Fix: DockPanel measure fix

components/Primitives/samples/DockPanelSample.xaml

@@ -1,4 +1,4 @@
-<!--  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.  -->
+<!--  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.  -->
 <Page x:Class="PrimitivesExperiment.Samples.DockPanelSample"
       xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
       xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
@@ -27,7 +27,7 @@
                     Content="Add Bottom child" />
             <Button Click="AddRightDock"
                     Content="Add Right child" />
-            <Button Click="AddRightDock"
+            <Button Click="AddStretchDock"
                     Content="Add Stretch child" />
             <Button Click="ClearAllDock"
                     Content="Clear all" />

components/Primitives/src/DockPanel/DockPanel.cs

@@ -32,13 +32,15 @@ protected override Size ArrangeOverride(Size finalSize)
         var currentBounds = new Rect(
             Padding.Left,
             Padding.Top,
-            GetPositiveOrZero(finalSize.Width - Padding.Left - Padding.Right),
-            GetPositiveOrZero(finalSize.Height - Padding.Top - Padding.Bottom));
+            Math.Max(0, finalSize.Width - Padding.Left - Padding.Right),
+            Math.Max(0, finalSize.Height - Padding.Top - Padding.Bottom));
         var childrenCount = LastChildFill ? Children.Count - 1 : Children.Count;
 
         for (var index = 0; index < childrenCount; ++index)
         {
             var child = Children[index];
+            if (child.Visibility is Visibility.Collapsed)
+                continue;
             var dock = (Dock)child.GetValue(DockProperty);
             double width, height;
             switch (dock)
@@ -49,7 +51,7 @@ protected override Size ArrangeOverride(Size finalSize)
                     child.Arrange(new Rect(currentBounds.X, currentBounds.Y, width, currentBounds.Height));
                     width += HorizontalSpacing;
                     currentBounds.X += width;
-                    currentBounds.Width = GetPositiveOrZero(currentBounds.Width - width);
+                    currentBounds.Width = Math.Max(0, currentBounds.Width - width);
 
                     break;
                 case Dock.Top:
@@ -58,29 +60,29 @@ protected override Size ArrangeOverride(Size finalSize)
                     child.Arrange(new Rect(currentBounds.X, currentBounds.Y, currentBounds.Width, height));
                     height += VerticalSpacing;
                     currentBounds.Y += height;
-                    currentBounds.Height = GetPositiveOrZero(currentBounds.Height - height);
+                    currentBounds.Height = Math.Max(0, currentBounds.Height - height);
 
                     break;
                 case Dock.Right:
 
                     width = Math.Min(child.DesiredSize.Width, currentBounds.Width);
                     child.Arrange(new Rect(currentBounds.X + currentBounds.Width - width, currentBounds.Y, width, currentBounds.Height));
                     width += HorizontalSpacing;
-                    currentBounds.Width = GetPositiveOrZero(currentBounds.Width - width);
+                    currentBounds.Width = Math.Max(0, currentBounds.Width - width);
 
                     break;
                 case Dock.Bottom:
 
                     height = Math.Min(child.DesiredSize.Height, currentBounds.Height);
                     child.Arrange(new Rect(currentBounds.X, currentBounds.Y + currentBounds.Height - height, currentBounds.Width, height));
                     height += VerticalSpacing;
-                    currentBounds.Height = GetPositiveOrZero(currentBounds.Height - height);
+                    currentBounds.Height = Math.Max(0, currentBounds.Height - height);
 
                     break;
             }
         }
 
-        if (LastChildFill)
+        if (LastChildFill && Children.Count > 0)
         {
             var child = Children[Children.Count - 1];
             child.Arrange(new Rect(currentBounds.X, currentBounds.Y, currentBounds.Width, currentBounds.Height));
@@ -92,70 +94,60 @@ protected override Size ArrangeOverride(Size finalSize)
     /// <inheritdoc />
     protected override Size MeasureOverride(Size availableSize)
     {
-        var parentWidth = 0.0;
-        var parentHeight = 0.0;
-        var accumulatedWidth = Padding.Left + Padding.Right;
-        var accumulatedHeight = Padding.Top + Padding.Bottom;
-
-        var leftSpacing = false;
-        var topSpacing = false;
-        var rightSpacing = false;
-        var bottomSpacing = false;
+        var parentWidth = 0d;
+        var parentHeight = 0d;
+        var accumulatedWidth = 0d;
+        var accumulatedHeight = 0d;
+
+        var horizontalSpacing = false;
+        var verticalSpacing = false;
         var childrenCount = LastChildFill ? Children.Count - 1 : Children.Count;
-    
+
         for (var index = 0; index < childrenCount; ++index)
         {
             var child = Children[index];
             var childConstraint = new Size(
-                GetPositiveOrZero(availableSize.Width - accumulatedWidth),
-                GetPositiveOrZero(availableSize.Height - accumulatedHeight));
-    
+                Math.Max(0, availableSize.Width - accumulatedWidth),
+                Math.Max(0, availableSize.Height - accumulatedHeight));
+
             child.Measure(childConstraint);
             var childDesiredSize = child.DesiredSize;
-    
-            switch ((Dock)child.GetValue(DockProperty))
+
+            switch (child.GetValue(DockProperty))
             {
                 case Dock.Left:
-                    leftSpacing = true;
-                    parentHeight = Math.Max(parentHeight, accumulatedHeight + childDesiredSize.Height);
-                    if (childConstraint.Width is not 0)
-                        accumulatedWidth += HorizontalSpacing;
-                    accumulatedWidth += childDesiredSize.Width;
-                    break;
-
                 case Dock.Right:
-                    rightSpacing = true;
                     parentHeight = Math.Max(parentHeight, accumulatedHeight + childDesiredSize.Height);
-                    if (childConstraint.Width is not 0)
+                    if (child.Visibility is Visibility.Visible)
+                    {
                         accumulatedWidth += HorizontalSpacing;
+                        horizontalSpacing = true;
+                    }
+
                     accumulatedWidth += childDesiredSize.Width;
                     break;
-    
+
                 case Dock.Top:
-                    topSpacing = true;
-                    parentWidth = Math.Max(parentWidth, accumulatedWidth + childDesiredSize.Width);
-                    if (childConstraint.Height is not 0)
-                        accumulatedHeight += VerticalSpacing;
-                    accumulatedHeight += childDesiredSize.Height;
-                    break;
-
                 case Dock.Bottom:
-                    bottomSpacing = true;
                     parentWidth = Math.Max(parentWidth, accumulatedWidth + childDesiredSize.Width);
-                    if (childConstraint.Height is not 0)
+                    if (child.Visibility is Visibility.Visible)
+                    {
                         accumulatedHeight += VerticalSpacing;
+                        verticalSpacing = true;
+                    }
+
                     accumulatedHeight += childDesiredSize.Height;
                     break;
             }
         }
-    
-        if (LastChildFill)
+
+        if (LastChildFill && Children.Count > 0)
         {
             var child = Children[Children.Count - 1];
             var childConstraint = new Size(
-                GetPositiveOrZero(availableSize.Width - accumulatedWidth),
-                GetPositiveOrZero(availableSize.Height - accumulatedHeight));
-    
+                Math.Max(0, availableSize.Width - accumulatedWidth),
+                Math.Max(0, availableSize.Height - accumulatedHeight));
+
             child.Measure(childConstraint);
             var childDesiredSize = child.DesiredSize;
             parentHeight = Math.Max(parentHeight, accumulatedHeight + childDesiredSize.Height);
@@ -165,16 +157,15 @@ protected override Size MeasureOverride(Size availableSize)
         }
         else
         {
-            if (leftSpacing || rightSpacing)
+            if (horizontalSpacing)
                 accumulatedWidth -= HorizontalSpacing;
-            if (bottomSpacing || topSpacing)
+            if (verticalSpacing)
                 accumulatedHeight -= VerticalSpacing;
         }
-
-        parentWidth = Math.Min(availableSize.Width, Math.Max(parentWidth, accumulatedWidth));
-        parentHeight = Math.Min(availableSize.Height, Math.Max(parentHeight, accumulatedHeight));
+
+        // Make sure the final accumulated size is reflected in parentSize.
+        parentWidth = Math.Max(parentWidth, accumulatedWidth);
+        parentHeight = Math.Max(parentHeight, accumulatedHeight);
         return new Size(parentWidth, parentHeight);
     }
-
-    private static double GetPositiveOrZero(double value) => Math.Max(value, 0);
 }

components/Primitives/tests/DockPanel/DockPanelSample.xaml

@@ -0,0 +1,17 @@
+<Page x:Class="PrimitivesTests.DockPanelSample"
+      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+      xmlns:controls="using:CommunityToolkit.WinUI.Controls"
+      xmlns:converters="using:CommunityToolkit.WinUI.Converters"
+      xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+      xmlns:local="using:PrimitivesTests"
+      xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+      xmlns:ui="using:CommunityToolkit.WinUI"
+      mc:Ignorable="d">
+
+    <controls:DockPanel x:Name="SampleDockPanel"
+                        Grid.Column="1"
+                        HorizontalSpacing="5"
+                        LastChildFill="True"
+                        VerticalSpacing="5" />
+</Page>

components/Primitives/tests/DockPanel/DockPanelSample.xaml.cs

@@ -0,0 +1,14 @@
+// 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.
+
+namespace PrimitivesTests;
+
+public sealed partial class DockPanelSample : Page
+{
+    public DockPanelSample()
+    {
+        this.InitializeComponent();
+    }
+}
+

components/Primitives/tests/DockPanel/DockPanelTests.cs

@@ -0,0 +1,20 @@
+// 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.Tests;
+using CommunityToolkit.Tooling.TestGen;
+
+namespace PrimitivesTests;
+
+[TestClass]
+public partial class DockPanelTests : VisualUITestBase
+{
+    [UIThreadTestMethod]
+    public void DockPanelTest(DockPanelSample page)
+    {
+        var dockPanel = page.FindDescendant<CommunityToolkit.WinUI.Controls.DockPanel>();
+
+        Assert.IsNotNull(dockPanel, "Couldn't find DockPanel");
+    }
+}

components/Primitives/tests/Primitives.Tests.projitems

@@ -9,6 +9,10 @@
     <Import_RootNamespace>PrimitivesTests</Import_RootNamespace>
   </PropertyGroup>
   <ItemGroup>
+    <Compile Include="$(MSBuildThisFileDirectory)DockPanel\DockPanelSample.xaml.cs">
+      <DependentUpon>DockPanelSample.xaml</DependentUpon>
+    </Compile>
+    <Compile Include="$(MSBuildThisFileDirectory)DockPanel\DockPanelTests.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)SwitchPresenter\SwitchConverterBrushSample.xaml.cs">
       <DependentUpon>%(Filename)</DependentUpon>
     </Compile>
@@ -35,6 +39,10 @@
     </Compile>
   </ItemGroup>
   <ItemGroup>
+    <Page Include="$(MSBuildThisFileDirectory)DockPanel\DockPanelSample.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </Page>
     <Page Include="$(MSBuildThisFileDirectory)UniformGrid\AutoLayoutFixedElementZeroZeroSpecialPage.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>