Added Control.Initialized.

src/Perspex.Controls/Control.cs

@@ -137,6 +137,16 @@ namespace Perspex.Controls
         /// </remarks>
         public event EventHandler DataContextChanged;
 
+        /// <summary>
+        /// Occurs when the control has finished initialization.
+        /// </summary>
+        /// <remarks>
+        /// The Initialized event indicates that all property values on the control have been set.
+        /// It occurs when <see cref="ISupportInitialize.EndInit"/> is called when loading the
+        /// control from markup, or when the control is attached to the visual tree otherwise.
+        /// </remarks>
+        public event EventHandler Initialized;
+
         /// <summary>
         /// Gets or sets the name of the control.
         /// </summary>
@@ -233,6 +243,15 @@ namespace Perspex.Controls
             set { _dataTemplates = value; }
         }
 
+        /// <summary>
+        /// Gets a value that indicates whether the element has finished initialization.
+        /// </summary>
+        /// <remarks>
+        /// For more information about when IsInitialized is set, see the <see cref="Initialized"/>
+        /// event.
+        /// </remarks>
+        public bool IsInitialized { get; private set; }
+
         /// <summary>
         /// Gets or sets the styles for the control.
         /// </summary>
@@ -334,11 +353,20 @@ namespace Perspex.Controls
                 throw new InvalidOperationException("BeginInit was not called.");
             }
 
-            if (--_initCount == 0 && _isAttachedToLogicalTree && !_styled)
+            if (--_initCount == 0)
             {
-                RegisterWithNameScope();
-                ApplyStyling();
-                _styled = true;
+                if (_isAttachedToLogicalTree && !_styled)
+                {
+                    RegisterWithNameScope();
+                    ApplyStyling();
+                    _styled = true;
+                }
+
+                if (!IsInitialized)
+                {
+                    IsInitialized = true;
+                    Initialized?.Invoke(this, EventArgs.Empty);
+                }
             }
         }
 
@@ -499,6 +527,24 @@ namespace Perspex.Controls
             DetachedFromLogicalTree?.Invoke(this, e);
         }
 
+        /// <inheritdoc/>
+        protected sealed override void OnAttachedToVisualTreeCore(VisualTreeAttachmentEventArgs e)
+        {
+            base.OnAttachedToVisualTreeCore(e);
+
+            if (!IsInitialized)
+            {
+                IsInitialized = true;
+                Initialized?.Invoke(this, EventArgs.Empty);
+            }
+        }
+
+        /// <inheritdoc/>
+        protected sealed override void OnDetachedFromVisualTreeCore(VisualTreeAttachmentEventArgs e)
+        {
+            base.OnDetachedFromVisualTreeCore(e);
+        }
+
         /// <inheritdoc/>
         protected override void OnGotFocus(GotFocusEventArgs e)
         {

src/Perspex.Controls/IControl.cs

@@ -17,14 +17,9 @@ namespace Perspex.Controls
     public interface IControl : IVisual, ILogical, ILayoutable, IInputElement, INamed, IStyleable, IStyleHost
     {
         /// <summary>
-        /// Raised when the control is attached to a rooted logical tree.
+        /// Occurs when the control has finished initialization.
         /// </summary>
-        event EventHandler<LogicalTreeAttachmentEventArgs> AttachedToLogicalTree;
-
-        /// <summary>
-        /// Raised when the control is detached from a rooted logical tree.
-        /// </summary>
-        event EventHandler<LogicalTreeAttachmentEventArgs> DetachedFromLogicalTree;
+        event EventHandler Initialized;
 
         /// <summary>
         /// Gets or sets the control's styling classes.
@@ -41,6 +36,11 @@ namespace Perspex.Controls
         /// </summary>
         DataTemplates DataTemplates { get; }
 
+        /// <summary>
+        /// Gets a value that indicates whether the element has finished initialization.
+        /// </summary>
+        bool IsInitialized { get; }
+
         /// <summary>
         /// Gets the control's logical parent.
         /// </summary>

src/Perspex.SceneGraph/Visual.cs

@@ -281,6 +281,60 @@ namespace Perspex
             }
         }
 
+        /// <summary>
+        /// Calls the <see cref="OnAttachedToVisualTree(VisualTreeAttachmentEventArgs)"/> method 
+        /// for this control and all of its visual descendents.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected virtual void OnAttachedToVisualTreeCore(VisualTreeAttachmentEventArgs e)
+        {
+            Logger.Verbose(LogArea.Visual, this, "Attached to visual tree");
+
+            VisualRoot = e.Root;
+
+            if (RenderTransform != null)
+            {
+                RenderTransform.Changed += RenderTransformChanged;
+            }
+
+            OnAttachedToVisualTree(e);
+
+            if (VisualChildren != null)
+            {
+                foreach (Visual child in VisualChildren.OfType<Visual>())
+                {
+                    child.OnAttachedToVisualTreeCore(e);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Calls the <see cref="OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs)"/> method 
+        /// for this control and all of its visual descendents.
+        /// </summary>
+        /// <param name="e">The event args.</param>
+        protected virtual void OnDetachedFromVisualTreeCore(VisualTreeAttachmentEventArgs e)
+        {
+            Logger.Verbose(LogArea.Visual, this, "Detached from visual tree");
+
+            VisualRoot = null;
+
+            if (RenderTransform != null)
+            {
+                RenderTransform.Changed -= RenderTransformChanged;
+            }
+
+            OnDetachedFromVisualTree(e);
+
+            if (VisualChildren != null)
+            {
+                foreach (Visual child in VisualChildren.OfType<Visual>())
+                {
+                    child.OnDetachedFromVisualTreeCore(e);
+                }
+            }
+        }
+
         /// <summary>
         /// Called when the control is added to a visual tree.
         /// </summary>
@@ -438,59 +492,5 @@ namespace Perspex
                     break;
             }
         }
-
-        /// <summary>
-        /// Calls the <see cref="OnAttachedToVisualTree(VisualTreeAttachmentEventArgs)"/> method 
-        /// for this control and all of its visual descendents.
-        /// </summary>
-        /// <param name="e">The event args.</param>
-        private void OnAttachedToVisualTreeCore(VisualTreeAttachmentEventArgs e)
-        {
-            Logger.Verbose(LogArea.Visual, this, "Attached to visual tree");
-
-            VisualRoot = e.Root;
-
-            if (RenderTransform != null)
-            {
-                RenderTransform.Changed += RenderTransformChanged;
-            }
-
-            OnAttachedToVisualTree(e);
-
-            if (VisualChildren != null)
-            {
-                foreach (Visual child in VisualChildren.OfType<Visual>())
-                {
-                    child.OnAttachedToVisualTreeCore(e);
-                }
-            }
-        }
-
-        /// <summary>
-        /// Calls the <see cref="OnDetachedFromVisualTree(VisualTreeAttachmentEventArgs)"/> method 
-        /// for this control and all of its visual descendents.
-        /// </summary>
-        /// <param name="e">The event args.</param>
-        private void OnDetachedFromVisualTreeCore(VisualTreeAttachmentEventArgs e)
-        {
-            Logger.Verbose(LogArea.Visual, this, "Detached from visual tree");
-
-            VisualRoot = null;
-
-            if (RenderTransform != null)
-            {
-                RenderTransform.Changed -= RenderTransformChanged;
-            }
-
-            OnDetachedFromVisualTree(e);
-
-            if (VisualChildren != null)
-            {
-                foreach (Visual child in VisualChildren.OfType<Visual>())
-                {
-                    child.OnDetachedFromVisualTreeCore(e);
-                }
-            }
-        }
     }
 }

tests/Perspex.Controls.UnitTests/ControlTests.cs

@@ -230,6 +230,34 @@ namespace Perspex.Controls.UnitTests
             }
         }
 
+        [Fact]
+        public void EndInit_Should_Raise_Initialized()
+        {
+            var target = new Border();
+            var called = false;
+
+            target.Initialized += (s, e) => called = true;
+            ((ISupportInitialize)target).BeginInit();
+            ((ISupportInitialize)target).EndInit();
+
+            Assert.True(called);
+            Assert.True(target.IsInitialized);
+        }
+
+        [Fact]
+        public void Attaching_To_Visual_Tree_Should_Raise_Initialized()
+        {
+            var root = new TestRoot();
+            var target = new Border();
+            var called = false;
+
+            target.Initialized += (s, e) => called = true;
+            root.Child = target;
+
+            Assert.True(called);
+            Assert.True(target.IsInitialized);
+        }
+
         private class TestControl : Control
         {
             public new PerspexObject InheritanceParent => base.InheritanceParent;