public BlimpCameraMan(ILocatable posLoc, ILocatable lookAt)
 {
     Dirty = true;
     Pos3d = posLoc.ToPositionAboveSeaLeveld (_altitude);
     LookAt = new Location (lookAt);
     LookAt3d = LookAt.ToPositionAboveSeaLeveld (0);
 }

 /// <summary>
 /// Initializes a new instance of the <see cref="LongPressAction"/> class.
 /// </summary>
 /// <param name="touchScreen">The <see cref="ITouchScreen"/> with which the action will be performed.</param>
 /// <param name="actionTarget">An <see cref="ILocatable"/> describing an element at which to perform the action.</param>
 public LongPressAction(ITouchScreen touchScreen, ILocatable actionTarget)
     : base(touchScreen, actionTarget)
 {
     if (actionTarget == null)
     {
         throw new ArgumentException("Must provide a location for a single tap action.", "actionTarget");
     }
 }

 /// <summary>
 /// Initializes a new instance of the <see cref="MoveMouseAction"/> class.
 /// </summary>
 /// <param name="mouse">The <see cref="IMouse"/> with which the action will be performed.</param>
 /// <param name="actionTarget">An <see cref="ILocatable"/> describing an element at which to perform the action.</param>
 public MoveMouseAction(IMouse mouse, ILocatable actionTarget)
     : base(mouse, actionTarget)
 {
     if (actionTarget == null)
     {
         throw new ArgumentException("Must provide a location for a move action.", "actionTarget");
     }
 }

        /// <summary>
        /// Initializes a new instance of the <see cref="SingleKeyAction"/> class.
        /// </summary>
        /// <param name="keyboard">The <see cref="IKeyboard"/> to use in performing the action.</param>
        /// <param name="mouse">The <see cref="IMouse"/> to use in setting focus to the element on which to perform the action.</param>
        /// <param name="actionTarget">An <see cref="ILocatable"/> object providing the element on which to perform the action.</param>
        /// <param name="key">The modifier key (<see cref="Keys.Shift"/>, <see cref="Keys.Control"/>, <see cref="Keys.Alt"/>) to use in the action.</param>
        protected SingleKeyAction(IKeyboard keyboard, IMouse mouse, ILocatable actionTarget, string key)
            : base(keyboard, mouse, actionTarget)
        {
            if (!ModifierKeys.Contains(key))
            {
                throw new ArgumentException("key must be a modifier key (Keys.Shift, Keys.Control, or Keys.Alt)", "key");
            }

            this.key = key;
        }

        /// <summary>
        /// Adds the specified <see cref="ILocatable"/> to the <see cref="GridBucket"/> that covers
        /// its current location
        /// </summary>
        /// <param name="item"></param>
        public void AddItem(ILocatable item)
        {
            int x = (int)(item.XPos / _xBlockWidth);
            int y = (int)(item.YPos / _yBlockHeight);

            // Ensure we clamp the ceiling value
            if (x == _numXBlocks) { x--; }
            if (y == _numYBlocks) { y--; }

            _buckets[x, y].Add(item);       
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="ScrollAction"/> class for use with the specified element.
        /// </summary>
        /// <param name="touchScreen">The <see cref="ITouchScreen"/> with which the action will be performed.</param>
        /// <param name="actionTarget">An <see cref="ILocatable"/> describing an element at which to perform the action.</param>
        /// <param name="offsetX">The x coordinate relative to the view port.</param>
        /// <param name="offsetY">The y coordinate relative to the view port.</param>
        public ScrollAction(ITouchScreen touchScreen, ILocatable actionTarget, int offsetX, int offsetY)
            : base(touchScreen, actionTarget)
        {
            if (actionTarget == null)
            {
                throw new ArgumentException("Must provide a location for a single tap action.", "actionTarget");
            }

            this.offsetX = offsetX;
            this.offsetY = offsetY;
        }

        /// <summary>
        /// Returns the distance between this ant and the <see cref="ILocatable"/> item
        /// </summary>
        /// <param name="target"></param>
        /// <returns></returns>
        private float GetDistance(ILocatable target)
        {
            // Use pythagora
            float xOffset = (float)XPos - (float)target.XPos;
            float yOffset = (float)YPos - (float)target.YPos;

            float xOffsetSquared = xOffset * xOffset;
            float yOffsetSquared = yOffset * yOffset;

            float distance = (float)Math.Sqrt(xOffset + yOffset);

            return distance;
        }

 public static Vector2 VectorTo(this ILocatable fr, ILocatable to)
 {
     return new Vector2((float)(to.Longitude - fr.Longitude),
                        (float)(to.Latitude - fr.Latitude));
 }

 /// <summary>
 /// Initializes a new instance of the <see cref="MoveToOffsetAction"/> class.
 /// </summary>
 /// <param name="mouse">The <see cref="IMouse"/> with which the action will be performed.</param>
 /// <param name="actionTarget">An <see cref="ILocatable"/> describing an element at which to perform the action.</param>
 /// <param name="offsetX">The horizontal offset from the origin of the target to which to move the mouse.</param>
 /// <param name="offsetY">The vertical offset from the origin of the target to which to move the mouse.</param>
 public MoveToOffsetAction(IMouse mouse, ILocatable actionTarget, int offsetX, int offsetY)
     : base(mouse, actionTarget)
 {
     this.offsetX = offsetX;
     this.offsetY = offsetY;
 }

 /// <summary>
 /// Initializes a new instance of the <see cref="ButtonReleaseAction"/> class.
 /// </summary>
 /// <param name="mouse">The <see cref="IMouse"/> with which the action will be performed.</param>
 /// <param name="actionTarget">An <see cref="ILocatable"/> describing an element at which to perform the action.</param>
 public ButtonReleaseAction(IMouse mouse, ILocatable actionTarget)
     : base(mouse, actionTarget)
 {
 }

 public LocLinAnim(double duration, ILocatable start, ILocatable end)
 {
     _start = new Location(start);
     _end = new Location(end);
     _current = _start;
     _duration = duration;
 }

 /// <summary>
 /// Initializes a new instance of the <see cref="SendKeysAction"/> class.
 /// </summary>
 /// <param name="keyboard">The <see cref="IKeyboard"/> to use in performing the action.</param>
 /// <param name="mouse">The <see cref="IMouse"/> to use in setting focus to the element on which to perform the action.</param>
 /// <param name="actionTarget">An <see cref="ILocatable"/> object providing the element on which to perform the action.</param>
 /// <param name="keysToSend">The key sequence to send.</param>
 public SendKeysAction(IKeyboard keyboard, IMouse mouse, ILocatable actionTarget, string keysToSend)
     : base(keyboard, mouse, actionTarget)
 {
     this.keysToSend = keysToSend;
 }

        /// <summary>
        /// Returns a Rect which describes the bounds of the element being dragged.
        /// </summary>
        private Rect CalculateDragElementRect(ILocatable el, double newHorizOffset, double newVertOffset, bool modLeftOffset, bool modTopOffset)
        {
            //if(this.elementsBeingDragged.Count == 0)
            //    throw new InvalidOperationException("ElementBeingDragged is null.");

            //double xMin = 10000000.0;
            //double yMin = 10000000.0;
            //double xMax = -10000000.0;
            //double yMax = -10000000.0;
            //foreach (UIElement el in this.elementsBeingDragged)
            //{
            //    double elX = Canvas.GetLeft(el);
            //    double elY = Canvas.GetTop(el);
            //    xMin = Math.Min(xMin, elX);
            //    yMin = Math.Min(yMin, elY);
            //    xMax = Math.Max(xMax, elX + el.RenderSize.Width);
            //    yMax = Math.Max(yMax, elY + el.RenderSize.Height);
            //}

            //Size elemSize = new Size(xMax - xMin, yMax - yMin);

            //if (this.ElementBeingDragged == null)
            //    throw new InvalidOperationException("ElementBeingDragged is null.");

            //Size elemSize = this.elementsBeingDragged.RenderSize;

            //Size elemSize = el.RenderSize;
            Size elemSize = new Size(el.Width, el.Height);

            double x, y;

            if (modLeftOffset)
                x = newHorizOffset;
            else
                x = this.ActualWidth - newHorizOffset - elemSize.Width;

            if (modTopOffset)
                y = newVertOffset;
            else
                y = this.ActualHeight - newVertOffset - elemSize.Height;

            Point elemLoc = new Point(x, y);

            return new Rect(elemLoc, elemSize);
        }

 /// <summary>
 /// Initializes a new instance of the <see cref="KeyDownAction"/> class.
 /// </summary>
 /// <param name="keyboard">The <see cref="IKeyboard"/> to use in performing the action.</param>
 /// <param name="mouse">The <see cref="IMouse"/> to use in setting focus to the element on which to perform the action.</param>
 /// <param name="actionTarget">An <see cref="ILocatable"/> object providing the element on which to perform the action.</param>
 /// <param name="key">The modifier key (<see cref="Keys.Shift"/>, <see cref="Keys.Control"/>, <see cref="Keys.Alt"/>) to use in the action.</param>
 public KeyDownAction(IKeyboard keyboard, IMouse mouse, ILocatable actionTarget, string key)
     : base(keyboard, mouse, actionTarget, key)
 {
 }

 /// <summary>
 /// Initializes a new instance of the <see cref="KeyboardAction"/> class.
 /// </summary>
 /// <param name="keyboard">The <see cref="IKeyboard"/> to use in performing the action.</param>
 /// <param name="mouse">The <see cref="IMouse"/> to use in setting focus to the element on which to perform the action.</param>
 /// <param name="actionTarget">An <see cref="ILocatable"/> object providing the element on which to perform the action.</param>
 protected KeyboardAction(IKeyboard keyboard, IMouse mouse, ILocatable actionTarget)
     : base(actionTarget)
 {
     this.keyboard = keyboard;
     this.mouse = mouse;
 }

 public Location(ILocatable loc)
 {
     Longitude = loc.Longitude;
     Latitude = loc.Latitude;
 }

 public void SetLookAt(ILocatable lookAt, bool animated)
 {
 }

        public void Scale(ILocatable loc, float scale)
        {
            var toCam = (Pos3d - LookAt3d);
            var dist = toCam.Length;

            var sdist = dist / scale;
            toCam.Normalize();
            var newPos = LookAt3d + toCam * sdist;

            var alt = newPos.Length - Location.EarthRadiusInKm;

            _altitude = (float)alt;
            if (_altitude > 12500.0f) _altitude = 12500.0f;
            if (_altitude < 0.03f) _altitude = 0.03f;

            Pos3d = _pos.ToPositionAboveSeaLeveld(_altitude);

            Dirty = true;
        }

        public void Rotate(ILocatable loc, float ddegs)
        {
            _pos = _pos.RotateAround(loc, ddegs);
            LookAt = LookAt.RotateAround(loc, ddegs);

            Pos3d = _pos.ToPositionAboveSeaLeveld (_altitude);
            LookAt3d = LookAt.ToPositionAboveSeaLeveld (0);

            Dirty = true;
        }

 public ManualCameraMan(ILocatable posLoc, ILocatable lookAt)
 {
     Dirty = true;
     _pos = new Location(posLoc);
     Pos3d = _pos.ToPositionAboveSeaLeveld (_altitude);
     LookAt = new Location (lookAt);
     LookAt3d = LookAt.ToPositionAboveSeaLeveld (0);
 }