sample: Add AsyncSample to showcase GLibSynchronizationContext

Add a sample to illustrate the point of having a
GLibSynchronizationContext, but with the async/await code ifdef'ed out
because we don't require Mono 3.0 for now. Instead, provide a crude
equivalent of what would be generated by the compiler, to show that it
works.

sample/AsyncSample.cs

@@ -0,0 +1,109 @@
+// AsyncSample.cs - Async call using SynchronizationContext
+//
+// Author: Bertrand Lorentz <bertrand.lorentz@gmail.com>
+//
+// Copyright (c) 2012 Bertrand Lorentz
+//
+// This program is free software; you can redistribute it and/or
+// modify it under the terms of version 2 of the Lesser GNU General
+// Public License as published by the Free Software Foundation.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this program; if not, write to the
+// Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+// Boston, MA 02111-1307, USA.
+
+namespace Samples
+{
+	using Gtk;
+	using Gdk;
+	using System;
+	using System.Threading;
+
+	public class AsyncSample
+	{
+		static Label msg;
+		static Label label;
+		static Button button;
+		static int count;
+		static Thread main_thread;
+		
+		public static int Main (string[] args)
+		{
+			Application.Init ();
+			main_thread = Thread.CurrentThread;
+
+			Gtk.Window win = new Gtk.Window ("Gtk# Hello Async World");
+			win.DeleteEvent += new DeleteEventHandler (Window_Delete);
+			label = new Label ("Doing nothing");
+			msg = new Label ("Do Work");
+			button = new Button (msg);
+			button.Clicked += delegate { DoWork (); };
+			VBox box = new VBox (true, 8);
+			box.Add (label);
+			box.Add (button);
+			win.Add (box);
+			win.BorderWidth = 4;
+			win.ShowAll ();
+
+			Application.Run ();
+			
+			return 0;
+		}
+
+#if NET_4_5 // Enable this when we require Mono 3.0
+		static async void DoWork ()
+		{
+			label.Text = "Starting Work";
+
+			int res = await DoLongOperation ();
+
+			CheckThread ("Updating UI");
+			label.Text = String.Format ("Work Done ({0})", res);
+		}
+#else
+		static void DoWork ()
+		{
+			label.Text = "Starting Work";
+
+			var sc = SynchronizationContext.Current;
+			ThreadPool.QueueUserWorkItem (delegate {
+				int res = DoLongOperation ();
+				sc.Post (delegate {
+					CheckThread ("Updating UI");
+					label.Text = String.Format ("Work Done ({0})", res);
+				}, null);
+			});
+		}
+#endif
+
+		static int DoLongOperation ()
+		{
+			count++;
+			CheckThread ("Doing long operation");
+			Thread.Sleep (2000);
+			return count;
+		}
+
+		static void CheckThread (string msg)
+		{
+			if (Thread.CurrentThread == main_thread) {
+				Console.WriteLine ("In main thread - {0}", msg);
+			} else {
+				Console.WriteLine ("Not in main thread - {0}", msg);
+			}
+		}
+
+		static void Window_Delete (object obj, DeleteEventArgs args)
+		{
+			Application.Quit ();
+			args.RetVal = true;
+		}
+	}
+}
+

sample/Makefile.am

@@ -8,7 +8,7 @@ DOTNET_TARGETS=
 DOTNET_ASSEMBLY=
 endif
 
-TARGETS = gtk-hello-world.exe button.exe calendar.exe subclass.exe menu.exe treeviewdemo.exe managedtreeviewdemo.exe nodeviewdemo.exe treemodeldemo.exe actions.exe spawn.exe assistant.exe registerprop.exe gexceptiontest.exe native-instantiation.exe polarfixed.exe cairo-sample.exe scribble.exe testdnd.exe custom-cellrenderer.exe custom-widget.exe custom-scrollable.exe #scribble-xinput.exe $(DOTNET_TARGETS)
+TARGETS = gtk-hello-world.exe async-sample.exe button.exe calendar.exe subclass.exe menu.exe treeviewdemo.exe managedtreeviewdemo.exe nodeviewdemo.exe treemodeldemo.exe actions.exe spawn.exe assistant.exe registerprop.exe gexceptiontest.exe native-instantiation.exe polarfixed.exe cairo-sample.exe scribble.exe testdnd.exe custom-cellrenderer.exe custom-widget.exe custom-scrollable.exe #scribble-xinput.exe $(DOTNET_TARGETS)
 
 DEBUGS = $(addsuffix .mdb, $(TARGETS))
 
@@ -29,6 +29,9 @@ CLEANFILES = $(TARGETS) $(DEBUGS)
 gtk-hello-world.exe: $(srcdir)/HelloWorld.cs $(assemblies)
 	$(CSC) $(CSFLAGS) -out:gtk-hello-world.exe $(references) $(srcdir)/HelloWorld.cs
 
+async-sample.exe: $(srcdir)/AsyncSample.cs $(assemblies)
+	$(CSC) $(CSFLAGS) -out:async-sample.exe $(references) $(srcdir)/AsyncSample.cs
+
 button.exe: $(srcdir)/ButtonApp.cs $(assemblies)
 	$(CSC) $(CSFLAGS) -out:button.exe $(references) $(srcdir)/ButtonApp.cs
 
@@ -103,6 +106,7 @@ gexceptiontest.exe: $(srcdir)/GExceptionTest.cs $(assemblies)
 EXTRA_DIST = 				\
 	HelloWorld.cs			\
 	Assistant.cs			\
+	AsyncSample.cs			\
 	ButtonApp.cs			\
 	CalendarApp.cs			\
 	Subclass.cs			\

sample/sample.csproj

@@ -104,6 +104,7 @@
     <Compile Include="test\TestStatusbar.cs" />
     <Compile Include="test\WidgetViewer.cs" />
     <Compile Include="CustomScrollableWidget.cs" />
+    <Compile Include="AsyncSample.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
   <ItemGroup>