Add Value Coercion to ConstrainedBox

Microsoft.Toolkit.Uwp.UI.Controls.Primitives/ConstrainedBox/ConstrainedBox.Properties.cs

@@ -61,7 +61,7 @@ public int MultipleX
         /// Identifies the <see cref="MultipleX"/> property.
         /// </summary>
         public static readonly DependencyProperty MultipleXProperty =
-            DependencyProperty.Register(nameof(MultipleX), typeof(int), typeof(ConstrainedBox), new PropertyMetadata(null));
+            DependencyProperty.Register(nameof(MultipleX), typeof(int), typeof(ConstrainedBox), new PropertyMetadata(null, ConstraintPropertyChanged));
 
         /// <summary>
         /// Gets or sets the integer multiple that the height of the panel should be floored to. Default is null (no snap).
@@ -76,7 +76,7 @@ public int MultipleY
         /// Identifies the <see cref="MultipleY"/> property.
         /// </summary>
         public static readonly DependencyProperty MultipleYProperty =
-            DependencyProperty.Register(nameof(MultipleY), typeof(int), typeof(ConstrainedBox), new PropertyMetadata(null));
+            DependencyProperty.Register(nameof(MultipleY), typeof(int), typeof(ConstrainedBox), new PropertyMetadata(null, ConstraintPropertyChanged));
 
         /// <summary>
         /// Gets or sets aspect Ratio to use for the contents of the Panel (after scaling).
@@ -93,11 +93,71 @@ public AspectRatio AspectRatio
         public static readonly DependencyProperty AspectRatioProperty =
             DependencyProperty.Register(nameof(AspectRatio), typeof(AspectRatio), typeof(ConstrainedBox), new PropertyMetadata(null, ConstraintPropertyChanged));
 
+        private bool _propertyUpdating;
+
         private static void ConstraintPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
         {
-            if (d is ConstrainedBox panel)
+            if (d is ConstrainedBox panel && !panel._propertyUpdating)
             {
+                panel._propertyUpdating = true;
+
+                panel.CoerceValues();
+
                 panel.InvalidateMeasure();
+
+                panel._propertyUpdating = false;
+            }
+        }
+
+        private void CoerceValues()
+        {
+            // Check if scale properties are in range
+            if (!double.IsNaN(ScaleX))
+            {
+                if (ScaleX < 0)
+                {
+                    ScaleX = 0;
+                }
+                else if (ScaleX > 1.0)
+                {
+                    ScaleX = 1.0;
+                }
+            }
+            else
+            {
+                ScaleX = 1.0;
+            }
+
+            if (!double.IsNaN(ScaleY))
+            {
+                if (ScaleY < 0)
+                {
+                    ScaleY = 0;
+                }
+                else if (ScaleY > 1.0)
+                {
+                    ScaleY = 1.0;
+                }
+            }
+            else
+            {
+                ScaleY = 1.0;
+            }
+
+            // Clear invalid values less than 0 for other properties
+            if (ReadLocalValue(MultipleXProperty) is int value && value <= 0)
+            {
+                ClearValue(MultipleXProperty);
+            }
+
+            if (ReadLocalValue(MultipleYProperty) is int value2 && value2 <= 0)
+            {
+                ClearValue(MultipleYProperty);
+            }
+
+            if (ReadLocalValue(AspectRatioProperty) is AspectRatio ratio && ratio <= 0)
+            {
+                ClearValue(AspectRatioProperty);
             }
         }
     }

UnitTests/UnitTests.UWP/UI/Controls/Test_ConstrainedBox.Alignment.cs

@@ -0,0 +1,89 @@
+// 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 System.Linq;
+using System.Threading.Tasks;
+using Microsoft.Toolkit.Uwp;
+using Microsoft.Toolkit.Uwp.UI;
+using Microsoft.Toolkit.Uwp.UI.Controls;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Microsoft.VisualStudio.TestTools.UnitTesting.AppContainer;
+using Windows.Foundation;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Markup;
+
+namespace UnitTests.UWP.UI.Controls
+{
+    /// <summary>
+    /// These tests check whether the inner alignment of the box within it's parent works as expected.
+    /// </summary>
+    public partial class Test_ConstrainedBox : VisualUITestBase
+    {
+        // For this test we're testing within the confines of a 200x200 box to position a contrained
+        // 50x100 element in all the different alignment combinations.
+        [TestCategory("ConstrainedBox")]
+        [TestMethod]
+        [DataRow("Left", 0, "Center", 50, DisplayName = "LeftCenter")]
+        [DataRow("Left", 0, "Top", 0, DisplayName = "LeftTop")]
+        [DataRow("Center", 75, "Top", 0, DisplayName = "CenterTop")]
+        [DataRow("Right", 150, "Top", 0, DisplayName = "RightTop")]
+        [DataRow("Right", 150, "Center", 50, DisplayName = "RightCenter")]
+        [DataRow("Right", 150, "Bottom", 100, DisplayName = "RightBottom")]
+        [DataRow("Center", 75, "Bottom", 100, DisplayName = "CenterBottom")]
+        [DataRow("Left", 0, "Bottom", 100, DisplayName = "LeftBottom")]
+        [DataRow("Center", 75, "Center", 50, DisplayName = "CenterCenter")]
+        public async Task Test_ConstrainedBox_Alignment_Aspect(string horizontalAlignment, int expectedLeft, string verticalAlignment, int expectedTop)
+        {
+            await App.DispatcherQueue.EnqueueAsync(async () =>
+            {
+                var treeRoot = XamlReader.Load(@$"<Page
+    xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""
+    xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml""
+    xmlns:controls=""using:Microsoft.Toolkit.Uwp.UI.Controls"">
+    <Grid x:Name=""ParentGrid""
+          Width=""200"" Height=""200"">
+      <controls:ConstrainedBox x:Name=""ConstrainedBox"" AspectRatio=""1:2"" MaxHeight=""100""
+                               UseLayoutRounding=""False""
+                               HorizontalAlignment=""{horizontalAlignment}""
+                               VerticalAlignment=""{verticalAlignment}"">
+        <Border HorizontalAlignment=""Stretch"" VerticalAlignment=""Stretch"" Background=""Red""/>
+      </controls:ConstrainedBox>
+    </Grid>
+</Page>") as FrameworkElement;
+
+                Assert.IsNotNull(treeRoot, "Could not load XAML tree.");
+
+                // Initialize Visual Tree
+                await SetTestContentAsync(treeRoot);
+
+                var grid = treeRoot.FindChild("ParentGrid") as Grid;
+
+                Assert.IsNotNull(grid, "Could not find the ParentGrid in tree.");
+
+                var panel = treeRoot.FindChild("ConstrainedBox") as ConstrainedBox;
+
+                Assert.IsNotNull(panel, "Could not find ConstrainedBox in tree.");
+
+                // Force Layout calculations
+                panel.UpdateLayout();
+
+                var child = panel.Content as Border;
+
+                Assert.IsNotNull(child, "Could not find inner Border");
+
+                // Check Size
+                Assert.AreEqual(50, child.ActualWidth, 0.01, "Actual width does not meet expected value of 50");
+                Assert.AreEqual(100, child.ActualHeight, 0.01, "Actual height does not meet expected value of 100");
+
+                // Check inner Positioning, we do this from the Grid as the ConstainedBox also modifies its own size
+                // and is hugging the child.
+                var position = grid.CoordinatesTo(child);
+
+                Assert.AreEqual(expectedLeft, position.X, 0.01, "X position does not meet expected value of 0");
+                Assert.AreEqual(expectedTop, position.Y, 0.01, "Y position does not meet expected value of 50");
+            });
+        }
+    }
+}

UnitTests/UnitTests.UWP/UI/Controls/Test_ConstrainedBox.Coerce.cs

@@ -0,0 +1,140 @@
+// 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 System.Linq;
+using System.Threading.Tasks;
+using Microsoft.Toolkit.Uwp;
+using Microsoft.Toolkit.Uwp.UI;
+using Microsoft.Toolkit.Uwp.UI.Controls;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Microsoft.VisualStudio.TestTools.UnitTesting.AppContainer;
+using Windows.Foundation;
+using Windows.UI.Xaml;
+using Windows.UI.Xaml.Controls;
+using Windows.UI.Xaml.Markup;
+
+namespace UnitTests.UWP.UI.Controls
+{
+    /// <summary>
+    /// These tests check for the various values which can be coerced and changed if out of bounds for each property.
+    /// </summary>
+    public partial class Test_ConstrainedBox : VisualUITestBase
+    {
+        [TestCategory("ConstrainedBox")]
+        [TestMethod]
+        public async Task Test_ConstrainedBox_Coerce_Scale()
+        {
+            await App.DispatcherQueue.EnqueueAsync(async () =>
+            {
+                var treeRoot = XamlReader.Load(@"<Page
+    xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""
+    xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml""
+    xmlns:controls=""using:Microsoft.Toolkit.Uwp.UI.Controls"">
+      <controls:ConstrainedBox x:Name=""ConstrainedBox"" ScaleX=""0.5"" ScaleY=""0.5""/>
+</Page>") as FrameworkElement;
+
+                Assert.IsNotNull(treeRoot, "Could not load XAML tree.");
+
+                // Initialize Visual Tree
+                await SetTestContentAsync(treeRoot);
+
+                var panel = treeRoot.FindChild("ConstrainedBox") as ConstrainedBox;
+
+                Assert.IsNotNull(panel, "Could not find ConstrainedBox in tree.");
+
+                // Check Size
+                Assert.AreEqual(0.5, panel.ScaleX, 0.01, "ScaleX does not meet expected initial value of 0.5");
+                Assert.AreEqual(0.5, panel.ScaleY, 0.01, "ScaleY does not meet expected initial value of 0.5");
+
+                // Change values now to be invalid
+                panel.ScaleX = double.NaN;
+                panel.ScaleY = double.NaN;
+
+                Assert.AreEqual(1.0, panel.ScaleX, 0.01, "ScaleX does not meet expected value of 1.0 after change.");
+                Assert.AreEqual(1.0, panel.ScaleY, 0.01, "ScaleY does not meet expected value of 1.0 after change.");
+
+                // Change values now to be invalid
+                panel.ScaleX = double.NegativeInfinity;
+                panel.ScaleY = double.NegativeInfinity;
+
+                Assert.AreEqual(0.0, panel.ScaleX, 0.01, "ScaleX does not meet expected value of 0.0 after change.");
+                Assert.AreEqual(0.0, panel.ScaleY, 0.01, "ScaleY does not meet expected value of 0.0 after change.");
+
+                // Change values now to be invalid
+                panel.ScaleX = double.PositiveInfinity;
+                panel.ScaleY = double.PositiveInfinity;
+
+                Assert.AreEqual(1.0, panel.ScaleX, 0.01, "ScaleX does not meet expected value of 1.0 after change.");
+                Assert.AreEqual(1.0, panel.ScaleY, 0.01, "ScaleY does not meet expected value of 1.0 after change.");
+            });
+        }
+
+        [TestCategory("ConstrainedBox")]
+        [TestMethod]
+        public async Task Test_ConstrainedBox_Coerce_Multiple()
+        {
+            await App.DispatcherQueue.EnqueueAsync(async () =>
+            {
+                var treeRoot = XamlReader.Load(@"<Page
+    xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""
+    xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml""
+    xmlns:controls=""using:Microsoft.Toolkit.Uwp.UI.Controls"">
+      <controls:ConstrainedBox x:Name=""ConstrainedBox"" MultipleX=""32"" MultipleY=""32""/>
+</Page>") as FrameworkElement;
+
+                Assert.IsNotNull(treeRoot, "Could not load XAML tree.");
+
+                // Initialize Visual Tree
+                await SetTestContentAsync(treeRoot);
+
+                var panel = treeRoot.FindChild("ConstrainedBox") as ConstrainedBox;
+
+                Assert.IsNotNull(panel, "Could not find ConstrainedBox in tree.");
+
+                // Check Size
+                Assert.AreEqual(32, panel.MultipleX, "MultipleX does not meet expected value of 32");
+                Assert.AreEqual(32, panel.MultipleY, "MultipleY does not meet expected value of 32");
+
+                // Change values now to be invalid
+                panel.MultipleX = 0;
+                panel.MultipleY = int.MinValue;
+
+                Assert.AreEqual(DependencyProperty.UnsetValue, panel.ReadLocalValue(ConstrainedBox.MultipleXProperty), "MultipleX does not meet expected value of UnsetValue after change.");
+                Assert.AreEqual(DependencyProperty.UnsetValue, panel.ReadLocalValue(ConstrainedBox.MultipleYProperty), "MultipleY does not meet expected value of UnsetValue after change.");
+            });
+        }
+
+        [TestCategory("ConstrainedBox")]
+        [TestMethod]
+        public async Task Test_ConstrainedBox_Coerce_AspectRatio()
+        {
+            await App.DispatcherQueue.EnqueueAsync(async () =>
+            {
+                var treeRoot = XamlReader.Load(@"<Page
+    xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""
+    xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml""
+    xmlns:controls=""using:Microsoft.Toolkit.Uwp.UI.Controls"">
+      <controls:ConstrainedBox x:Name=""ConstrainedBox"" AspectRatio=""1.25:3.5""/>
+</Page>") as FrameworkElement;
+
+                Assert.IsNotNull(treeRoot, "Could not load XAML tree.");
+
+                // Initialize Visual Tree
+                await SetTestContentAsync(treeRoot);
+
+                var panel = treeRoot.FindChild("ConstrainedBox") as ConstrainedBox;
+
+                Assert.IsNotNull(panel, "Could not find ConstrainedBox in tree.");
+
+                // Check Size
+                Assert.AreEqual(1.25 / 3.5, panel.AspectRatio, 0.01, "ApectRatio does not meet expected value of 1.25/3.5");
+
+                // Change values now to be invalid
+                panel.AspectRatio = -1;
+
+                Assert.AreEqual(DependencyProperty.UnsetValue, panel.ReadLocalValue(ConstrainedBox.AspectRatioProperty), "AspectRatio does not meet expected value of UnsetValue after change.");
+            });
+        }
+    }
+}

UnitTests/UnitTests.UWP/UI/Controls/Test_ConstrainedBox.Combined.cs

@@ -17,6 +17,9 @@
 
 namespace UnitTests.UWP.UI.Controls
 {
+    /// <summary>
+    /// These tests check multiple constraints are applied together in the correct order.
+    /// </summary>
     public partial class Test_ConstrainedBox : VisualUITestBase
     {
         [TestCategory("ConstrainedBox")]