fix Transitioning Content Control DPI issue (#2827)

RenderTargetBitmap take an int therefore the minimum input value must be 1.

src/ReactiveUI.Tests/Platforms/wpf/Mocks/TransitionMock/FirstView.xaml

@@ -0,0 +1,12 @@
+<UserControl
+    x:Class="ReactiveUI.Tests.Wpf.FirstView"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:local="clr-namespace:ReactiveUI.Tests.Wpf"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    Width="450"
+    Height="450"
+    mc:Ignorable="d">
+    <Grid Background="#FFF80606" />
+</UserControl>

src/ReactiveUI.Tests/Platforms/wpf/Mocks/TransitionMock/FirstView.xaml.cs

@@ -0,0 +1,20 @@
+// Copyright (c) 2021 .NET Foundation and Contributors. All rights reserved.
+// 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 full license information.
+
+using System.Windows.Controls;
+
+namespace ReactiveUI.Tests.Wpf
+{
+    /// <summary>
+    /// Interaction logic for FirstView.xaml.
+    /// </summary>
+    public partial class FirstView : UserControl
+    {
+        public FirstView()
+        {
+            InitializeComponent();
+        }
+    }
+}

src/ReactiveUI.Tests/Platforms/wpf/Mocks/TransitionMock/SecondView.xaml

@@ -0,0 +1,12 @@
+<UserControl
+    x:Class="ReactiveUI.Tests.Wpf.SecondView"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:local="clr-namespace:ReactiveUI.Tests.Wpf"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    Width="0.5"
+    Height="0.5"
+    mc:Ignorable="d">
+    <Grid Background="#FFF7E40D" />
+</UserControl>

src/ReactiveUI.Tests/Platforms/wpf/Mocks/TransitionMock/SecondView.xaml.cs

@@ -0,0 +1,20 @@
+// Copyright (c) 2021 .NET Foundation and Contributors. All rights reserved.
+// 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 full license information.
+
+using System.Windows.Controls;
+
+namespace ReactiveUI.Tests.Wpf
+{
+    /// <summary>
+    /// Interaction logic for SecondView.xaml.
+    /// </summary>
+    public partial class SecondView : UserControl
+    {
+        public SecondView()
+        {
+            InitializeComponent();
+        }
+    }
+}

src/ReactiveUI.Tests/Platforms/wpf/Mocks/TransitionMock/TCMockWindow.xaml

@@ -0,0 +1,20 @@
+<rxui:ReactiveWindow
+    x:Class="ReactiveUI.Tests.Wpf.TCMockWindow"
+    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:local="clr-namespace:ReactiveUI.Tests.Wpf"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    xmlns:rxui="http://reactiveui.net"
+    Title="DPITest"
+    Width="600"
+    Height="600"
+    x:TypeArguments="local:TCMockWindowViewModel"
+    mc:Ignorable="d">
+    <Grid>
+        <rxui:TransitioningContentControl
+            x:Name="TransitioningContent"
+            Width="500"
+            Height="500" />
+    </Grid>
+</rxui:ReactiveWindow>

src/ReactiveUI.Tests/Platforms/wpf/Mocks/TransitionMock/TCMockWindow.xaml.cs

@@ -0,0 +1,18 @@
+// Copyright (c) 2021 .NET Foundation and Contributors. All rights reserved.
+// 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 full license information.
+
+namespace ReactiveUI.Tests.Wpf
+{
+    /// <summary>
+    /// Interaction logic for MainWindow.xaml.
+    /// </summary>
+    public partial class TCMockWindow
+    {
+        public TCMockWindow()
+        {
+            InitializeComponent();
+        }
+    }
+}

src/ReactiveUI.Tests/Platforms/wpf/Mocks/TransitionMock/TCMockWindowViewModel.cs

@@ -0,0 +1,11 @@
+// Copyright (c) 2021 .NET Foundation and Contributors. All rights reserved.
+// 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 full license information.
+
+namespace ReactiveUI.Tests.Wpf
+{
+    public class TCMockWindowViewModel : ReactiveObject
+    {
+    }
+}

src/ReactiveUI.Tests/Platforms/wpf/Mocks/WpfTestWindow.cs

@@ -4,17 +4,17 @@
 // See the LICENSE file in the project root for full license information.
 
 using System.Windows;
-using System.Windows.Controls;
-
+using System.Windows.Controls;
+
 namespace ReactiveUI.Tests.Wpf
 {
     public class WpfTestWindow : Window, IActivatableView
     {
-        public WpfTestWindow()
-        {
-            RootGrid = new Grid();
-
-            AddChild(RootGrid);
+        public WpfTestWindow()
+        {
+            RootGrid = new Grid();
+
+            AddChild(RootGrid);
         }
 
         public Grid RootGrid { get; }