Make template find methods to extension class.

Perspex.Controls/ContentControl.cs

@@ -10,6 +10,7 @@ namespace Perspex.Controls
     using Perspex.Collections;
     using Perspex.Controls.Presenters;
     using Perspex.Controls.Primitives;
+    using Perspex.Controls.Templates;
     using Perspex.Layout;
 
     public class ContentControl : TemplatedControl, IContentControl, ILogical

Perspex.Controls/ControlExtensions.cs

@@ -22,21 +22,5 @@ namespace Perspex.Controls
                 .OfType<T>()
                 .FirstOrDefault(x => x.Id == id);
         }
-
-        public static IEnumerable<Control> GetTemplateControls(this ITemplatedControl control)
-        {
-            var visual = control as IVisual;
-
-            if (visual != null)
-            {
-                return visual.GetVisualDescendents()
-                    .OfType<Control>()
-                    .Where(x => x.TemplatedParent != null);
-            }
-            else
-            {
-                return Enumerable.Empty<Control>();
-            }
-        }
     }
 }

Perspex.Controls/DropDown.cs

@@ -10,6 +10,7 @@ namespace Perspex.Controls
     using Perspex.Collections;
     using Perspex.Controls.Presenters;
     using Perspex.Controls.Primitives;
+    using Perspex.Controls.Templates;
     using Perspex.Layout;
 
     public class DropDown : SelectingItemsControl, IContentControl, ILogical

Perspex.Controls/ItemsControl.cs

@@ -15,6 +15,7 @@ namespace Perspex.Controls
     using Perspex.Controls.Generators;
     using Perspex.Controls.Presenters;
     using Perspex.Controls.Primitives;
+    using Perspex.Controls.Templates;
     using Perspex.VisualTree;
 
     public class ItemsControl : TemplatedControl, ILogical
@@ -87,10 +88,14 @@ namespace Perspex.Controls
                 this.logicalChildren = null;
             }
 
-            this.presenter = this.GetTemplateChild<ItemsPresenter>("itemsPresenter");
-            this.logicalChildren = new PerspexReadOnlyListView<IVisual, ILogical>(
-                ((IVisual)presenter.Panel).VisualChildren,
-                x => (ILogical)x);
+            this.presenter = this.FindTemplateChild<ItemsPresenter>("itemsPresenter");
+
+            if (this.presenter != null)
+            {
+                this.logicalChildren = new PerspexReadOnlyListView<IVisual, ILogical>(
+                    ((IVisual)presenter.Panel).VisualChildren,
+                    x => (ILogical)x);
+            }
         }
 
         private void ItemsChanged(Tuple<IEnumerable, IEnumerable> value)

Perspex.Controls/Perspex.Controls.csproj

@@ -85,6 +85,7 @@
     <Compile Include="Primitives\Thumb.cs" />
     <Compile Include="RequestBringIntoViewEventArgs.cs" />
     <Compile Include="Shapes\Ellipse.cs" />
+    <Compile Include="Templates\TemplateExtensions.cs" />
     <Compile Include="TextWrapping.cs" />
     <Compile Include="Utils\StringUtils.cs" />
     <Compile Include="TopLevel.cs" />

Perspex.Controls/Primitives/TemplatedControl.cs

@@ -9,6 +9,7 @@ namespace Perspex.Controls.Primitives
     using System;
     using System.Linq;
     using Perspex.Controls.Presenters;
+    using Perspex.Controls.Templates;
     using Perspex.Media;
     using Perspex.Styling;
     using Perspex.VisualTree;
@@ -122,7 +123,7 @@ namespace Perspex.Controls.Primitives
                     this.AddVisualChild(child);
                     child.Parent = this;
 
-                    foreach (var i in this.GetTemplateControls())
+                    foreach (var i in this.GetTemplateChildren())
                     {
                         i.ApplyTemplate();
                     }
@@ -162,57 +163,6 @@ namespace Perspex.Controls.Primitives
             return new Size();
         }
 
-        protected T FindTemplateChild<T>(string id) where T : Control
-        {
-            var matches = this.GetTemplateControls()
-                .OfType<T>()
-                .Where(x => x.Id == id)
-                .ToList();
-
-            if (matches.Count == 1)
-            {
-                return matches[0];
-            }
-            else if (matches.Count == 0)
-            {
-                return null;
-            }
-            else
-            {
-                // If there are multiple matches, try filtering out nested matches.
-                matches = matches.Where(x => x.TemplatedParent == this).ToList();
-                
-                if (matches.Count > 1)
-                {
-                    throw new InvalidOperationException(string.Format(
-                        "Found multiple template children '{0}' of type '{1}' in template for '{2}'.",
-                        id,
-                        typeof(T).FullName,
-                        this.GetType().FullName));
-                }
-                else
-                {
-                    return matches.FirstOrDefault();
-                }
-            }
-        }
-
-        protected T GetTemplateChild<T>(string id) where T : Control
-        {
-            var result = this.FindTemplateChild<T>(id);
-
-            if (result == null)
-            {
-                throw new InvalidOperationException(string.Format(
-                    "Could not find template child '{0}' of type '{1}' in template for '{2}'.",
-                    id,
-                    typeof(T).FullName,
-                    this.GetType().FullName));
-            }
-
-            return result;
-        }
-
         protected virtual void OnTemplateApplied()
         {
         }

Perspex.Controls/Templates/TemplateExtensions.cs

@@ -0,0 +1,57 @@
+// -----------------------------------------------------------------------
+// <copyright file="TemplateExtensions.cs" company="Steven Kirk">
+// Copyright 2014 MIT Licence. See licence.md for more information.
+// </copyright>
+// -----------------------------------------------------------------------
+
+namespace Perspex.Controls.Templates
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Linq;
+    using Perspex.Controls;
+    using Perspex.Styling;
+    using Perspex.VisualTree;
+
+    public static class TemplateExtensions
+    {
+        public static T FindTemplateChild<T>(this ITemplatedControl control, string id) where T : Control
+        {
+            return control.GetTemplateChildren().OfType<T>().SingleOrDefault(x => x.Id == id);
+        }
+
+        public static T GetTemplateChild<T>(this ITemplatedControl control, string id) where T : Control
+        {
+            var result = control.FindTemplateChild<T>(id);
+
+            if (result == null)
+            {
+                throw new InvalidOperationException(string.Format(
+                    "Could not find template child '{0}' of type '{1}' in template for '{2}'.",
+                    id,
+                    typeof(T).FullName,
+                    control.GetType().FullName));
+            }
+
+            return result;
+        }
+
+        public static IEnumerable<Control> GetTemplateChildren(this ITemplatedControl control)
+        {
+            var visual = control as IVisual;
+
+            if (visual != null)
+            {
+                // TODO: This searches the whole descendent tree - it can stop when it exits the 
+                // template.
+                return visual.GetVisualDescendents()
+                    .OfType<Control>()
+                    .Where(x => x.TemplatedParent == control);
+            }
+            else
+            {
+                return Enumerable.Empty<Control>();
+            }
+        }
+    }
+}

Tests/Perspex.Controls.UnitTests/ContentControlTests.cs

@@ -12,6 +12,7 @@ namespace Perspex.Controls.UnitTests
     using Moq;
     using Perspex.Controls;
     using Perspex.Controls.Presenters;
+    using Perspex.Controls.Templates;
     using Perspex.Layout;
     using Perspex.Platform;
     using Perspex.Styling;
@@ -173,7 +174,7 @@ namespace Perspex.Controls.UnitTests
             contentControl.ApplyTemplate();
 
             // Need to call ApplyTemplate on presenter for CollectionChanged to be called.
-            var presenter = contentControl.GetTemplateControls().Single(x => x.Id == "contentPresenter");
+            var presenter = contentControl.GetTemplateChildren().Single(x => x.Id == "contentPresenter");
             presenter.ApplyTemplate();
 
             Assert.True(called);
@@ -196,7 +197,7 @@ namespace Perspex.Controls.UnitTests
             contentControl.Content = null;
 
             // Need to call ApplyTemplate on presenter for CollectionChanged to be called.
-            var presenter = contentControl.GetTemplateControls().Single(x => x.Id == "contentPresenter");
+            var presenter = contentControl.GetTemplateChildren().Single(x => x.Id == "contentPresenter");
             presenter.ApplyTemplate();
 
             Assert.True(called);
@@ -220,7 +221,7 @@ namespace Perspex.Controls.UnitTests
             contentControl.Content = child2;
 
             // Need to call ApplyTemplate on presenter for CollectionChanged to be called.
-            var presenter = contentControl.GetTemplateControls().Single(x => x.Id == "contentPresenter");
+            var presenter = contentControl.GetTemplateChildren().Single(x => x.Id == "contentPresenter");
             presenter.ApplyTemplate();
 
             Assert.True(called);

Tests/Perspex.Controls.UnitTests/DropDownTests.cs

@@ -12,6 +12,7 @@ namespace Perspex.Controls.UnitTests
     using Moq;
     using Perspex.Controls;
     using Perspex.Controls.Presenters;
+    using Perspex.Controls.Templates;
     using Perspex.Platform;
     using Perspex.Styling;
     using Perspex.VisualTree;
@@ -172,7 +173,7 @@ namespace Perspex.Controls.UnitTests
             target.ApplyTemplate();
 
             // Need to call ApplyTemplate on presenter for CollectionChanged to be called.
-            var presenter = target.GetTemplateControls().Single(x => x.Id == "contentPresenter");
+            var presenter = target.GetTemplateChildren().Single(x => x.Id == "contentPresenter");
             presenter.ApplyTemplate();
 
             Assert.True(called);
@@ -195,7 +196,7 @@ namespace Perspex.Controls.UnitTests
             target.Content = null;
 
             // Need to call ApplyTemplate on presenter for CollectionChanged to be called.
-            var presenter = target.GetTemplateControls().Single(x => x.Id == "contentPresenter");
+            var presenter = target.GetTemplateChildren().Single(x => x.Id == "contentPresenter");
             presenter.ApplyTemplate();
 
             Assert.True(called);
@@ -219,7 +220,7 @@ namespace Perspex.Controls.UnitTests
             target.Content = child2;
 
             // Need to call ApplyTemplate on presenter for CollectionChanged to be called.
-            var presenter = target.GetTemplateControls().Single(x => x.Id == "contentPresenter");
+            var presenter = target.GetTemplateChildren().Single(x => x.Id == "contentPresenter");
             presenter.ApplyTemplate();
 
             Assert.True(called);

Tests/Perspex.Controls.UnitTests/ItemsControlTests.cs

@@ -12,6 +12,7 @@ namespace Perspex.Controls.UnitTests
     using Perspex.Collections;
     using Perspex.Controls;
     using Perspex.Controls.Presenters;
+    using Perspex.Controls.Templates;
     using Perspex.Platform;
     using Perspex.Styling;
     using Perspex.VisualTree;
@@ -31,8 +32,8 @@ namespace Perspex.Controls.UnitTests
             target.Items = new[] { "Foo" };
             target.ApplyTemplate();
 
-            var presenter = target.GetTemplateControls().OfType<ItemsPresenter>().Single();
-            var panel = presenter.GetTemplateControls().OfType<StackPanel>().Single();
+            var presenter = target.GetTemplateChildren().OfType<ItemsPresenter>().Single();
+            var panel = presenter.GetTemplateChildren().OfType<StackPanel>().Single();
 
             Assert.Equal(presenter, panel.TemplatedParent);
         }
@@ -46,8 +47,8 @@ namespace Perspex.Controls.UnitTests
             target.Items = new[] { "Foo" };
             target.ApplyTemplate();
 
-            var presenter = target.GetTemplateControls().OfType<ItemsPresenter>().Single();
-            var panel = presenter.GetTemplateControls().OfType<StackPanel>().Single();
+            var presenter = target.GetTemplateChildren().OfType<ItemsPresenter>().Single();
+            var panel = presenter.GetTemplateChildren().OfType<StackPanel>().Single();
             var item = (TextBlock)panel.GetVisualChildren().First();
 
             Assert.Null(item.TemplatedParent);

Tests/Perspex.Controls.UnitTests/TemplatedControlTests.cs

@@ -11,6 +11,7 @@ namespace Perspex.Controls.UnitTests
     using Perspex.Controls;
     using Perspex.Controls.Presenters;
     using Perspex.Controls.Primitives;
+    using Perspex.Controls.Templates;
     using Perspex.Styling;
     using Perspex.VisualTree;
     using Splat;
@@ -201,8 +202,8 @@ namespace Perspex.Controls.UnitTests
 
             target.ApplyTemplate();
 
-            var panel = target.GetTemplateControls().OfType<StackPanel>().Single();
-            var textBlock = target.GetTemplateControls().OfType<TextBlock>().Single();
+            var panel = target.GetTemplateChildren().OfType<StackPanel>().Single();
+            var textBlock = target.GetTemplateChildren().OfType<TextBlock>().Single();
 
             Assert.Equal(target, panel.TemplatedParent);
             Assert.Equal(target, textBlock.TemplatedParent);
@@ -226,7 +227,7 @@ namespace Perspex.Controls.UnitTests
 
             target.ApplyTemplate();
 
-            var presenter = target.GetTemplateControls().OfType<ContentPresenter>().Single();
+            var presenter = target.GetTemplateChildren().OfType<ContentPresenter>().Single();
             var textBlock = (TextBlock)presenter.Child;
 
             Assert.Equal(target, presenter.TemplatedParent);
@@ -261,9 +262,9 @@ namespace Perspex.Controls.UnitTests
 
             target.ApplyTemplate();
 
-            var contentControl = target.GetTemplateControls().OfType<ContentControl>().Single();
-            var border = contentControl.GetTemplateControls().OfType<Border>().Single();
-            var presenter = contentControl.GetTemplateControls().OfType<ContentPresenter>().Single();
+            var contentControl = target.GetTemplateChildren().OfType<ContentControl>().Single();
+            var border = contentControl.GetTemplateChildren().OfType<Border>().Single();
+            var presenter = contentControl.GetTemplateChildren().OfType<ContentPresenter>().Single();
             var textBlock = (TextBlock)presenter.Content;
 
             Assert.Equal(target, contentControl.TemplatedParent);

Tests/Perspex.Layout.UnitTests/FullLayoutTests.cs

@@ -11,6 +11,7 @@ namespace Perspex.Layout.UnitTests
     using Perspex.Controls;
     using Perspex.Controls.Presenters;
     using Perspex.Controls.Primitives;
+    using Perspex.Controls.Templates;
     using Perspex.Input;
     using Perspex.Platform;
     using Perspex.Rendering;
@@ -98,8 +99,8 @@ namespace Perspex.Layout.UnitTests
                 Assert.Equal(new Point(300, 200), Position(scrollViewer));
                 Assert.Equal(new Size(400, 400), textBlock.ActualSize);
 
-                var scrollBars = scrollViewer.GetTemplateControls().OfType<ScrollBar>().ToList();
-                var presenters = scrollViewer.GetTemplateControls().OfType<ScrollContentPresenter>().ToList();
+                var scrollBars = scrollViewer.GetTemplateChildren().OfType<ScrollBar>().ToList();
+                var presenters = scrollViewer.GetTemplateChildren().OfType<ScrollContentPresenter>().ToList();
 
                 Assert.Equal(2, scrollBars.Count);
                 Assert.Equal(1, presenters.Count);