/Okra.Core/UI/FlyoutPane.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using Windows.Foundation;

using Windows.UI.ApplicationSettings;

using Windows.UI.Core;

using Windows.UI.Xaml;

using Windows.UI.Xaml.Controls;

using Windows.UI.Xaml.Controls.Primitives;

using Windows.UI.Xaml.Media.Animation;



namespace Okra.UI

{

    public class FlyoutPane

    {

        // *** Fields ***



        private Popup popup;

        private ContentControl contentControl;



        private readonly FlyoutEdge flyoutEdge;

        private readonly bool isLightDismissEnabled;



        // *** Events ***



        public event EventHandler Closed;

        public event EventHandler Opened;



        // *** Constructors ***



        public FlyoutPane(FlyoutEdge flyoutEdge = FlyoutEdge.Right, bool isLightDismissEnabled = false)

        {

            this.flyoutEdge = flyoutEdge;

            this.isLightDismissEnabled = isLightDismissEnabled;

        }



        // *** Properties ***



        public FlyoutEdge FlyoutEdge

        {

            get

            {

                return flyoutEdge;

            }

        }



        public bool IsLightDismissEnabled

        {

            get

            {

                return isLightDismissEnabled;

            }

        }



        public bool IsOpen

        {

            get

            {

                if (popup == null)

                    return false;

                else

                    return popup.IsOpen;

            }

        }



        // *** Methods ***



        public void Close()

        {

            // Hide the popup



            popup.IsOpen = false;

        }



        public void Show(object content)

        {

            // Create the popup if required



            if (popup == null)

                CreatePopup();



            // Update the content control



            contentControl.Content = content;

            contentControl.Measure(new Size(double.PositiveInfinity, contentControl.Height));



            // Position the flyout on the screen



            SetFlyoutPosition();



            // Ensure that the popup is displayed



            popup.IsOpen = true;

        }



        // *** Protected Methods ***



        protected virtual void OnClosed()

        {

            EventHandler eventHandler = Closed;



            if (eventHandler != null)

                eventHandler(this, EventArgs.Empty);

        }



        protected virtual void OnOpened()

        {

            EventHandler eventHandler = Opened;



            if (eventHandler != null)

                eventHandler(this, EventArgs.Empty);

        }



        // *** Private Methods ***



        private void CreatePopup()

        {

            // Create the transitions



            TransitionCollection childTransitions = new TransitionCollection();

            childTransitions.Add(new PaneThemeTransition() { Edge =  GetPopupTransitionEdge() });



            // Create a new Popup to display the content



            popup = new Popup()

                {

                    IsLightDismissEnabled = isLightDismissEnabled,

                    ChildTransitions = childTransitions

                };



            // Register for the Opened and Closed events



            popup.Opened += Popup_Opened;

            popup.Closed += Popup_Closed;



            // Create a content control to display the content



            contentControl = new ContentControl()

                {

                    Height = Window.Current.Bounds.Height,

                    HorizontalContentAlignment = HorizontalAlignment.Stretch,

                    VerticalContentAlignment = VerticalAlignment.Stretch

                };



            popup.Child = contentControl;

        }



        private EdgeTransitionLocation GetPopupTransitionEdge()

        {

            switch (flyoutEdge)

            {

                case FlyoutEdge.Left:

                    return EdgeTransitionLocation.Left;

                case FlyoutEdge.Right:

                    return EdgeTransitionLocation.Right;

                default:

                    throw new InvalidOperationException();

            }

        }



        private void SetFlyoutPosition()

        {

            // Position the flyout on the screen



            double width = contentControl.DesiredSize.Width;

            double left = flyoutEdge == FlyoutEdge.Left ? 0.0 : Window.Current.Bounds.Width - width;



            Canvas.SetTop(popup, 0);

            Canvas.SetLeft(popup, left);



            // Make sure that the flyout is always the height of the screen



            contentControl.Height = Window.Current.Bounds.Height;

        }



        private void Window_SizeChanged(object sender, WindowSizeChangedEventArgs e)

        {

            // Reset the flyout position every time the window size changes



            SetFlyoutPosition();

        }



        private void Popup_Closed(object sender, object e)

        {

            // Unsubscribe from the Window.SizeChanged event



            Window.Current.SizeChanged -= Window_SizeChanged;



            // Clear the content control (so the garbage collector can dispose of it)



            contentControl.Content = null;



            // Raise the 'Closed' event



            OnClosed();

        }



        private void Popup_Opened(object sender, object e)

        {

            // Register to the Window.SizeChanged event



            Window.Current.SizeChanged += Window_SizeChanged;



            // Raise the 'Opened' event



            OnOpened();

        }

    }

}