push(child);
+                    }
+                });
+                return results;
+            }
         },
         /**
          * determine if node has children

test/unit/Container-test.js

@@ -1387,6 +1387,50 @@ suite('Container', function() {
 
 
 
+        layer.draw();
+    });
+
+    // ======================================================
+    test('getChildren may use filter function', function() {
+        var stage = addStage();
+        var layer = new Kinetic.Layer();
+        var group = new Kinetic.Group();
+
+        var circle1 = new Kinetic.Circle({
+            x: 200,
+            y: stage.getHeight() / 2,
+            radius: 70,
+            fill: 'blue',
+            stroke: 'black',
+            strokeWidth: 4
+        });
+        var circle2 = circle1.clone();
+        group.add(circle1).add(circle2);
+
+        var rect = new Kinetic.Rect({
+            name : 'test'
+        });
+        group.add(rect);
+
+        var circles = group.getChildren(function(node){
+            return node.getClassName() === 'Circle';
+        });
+        assert.equal(circles.length, 2, 'group has two circle children');
+        assert.equal(circles.indexOf(circle1) > -1, true);
+        assert.equal(circles.indexOf(circle2) > -1, true);
+
+        var testName = group.getChildren(function(node){
+            return node.name() === 'test';
+        });
+
+        assert.equal(testName.length, 1, 'group has one children with test name');
+
+
+        layer.add(group);
+
+
+
+
         layer.draw();
     });