XAML-Map-Control/MapControl/MapImageLayer.cs

// XAML Map Control - http://xamlmapcontrol.codeplex.com/
// © 2015 Clemens Fischer
// Licensed under the Microsoft Public License (Ms-PL)

using System;
using System.Globalization;
#if WINDOWS_RUNTIME
using Windows.Foundation;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Media.Imaging;
using Windows.UI.Xaml.Media.Animation;
#else
using System.Windows;
using System.Windows.Media.Animation;
using System.Windows.Media.Imaging;
using System.Windows.Threading;
#endif

namespace MapControl
{
    /// <summary>
    /// Map image overlay. Fills the entire viewport with map images provided by a web service,
    /// e.g. a Web Map Service (WMS). The image request Uri is specified by the UriFormat property.
    /// </summary>
    public partial class MapImageLayer : MapPanel
    {
        public static readonly DependencyProperty UriFormatProperty = DependencyProperty.Register(
            "UriFormat", typeof(string), typeof(MapImageLayer),
            new PropertyMetadata(null, (o, e) => ((MapImageLayer)o).UpdateImage()));

        public static readonly DependencyProperty RelativeImageSizeProperty = DependencyProperty.Register(
            "RelativeImageSize", typeof(double), typeof(MapImageLayer), new PropertyMetadata(1d));

        private readonly DispatcherTimer updateTimer;
        private int currentImageIndex;
        private bool updateInProgress;

        public MapImageLayer()
        {
            Children.Add(new MapImage { Opacity = 0d });
            Children.Add(new MapImage { Opacity = 0d });

            updateTimer = new DispatcherTimer { Interval = MapBase.TileUpdateInterval };
            updateTimer.Tick += (s, e) => UpdateImage();
        }

        /// <summary>
        /// The format string of the image request Uri. The format must contain
        /// {X} and {Y} format specifiers for the map width and height in pixels and either
        /// {w},{s},{e},{n} for the bounding box in lat/lon (like EPSG:4326) or
        /// {W},{S},{E},{N} for the bounding box in meters (like EPSG:3857).
        /// </summary>
        public string UriFormat
        {
            get { return (string)GetValue(UriFormatProperty); }
            set { SetValue(UriFormatProperty, value); }
        }

        /// <summary>
        /// Relative size of the map images in relation to the current viewport size.
        /// Setting a value greater than one will let MapImageLayer request images that
        /// are larger than the viewport, in order to support smooth panning.
        /// </summary>
        public double RelativeImageSize
        {
            get { return (double)GetValue(RelativeImageSizeProperty); }
            set { SetValue(RelativeImageSizeProperty, value); }
        }

        protected override void OnViewportChanged()
        {
            base.OnViewportChanged();

            updateTimer.Stop();
            updateTimer.Start();
        }

        protected void UpdateImage()
        {
            updateTimer.Stop();

            if (updateInProgress)
            {
                updateTimer.Start(); // update image on next timer tick
            }
            else if (ParentMap != null && RenderSize.Width > 0 && RenderSize.Height > 0)
            {
                updateInProgress = true;

                var relativeSize = Math.Max(RelativeImageSize, 1d);
                var width = RenderSize.Width * relativeSize;
                var height = RenderSize.Height * relativeSize;
                var dx = (RenderSize.Width - width) / 2d;
                var dy = (RenderSize.Height - height) / 2d;

                var loc1 = ParentMap.ViewportPointToLocation(new Point(dx, dy));
                var loc2 = ParentMap.ViewportPointToLocation(new Point(dx + width, dy));
                var loc3 = ParentMap.ViewportPointToLocation(new Point(dx, dy + height));
                var loc4 = ParentMap.ViewportPointToLocation(new Point(dx + width, dy + height));

                var west = Math.Min(loc1.Longitude, Math.Min(loc2.Longitude, Math.Min(loc3.Longitude, loc4.Longitude)));
                var east = Math.Max(loc1.Longitude, Math.Max(loc2.Longitude, Math.Max(loc3.Longitude, loc4.Longitude)));
                var south = Math.Min(loc1.Latitude, Math.Min(loc2.Latitude, Math.Min(loc3.Latitude, loc4.Latitude)));
                var north = Math.Max(loc1.Latitude, Math.Max(loc2.Latitude, Math.Max(loc3.Latitude, loc4.Latitude)));

                var p1 = ParentMap.MapTransform.Transform(new Location(south, west));
                var p2 = ParentMap.MapTransform.Transform(new Location(north, east));

                width = Math.Round((p2.X - p1.X) * ParentMap.ViewportScale);
                height = Math.Round((p2.Y - p1.Y) * ParentMap.ViewportScale);

                UpdateImage(west, east, south, north, (int)width, (int)height);
            }
        }

        protected virtual void UpdateImage(double west, double east, double south, double north, int width, int height)
        {
            if (UriFormat != null && width > 0 && height > 0)
            {
                var uri = UriFormat.Replace("{X}", width.ToString()).Replace("{Y}", height.ToString());

                if (uri.Contains("{W}") && uri.Contains("{S}") && uri.Contains("{E}") && uri.Contains("{N}"))
                {
                    var p1 = ParentMap.MapTransform.Transform(new Location(south, west));
                    var p2 = ParentMap.MapTransform.Transform(new Location(north, east));

                    uri = uri.
                        Replace("{W}", (TileSource.MetersPerDegree * p1.X).ToString(CultureInfo.InvariantCulture)).
                        Replace("{S}", (TileSource.MetersPerDegree * p1.Y).ToString(CultureInfo.InvariantCulture)).
                        Replace("{E}", (TileSource.MetersPerDegree * p2.X).ToString(CultureInfo.InvariantCulture)).
                        Replace("{N}", (TileSource.MetersPerDegree * p2.Y).ToString(CultureInfo.InvariantCulture));
                }
                else
                {
                    uri = uri.
                        Replace("{w}", west.ToString(CultureInfo.InvariantCulture)).
                        Replace("{s}", south.ToString(CultureInfo.InvariantCulture)).
                        Replace("{e}", east.ToString(CultureInfo.InvariantCulture)).
                        Replace("{n}", north.ToString(CultureInfo.InvariantCulture));
                }

                UpdateImage(west, east, south, north, new Uri(uri));
            }
            else
            {
                UpdateImage(west, east, south, north, (BitmapSource)null);
            }
        }

        protected virtual void UpdateImage(double west, double east, double south, double north, Uri uri)
        {
            UpdateImage(west, east, south, north, new BitmapImage(uri));
        }

        protected void UpdateImage(double west, double east, double south, double north, BitmapSource bitmap)
        {
            currentImageIndex = (currentImageIndex + 1) % 2;
            var mapImage = (MapImage)Children[currentImageIndex];

            mapImage.North = double.NaN; // avoid frequent MapRectangle.UpdateData() calls
            mapImage.West = west;
            mapImage.East = east;
            mapImage.South = south;
            mapImage.North = north;
            mapImage.Source = bitmap;

            ImageUpdated(bitmap);
        }

        private void BlendImages()
        {
            var topImage = (MapImage)Children[currentImageIndex];
            var bottomImage = (MapImage)Children[(currentImageIndex + 1) % 2];

            if (topImage.Source != null)
            {
                topImage.BeginAnimation(UIElement.OpacityProperty,
                    new DoubleAnimation { To = 1d, Duration = Tile.OpacityAnimationDuration });
            }

            if (bottomImage.Source != null)
            {
                var fadeOutAnimation = new DoubleAnimation { To = 0d, Duration = Tile.OpacityAnimationDuration };

                if (topImage.Source != null)
                {
                    fadeOutAnimation.BeginTime = Tile.OpacityAnimationDuration;
                }

                bottomImage.BeginAnimation(UIElement.OpacityProperty, fadeOutAnimation);
            }

            updateInProgress = false;
        }
    }
}