TiltEffect for Windows Metro XAML apps

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.Foundation;
using Windows.UI.Input;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Media.Animation;

namespace SharpGIS.Metro.Controls
{
    /// <summary>
    /// This code provides attached properties for adding a 'tilt' effect to all
    /// controls within a container.
    /// </summary>
    /// <QualityBand>Preview</QualityBand>
    [SuppressMessage("Microsoft.Design", "CA1052:StaticHolderTypesShouldBeSealed", Justification = "Cannot be static and derive from DependencyObject.")]
    public partial class TiltEffect : DependencyObject
    {
        /// <summary>
        /// Cache of previous cache modes. Not using weak references for now.
        /// </summary>
        private static Dictionary<DependencyObject, CacheMode> _originalCacheMode = new Dictionary<DependencyObject, CacheMode>();

        /// <summary>
        /// Maximum amount of tilt, in radians.
        /// </summary>
        private const double MaxAngle = 0.3;

        /// <summary>
        /// Maximum amount of depression, in pixels
        /// </summary>
        private const double MaxDepression = 25;

        /// <summary>
        /// Delay between releasing an element and the tilt release animation
        /// playing.
        /// </summary>
        private static readonly TimeSpan TiltReturnAnimationDelay = TimeSpan.FromMilliseconds(200);

        /// <summary>
        /// Duration of tilt release animation.
        /// </summary>
        private static readonly TimeSpan TiltReturnAnimationDuration = TimeSpan.FromMilliseconds(100);

        /// <summary>
        /// The control that is currently being tilted.
        /// </summary>
        private static FrameworkElement currentTiltElement;

        /// <summary>
        /// The single instance of a storyboard used for all tilts.
        /// </summary>
        private static Storyboard tiltReturnStoryboard;

        /// <summary>
        /// The single instance of an X rotation used for all tilts.
        /// </summary>
        private static DoubleAnimation tiltReturnXAnimation;

        /// <summary>
        /// The single instance of a Y rotation used for all tilts.
        /// </summary>
        private static DoubleAnimation tiltReturnYAnimation;

        /// <summary>
        /// The single instance of a Z depression used for all tilts.
        /// </summary>
        private static DoubleAnimation tiltReturnZAnimation;

        /// <summary>
        /// The center of the tilt element.
        /// </summary>
        private static Point currentTiltElementCenter;

        /// <summary>
        /// Whether the animation just completed was for a 'pause' or not.
        /// </summary>
        private static bool wasPauseAnimation = false;

        /// <summary>
        /// Default list of items that are tiltable.
        /// </summary>
        [SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "Tiltable", Justification = "By design.")]
        [SuppressMessage("Microsoft.Design", "CA1002:DoNotExposeGenericLists", Justification = "Keeping it simple.")]
        public static List<Type> TiltableItems { get; private set; }

        #region Constructor and Static Constructor
        /// <summary>
        /// This is not a constructable class, but it cannot be static because
        /// it derives from DependencyObject.
        /// </summary>
        private TiltEffect()
        {
        }

        /// <summary>
        /// Initialize the static properties
        /// </summary>
        [SuppressMessage("Microsoft.Performance", "CA1810:InitializeReferenceTypeStaticFieldsInline", Justification = "Need to initialize the tiltable items property.")]
        static TiltEffect()
        {
            // The tiltable items list.
            TiltableItems = new List<Type>()
            {
                typeof(ButtonBase),
                typeof(ListBoxItem),
                //typeof(MenuItem),
            };
        }

        #endregion

        #region Dependency properties

        /// <summary>
        /// Whether the tilt effect is enabled on a container (and all its
        /// children).
        /// </summary>
        public static readonly DependencyProperty IsTiltEnabledProperty = DependencyProperty.RegisterAttached(
          "IsTiltEnabled",
          typeof(bool),
          typeof(TiltEffect),
          new PropertyMetadata(false, OnIsTiltEnabledChanged)
          );

        /// <summary>
        /// Gets the IsTiltEnabled dependency property from an object.
        /// </summary>
        /// <param name="source">The object to get the property from.</param>
        /// <returns>The property's value.</returns>
        [SuppressMessage("Microsoft.Design", "CA1062:Validate arguments of public methods", MessageId = "0", Justification = "Standard pattern.")]
        public static bool GetIsTiltEnabled(DependencyObject source)
        {
            return (bool)source.GetValue(IsTiltEnabledProperty);
        }

        /// <summary>
        /// Sets the IsTiltEnabled dependency property on an object.
        /// </summary>
        /// <param name="source">The object to set the property on.</param>
        /// <param name="value">The value to set.</param>
        [SuppressMessage("Microsoft.Design", "CA1062:Validate arguments of public methods", MessageId = "0", Justification = "Standard pattern.")]
        public static void SetIsTiltEnabled(DependencyObject source, bool value)
        {
            source.SetValue(IsTiltEnabledProperty, value);
        }

        /// <summary>
        /// Suppresses the tilt effect on a single control that would otherwise
        /// be tilted.
        /// </summary>
        public static readonly DependencyProperty SuppressTiltProperty = DependencyProperty.RegisterAttached(
          "SuppressTilt",
          typeof(bool),
          typeof(TiltEffect),
          null
          );

        /// <summary>
        /// Gets the SuppressTilt dependency property from an object.
        /// </summary>
        /// <param name="source">The object to get the property from.</param>
        /// <returns>The property's value.</returns>
        [SuppressMessage("Microsoft.Design", "CA1062:Validate arguments of public methods", MessageId = "0", Justification = "Standard pattern.")]
        public static bool GetSuppressTilt(DependencyObject source)
        {
            return (bool)source.GetValue(SuppressTiltProperty);
        }

        /// <summary>
        /// Sets the SuppressTilt dependency property from an object.
        /// </summary>
        /// <param name="source">The object to get the property from.</param>
        /// <param name="value">The property's value.</param>
        [SuppressMessage("Microsoft.Design", "CA1062:Validate arguments of public methods", MessageId = "0", Justification = "Standard pattern.")]
        public static void SetSuppressTilt(DependencyObject source, bool value)
        {
            source.SetValue(SuppressTiltProperty, value);
        }

        /// <summary>
        /// Property change handler for the IsTiltEnabled dependency property.
        /// </summary>
        /// <param name="target">The element that the property is atteched to.</param>
        /// <param name="args">Event arguments.</param>
        /// <remarks>
        /// Adds or removes event handlers from the element that has been
        /// (un)registered for tilting.
        /// </remarks>
        static void OnIsTiltEnabledChanged(DependencyObject target, DependencyPropertyChangedEventArgs args)
        {
            FrameworkElement fe = target as FrameworkElement;
            if (fe != null)
            {
                // Add / remove the event handler if necessary
                if ((bool)args.NewValue == true)
                {
                    fe.PointerPressed += TiltEffect_PointerPressed;
                }
                else
                {
                    fe.PointerPressed -= TiltEffect_PointerPressed;
                }
            }
        }


        #endregion

        #region Top-level manipulation event handlers

        /// <summary>
        /// Event handler for ManipulationStarted.
        /// </summary>
        /// <param name="sender">sender of the event - this will be the tilt
        /// container (eg, entire page).</param>
        /// <param name="e">Event arguments.</param>
        private static void TiltEffect_PointerPressed(object sender, PointerEventArgs e)
        {
            TryStartTiltEffect(sender as FrameworkElement, e);
        }

        /// <summary>
        /// Event handler for ManipulationDelta
        /// </summary>
        /// <param name="sender">sender of the event - this will be the tilting
        /// object (eg a button).</param>
        /// <param name="e">Event arguments.</param>
        private static void TiltEffect_PointerMoved(object sender, PointerEventArgs e)
        {
            ContinueTiltEffect(sender as FrameworkElement, e);
        }

        /// <summary>
        /// Event handler for ManipulationCompleted.
        /// </summary>
        /// <param name="sender">sender of the event - this will be the tilting
        /// object (eg a button).</param>
        /// <param name="e">Event arguments.</param>
        static void TiltEffect_PointerReleased(object sender, PointerEventArgs e)
        {
            EndTiltEffect(currentTiltElement);
        }

        #endregion

        #region Core tilt logic

        /// <summary>
        /// Checks if the manipulation should cause a tilt, and if so starts the
        /// tilt effect.
        /// </summary>
        /// <param name="source">The source of the manipulation (the tilt
        /// container, eg entire page).</param>
        /// <param name="e">The args from the ManipulationStarted event.</param>
        static void TryStartTiltEffect(FrameworkElement source, PointerEventArgs e)
        {
            FrameworkElement element = source; // VisualTreeHelper.GetChild(ancestor, 0) as FrameworkElement;
            FrameworkElement container = source;// e.Container as FrameworkElement;

            if (element == null || container == null)
                return;

            // Touch point relative to the element being tilted.
            Point tiltTouchPoint = e.GetCurrentPoint(element).Position; // container.TransformToVisual(element).TransformPoint(e.GetCurrentPoint(element));

            // Center of the element being tilted.
            Point elementCenter = new Point(element.ActualWidth / 2, element.ActualHeight / 2);

            // Camera adjustment.
            Point centerToCenterDelta = GetCenterToCenterDelta(element, source);

            BeginTiltEffect(element, tiltTouchPoint, elementCenter, centerToCenterDelta, e.Pointer);
            return;


        }

        /// <summary>
        /// Computes the delta between the centre of an element and its
        /// container.
        /// </summary>
        /// <param name="element">The element to compare.</param>
        /// <param name="container">The element to compare against.</param>
        /// <returns>A point that represents the delta between the two centers.</returns>
        static Point GetCenterToCenterDelta(FrameworkElement element, FrameworkElement container)
        {
            Point elementCenter = new Point(element.ActualWidth / 2, element.ActualHeight / 2);
            Point containerCenter;

#if WINDOWS_PHONE

            // Need to special-case the frame to handle different orientations.
            PhoneApplicationFrame frame = container as PhoneApplicationFrame;
            if (frame != null)
            {
                // Switch width and height in landscape mode
                if ((frame.Orientation & PageOrientation.Landscape) == PageOrientation.Landscape)
                {
                    containerCenter = new Point(container.ActualHeight / 2, container.ActualWidth / 2);
                }
                else
                {
                    containerCenter = new Point(container.ActualWidth / 2, container.ActualHeight / 2);
                }
            }
            else
            {
                containerCenter = new Point(container.ActualWidth / 2, container.ActualHeight / 2);
            }
#else
            containerCenter = new Point(container.ActualWidth / 2, container.ActualHeight / 2);
#endif

            Point transformedElementCenter = element.TransformToVisual(container).TransformPoint(elementCenter);
            Point result = new Point(containerCenter.X - transformedElementCenter.X, containerCenter.Y - transformedElementCenter.Y);

            return result;
        }

        /// <summary>
        /// Begins the tilt effect by preparing the control and doing the
        /// initial animation.
        /// </summary>
        /// <param name="element">The element to tilt.</param>
        /// <param name="touchPoint">The touch point, in element coordinates.</param>
        /// <param name="centerPoint">The center point of the element in element
        /// coordinates.</param>
        /// <param name="centerDelta">The delta between the
        /// <paramref name="element"/>'s center and the container's center.</param>
        static void BeginTiltEffect(FrameworkElement element, Point touchPoint, Point centerPoint, Point centerDelta, Pointer p)
        {
            if (tiltReturnStoryboard != null)
            {
                StopTiltReturnStoryboardAndCleanup();
            }

            if (PrepareControlForTilt(element, centerDelta, p) == false)
            {
                return;
            }

            currentTiltElement = element;
            currentTiltElementCenter = centerPoint;
            PrepareTiltReturnStoryboard(element);

            ApplyTiltEffect(currentTiltElement, touchPoint, currentTiltElementCenter);
        }

        /// <summary>
        /// Prepares a control to be tilted by setting up a plane projection and
        /// some event handlers.
        /// </summary>
        /// <param name="element">The control that is to be tilted.</param>
        /// <param name="centerDelta">Delta between the element's center and the
        /// tilt container's.</param>
        /// <returns>true if successful; false otherwise.</returns>
        /// <remarks>
        /// This method is conservative; it will fail any attempt to tilt a
        /// control that already has a projection on it.
        /// </remarks>
        static bool PrepareControlForTilt(FrameworkElement element, Point centerDelta, Pointer p)
        {
            // Prevents interference with any existing transforms
            if (element.Projection != null || (element.RenderTransform != null && element.RenderTransform.GetType() != typeof(MatrixTransform)))
            {
                return false;
            }

            _originalCacheMode[element] = element.CacheMode;
            element.CacheMode = new BitmapCache();

            TranslateTransform transform = new TranslateTransform();
            transform.X = centerDelta.X;
            transform.Y = centerDelta.Y;
            element.RenderTransform = transform;

            PlaneProjection projection = new PlaneProjection();
            projection.GlobalOffsetX = -1 * centerDelta.X;
            projection.GlobalOffsetY = -1 * centerDelta.Y;
            element.Projection = projection;

            element.PointerMoved += TiltEffect_PointerMoved;
            element.PointerReleased += TiltEffect_PointerReleased;
            element.CapturePointer(p);
            return true;
        }

        /// <summary>
        /// Removes modifications made by PrepareControlForTilt.
        /// </summary>
        /// <param name="element">THe control to be un-prepared.</param>
        /// <remarks>
        /// This method is basic; it does not do anything to detect if the
        /// control being un-prepared was previously prepared.
        /// </remarks>
        private static void RevertPrepareControlForTilt(FrameworkElement element)
        {
            element.PointerMoved -= TiltEffect_PointerMoved;
            element.PointerReleased -= TiltEffect_PointerReleased;
            element.Projection = null;
            element.RenderTransform = null;

            CacheMode original;
            if (_originalCacheMode.TryGetValue(element, out original))
            {
                element.CacheMode = original;
                _originalCacheMode.Remove(element);
            }
            else
            {
                element.CacheMode = null;
            }
        }

        /// <summary>
        /// Creates the tilt return storyboard (if not already created) and
        /// targets it to the projection.
        /// </summary>
        /// <param name="element">The framework element to prepare for
        /// projection.</param>
        static void PrepareTiltReturnStoryboard(FrameworkElement element)
        {
            if (tiltReturnStoryboard == null)
            {
                tiltReturnStoryboard = new Storyboard();
                tiltReturnStoryboard.Completed += TiltReturnStoryboard_Completed;
                tiltReturnXAnimation = new DoubleAnimation();
                Storyboard.SetTargetProperty(tiltReturnXAnimation, "RotationX");
                tiltReturnXAnimation.BeginTime = TiltReturnAnimationDelay;
                tiltReturnXAnimation.To = 0;
                tiltReturnXAnimation.Duration = TiltReturnAnimationDuration;

                tiltReturnYAnimation = new DoubleAnimation();
                Storyboard.SetTargetProperty(tiltReturnYAnimation, "RotationY");
                tiltReturnYAnimation.BeginTime = TiltReturnAnimationDelay;
                tiltReturnYAnimation.To = 0;
                tiltReturnYAnimation.Duration = TiltReturnAnimationDuration;

                tiltReturnZAnimation = new DoubleAnimation();
                Storyboard.SetTargetProperty(tiltReturnZAnimation, "GlobalOffsetZ");
                tiltReturnZAnimation.BeginTime = TiltReturnAnimationDelay;
                tiltReturnZAnimation.To = 0;
                tiltReturnZAnimation.Duration = TiltReturnAnimationDuration;

                tiltReturnStoryboard.Children.Add(tiltReturnXAnimation);
                tiltReturnStoryboard.Children.Add(tiltReturnYAnimation);
                tiltReturnStoryboard.Children.Add(tiltReturnZAnimation);
            }

            Storyboard.SetTarget(tiltReturnXAnimation, element.Projection);
            Storyboard.SetTarget(tiltReturnYAnimation, element.Projection);
            Storyboard.SetTarget(tiltReturnZAnimation, element.Projection);
        }

        /// <summary>
        /// Continues a tilt effect that is currently applied to an element,
        /// presumably because the user moved their finger.
        /// </summary>
        /// <param name="element">The element being tilted.</param>
        /// <param name="e">The manipulation event args.</param>
        static void ContinueTiltEffect(FrameworkElement element, PointerEventArgs e)
        {
            FrameworkElement container = element;
            if (container == null || element == null)
            {
                return;
            }

            Point tiltTouchPoint =  e.GetCurrentPoint(element).Position;

            // If touch moved outside bounds of element, then pause the tilt
            // (but don't cancel it)
            if (new Rect(0, 0, currentTiltElement.ActualWidth, currentTiltElement.ActualHeight).Contains(tiltTouchPoint) != true)
            {
                PauseTiltEffect();
            }
            else
            {
                // Apply the updated tilt effect
                ApplyTiltEffect(currentTiltElement, tiltTouchPoint, currentTiltElementCenter);
            }
        }

        /// <summary>
        /// Ends the tilt effect by playing the animation.
        /// </summary>
        /// <param name="element">The element being tilted.</param>
        private static void EndTiltEffect(FrameworkElement element)
        {
            if (element != null)
            {
                element.PointerReleased -= TiltEffect_PointerPressed;
                element.PointerMoved -= TiltEffect_PointerMoved;
            }

            if (tiltReturnStoryboard != null)
            {
                wasPauseAnimation = false;
                if (tiltReturnStoryboard.GetCurrentState() != ClockState.Active)
                {
                    tiltReturnStoryboard.Begin();
                }
            }
            else
            {
                StopTiltReturnStoryboardAndCleanup();
            }
        }

        /// <summary>
        /// Handler for the storyboard complete event.
        /// </summary>
        /// <param name="sender">sender of the event.</param>
        /// <param name="e">event args.</param>
        private static void TiltReturnStoryboard_Completed(object sender, object e)
        {
            if (wasPauseAnimation)
            {
                ResetTiltEffect(currentTiltElement);
            }
            else
            {
                StopTiltReturnStoryboardAndCleanup();
            }
        }

        /// <summary>
        /// Resets the tilt effect on the control, making it appear 'normal'
        /// again.
        /// </summary>
        /// <param name="element">The element to reset the tilt on.</param>
        /// <remarks>
        /// This method doesn't turn off the tilt effect or cancel any current
        /// manipulation; it just temporarily cancels the effect.
        /// </remarks>
        private static void ResetTiltEffect(FrameworkElement element)
        {
            PlaneProjection projection = element.Projection as PlaneProjection;
            projection.RotationY = 0;
            projection.RotationX = 0;
            projection.GlobalOffsetZ = 0;
        }

        /// <summary>
        /// Stops the tilt effect and release resources applied to the currently
        /// tilted control.
        /// </summary>
        private static void StopTiltReturnStoryboardAndCleanup()
        {
            if (tiltReturnStoryboard != null)
            {
                tiltReturnStoryboard.Stop();
            }

            RevertPrepareControlForTilt(currentTiltElement);
        }

        /// <summary>
        /// Pauses the tilt effect so that the control returns to the 'at rest'
        /// position, but doesn't stop the tilt effect (handlers are still
        /// attached).
        /// </summary>
        private static void PauseTiltEffect()
        {
            if ((tiltReturnStoryboard != null) && !wasPauseAnimation)
            {
                tiltReturnStoryboard.Stop();
                wasPauseAnimation = true;
                tiltReturnStoryboard.Begin();
            }
        }

        /// <summary>
        /// Resets the storyboard to not running.
        /// </summary>
        private static void ResetTiltReturnStoryboard()
        {
            tiltReturnStoryboard.Stop();
            wasPauseAnimation = false;
        }

        /// <summary>
        /// Applies the tilt effect to the control.
        /// </summary>
        /// <param name="element">the control to tilt.</param>
        /// <param name="touchPoint">The touch point, in the container's
        /// coordinates.</param>
        /// <param name="centerPoint">The center point of the container.</param>
        private static void ApplyTiltEffect(FrameworkElement element, Point touchPoint, Point centerPoint)
        {
            // Stop any active animation
            ResetTiltReturnStoryboard();

            // Get relative point of the touch in percentage of container size
            Point normalizedPoint = new Point(
                Math.Min(Math.Max(touchPoint.X / (centerPoint.X * 2), 0), 1),
                Math.Min(Math.Max(touchPoint.Y / (centerPoint.Y * 2), 0), 1));

            if (double.IsNaN(normalizedPoint.X) || double.IsNaN(normalizedPoint.Y))
            {
                return;
            }

            // Shell values
            double xMagnitude = Math.Abs(normalizedPoint.X - 0.5);
            double yMagnitude = Math.Abs(normalizedPoint.Y - 0.5);
            double xDirection = -Math.Sign(normalizedPoint.X - 0.5);
            double yDirection = Math.Sign(normalizedPoint.Y - 0.5);
            double angleMagnitude = xMagnitude + yMagnitude;
            double xAngleContribution = xMagnitude + yMagnitude > 0 ? xMagnitude / (xMagnitude + yMagnitude) : 0;

            double angle = angleMagnitude * MaxAngle * 180 / Math.PI;
            double depression = (1 - angleMagnitude) * MaxDepression;

            // RotationX and RotationY are the angles of rotations about the x-
            // or y-*axis*; to achieve a rotation in the x- or y-*direction*, we
            // need to swap the two. That is, a rotation to the left about the
            // y-axis is a rotation to the left in the x-direction, and a
            // rotation up about the x-axis is a rotation up in the y-direction.
            PlaneProjection projection = element.Projection as PlaneProjection;
            projection.RotationY = angle * xAngleContribution * xDirection;
            projection.RotationX = angle * (1 - xAngleContribution) * yDirection;
            projection.GlobalOffsetZ = -depression;
        }

        #endregion
    }

    /// <summary>
    /// Couple of simple helpers for walking the visual tree.
    /// </summary>
    static class TreeHelpers
    {
        /// <summary>
        /// Gets the ancestors of the element, up to the root.
        /// </summary>
        /// <param name="node">The element to start from.</param>
        /// <returns>An enumerator of the ancestors.</returns>
        public static IEnumerable<FrameworkElement> GetVisualAncestors(this FrameworkElement node)
        {
            FrameworkElement parent = node.GetVisualParent();
            while (parent != null)
            {
                yield return parent;
                parent = parent.GetVisualParent();
            }
        }

        /// <summary>
        /// Gets the visual parent of the element.
        /// </summary>
        /// <param name="node">The element to check.</param>
        /// <returns>The visual parent.</returns>
        public static FrameworkElement GetVisualParent(this FrameworkElement node)
        {
            return VisualTreeHelper.GetParent(node) as FrameworkElement;
        }
    }
}