Fix ScrollViewer.

Make various properties Direct properties, which gives them the correct
binding behavior.

src/Perspex.Controls/Presenters/ScrollContentPresenter.cs

@@ -21,19 +21,25 @@ namespace Perspex.Controls.Presenters
         /// Defines the <see cref="Extent"/> property.
         /// </summary>
         public static readonly PerspexProperty<Size> ExtentProperty =
-            ScrollViewer.ExtentProperty.AddOwner<ScrollContentPresenter>();
+            ScrollViewer.ExtentProperty.AddOwner<ScrollContentPresenter>(
+                o => o.Extent,
+                (o, v) => o.Extent = v);
 
         /// <summary>
         /// Defines the <see cref="Offset"/> property.
         /// </summary>
         public static readonly PerspexProperty<Vector> OffsetProperty =
-            ScrollViewer.OffsetProperty.AddOwner<ScrollContentPresenter>();
+            ScrollViewer.OffsetProperty.AddOwner<ScrollContentPresenter>(
+                o => o.Offset,
+                (o, v) => o.Offset = v);
 
         /// <summary>
         /// Defines the <see cref="Viewport"/> property.
         /// </summary>
         public static readonly PerspexProperty<Size> ViewportProperty =
-            ScrollViewer.ViewportProperty.AddOwner<ScrollContentPresenter>();
+            ScrollViewer.ViewportProperty.AddOwner<ScrollContentPresenter>(
+                o => o.Viewport,
+                (o, v) => o.Viewport = v);
 
         /// <summary>
         /// Defines the <see cref="CanScrollHorizontally"/> property.
@@ -41,8 +47,11 @@ namespace Perspex.Controls.Presenters
         public static readonly PerspexProperty<bool> CanScrollHorizontallyProperty =
             PerspexProperty.Register<ScrollContentPresenter, bool>("CanScrollHorizontally", true);
 
+        private Size _extent;
         private Size _measuredExtent;
+        private Vector _offset;
         private IDisposable _scrollableSubscription;
+        private Size _viewport;
 
         /// <summary>
         /// Initializes static members of the <see cref="ScrollContentPresenter"/> class.
@@ -69,8 +78,8 @@ namespace Perspex.Controls.Presenters
         /// </summary>
         public Size Extent
         {
-            get { return GetValue(ExtentProperty); }
-            private set { SetValue(ExtentProperty, value); }
+            get { return _extent; }
+            private set { SetAndRaise(ExtentProperty, ref _extent, value); }
         }
 
         /// <summary>
@@ -78,8 +87,8 @@ namespace Perspex.Controls.Presenters
         /// </summary>
         public Vector Offset
         {
-            get { return GetValue(OffsetProperty); }
-            set { SetValue(OffsetProperty, value); }
+            get { return _offset; }
+            set { SetAndRaise(OffsetProperty, ref _offset, value); }
         }
 
         /// <summary>
@@ -87,8 +96,8 @@ namespace Perspex.Controls.Presenters
         /// </summary>
         public Size Viewport
         {
-            get { return GetValue(ViewportProperty); }
-            private set { SetValue(ViewportProperty, value); }
+            get { return _viewport; }
+            private set { SetAndRaise(ViewportProperty, ref _viewport, value); }
         }
 
         /// <summary>

src/Perspex.Controls/Primitives/RangeBase.cs

@@ -15,34 +15,38 @@ namespace Perspex.Controls.Primitives
         /// Defines the <see cref="Minimum"/> property.
         /// </summary>
         public static readonly PerspexProperty<double> MinimumProperty =
-            PerspexProperty.Register<RangeBase, double>(
+            PerspexProperty.RegisterDirect<RangeBase, double>(
                 nameof(Minimum),
-                validate: ValidateMinimum);
+                o => o.Minimum,
+                (o, v) => o.Minimum = v);
 
         /// <summary>
         /// Defines the <see cref="Maximum"/> property.
         /// </summary>
         public static readonly PerspexProperty<double> MaximumProperty =
-            PerspexProperty.Register<RangeBase, double>(
+            PerspexProperty.RegisterDirect<RangeBase, double>(
                 nameof(Maximum),
-                defaultValue: 100.0,
-                validate: ValidateMaximum);
+                o => o.Maximum,
+                (o, v) => o.Maximum = v);
 
         /// <summary>
         /// Defines the <see cref="Value"/> property.
         /// </summary>
         public static readonly PerspexProperty<double> ValueProperty =
-            PerspexProperty.Register<RangeBase, double>(
+            PerspexProperty.RegisterDirect<RangeBase, double>(
                 nameof(Value),
-                validate: ValidateValue);
+                o => o.Value,
+                (o, v) => o.Value = v);
+
+        private double _minimum;
+        private double _maximum = 100.0;
+        private double _value;
 
         /// <summary>
         /// Initializes a new instance of the <see cref="RangeBase"/> class.
         /// </summary>
         public RangeBase()
         {
-            AffectsValidation(MinimumProperty, MaximumProperty, ValueProperty);
-            AffectsValidation(MaximumProperty, ValueProperty);
         }
 
         /// <summary>
@@ -50,8 +54,18 @@ namespace Perspex.Controls.Primitives
         /// </summary>
         public double Minimum
         {
-            get { return GetValue(MinimumProperty); }
-            set { SetValue(MinimumProperty, value); }
+            get
+            {
+                return _minimum;
+            }
+
+            set
+            {
+                value = ValidateMinimum(value);
+                SetAndRaise(MinimumProperty, ref _minimum, value);
+                Maximum = ValidateMaximum(Maximum);
+                Value = ValidateValue(Value);
+            }
         }
 
         /// <summary>
@@ -59,8 +73,17 @@ namespace Perspex.Controls.Primitives
         /// </summary>
         public double Maximum
         {
-            get { return GetValue(MaximumProperty); }
-            set { SetValue(MaximumProperty, value); }
+            get
+            {
+                return _maximum;
+            }
+
+            set
+            {
+                value = ValidateMaximum(value);
+                SetAndRaise(MaximumProperty, ref _maximum, value);
+                Value = ValidateValue(Value);
+            }
         }
 
         /// <summary>
@@ -68,8 +91,16 @@ namespace Perspex.Controls.Primitives
         /// </summary>
         public double Value
         {
-            get { return GetValue(ValueProperty); }
-            set { SetValue(ValueProperty, value); }
+            get
+            {
+                return _value;
+            }
+
+            set
+            {
+                value = ValidateValue(value);
+                SetAndRaise(ValueProperty, ref _value, value);
+            }
         }
 
         /// <summary>
@@ -88,10 +119,9 @@ namespace Perspex.Controls.Primitives
         /// <summary>
         /// Validates the <see cref="Minimum"/> property.
         /// </summary>
-        /// <param name="sender">The RangeBase control.</param>
         /// <param name="value">The value.</param>
         /// <returns>The coerced value.</returns>
-        private static double ValidateMinimum(RangeBase sender, double value)
+        private double ValidateMinimum(double value)
         {
             ValidateDouble(value, "Minimum");
             return value;
@@ -100,25 +130,23 @@ namespace Perspex.Controls.Primitives
         /// <summary>
         /// Validates/coerces the <see cref="Maximum"/> property.
         /// </summary>
-        /// <param name="sender">The RangeBase control.</param>
         /// <param name="value">The value.</param>
         /// <returns>The coerced value.</returns>
-        private static double ValidateMaximum(RangeBase sender, double value)
+        private double ValidateMaximum(double value)
         {
             ValidateDouble(value, "Maximum");
-            return Math.Max(value, sender.Minimum);
+            return Math.Max(value, Minimum);
         }
 
         /// <summary>
         /// Validates/coerces the <see cref="Value"/> property.
         /// </summary>
-        /// <param name="sender">The RangeBase control.</param>
         /// <param name="value">The value.</param>
         /// <returns>The coerced value.</returns>
-        private static double ValidateValue(RangeBase sender, double value)
+        private double ValidateValue(double value)
         {
             ValidateDouble(value, "Value");
-            return MathUtilities.Clamp(value, sender.Minimum, sender.Maximum);
+            return MathUtilities.Clamp(value, Minimum, Maximum);
         }
     }
 }

src/Perspex.Controls/Primitives/Track.cs

@@ -11,13 +11,13 @@ namespace Perspex.Controls.Primitives
     public class Track : Control
     {
         public static readonly PerspexProperty<double> MinimumProperty =
-            RangeBase.MinimumProperty.AddOwner<Track>();
+            RangeBase.MinimumProperty.AddOwner<Track>(o => o.Minimum, (o,v) => o.Minimum = v);
 
         public static readonly PerspexProperty<double> MaximumProperty =
-            RangeBase.MaximumProperty.AddOwner<Track>();
+            RangeBase.MaximumProperty.AddOwner<Track>(o => o.Maximum, (o, v) => o.Maximum = v);
 
         public static readonly PerspexProperty<double> ValueProperty =
-            RangeBase.ValueProperty.AddOwner<Track>();
+            RangeBase.ValueProperty.AddOwner<Track>(o => o.Value, (o, v) => o.Value = v);
 
         public static readonly PerspexProperty<double> ViewportSizeProperty =
             ScrollBar.ViewportSizeProperty.AddOwner<Track>();
@@ -28,6 +28,10 @@ namespace Perspex.Controls.Primitives
         public static readonly PerspexProperty<Thumb> ThumbProperty =
             PerspexProperty.Register<Track, Thumb>("Thumb");
 
+        private double _minimum;
+        private double _maximum = 100.0;
+        private double _value;
+
         static Track()
         {
             AffectsArrange(MinimumProperty);
@@ -57,20 +61,20 @@ namespace Perspex.Controls.Primitives
 
         public double Minimum
         {
-            get { return GetValue(MinimumProperty); }
-            set { SetValue(MinimumProperty, value); }
+            get { return _minimum; }
+            set { SetAndRaise(MinimumProperty, ref _minimum, value); }
         }
 
         public double Maximum
         {
-            get { return GetValue(MaximumProperty); }
-            set { SetValue(MaximumProperty, value); }
+            get { return _maximum; }
+            set { SetAndRaise(MaximumProperty, ref _maximum, value); }
         }
 
         public double Value
         {
-            get { return GetValue(ValueProperty); }
-            set { SetValue(ValueProperty, value); }
+            get { return _value; }
+            set { SetAndRaise(ValueProperty, ref _value, value); }
         }
 
         public double ViewportSize

src/Perspex.Controls/ScrollViewer.cs

@@ -26,19 +26,26 @@ namespace Perspex.Controls
         /// Defines the <see cref="Extent"/> property.
         /// </summary>
         public static readonly PerspexProperty<Size> ExtentProperty =
-            PerspexProperty.Register<ScrollViewer, Size>(nameof(Extent));
+            PerspexProperty.RegisterDirect<ScrollViewer, Size>(nameof(Extent), 
+                o => o.Extent,
+                (o, v) => o.Extent = v);
 
         /// <summary>
         /// Defines the <see cref="Offset"/> property.
         /// </summary>
         public static readonly PerspexProperty<Vector> OffsetProperty =
-            PerspexProperty.Register<ScrollViewer, Vector>(nameof(Offset), validate: ValidateOffset);
+            PerspexProperty.RegisterDirect<ScrollViewer, Vector>(
+                nameof(Offset),
+                o => o.Offset,
+                (o, v) => o.Offset = v);
 
         /// <summary>
         /// Defines the <see cref="Viewport"/> property.
         /// </summary>
         public static readonly PerspexProperty<Size> ViewportProperty =
-            PerspexProperty.Register<ScrollViewer, Size>(nameof(Viewport));
+            PerspexProperty.RegisterDirect<ScrollViewer, Size>(nameof(Viewport), 
+                o => o.Viewport,
+                (o, v) => o.Viewport = v);
 
         /// <summary>
         /// Defines the HorizontalScrollBarMaximum property.
@@ -120,6 +127,10 @@ namespace Perspex.Controls
                 nameof(VerticalScrollBarVisibility), 
                 ScrollBarVisibility.Auto);
 
+        private Size _extent;
+        private Vector _offset;
+        private Size _viewport;
+
         /// <summary>
         /// Initializes static members of the <see cref="ScrollViewer"/> class.
         /// </summary>
@@ -173,8 +184,8 @@ namespace Perspex.Controls
         /// </summary>
         public Size Extent
         {
-            get { return GetValue(ExtentProperty); }
-            private set { SetValue(ExtentProperty, value); }
+            get { return _extent; }
+            private set { SetAndRaise(ExtentProperty, ref _extent, value); }
         }
 
         /// <summary>
@@ -182,8 +193,16 @@ namespace Perspex.Controls
         /// </summary>
         public Vector Offset
         {
-            get { return GetValue(OffsetProperty); }
-            set { SetValue(OffsetProperty, value); }
+            get
+            {
+                return _offset;
+            }
+
+            set
+            {
+                value = ValidateOffset(this, value);
+                SetAndRaise(OffsetProperty, ref _offset, value);
+            }
         }
 
         /// <summary>
@@ -191,8 +210,8 @@ namespace Perspex.Controls
         /// </summary>
         public Size Viewport
         {
-            get { return GetValue(ViewportProperty); }
-            private set { SetValue(ViewportProperty, value); }
+            get { return _viewport; }
+            private set { SetAndRaise(ViewportProperty, ref _viewport, value); }
         }
 
         /// <summary>

tests/Perspex.Controls.UnitTests/Presenters/ScrollContentPresenterTests.cs

@@ -218,17 +218,6 @@ namespace Perspex.Controls.UnitTests.Presenters
             Assert.False(target.IsArrangeValid);
         }
 
-        [Fact]
-        public void Offset_Should_Be_Coerced_To_Viewport()
-        {
-            var target = new ScrollContentPresenter();
-            target.SetValue(ScrollContentPresenter.ExtentProperty, new Size(20, 20));
-            target.SetValue(ScrollContentPresenter.ViewportProperty, new Size(10, 10));
-            target.Offset = new Vector(12, 12);
-
-            Assert.Equal(new Vector(10, 10), target.Offset);
-        }
-
         [Fact]
         public void BringDescendentIntoView_Should_Update_Offset()
         {