step-11 Context Selections

* Creating an ISelectionContext with a selection() getter function
* Creating another Context which listens and responds to changes on the
ISelectionContext via a contextSelectionValidator

src/helloWorld/contexts/HelloWorldContext.as

@@ -2,16 +2,25 @@ package helloWorld.contexts
 {
 	import helloWorld.ui.views.HelloWorldView;
 	import flash.display.DisplayObject;
+
+	import core.appEx.core.contexts.ISelectionContext;
 	import core.appEx.core.contexts.IVisualContext;
+	import core.appEx.events.ContextSelectionValidatorEvent;
+	import core.appEx.validators.ContextSelectionValidator;
+	import core.editor.CoreEditor;
 
 	public class HelloWorldContext implements IVisualContext
 	{
 		private var _view       :HelloWorldView;
+		private var contextSelectionValidator   :ContextSelectionValidator;
 
 		public function HelloWorldContext()
 		{
 			_view = new HelloWorldView();
 			_view.text = "Hello World";
+
+			contextSelectionValidator = new ContextSelectionValidator(CoreEditor.contextManager, ISelectionContext, String);
+			contextSelectionValidator.addEventListener(ContextSelectionValidatorEvent.VALID_SELECTION_CHANGED, selectionChangeHandler);
 		}
 
 		public function get view():DisplayObject
@@ -21,7 +30,20 @@ package helloWorld.contexts
 
 		public function dispose():void
 		{
-
+			contextSelectionValidator.removeEventListener(ContextSelectionValidatorEvent.VALID_SELECTION_CHANGED, selectionChangeHandler);
+			contextSelectionValidator.dispose();
 		}
+
+		private function selectionChangeHandler(event:ContextSelectionValidatorEvent):void
+		{
+			_view.text = "";
+
+			var selection:Array = contextSelectionValidator.getValidSelection();
+			for ( var i:int = 0; i < selection.length; i++ )
+			{
+				var item:String = selection[i];
+				_view.text += item + "\n";
+			}
+		}       
 	}
 }

src/helloWorld/contexts/StringListContext.as

@@ -8,6 +8,7 @@ package helloWorld.contexts
 	import core.app.entities.URI;
 	import core.app.operations.ReadFileAndDeserializeOperation;
 	import core.appEx.core.contexts.IOperationManagerContext;
+	import core.appEx.core.contexts.ISelectionContext;
 	import core.appEx.events.OperationManagerEvent;
 	import core.appEx.managers.OperationManager;
 	import core.appEx.operations.SerializeAndWriteFileOperation;
@@ -19,11 +20,12 @@ package helloWorld.contexts
 
 	[Event( type="flash.events.Event", name="change" )]
 
-	public class StringListContext extends EventDispatcher implements IEditorContext, IOperationManagerContext
+	public class StringListContext extends EventDispatcher implements IEditorContext, IOperationManagerContext, ISelectionContext
 	{
 		private var _view       :StringListView;
 
 		private var _dataProvider   :ArrayCollection;
+		private var _selection      :ArrayCollection;
 
 		private var _operationManager   :OperationManager;
 
@@ -40,6 +42,9 @@ package helloWorld.contexts
 
 			_operationManager = new OperationManager();
 			_operationManager.addEventListener(OperationManagerEvent.CHANGE, changeOperationManagerHandler);
+
+			_selection = new ArrayCollection();
+			_view.addEventListener(Event.CHANGE, listChangeHandler);
 		}
 
 		public function get view():DisplayObject
@@ -51,6 +56,13 @@ package helloWorld.contexts
 		{
 			_operationManager.removeEventListener(OperationManagerEvent.CHANGE, changeOperationManagerHandler);
 			_operationManager.dispose();
+
+			_view.removeEventListener(Event.CHANGE, listChangeHandler);
+		}
+
+		private function listChangeHandler( event:Event ):void
+		{
+			_selection.source = _view.selectedItems;
 		}
 
 		public function enable():void
@@ -130,5 +142,7 @@ package helloWorld.contexts
 		public function get dataProvider():ArrayCollection { return _dataProvider; }
 
 		public function get operationManager():OperationManager { return _operationManager; }
+
+		public function get selection():ArrayCollection { return _selection; }
 	}
 }