/V4/Quickstarts/State-Based Navigation/State-Based Navigation/Infrastructure/Behaviors/RelocatePopupBehavior.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;

using System.Windows;

using System.Windows.Controls.Primitives;

using System.Windows.Interactivity;



namespace StateBasedNavigation.Infrastructure.Behaviors

{

    /// <summary>

    /// Behavior that ensures a popup is located at the bottom-right corner of its parent.

    /// </summary>

    public class RelocatePopupBehavior : Behavior<Popup>

    {

        protected override void OnAttached()

        {

            base.OnAttached();



            this.AssociatedObject.Opened += this.OnPopupOpened;

            this.AssociatedObject.Closed += this.OnPopupClosed;

        }



        protected override void OnDetaching()

        {

            this.AssociatedObject.Opened -= this.OnPopupOpened;

            this.AssociatedObject.Closed -= this.OnPopupClosed;



            this.DetachSizeChangeHandlers();



            base.OnDetaching();

        }



        private void OnPopupOpened(object sender, EventArgs e)

        {

            this.UpdatePopupOffsets();

            this.AttachSizeChangeHandlers();

        }



        private void OnPopupClosed(object sender, EventArgs e)

        {

            this.DetachSizeChangeHandlers();

        }



        private void AttachSizeChangeHandlers()

        {

            var child = this.AssociatedObject.Child as FrameworkElement;

            if (child != null)

            {

                child.SizeChanged += this.OnChildSizeChanged;

            }



            var parent = this.AssociatedObject.Parent as FrameworkElement;

            if (parent != null)

            {

                parent.SizeChanged += this.OnParentSizeChanged;

            }

        }



        private void DetachSizeChangeHandlers()

        {

            var child = this.AssociatedObject.Child as FrameworkElement;

            if (child != null)

            {

                child.SizeChanged -= this.OnChildSizeChanged;

            }



            var parent = this.AssociatedObject.Parent as FrameworkElement;

            if (parent != null)

            {

                parent.SizeChanged -= this.OnParentSizeChanged;

            }

        }



        private void OnChildSizeChanged(object sender, EventArgs e)

        {

            this.UpdatePopupOffsets();

        }



        private void OnParentSizeChanged(object sender, EventArgs e)

        {

            this.UpdatePopupOffsets();

        }



        private void UpdatePopupOffsets()

        {

            if (this.AssociatedObject != null)

            {

                var child = this.AssociatedObject.Child as FrameworkElement;

                var parent = this.AssociatedObject.Parent as FrameworkElement;



                if (child != null && parent != null)

                {

                    var anchor = new Point(parent.ActualWidth, parent.ActualHeight);



                    this.AssociatedObject.HorizontalOffset = anchor.X - child.ActualWidth;

                    this.AssociatedObject.VerticalOffset = anchor.Y - child.ActualHeight;

                }

            }

        }

    }

}