Refactor out some properties and helper methods of SizerBase to their…

… own files in the partial class.

Move IsDragInverted to ContentSizer as it is specific to that class for now.

Microsoft.Toolkit.Uwp.UI.Controls.Layout/Sizers/ContentSizer/ContentSizer.Properties.cs

@@ -12,6 +12,21 @@ namespace Microsoft.Toolkit.Uwp.UI.Controls
     /// </summary>
     public partial class ContentSizer
     {
+        /// <summary>
+        /// Gets or sets a value indicating whether the <see cref="ContentSizer"/> control is resizing in the opposite direction.
+        /// </summary>
+        public bool IsDragInverted
+        {
+            get { return (bool)GetValue(IsDragInvertedProperty); }
+            set { SetValue(IsDragInvertedProperty, value); }
+        }
+
+        /// <summary>
+        /// Identifies the <see cref="IsDragInverted"/> dependency property.
+        /// </summary>
+        public static readonly DependencyProperty IsDragInvertedProperty =
+            DependencyProperty.Register(nameof(IsDragInverted), typeof(bool), typeof(ContentSizer), new PropertyMetadata(false));
+
         /// <summary>
         /// Gets or sets the control that the <see cref="ContentSizer"/> is resizing. Be default, this will be the visual ancestor of the <see cref="ContentSizer"/>.
         /// </summary>

Microsoft.Toolkit.Uwp.UI.Controls.Layout/Sizers/SizerBase.Events.cs

@@ -14,7 +14,7 @@
 namespace Microsoft.Toolkit.Uwp.UI.Controls
 {
     /// <summary>
-    /// Events for <see cref="SizerBase"/>.
+    /// Event implementations for <see cref="SizerBase"/>.
     /// </summary>
     public partial class SizerBase
     {

Microsoft.Toolkit.Uwp.UI.Controls.Layout/Sizers/SizerBase.Helpers.cs

@@ -0,0 +1,80 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Windows.UI.Core;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Input;
+using Windows.UI.Xaml.Markup;
+
+namespace Microsoft.Toolkit.Uwp.UI.Controls
+{
+    /// <summary>
+    /// Protected helper methods for <see cref="SizerBase"/> and subclasses.
+    /// </summary>
+    public partial class SizerBase : Control
+    {
+        /// <summary>
+        /// Check for new requested vertical size is valid or not
+        /// </summary>
+        /// <param name="target">Target control being resized</param>
+        /// <param name="verticalChange">The requested vertical change</param>
+        /// <param name="parentActualHeight">The parent control's ActualHeight</param>
+        /// <returns>Bool result if requested vertical change is valid or not</returns>
+        protected static bool IsValidHeight(FrameworkElement target, double verticalChange, double parentActualHeight)
+        {
+            var newHeight = target.ActualHeight + verticalChange;
+
+            var minHeight = target.MinHeight;
+            if (newHeight < 0 || (!double.IsNaN(minHeight) && newHeight < minHeight))
+            {
+                return false;
+            }
+
+            var maxHeight = target.MaxHeight;
+            if (!double.IsNaN(maxHeight) && newHeight > maxHeight)
+            {
+                return false;
+            }
+
+            if (newHeight <= parentActualHeight)
+            {
+                return false;
+            }
+
+            return true;
+        }
+
+        /// <summary>
+        /// Check for new requested horizontal size is valid or not
+        /// </summary>
+        /// <param name="target">Target control being resized</param>
+        /// <param name="horizontalChange">The requested horizontal change</param>
+        /// <param name="parentActualWidth">The parent control's ActualWidth</param>
+        /// <returns>Bool result if requested horizontal change is valid or not</returns>
+        protected static bool IsValidWidth(FrameworkElement target, double horizontalChange, double parentActualWidth)
+        {
+            var newWidth = target.ActualWidth + horizontalChange;
+
+            var minWidth = target.MinWidth;
+            if (newWidth < 0 || (!double.IsNaN(minWidth) && newWidth < minWidth))
+            {
+                return false;
+            }
+
+            var maxWidth = target.MaxWidth;
+            if (!double.IsNaN(maxWidth) && newWidth > maxWidth)
+            {
+                return false;
+            }
+
+            if (newWidth <= parentActualWidth)
+            {
+                return false;
+            }
+
+            return true;
+        }
+    }
+}

Microsoft.Toolkit.Uwp.UI.Controls.Layout/Sizers/SizerBase.Properties.cs

@@ -0,0 +1,96 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using Windows.UI.Core;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Input;
+using Windows.UI.Xaml.Markup;
+
+namespace Microsoft.Toolkit.Uwp.UI.Controls
+{
+    /// <summary>
+    /// Properties for <see cref="SizerBase"/>
+    /// </summary>
+    public partial class SizerBase : Control
+    {
+        /// <summary>
+        /// Vertical symbol for GripperBar in Segoe MDL2 Font asset.
+        /// </summary>
+        protected const string GripperBarVertical = "\xE784";
+
+        /// <summary>
+        /// Horizontal symbol for GripperBar in Segoe MDL2 Font asset.
+        /// </summary>
+        protected const string GripperBarHorizontal = "\xE76F";
+
+        /// <summary>
+        /// Distance (horizontal or vertical) to move, in response to keyboard activity.
+        /// </summary>
+        protected const double GripperKeyboardChange = 8.0d;
+
+        /// <summary>
+        /// Gets or sets the content of the splitter control.
+        /// </summary>
+        public object Content
+        {
+            get { return (object)GetValue(ContentProperty); }
+            set { SetValue(ContentProperty, value); }
+        }
+
+        /// <summary>
+        /// Identifies the <see cref="Content"/> dependency property.
+        /// </summary>
+        public static readonly DependencyProperty ContentProperty =
+            DependencyProperty.Register(nameof(Content), typeof(object), typeof(SizerBase), new PropertyMetadata(null));
+
+        /// <summary>
+        /// Gets or sets the content template for the <see cref="Content"/>.
+        /// </summary>
+        public DataTemplate ContentTemplate
+        {
+            get { return (DataTemplate)GetValue(ContentTemplateProperty); }
+            set { SetValue(ContentTemplateProperty, value); }
+        }
+
+        /// <summary>
+        /// Identifies the <see cref="ContentTemplate"/> dependency property.
+        /// </summary>
+        public static readonly DependencyProperty ContentTemplateProperty =
+            DependencyProperty.Register(nameof(ContentTemplate), typeof(DataTemplate), typeof(SizerBase), new PropertyMetadata(null));
+
+        /// <summary>
+        /// Gets or sets the cursor to use when hovering over the sizer.
+        /// </summary>
+        public CoreCursorType GripperCursor
+        {
+            get { return (CoreCursorType)GetValue(GripperCursorProperty); }
+            set { SetValue(GripperCursorProperty, value); }
+        }
+
+        /// <summary>
+        /// Identifies the <see cref="GripperCursor"/> dependency property.
+        /// </summary>
+        public static readonly DependencyProperty GripperCursorProperty =
+            DependencyProperty.Register(nameof(GripperCursor), typeof(CoreCursorType), typeof(SizerBase), new PropertyMetadata(CoreCursorType.SizeWestEast));
+
+        /// <summary>
+        /// Gets or sets the orientation the sizer will be and how it will interact with other elements. Defaults to <see cref="Orientation.Vertical"/>.
+        /// </summary>
+        /// <remarks>
+        /// Note if using <see cref="GridSplitter"/>, use the <see cref="GridSplitter.ResizeDirection"/> property instead.
+        /// </remarks>
+        public Orientation Orientation
+        {
+            get { return (Orientation)GetValue(OrientationProperty); }
+            set { SetValue(OrientationProperty, value); }
+        }
+
+        /// <summary>
+        /// Identifies the <see cref="Orientation"/> dependency property.
+        /// </summary>
+        public static readonly DependencyProperty OrientationProperty =
+            DependencyProperty.Register(nameof(Orientation), typeof(Orientation), typeof(SizerBase), new PropertyMetadata(Orientation.Vertical));
+    }
+}

Microsoft.Toolkit.Uwp.UI.Controls.Layout/Sizers/SizerBase.cs

@@ -11,168 +11,11 @@
 namespace Microsoft.Toolkit.Uwp.UI.Controls
 {
     /// <summary>
-    /// Base class for splitting/resizing controls
+    /// Base class for splitting/resizing type controls like <see cref="GridSplitter"/> and <see cref="ContentSizer"/>. Acts similar to an enlarged <see cref="Windows.UI.Xaml.Controls.Primitives.Thumb"/> type control, but with keyboard support. Subclasses should override the various abstract methods here to implement their behavior.
     /// </summary>
     [ContentProperty(Name = nameof(Content))]
     public abstract partial class SizerBase : Control
     {
-        /// <summary>
-        /// Check for new requested vertical size is valid or not
-        /// </summary>
-        /// <param name="target">Target control being resized</param>
-        /// <param name="verticalChange">The requested vertical change</param>
-        /// <param name="parentActualHeight">The parent control's ActualHeight</param>
-        /// <returns>Bool result if requested vertical change is valid or not</returns>
-        protected static bool IsValidHeight(FrameworkElement target, double verticalChange, double parentActualHeight)
-        {
-            var newHeight = target.ActualHeight + verticalChange;
-
-            var minHeight = target.MinHeight;
-            if (newHeight < 0 || (!double.IsNaN(minHeight) && newHeight < minHeight))
-            {
-                return false;
-            }
-
-            var maxHeight = target.MaxHeight;
-            if (!double.IsNaN(maxHeight) && newHeight > maxHeight)
-            {
-                return false;
-            }
-
-            if (newHeight <= parentActualHeight)
-            {
-                return false;
-            }
-
-            return true;
-        }
-
-        /// <summary>
-        /// Check for new requested horizontal size is valid or not
-        /// </summary>
-        /// <param name="target">Target control being resized</param>
-        /// <param name="horizontalChange">The requested horizontal change</param>
-        /// <param name="parentActualWidth">The parent control's ActualWidth</param>
-        /// <returns>Bool result if requested horizontal change is valid or not</returns>
-        protected static bool IsValidWidth(FrameworkElement target, double horizontalChange, double parentActualWidth)
-        {
-            var newWidth = target.ActualWidth + horizontalChange;
-
-            var minWidth = target.MinWidth;
-            if (newWidth < 0 || (!double.IsNaN(minWidth) && newWidth < minWidth))
-            {
-                return false;
-            }
-
-            var maxWidth = target.MaxWidth;
-            if (!double.IsNaN(maxWidth) && newWidth > maxWidth)
-            {
-                return false;
-            }
-
-            if (newWidth <= parentActualWidth)
-            {
-                return false;
-            }
-
-            return true;
-        }
-
-        /// <summary>
-        /// Vertical symbol for GripperBar in Segoe MDL2 Font asset.
-        /// </summary>
-        protected const string GripperBarVertical = "\xE784";
-
-        /// <summary>
-        /// Horizontal symbol for GripperBar in Segoe MDL2 Font asset.
-        /// </summary>
-        protected const string GripperBarHorizontal = "\xE76F";
-
-        /// <summary>
-        /// Distance (horizontal or vertical) to move, in response to keyboard activity.
-        /// </summary>
-        protected const double GripperKeyboardChange = 8.0d;
-
-        /// <summary>
-        /// Gets or sets the content of the splitter control.
-        /// </summary>
-        public object Content
-        {
-            get { return (object)GetValue(ContentProperty); }
-            set { SetValue(ContentProperty, value); }
-        }
-
-        /// <summary>
-        /// Identifies the <see cref="Content"/> dependency property.
-        /// </summary>
-        public static readonly DependencyProperty ContentProperty =
-            DependencyProperty.Register(nameof(Content), typeof(object), typeof(SizerBase), new PropertyMetadata(null));
-
-        /// <summary>
-        /// Gets or sets the content template for the <see cref="Content"/>.
-        /// </summary>
-        public DataTemplate ContentTemplate
-        {
-            get { return (DataTemplate)GetValue(ContentTemplateProperty); }
-            set { SetValue(ContentTemplateProperty, value); }
-        }
-
-        /// <summary>
-        /// Identifies the <see cref="ContentTemplate"/> dependency property.
-        /// </summary>
-        public static readonly DependencyProperty ContentTemplateProperty =
-            DependencyProperty.Register(nameof(ContentTemplate), typeof(DataTemplate), typeof(SizerBase), new PropertyMetadata(null));
-
-        /// <summary>
-        /// Gets or sets the cursor to use when hovering over the sizer.
-        /// </summary>
-        public CoreCursorType GripperCursor
-        {
-            get { return (CoreCursorType)GetValue(GripperCursorProperty); }
-            set { SetValue(GripperCursorProperty, value); }
-        }
-
-        /// <summary>
-        /// Identifies the <see cref="GripperCursor"/> dependency property.
-        /// </summary>
-        public static readonly DependencyProperty GripperCursorProperty =
-            DependencyProperty.Register(nameof(GripperCursor), typeof(CoreCursorType), typeof(SizerBase), new PropertyMetadata(CoreCursorType.SizeWestEast));
-
-        /// <summary>
-        /// Gets or sets the orientation the sizer will be and how it will interact with other elements. Defaults to <see cref="Orientation.Vertical"/>.
-        /// </summary>
-        /// <remarks>
-        /// Note if using <see cref="GridSplitter"/>, use the <see cref="GridSplitter.ResizeDirection"/> property instead.
-        /// </remarks>
-        public Orientation Orientation
-        {
-            get { return (Orientation)GetValue(OrientationProperty); }
-            set { SetValue(OrientationProperty, value); }
-        }
-
-        /// <summary>
-        /// Identifies the <see cref="Orientation"/> dependency property.
-        /// </summary>
-        public static readonly DependencyProperty OrientationProperty =
-            DependencyProperty.Register(nameof(Orientation), typeof(Orientation), typeof(SizerBase), new PropertyMetadata(Orientation.Vertical));
-
-        //// TODO: Check if this is ContentSizer only property
-
-        /// <summary>
-        /// Gets or sets a value indicating whether the <see cref="SizerBase"/> control is resizing in the opposite direction.
-        /// </summary>
-        public bool IsDragInverted
-        {
-            get { return (bool)GetValue(IsDragInvertedProperty); }
-            set { SetValue(IsDragInvertedProperty, value); }
-        }
-
-        /// <summary>
-        /// Identifies the <see cref="IsDragInverted"/> dependency property.
-        /// </summary>
-        public static readonly DependencyProperty IsDragInvertedProperty =
-            DependencyProperty.Register(nameof(IsDragInverted), typeof(bool), typeof(SizerBase), new PropertyMetadata(false));
-
         /// <summary>
         /// Method to process the requested horizontal resizing.
         /// </summary>