Implement ImageRenderer (fixes #44)

Ooui.AspNetCore/OouiMiddlewareExtensions.cs

@@ -25,10 +25,13 @@ namespace Microsoft.AspNetCore.Builder
             };
             app.UseWebSockets (webSocketOptions);
 
+            Ooui.UI.ServerEnabled = false;
+
             app.Use (async (context, next) =>
             {
-                if (context.Request.Path == jsPath) {
                 var response = context.Response;
+
+                if (context.Request.Path == jsPath) {
                     var clientJsBytes = Ooui.UI.ClientJsBytes;
                     var clientJsEtag = Ooui.UI.ClientJsEtag;
                     if (context.Request.Headers.TryGetValue ("If-None-Match", out var inms) && inms.Count > 0 && inms[0] == clientJsEtag) {
@@ -53,6 +56,21 @@ namespace Microsoft.AspNetCore.Builder
                         context.Response.StatusCode = 400;
                     }
                 }
+                else if (Ooui.UI.TryGetFileContentAtPath (context.Request.Path, out var file)) {
+                    if (context.Request.Headers.TryGetValue ("If-None-Match", out var inms) && inms.Count > 0 && inms[0] == file.Etag) {
+                        response.StatusCode = 304;
+                    }
+                    else {
+                        response.StatusCode = 200;
+                        response.ContentLength = file.Content.Length;
+                        response.ContentType = file.ContentType;
+                        response.Headers.Add ("Cache-Control", "public, max-age=60");
+                        response.Headers.Add ("Etag", file.Etag);
+                        using (var s = response.Body) {
+                            await s.WriteAsync (file.Content, 0, file.Content.Length).ConfigureAwait (false);
+                        }
+                    }
+                }
                 else {
                     await next ().ConfigureAwait (false);
                 }

Ooui.Forms/Exports.cs

@@ -12,9 +12,13 @@ using Xamarin.Forms.Internals;
 [assembly: ExportRenderer (typeof (Editor), typeof (EditorRenderer))]
 [assembly: ExportRenderer (typeof (Entry), typeof (EntryRenderer))]
 [assembly: ExportRenderer (typeof (Frame), typeof (FrameRenderer))]
+[assembly: ExportRenderer (typeof (Image), typeof (ImageRenderer))]
 [assembly: ExportRenderer (typeof (Label), typeof (LabelRenderer))]
 [assembly: ExportRenderer (typeof (ProgressBar), typeof (ProgressBarRenderer))]
 [assembly: ExportRenderer (typeof (Switch), typeof (SwitchRenderer))]
+[assembly: ExportImageSourceHandler (typeof (FileImageSource), typeof (FileImageSourceHandler))]
+[assembly: ExportImageSourceHandler (typeof (StreamImageSource), typeof (StreamImagesourceHandler))]
+[assembly: ExportImageSourceHandler (typeof (UriImageSource), typeof (ImageLoaderSourceHandler))]
 
 namespace Ooui.Forms
 {
@@ -26,4 +30,13 @@ namespace Ooui.Forms
         {
         }
     }
+
+    [AttributeUsage (AttributeTargets.Assembly, AllowMultiple = true)]
+    public sealed class ExportImageSourceHandlerAttribute : HandlerAttribute
+    {
+        public ExportImageSourceHandlerAttribute (Type handler, Type target)
+            : base (handler, target)
+        {
+        }
+    }
 }

Ooui.Forms/Forms.cs

@@ -31,7 +31,7 @@ namespace Xamarin.Forms
             Registrar.RegisterAll (new[] {
                 typeof(ExportRendererAttribute),
                 //typeof(ExportCellAttribute),
-                //typeof(ExportImageSourceHandlerAttribute),
+                typeof(ExportImageSourceHandlerAttribute),
             });
         }
 

Ooui.Forms/Renderers/ImageRenderer.cs

@@ -0,0 +1,201 @@
+using System;
+using System.ComponentModel;
+using System.Threading;
+using System.Threading.Tasks;
+using Xamarin.Forms;
+
+namespace Ooui.Forms.Renderers
+{
+    public class ImageRenderer : ViewRenderer<Xamarin.Forms.Image, Ooui.Image>
+    {
+        bool _isDisposed;
+
+        protected override void Dispose (bool disposing)
+        {
+            if (_isDisposed)
+                return;
+
+            if (disposing) {
+            }
+
+            _isDisposed = true;
+
+            base.Dispose (disposing);
+        }
+
+        protected override async void OnElementChanged (ElementChangedEventArgs<Xamarin.Forms.Image> e)
+        {
+            if (Control == null) {
+                var imageView = new Ooui.Image ();
+                SetNativeControl (imageView);
+            }
+
+            if (e.NewElement != null) {
+                SetAspect ();
+                await TrySetImage (e.OldElement);
+                SetOpacity ();
+            }
+
+            base.OnElementChanged (e);
+        }
+
+        protected override async void OnElementPropertyChanged (object sender, PropertyChangedEventArgs e)
+        {
+            base.OnElementPropertyChanged (sender, e);
+            if (e.PropertyName == Xamarin.Forms.Image.SourceProperty.PropertyName)
+                await TrySetImage ();
+            else if (e.PropertyName == Xamarin.Forms.Image.IsOpaqueProperty.PropertyName)
+                SetOpacity ();
+            else if (e.PropertyName == Xamarin.Forms.Image.AspectProperty.PropertyName)
+                SetAspect ();
+        }
+
+        void SetAspect ()
+        {
+            if (_isDisposed || Element == null || Control == null) {
+                return;
+            }
+        }
+
+        protected virtual async Task TrySetImage (Xamarin.Forms.Image previous = null)
+        {
+            // By default we'll just catch and log any exceptions thrown by SetImage so they don't bring down
+            // the application; a custom renderer can override this method and handle exceptions from
+            // SetImage differently if it wants to
+
+            try {
+                await SetImage (previous).ConfigureAwait (false);
+            }
+            catch (Exception ex) {
+                System.Diagnostics.Debug.WriteLine ("Error loading image: {0}", ex);
+            }
+            finally {
+                ((IImageController)Element)?.SetIsLoading (false);
+            }
+        }
+
+        protected async Task SetImage (Xamarin.Forms.Image oldElement = null)
+        {
+            if (_isDisposed || Element == null || Control == null) {
+                return;
+            }
+
+            var source = Element.Source;
+
+            if (oldElement != null) {
+                var oldSource = oldElement.Source;
+                if (Equals (oldSource, source))
+                    return;
+
+                if (oldSource is FileImageSource && source is FileImageSource && ((FileImageSource)oldSource).File == ((FileImageSource)source).File)
+                    return;
+
+                Control.Source = "";
+            }
+
+            IImageSourceHandler handler;
+
+            Element.SetIsLoading (true);
+
+            if (source != null &&
+                (handler = Xamarin.Forms.Internals.Registrar.Registered.GetHandler<IImageSourceHandler> (source.GetType ())) != null) {
+                string uiimage;
+                try {
+                    uiimage = await handler.LoadImageAsync (source, scale: 1.0f);
+                }
+                catch (OperationCanceledException) {
+                    uiimage = null;
+                }
+
+                if (_isDisposed)
+                    return;
+
+                var imageView = Control;
+                if (imageView != null)
+                    imageView.Source = uiimage;
+
+                ((IVisualElementController)Element).NativeSizeChanged ();
+            }
+            else {
+                Control.Source = "";
+            }
+
+            Element.SetIsLoading (false);
+        }
+
+        void SetOpacity ()
+        {
+            if (_isDisposed || Element == null || Control == null) {
+                return;
+            }
+        }
+    }
+
+    public interface IImageSourceHandler : IRegisterable
+    {
+        Task<string> LoadImageAsync (ImageSource imagesource, CancellationToken cancelationToken = default (CancellationToken), float scale = 1);
+    }
+
+    public sealed class FileImageSourceHandler : IImageSourceHandler
+    {
+        public async Task<string> LoadImageAsync (ImageSource imagesource, CancellationToken cancelationToken = default (CancellationToken), float scale = 1f)
+        {
+            string image = null;
+            var filesource = imagesource as FileImageSource;
+            var file = filesource?.File;
+            if (!string.IsNullOrEmpty (file)) {
+                var name = System.IO.Path.GetFileName (file);
+                image = "/images/" + name;
+                if (Ooui.UI.TryGetFileContentAtPath (image, out var f)) {
+                    // Already published
+                }
+                else {
+                    await Task.Run (() => Ooui.UI.PublishFile (image, file), cancelationToken);
+                }
+            }
+            return image;
+        }
+    }
+
+    public sealed class StreamImagesourceHandler : IImageSourceHandler
+    {
+        public async Task<string> LoadImageAsync (ImageSource imagesource, CancellationToken cancelationToken = default (CancellationToken), float scale = 1f)
+        {
+            string image = null;
+            var streamsource = imagesource as StreamImageSource;
+            if (streamsource?.Stream != null) {
+                using (var streamImage = await ((IStreamImageSource)streamsource).GetStreamAsync (cancelationToken).ConfigureAwait (false)) {
+                    if (streamImage != null) {
+                        var data = new byte[streamImage.Length];
+                        using (var outputStream = new System.IO.MemoryStream (data)) {
+                            await streamImage.CopyToAsync (outputStream, 4096, cancelationToken).ConfigureAwait (false);
+                        }
+                        var hash = Ooui.UI.Hash (data);
+                        var etag = "\"" + hash + "\"";
+                        image = "/images/" + hash;
+                        if (Ooui.UI.TryGetFileContentAtPath (image, out var file) && file.Etag == etag) {
+                            // Already published
+                        }
+                        else {
+                            Ooui.UI.PublishFile (image, data, etag, "image");
+                        }
+                    }
+                }
+            }
+
+            if (image == null) {
+                System.Diagnostics.Debug.WriteLine ("Could not load image: {0}", streamsource);
+            }
+            return image;
+        }
+    }
+
+    public sealed class ImageLoaderSourceHandler : IImageSourceHandler
+    {
+        public Task<string> LoadImageAsync (ImageSource imagesource, CancellationToken cancelationToken = default (CancellationToken), float scale = 1f)
+        {
+            var imageLoader = imagesource as UriImageSource;
+            return Task.FromResult (imageLoader?.Uri.ToString () ?? "");
+        }
+    }
+}

Ooui/UI.cs

@@ -73,6 +73,19 @@ namespace Ooui
                 }
             }
         }
+        static bool serverEnabled = true;
+        public static bool ServerEnabled {
+            get => serverEnabled;
+            set {
+                if (serverEnabled != value) {
+                    serverEnabled = value;
+                    if (serverEnabled)
+                        Restart ();
+                    else
+                        Stop ();
+                }
+            }
+        }
 
         static UI ()
         {
@@ -91,7 +104,7 @@ namespace Ooui
             clientJsEtag = "\"" + Hash (clientJsBytes) + "\"";
         }
 
-        static string Hash (byte[] bytes)
+        public static string Hash (byte[] bytes)
         {
             var sha = sha256;
             if (sha == null) {
@@ -135,7 +148,47 @@ namespace Ooui
             if (contentType == null) {
                 contentType = GuessContentType (path, filePath);
             }
-            Publish (path, new DataHandler (data, contentType));
+            var etag = "\"" + Hash (data) + "\"";
+            Publish (path, new DataHandler (data, etag, contentType));
+        }
+
+        public static void PublishFile (string path, byte[] data, string contentType)
+        {
+            var etag = "\"" + Hash (data) + "\"";
+            Publish (path, new DataHandler (data, etag, contentType));
+        }
+
+        public static void PublishFile (string path, byte[] data, string etag, string contentType)
+        {            
+            Publish (path, new DataHandler (data, etag, contentType));
+        }
+
+        public static bool TryGetFileContentAtPath (string path, out FileContent file)
+        {
+            RequestHandler handler;
+            lock (publishedPaths) {
+                if (!publishedPaths.TryGetValue (path, out handler)) {
+                    file = null;
+                    return false;
+                }
+            }
+            if (handler is DataHandler dh) {
+                file = new FileContent {
+                    Etag = dh.Etag,
+                    Content = dh.Data,
+                    ContentType = dh.ContentType,
+                };
+                return true;
+            }
+            file = null;
+            return false;
+        }
+
+        public class FileContent
+        {
+            public string ContentType { get; set; }
+            public string Etag { get; set; }
+            public byte[] Content { get; set; }
         }
 
         public static void PublishJson (string path, Func<object> ctor)
@@ -146,7 +199,8 @@ namespace Ooui
         public static void PublishJson (string path, object value)
         {
             var data = JsonHandler.GetData (value);
-            Publish (path, new DataHandler (data, JsonHandler.ContentType));
+            var etag = "\"" + Hash (data) + "\"";
+            Publish (path, new DataHandler (data, etag, JsonHandler.ContentType));
         }
 
 		public static void PublishCustomResponse (string path, Action<HttpListenerContext, CancellationToken> responder)
@@ -178,6 +232,7 @@ namespace Ooui
 
         static void Start ()
         {
+            if (!serverEnabled) return;
             if (serverCts != null) return;
             serverCts = new CancellationTokenSource ();
             var token = serverCts.Token;
@@ -343,11 +398,17 @@ namespace Ooui
         class DataHandler : RequestHandler
         {
             readonly byte[] data;
+            readonly string etag;
             readonly string contentType;
 
-            public DataHandler (byte[] data, string contentType = null)
+            public byte[] Data => data;
+            public string Etag => etag;
+            public string ContentType => contentType;
+
+            public DataHandler (byte[] data, string etag, string contentType = null)
             {
                 this.data = data;
+                this.etag = etag;
                 this.contentType = contentType;
             }
 
@@ -357,7 +418,13 @@ namespace Ooui
                 var path = url.LocalPath;
                 var response = listenerContext.Response;
 
+                var inm = listenerContext.Request.Headers.Get ("If-None-Match");
+                if (!string.IsNullOrEmpty (inm) && inm == etag) {
+                    response.StatusCode = 304;
+                }
+                else {
                     response.StatusCode = 200;
+                    response.AddHeader ("Etag", etag);
                     if (!string.IsNullOrEmpty (contentType))
                         response.ContentType = contentType;
                     response.ContentLength64 = data.LongLength;
@@ -365,6 +432,7 @@ namespace Ooui
                     using (var s = response.OutputStream) {
                         s.Write (data, 0, data.Length);
                     }
+                }
                 response.Close ();
             }
         }