Add MetroWindowAutomationPeer to prevent Win32Exception

src/MahApps.Metro/Automation/Peers/MetroWindowAutomationPeer.cs

@@ -0,0 +1,56 @@
+// 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.Windows;
+using System.Windows.Automation.Peers;
+using JetBrains.Annotations;
+using MahApps.Metro.Controls;
+
+namespace MahApps.Metro.Automation.Peers
+{
+ public class MetroWindowAutomationPeer : FrameworkElementAutomationPeer
+ {
+ public MetroWindowAutomationPeer([NotNull] Window owner)
+ : base(owner)
+ {
+ }
+
+ protected override string GetClassNameCore()
+ {
+ return "MetroWindow";
+ }
+
+ protected override string GetNameCore()
+ {
+ string name = base.GetNameCore();
+
+ if (name == string.Empty)
+ {
+ MetroWindow window = (MetroWindow)this.Owner;
+
+ name = window.GetWindowText();
+ if (name == null)
+ {
+ name = string.Empty;
+ }
+ }
+
+ return name;
+ }
+
+ protected override AutomationControlType GetAutomationControlTypeCore()
+ {
+ return AutomationControlType.Window;
+ }
+
+ protected override Rect GetBoundingRectangleCore()
+ {
+ MetroWindow window = (MetroWindow)this.Owner;
+
+ Rect bounds = window.GetWindowBoundingRectangle();
+
+ return bounds;
+ }
+ }
+}

src/MahApps.Metro/Controls/MetroWindow.cs

@@ -9,6 +9,7 @@
 using System.Linq;
 using System.Reflection;
 using System.Windows;
+using System.Windows.Automation.Peers;
 using System.Windows.Controls;
 using System.Windows.Input;
 using System.Windows.Media;
@@ -21,6 +22,7 @@
 using ControlzEx.Standard;
 using ControlzEx.Theming;
 using JetBrains.Annotations;
+using MahApps.Metro.Automation.Peers;
 using MahApps.Metro.Behaviors;
 using MahApps.Metro.Controls.Dialogs;
 using MahApps.Metro.ValueBoxes;
@@ -1246,13 +1248,20 @@ public override void OnApplyTemplate()
  }
  }
 
- protected IntPtr CriticalHandle
+ /// <summary>
+ /// Creates AutomationPeer (<see cref="UIElement.OnCreateAutomationPeer"/>)
+ /// </summary>
+ protected override AutomationPeer OnCreateAutomationPeer()
+ {
+ return new MetroWindowAutomationPeer(this);
+ }
+
+ protected internal IntPtr CriticalHandle
  {
  get
  {
- var value = typeof(Window)
- .GetProperty("CriticalHandle", BindingFlags.NonPublic | BindingFlags.Instance)
- .GetValue(this, new object[0]);
+ this.VerifyAccess();
+ var value = typeof(Window).GetProperty("CriticalHandle", BindingFlags.NonPublic | BindingFlags.Instance)?.GetValue(this, new object[0]) ?? IntPtr.Zero;
  return (IntPtr)value;
  }
  }

src/MahApps.Metro/Controls/WinApiHelper.cs

@@ -3,6 +3,8 @@
 // See the LICENSE file in the project root for more information.
 
 using System;
+using System.ComponentModel;
+using System.Text;
 using System.Windows;
 using System.Windows.Interop;
 using System.Windows.Media;
@@ -36,5 +38,82 @@ public static Size GetMonitorWorkSize(this Visual visual)
  return default;
  }
 #pragma warning restore 618
+
+ /// <summary> Gets the text associated with the given window handle. </summary>
+ /// <param name="window"> The window to act on. </param>
+ /// <returns> The window text. </returns>
+#pragma warning disable 618
+ internal static string GetWindowText(this Window window)
+ {
+ if (window != null
+ && PresentationSource.FromVisual(window) is HwndSource source
+ && source.IsDisposed == false
+ && source.RootVisual is null == false
+ && source.Handle != IntPtr.Zero)
+ {
+ int size = NativeMethods.GetWindowTextLength(source.Handle);
+ if (size == 0)
+ {
+ var lastError = Win32Error.GetLastError();
+ if (lastError != Win32Error.ERROR_SUCCESS)
+ {
+ throw new Win32Exception(lastError.Error);
+ }
+
+ return string.Empty;
+ }
+
+ var builder = new StringBuilder(size + 1);
+ var finalLength = NativeMethods.GetWindowText(source.Handle, builder, builder.Capacity);
+ if (finalLength == 0)
+ {
+ var lastError = Win32Error.GetLastError();
+ if (lastError != Win32Error.ERROR_SUCCESS)
+ {
+ throw new Win32Exception(lastError.Error);
+ }
+
+ return string.Empty;
+ }
+
+ return builder.ToString();
+ }
+
+ return default;
+ }
+
+ /// <summary> Gets the text associated with the given window handle. </summary>
+ /// <param name="window"> The window to act on. </param>
+ /// <returns> The window text. </returns>
+ internal static Rect GetWindowBoundingRectangle(this Window window)
+ {
+ Rect bounds = new Rect(0, 0, 0, 0);
+
+ if (window != null
+ && PresentationSource.FromVisual(window) is HwndSource source
+ && source.IsDisposed == false
+ && source.RootVisual is null == false
+ && source.Handle != IntPtr.Zero)
+ {
+ RECT rc = new RECT(0, 0, 0, 0);
+
+ try
+ {
+ rc = NativeMethods.GetWindowRect(source.Handle);
+ }
+ // Allow empty catch statements.
+#pragma warning disable 56502
+ catch (Win32Exception)
+ {
+ }
+ // Disallow empty catch statements.
+#pragma warning restore 56502
+
+ bounds = new Rect(rc.Left, rc.Top, rc.Width, rc.Height);
+ }
+
+ return bounds;
+ }
+#pragma warning restore 618
  }
 }