Initial port of GridSplitter PR from Toolkit Repo

CommunityToolkit/WindowsCommunityToolkit#4083

Author: michael-hawker

labs/SizerBase/src/CommunityToolkit.Labs.WinUI.SizerBase.csproj

@@ -12,4 +12,8 @@
     </Description>
     <Version>0.0.1</Version>
   </PropertyGroup>
+
+  <ItemGroup>
+    <Folder Include="Dependencies\" />
+  </ItemGroup>
 </Project>

labs/SizerBase/src/ContentSizer/ContentSizer.Events.cs

@@ -0,0 +1,82 @@
+// 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 CommunityToolkit.WinUI.UI;
+
+#if !WINAPPSDK
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+#else
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+#endif
+
+namespace CommunityToolkit.Labs.WinUI;
+
+// Events for ContentSizer.
+public partial class ContentSizer
+{
+    /// <inheritdoc/>
+    protected override void OnLoaded(RoutedEventArgs e)
+    {
+        if (TargetControl == null)
+        {
+            TargetControl = this.FindAscendant<FrameworkElement>();
+        }
+    }
+
+    private double _currentSize;
+
+    /// <inheritdoc/>
+    protected override void OnDragStarting()
+    {
+        if (TargetControl != null)
+        {
+            _currentSize =
+                Orientation == Orientation.Vertical ?
+                    TargetControl.ActualWidth :
+                    TargetControl.ActualHeight;
+        }
+    }
+
+    /// <inheritdoc/>
+    protected override bool OnDragHorizontal(double horizontalChange)
+    {
+        if (TargetControl == null)
+        {
+            return true;
+        }
+
+        horizontalChange = IsDragInverted ? -horizontalChange : horizontalChange;
+
+        if (!IsValidWidth(TargetControl, _currentSize + horizontalChange, ActualWidth))
+        {
+            return false;
+        }
+
+        TargetControl.Width = _currentSize + horizontalChange;
+
+        return true;
+    }
+
+    /// <inheritdoc/>
+    protected override bool OnDragVertical(double verticalChange)
+    {
+        if (TargetControl == null)
+        {
+            return false;
+        }
+
+        verticalChange = IsDragInverted ? -verticalChange : verticalChange;
+
+        if (!IsValidHeight(TargetControl, _currentSize + verticalChange, ActualHeight))
+        {
+            return false;
+        }
+
+        TargetControl.Height = _currentSize + verticalChange;
+
+        return true;
+    }
+}

labs/SizerBase/src/ContentSizer/ContentSizer.Properties.cs

@@ -0,0 +1,71 @@
+// 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.
+
+#if !WINAPPSDK
+using System;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+#else
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+#endif
+
+namespace CommunityToolkit.Labs.WinUI;
+
+// Properties for ContentSizer.
+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>
+    public FrameworkElement? TargetControl
+    {
+        get { return (FrameworkElement?)GetValue(TargetControlProperty); }
+        set { SetValue(TargetControlProperty, value); }
+    }
+
+    /// <summary>
+    /// Identifies the <see cref="TargetControl"/> dependency property.
+    /// </summary>
+    public static readonly DependencyProperty TargetControlProperty =
+        DependencyProperty.Register(nameof(TargetControl), typeof(FrameworkElement), typeof(ContentSizer), new PropertyMetadata(null, OnTargetControlChanged));
+
+    private static void OnTargetControlChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
+    {
+        // TODO: Should we do this after the TargetControl is Loaded? (And use ActualWidth?)
+        // Or should we just do it in the manipulation event if Width is null?
+
+        // Check if our width can be manipulated
+        if (d is SizerBase splitterBase && e.NewValue is FrameworkElement element)
+        {
+            // TODO: For Auto ResizeDirection we might want to do detection logic (TBD) here first?
+            if (splitterBase.Orientation != Orientation.Horizontal && double.IsNaN(element.Width))
+            {
+                // We need to set the Width or Height somewhere,
+                // as if it's NaN we won't be able to manipulate it.
+                element.Width = element.DesiredSize.Width;
+            }
+
+            if (splitterBase.Orientation != Orientation.Vertical && double.IsNaN(element.Height))
+            {
+                element.Height = element.DesiredSize.Height;
+            }
+        }
+    }
+}

labs/SizerBase/src/ContentSizer/ContentSizer.cs

@@ -0,0 +1,18 @@
+// 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.
+
+#if !WINAPPSDK
+using Windows.UI.Xaml.Controls;
+#else
+using Microsoft.UI.Xaml.Controls;
+#endif
+
+namespace CommunityToolkit.Labs.WinUI;
+
+/// <summary>
+/// The <see cref="ContentSizer"/> is a control which can be used to resize any element, usually its parent. If you are using a <see cref="Grid"/>, use <see cref="GridSplitter"/> instead.
+/// </summary>
+public partial class ContentSizer : SizerBase
+{
+}