Added a logging manager...

To try and figure out why stuff is flashing up on the screen when you
open a new tree view node, and then decided to put that off for later ;)

Perspex.Diagnostics/LogManager.cs

@@ -0,0 +1,67 @@
+// -----------------------------------------------------------------------
+// <copyright file="LogManager.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Diagnostics
+{
+    using System;
+    using Perspex.Layout;
+    using Splat;
+
+    public class LogManager : ILogManager
+    {
+        private static LogManager instance;
+
+        public static LogManager Instance
+        {
+            get
+            {
+                if (instance == null)
+                {
+                    instance = new LogManager();
+                }
+
+                return instance;
+            }
+        }
+
+        public ILogger Logger
+        {
+            get;
+            set;
+        }
+
+        public bool LogPropertyMessages
+        {
+            get;
+            set;
+        }
+
+        public bool LogLayoutMessages
+        {
+            get;
+            set;
+        }
+
+        public static void Enable(ILogger logger)
+        {
+            Instance.Logger = logger;
+            Locator.CurrentMutable.Register(() => Instance, typeof(ILogManager));
+        }
+
+        public IFullLogger GetLogger(Type type)
+        {
+            if ((type == typeof(PerspexObject) && LogPropertyMessages) ||
+                (type == typeof(Layoutable) && LogLayoutMessages))
+            {
+                return new WrappingFullLogger(this.Logger, type);
+            }
+            else
+            {
+                return new WrappingFullLogger(new NullLogger(), type);
+            }
+        }
+    }
+}

Perspex.Diagnostics/Perspex.Diagnostics.csproj

@@ -21,7 +21,7 @@
     <DebugType>full</DebugType>
     <Optimize>false</Optimize>
     <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE</DefineConstants>
+    <DefineConstants>TRACE;DEBUG</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
   </PropertyGroup>
@@ -65,11 +65,15 @@
     </ProjectReference>
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="LogManager.cs" />
     <Compile Include="DevTools.cs" />
     <Compile Include="Debug.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>
+    <Reference Include="Splat">
+      <HintPath>..\packages\Splat.1.3.3\lib\Portable-net45+win+wpa81+wp80\Splat.dll</HintPath>
+    </Reference>
     <Reference Include="System.Reactive.Core">
       <HintPath>..\packages\Rx-Core.2.1.30214.0\lib\Portable-Net45+WinRT45+WP8\System.Reactive.Core.dll</HintPath>
     </Reference>

Perspex.Diagnostics/packages.config

@@ -5,4 +5,5 @@
   <package id="Rx-Linq" version="2.1.30214.0" targetFramework="portable-net45+win" />
   <package id="Rx-Main" version="2.1.30214.0" targetFramework="portable-net45+win" />
   <package id="Rx-PlatformServices" version="2.1.30214.0" targetFramework="portable-net45+win" />
+  <package id="Splat" version="1.3.3" targetFramework="portable-net45+win" />
 </packages>

Perspex.Layout/ILayoutManager.cs

@@ -13,6 +13,8 @@ namespace Perspex.Layout
     {
         IObservable<Unit> LayoutNeeded { get; }
 
+        bool LayoutQueued { get; }
+
         void ExecuteLayoutPass();
 
         void InvalidateMeasure(ILayoutable item);

Perspex.Layout/LayoutManager.cs

@@ -7,7 +7,6 @@
 namespace Perspex.Layout
 {
     using System;
-    using System.Linq;
     using System.Reactive;
     using System.Reactive.Subjects;
 
@@ -30,25 +29,42 @@ namespace Perspex.Layout
             get { return this.layoutNeeded; }
         }
 
+        public bool LayoutQueued
+        {
+            get;
+            private set;
+        }
+
         public void ExecuteLayoutPass()
         {
-            if (this.root != null)
+            this.root.Measure(this.root.ClientSize);
-            {
+            this.root.Arrange(new Rect(this.root.ClientSize));
-                this.root.Measure(this.root.ClientSize);
+            this.LayoutQueued = false;
-                this.root.Arrange(new Rect(this.root.ClientSize));
-            }
         }
 
         public void InvalidateMeasure(ILayoutable item)
         {
-            IVisual visual = item as IVisual;
+            if (!this.LayoutQueued)
-            this.layoutNeeded.OnNext(Unit.Default);
+            {
+                IVisual visual = item as IVisual;
+                this.layoutNeeded.OnNext(Unit.Default);
+                this.LayoutQueued = true;
+            }
         }
 
         public void InvalidateArrange(ILayoutable item)
         {
-            IVisual visual = item as IVisual;
+            if (!this.LayoutQueued)
-            this.layoutNeeded.OnNext(Unit.Default);
+            {
+                IVisual visual = item as IVisual;
+                this.layoutNeeded.OnNext(Unit.Default);
+                this.LayoutQueued = true;
+            }
+        }
+
+        public void LayoutFinished()
+        {
+            this.LayoutQueued = false;
         }
     }
 }

Perspex.Windows/Window.cs

@@ -59,14 +59,18 @@ namespace Perspex.Windows
             });
 
             this.RenderManager.RenderNeeded
+                .Where(_ => !this.LayoutManager.LayoutQueued)
                 .Subscribe(x =>
             {
                 WindowsDispatcher.CurrentDispatcher.BeginInvoke(
                     DispatcherPriority.Render,
                     () =>
                     {
-                        this.renderer.Render(this);
+                        if (!this.LayoutManager.LayoutQueued)
-                        this.RenderManager.RenderFinished();
+                        {
+                            this.renderer.Render(this);
+                            this.RenderManager.RenderFinished();
+                        }
                     });
             });
         }

TestApplication/Program.cs

@@ -1,12 +1,8 @@
-using System.Collections;
+using Perspex;
-using System.Collections.Generic;
-using System.Linq;
-using Perspex;
 using Perspex.Controls;
 using Perspex.Layout;
 using Perspex.Media;
 using Perspex.Media.Imaging;
-using Perspex.Threading;
 using Perspex.Windows;
 using Splat;
 
@@ -86,7 +82,8 @@ namespace TestApplication
 
         static void Main(string[] args)
         {
-            //Locator.CurrentMutable.Register(() => new TestLogger { Level = LogLevel.Debug } , typeof(ILogger));
+            //LogManager.Enable(new TestLogger());
+            //LogManager.Instance.LogLayoutMessages = true;
 
             App application = new App
             {