Improve disposal of resources

Backends can now opt-in to automatic disposal of resources in the
UI thread.

Xwt.Gtk/Xwt.CairoBackend/CairoGradientBackendHandler.cs

@@ -36,7 +36,7 @@ namespace Xwt.CairoBackend
 			return new Cairo.LinearGradient (x0, y0, x1, y1);
 		}
 
-		public override void DisposeLinear (object backend)
+		public override void Dispose (object backend)
 		{
 			((IDisposable)backend).Dispose ();
 		}
@@ -46,11 +46,6 @@ namespace Xwt.CairoBackend
 			return new Cairo.RadialGradient (cx0, cy0, radius0, cx1, cy1, radius1);
 		}
 
-		public override void DisposeRadial (object backend)
-		{
-			((IDisposable)backend).Dispose ();
-		}
-		
 		public override void AddColorStop (object backend, double position, Xwt.Drawing.Color color)
 		{
 			Cairo.Gradient g = (Cairo.Gradient) backend;

Xwt.Gtk/Xwt.GtkBackend/TextLayoutBackendHandler.cs

@@ -201,7 +201,7 @@ namespace Xwt.GtkBackend
 			return new Point (pos.X, pos.Y);
 		}
 
-		public override void DisposeBackend (object backend)
+		public override void Dispose (object backend)
 		{
 			var tl = (IDisposable) backend;
 			tl.Dispose ();

Xwt.Mac/Xwt.Mac/GradientBackendHandler.cs

@@ -44,7 +44,7 @@ namespace Xwt.Mac
 			};
 		}
 
-		public override void DisposeLinear (object backend)
+		public override void Dispose (object backend)
 		{
 		}
 
@@ -59,10 +59,6 @@ namespace Xwt.Mac
 			};
 		}
 
-		public override void DisposeRadial (object backend)
-		{
-		}
-
 		public override void AddColorStop (object backend, double position, Xwt.Drawing.Color color)
 		{
 			GradientInfo gr = (GradientInfo) backend;

Xwt.Mac/Xwt.Mac/TextLayoutBackendHandler.cs

@@ -205,7 +205,7 @@ namespace Xwt.Mac
 			return new Point (0,0);
 		}
 
-		public override void DisposeBackend (object backend)
+		public override void Dispose (object backend)
 		{
 			// nothing
 		}

Xwt.WPF/Xwt.WPFBackend/GradientBackendHandler.cs

@@ -47,7 +47,7 @@ namespace Xwt.WPFBackend
 			};
 		}
 
-		public override void DisposeLinear (object backend)
+		public override void Dispose (object backend)
 		{
 		}
 
@@ -62,10 +62,6 @@ namespace Xwt.WPFBackend
 			};
 		}
 
-		public override void DisposeRadial (object backend)
-		{
-		}
-
 		public override void AddColorStop (object backend, double position, Color color)
 		{
 			((GradientBrush)backend).GradientStops.Add (new GradientStop (color.ToWpfColor (), position));

Xwt/Xwt.Backends/DisposableResourceBackendHandler.cs

@@ -0,0 +1,41 @@
+//
+// ResourceBackendHandler.cs
+//
+// Author:
+//       Lluis Sanchez <lluis@xamarin.com>
+//
+// Copyright (c) 2013 Xamarin Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+
+namespace Xwt.Backends
+{
+	public class DisposableResourceBackendHandler: BackendHandler
+	{
+		public virtual bool DisposeHandleOnUiThread {
+			get { return false; }
+		}
+
+		public virtual void Dispose (object backend)
+		{
+		}
+	}
+}
+

Xwt/Xwt.Backends/DrawingPathBackendHandler.cs

@@ -29,7 +29,7 @@ using Xwt.Drawing;
 
 namespace Xwt.Backends
 {
-	public abstract class DrawingPathBackendHandler: BackendHandler
+	public abstract class DrawingPathBackendHandler: DisposableResourceBackendHandler
 	{
 		public abstract void Arc (object backend, double xc, double yc, double radius, double angle1, double angle2);
 
@@ -58,8 +58,6 @@ namespace Xwt.Backends
 		public abstract void AppendPath (object backend, object otherBackend);
 
 		public abstract bool IsPointInFill (object backend, double x, double y);
-
-		public abstract void Dispose (object backend);
 	}
 }
 

Xwt/Xwt.Backends/GradientBackendHandler.cs

@@ -29,12 +29,10 @@ using Xwt.Drawing;
 
 namespace Xwt.Backends
 {
-	public abstract class GradientBackendHandler: BackendHandler
+	public abstract class GradientBackendHandler: DisposableResourceBackendHandler
 	{
 		public abstract object CreateLinear (double x0, double y0, double x1, double y1);
-		public abstract void DisposeLinear (object backend);
 		public abstract object CreateRadial (double cx0, double cy0, double radius0, double cx1, double cy1, double radius1);
-		public abstract void DisposeRadial (object backend);
 		public abstract void AddColorStop (object backend, double position, Color color);
 	}
 }

Xwt/Xwt.Backends/ImageBackendHandler.cs

@@ -32,17 +32,13 @@ using System.Collections.Generic;
 
 namespace Xwt.Backends
 {
-	public abstract class ImageBackendHandler: BackendHandler
+	public abstract class ImageBackendHandler: DisposableResourceBackendHandler
 	{
 		public virtual object CreateBackend ()
 		{
 			throw new NotSupportedException ();
 		}
 		
-		public virtual void Dispose (object backend)
-		{
-		}
-
 		public virtual object LoadFromResource (Assembly asm, string name)
 		{
 			using (var s = asm.GetManifestResourceStream (name)) {

Xwt/Xwt.Backends/ImageBuilderBackendHandler.cs

@@ -28,12 +28,11 @@ using Xwt.Drawing;
 
 namespace Xwt.Backends
 {
-	public abstract class ImageBuilderBackendHandler: BackendHandler
+	public abstract class ImageBuilderBackendHandler: DisposableResourceBackendHandler
 	{
 		public abstract object CreateImageBuilder (int width, int height, ImageFormat format);
 		public abstract object CreateContext (object backend);
 		public abstract object CreateImage (object backend);
-		public abstract void Dispose (object backend);
 	}
 }
 

Xwt/Xwt.Backends/ImagePatternBackendHandler.cs

@@ -27,10 +27,9 @@ using System;
 
 namespace Xwt.Backends
 {
-	public abstract class ImagePatternBackendHandler: BackendHandler
+	public abstract class ImagePatternBackendHandler: DisposableResourceBackendHandler
 	{
 		public abstract object Create (ImageDescription img);
-		public abstract void Dispose (object backend);
 	}
 }
 

Xwt/Xwt.Backends/ResourceManager.cs

@@ -0,0 +1,103 @@
+//
+// ResourceManager.cs
+//
+// Author:
+//       Lluis Sanchez <lluis@xamarin.com>
+//
+// Copyright (c) 2013 Xamarin Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+using System;
+using System.Collections.Generic;
+
+namespace Xwt.Backends
+{
+	static class ResourceManager
+	{
+		static bool finalized;
+		static Dictionary<object,Action<object>> resources = new Dictionary<object,Action<object>> ();
+		static Dictionary<object,Action<object>> freedResources = new Dictionary<object,Action<object>> ();
+
+		public static void RegisterResource (object res, Action<object> disposeCallback = null)
+		{
+			if (finalized)
+				return;
+			lock (resources)
+				resources [res] = disposeCallback;
+		}
+
+		public static bool FreeResource (object res)
+		{
+			if (finalized || res == null)
+				return true;
+
+			lock (resources) {
+				Action<object> disposer;
+				if (!resources.TryGetValue (res, out disposer))
+					return false;
+
+				resources.Remove (res);
+
+				if (System.Threading.Thread.CurrentThread == Application.UIThread) {
+					DisposeResource (res, disposer);
+				} else {
+					lock (freedResources) {
+						if (freedResources.Count == 0)
+							Application.Invoke (DisposeResources);
+						freedResources [res] = disposer;
+					}
+				}
+				return true;
+			}
+		}
+
+		static void DisposeResource (object res, Action<object> disposer)
+		{
+			try {
+				if (disposer != null)
+					disposer (res);
+				else if (res is IDisposable)
+					((IDisposable)res).Dispose ();
+			} catch (Exception ex) {
+				Application.NotifyException (ex);
+			}
+		}
+
+		internal static void DisposeResources ()
+		{
+			lock (freedResources) {
+				if (finalized)
+					return;
+				foreach (var r in freedResources) {
+					DisposeResource (r.Key, r.Value);
+				}
+				freedResources.Clear ();
+			}
+		}
+
+		internal static void Dispose ()
+		{
+			lock (freedResources) {
+				DisposeResources ();
+				finalized = true;
+			}
+		}
+	}
+}
+

Xwt/Xwt.Backends/TextLayoutBackendHandler.cs

@@ -31,7 +31,7 @@ using System.Collections.Generic;
 
 namespace Xwt.Backends
 {
-	public abstract class TextLayoutBackendHandler: BackendHandler
+	public abstract class TextLayoutBackendHandler: DisposableResourceBackendHandler
 	{
 		public abstract object Create ();
 
@@ -43,7 +43,6 @@ namespace Xwt.Backends
 		public abstract Size GetSize (object backend);
 		public abstract int GetIndexFromCoordinates (object backend, double x, double y);
 		public abstract Point GetCoordinateFromIndex (object backend, int index);
-		public abstract void DisposeBackend (object backend);
 
 		public abstract void AddAttribute (object backend, TextAttribute attribute);
 		public abstract void ClearAttributes (object backend);

Xwt/Xwt.Drawing/DrawingPath.cs

@@ -36,11 +36,36 @@ namespace Xwt.Drawing
 		{
 			handler = Toolkit.CurrentEngine.VectorImageRecorderContextHandler;
 			Backend = handler.CreatePath ();
+			Init ();
 		}
 
 		internal DrawingPath (object backend, Toolkit toolkit, DrawingPathBackendHandler h): base (backend, toolkit)
 		{
 			handler = h;
+			Init ();
+		}
+
+		void Init ()
+		{
+			if (handler.DisposeHandleOnUiThread)
+				ResourceManager.RegisterResource (Backend, handler.Dispose);
+			else
+				GC.SuppressFinalize (this);
+		}
+		
+		public void Dispose ()
+		{
+			if (handler.DisposeHandleOnUiThread) {
+				GC.SuppressFinalize (this);
+				ResourceManager.FreeResource (Backend);
+			}
+			else
+				handler.Dispose (Backend);
+		}
+
+		~DrawingPath ()
+		{
+			ResourceManager.FreeResource (Backend);
 		}
 
 		/// <summary>
@@ -318,11 +343,6 @@ namespace Xwt.Drawing
 		{
 			return handler.IsPointInFill (Backend, x, y);
 		}
-
-		public void Dispose ()
-		{
-			handler.Dispose (Backend);
-		}
 	}
 }
 

Xwt/Xwt.Drawing/Image.cs

@@ -488,6 +488,9 @@ namespace Xwt.Drawing
 		{
 			this.backend = backend;
 			this.toolkit = toolkit;
+
+			if (toolkit.ImageBackendHandler.DisposeHandleOnUiThread)
+				ResourceManager.RegisterResource (backend, toolkit.ImageBackendHandler.Dispose);
 		}
 
 		public void AddReference ()
@@ -497,8 +500,15 @@ namespace Xwt.Drawing
 
 		public void ReleaseReference (bool disposing)
 		{
-			if (System.Threading.Interlocked.Decrement (ref referenceCount) == 0 && disposing)
-				toolkit.ImageBackendHandler.Dispose (backend);
+			if (System.Threading.Interlocked.Decrement (ref referenceCount) == 0) {
+				if (disposing) {
+					if (toolkit.ImageBackendHandler.DisposeHandleOnUiThread)
+						ResourceManager.FreeResource (backend);
+					else
+						toolkit.ImageBackendHandler.Dispose (backend);
+				} else
+					ResourceManager.FreeResource (backend);
+			}
 		}
 	}
 }

Xwt/Xwt.Drawing/ImagePattern.cs

@@ -33,14 +33,8 @@ namespace Xwt.Drawing
 	{
 		public ImagePattern (Image image)
 		{
-			Backend = ToolkitEngine.ImagePatternBackendHandler.Create (image != null ? image.ImageDescription : ImageDescription.Null);
+			SetBackend (ToolkitEngine.ImagePatternBackendHandler, ToolkitEngine.ImagePatternBackendHandler.Create (image != null ? image.ImageDescription : ImageDescription.Null));
 		}
-
-		public override void Dispose ()
-		{
-			ToolkitEngine.ImagePatternBackendHandler.Dispose (Backend);
-		}
-
 	}
 }
 

Xwt/Xwt.Drawing/LinearGradient.cs

@@ -33,12 +33,7 @@ namespace Xwt.Drawing
 	{
 		public LinearGradient (double xStart, double yStart, double xEnd, double yEnd)
 		{
-			Backend = ToolkitEngine.GradientBackendHandler.CreateLinear (xStart, yStart, xEnd, yEnd);
-		}
-
-		public override void Dispose ()
-		{
-			ToolkitEngine.GradientBackendHandler.DisposeLinear (Backend);
+			SetBackend (ToolkitEngine.GradientBackendHandler, ToolkitEngine.GradientBackendHandler.CreateLinear (xStart, yStart, xEnd, yEnd));
 		}
 	}
 }

Xwt/Xwt.Drawing/Pattern.cs

@@ -25,16 +25,41 @@
 // THE SOFTWARE.
 
 using System;
+using Xwt.Backends;
 
 namespace Xwt.Drawing
 {
 	public abstract class Pattern: XwtObject, IDisposable
 	{
+		DisposableResourceBackendHandler handler;
+
 		internal Pattern ()
 		{
 		}
 
-		public abstract void Dispose ();
+		internal void SetBackend (DisposableResourceBackendHandler handler, object backend)
+		{
+			Backend = backend;
+			this.handler = handler;
+			if (handler.DisposeHandleOnUiThread)
+				ResourceManager.RegisterResource (backend, handler.Dispose);
+			else
+				GC.SuppressFinalize (this);
+		}
+
+		~Pattern ()
+		{
+			ResourceManager.FreeResource (Backend);
+		}
+
+		public void Dispose ()
+		{
+			if (handler.DisposeHandleOnUiThread) {
+				GC.SuppressFinalize (this);
+				ResourceManager.FreeResource (Backend);
+			} else
+				handler.Dispose (Backend);
+		}
 	}
 }
 

Xwt/Xwt.Drawing/RadialGradient.cs

@@ -33,12 +33,7 @@ namespace Xwt.Drawing
 	{
 		public RadialGradient (double cx0, double cy0, double radius0, double cx1, double cy1, double radius1)
 		{
-			Backend = ToolkitEngine.GradientBackendHandler.CreateRadial (cx0, cy0, radius0, cx1, cy1, radius1);
-		}
-
-		public override void Dispose ()
-		{
-			ToolkitEngine.GradientBackendHandler.DisposeRadial (Backend);
+			SetBackend (ToolkitEngine.GradientBackendHandler, ToolkitEngine.GradientBackendHandler.CreateRadial (cx0, cy0, radius0, cx1, cy1, radius1));
 		}
 	}
 }

Xwt/Xwt.Drawing/TextLayout.cs

@@ -48,6 +48,7 @@ namespace Xwt.Drawing
 			handler = ToolkitEngine.TextLayoutBackendHandler;
 			Backend = handler.Create ();
 			Font = Font.SystemFont;
+			Setup ();
 		}
 
 		public TextLayout (Canvas canvas)
@@ -56,6 +57,7 @@ namespace Xwt.Drawing
 			handler = ToolkitEngine.TextLayoutBackendHandler;
 			Backend = handler.Create ();
 			Font = canvas.Font;
+			Setup ();
 		}
 
 		internal TextLayout (Toolkit tk)
@@ -63,6 +65,29 @@ namespace Xwt.Drawing
 			ToolkitEngine = tk;
 			handler = ToolkitEngine.TextLayoutBackendHandler;
 			Backend = handler.Create ();
+			Setup ();
+		}
+
+		void Setup ()
+		{
+			if (handler.DisposeHandleOnUiThread)
+				ResourceManager.RegisterResource (Backend, handler.Dispose);
+			else
+				GC.SuppressFinalize (this);
+		}
+		
+		public void Dispose ()
+		{
+			if (handler.DisposeHandleOnUiThread) {
+				GC.SuppressFinalize (this);
+				ResourceManager.FreeResource (Backend);
+			} else
+				handler.Dispose (Backend);
+		}
+
+		~TextLayout ()
+		{
+			ResourceManager.FreeResource (Backend);
 		}
 
 		internal TextLayoutData GetData ()
@@ -255,11 +280,6 @@ namespace Xwt.Drawing
 		{
 			AddAttribute (new StrikethroughTextAttribute () { StartIndex = startIndex, Count = count});
 		}
-
-		public void Dispose ()
-		{
-			handler.DisposeBackend (Backend);
-		}
 	}
 
 	public enum TextTrimming {

Xwt/Xwt.Drawing/VectorImage.cs

@@ -116,14 +116,31 @@ namespace Xwt.Drawing
 		public override object CreateNativeBackend ()
 		{
 			imageBuilder = toolkit.ImageBuilderBackendHandler.CreateImageBuilder ((int)width, (int)height, ImageFormat.ARGB32);
+			if (toolkit.ImageBuilderBackendHandler.DisposeHandleOnUiThread)
+				ResourceManager.RegisterResource (imageBuilder);
+			else
+				GC.SuppressFinalize (this);
+
 			return toolkit.ImageBuilderBackendHandler.CreateContext (imageBuilder);
 		}
 
+		~VectorContextBackend ()
+		{
+			if (imageBuilder != null)
+				ResourceManager.FreeResource (imageBuilder);
+		}
+
 		public override void Dispose ()
 		{
 			base.Dispose ();
-			if (imageBuilder != null)
-				toolkit.ImageBuilderBackendHandler.Dispose (imageBuilder);
+			if (imageBuilder != null) {
+				if (toolkit.ImageBuilderBackendHandler.DisposeHandleOnUiThread) {
+					GC.SuppressFinalize (this);
+					ResourceManager.FreeResource (imageBuilder);
+				}
+				else
+					toolkit.ImageBuilderBackendHandler.Dispose (imageBuilder);
+			}
 		}
 	}
 

Xwt/Xwt.csproj

@@ -414,6 +414,8 @@
     <Compile Include="Xwt\TableCalc.cs" />
     <Compile Include="Xwt\VSlider.cs" />
     <Compile Include="Xwt\HSlider.cs" />
+    <Compile Include="Xwt.Backends\ResourceManager.cs" />
+    <Compile Include="Xwt.Backends\DisposableResourceBackendHandler.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <ItemGroup />

Xwt/Xwt/Application.cs

@@ -102,7 +102,18 @@ namespace Xwt
 				engine.ExitApplication ();
 			});
 		}
-			/// <summary>
+
+		/// <summary>
+		/// Releases all resource used by the application
+		/// </summary>
+		/// <remarks>This method must be called before the application process ends</remarks>
+		public static void Dispose ()
+		{
+			ResourceManager.Dispose ();
+		}
+
+
+		/// <summary>
 		/// Invokes an action in the GUI thread
 		/// </summary>
 		/// <param name='action'>