/V2.2/trunk/CAL/Desktop/Composite.Presentation/Regions/Behaviors/BindRegionContextToDependencyObjectBehavior.cs

//===================================================================================

// Microsoft patterns & practices

// Composite Application Guidance for Windows Presentation Foundation and Silverlight

//===================================================================================

// Copyright (c) Microsoft Corporation.  All rights reserved.

// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY

// OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT

// LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND

// FITNESS FOR A PARTICULAR PURPOSE.

//===================================================================================

// The example companies, organizations, products, domain names,

// e-mail addresses, logos, people, places, and events depicted

// herein are fictitious.  No association with any real company,

// organization, product, domain name, email address, logo, person,

// places, or events is intended or should be inferred.

//===================================================================================

using System.Collections;

using System.Collections.Specialized;

using System.ComponentModel;

using System.Windows;

using Microsoft.Practices.Composite.Regions;



namespace Microsoft.Practices.Composite.Presentation.Regions.Behaviors

{

    /// <summary>

    /// Defines a behavior that forwards the <see cref="RegionManager.RegionContextProperty"/> 

    /// to the views in the region.

    /// </summary>

    public class BindRegionContextToDependencyObjectBehavior : IRegionBehavior

    {

        /// <summary>

        /// The key of this behavior.

        /// </summary>

        public const string BehaviorKey = "ContextToDependencyObject";



        /// <summary>

        /// Behavior's attached region.

        /// </summary>

        public IRegion Region { get; set; }



        /// <summary>

        /// Attaches the behavior to the specified region.

        /// </summary>

        public void Attach()

        {

            this.Region.Views.CollectionChanged += this.Views_CollectionChanged;

            this.Region.PropertyChanged += this.Region_PropertyChanged;

            SetContextToViews(this.Region.Views, this.Region.Context);

            this.AttachNotifyChangeEvent(this.Region.Views);

        }



        private static void SetContextToViews(IEnumerable views, object context)

        {

            foreach (var view in views)

            {

                DependencyObject dependencyObjectView = view as DependencyObject;

                if (dependencyObjectView != null)

                {

                    ObservableObject<object> contextWrapper = RegionContext.GetObservableContext(dependencyObjectView);

                    contextWrapper.Value = context;

                }

            }

        }



        private void AttachNotifyChangeEvent(IEnumerable views)

        {

            foreach (var view in views)

            {

                var dependencyObject = view as DependencyObject;

                if (dependencyObject != null)

                {

                    ObservableObject<object> viewRegionContext = RegionContext.GetObservableContext(dependencyObject);

                    viewRegionContext.PropertyChanged += this.ViewRegionContext_OnPropertyChangedEvent;

                }

            }

        }



        private void DetachNotifyChangeEvent(IEnumerable views)

        {

            foreach (var view in views)

            {

                var dependencyObject = view as DependencyObject;

                if (dependencyObject != null)

                {

                    ObservableObject<object> viewRegionContext = RegionContext.GetObservableContext(dependencyObject);

                    viewRegionContext.PropertyChanged -= this.ViewRegionContext_OnPropertyChangedEvent;

                }

            }

        }



        private void ViewRegionContext_OnPropertyChangedEvent(object sender, PropertyChangedEventArgs args)

        {

            if (args.PropertyName == "Value")

            {

                var context = (ObservableObject<object>) sender;

                this.Region.Context = context.Value;

            }

        }



        private void Views_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)

        {

            if (e.Action == NotifyCollectionChangedAction.Add)

            {

                SetContextToViews(e.NewItems, this.Region.Context);

                this.AttachNotifyChangeEvent(e.NewItems);

            }

            else if (e.Action == NotifyCollectionChangedAction.Remove && this.Region.Context != null)

            {

                SetContextToViews(e.OldItems, null);

                this.DetachNotifyChangeEvent(e.OldItems);

            }

        }



        private void Region_PropertyChanged(object sender, PropertyChangedEventArgs e)

        {

            if (e.PropertyName == "Context")

            {

                SetContextToViews(this.Region.Views, this.Region.Context);

            }

        }

    }

}