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// 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.Input;
namespace System.Windows.Interop
{
internal class HwndSourceKeyboardInputSite : IKeyboardInputSite
{
public HwndSourceKeyboardInputSite(HwndSource source, IKeyboardInputSink sink)
{
ArgumentNullException.ThrowIfNull(source);
ArgumentNullException.ThrowIfNull(sink);
if (!(sink is UIElement))
{
throw new ArgumentException(SR.KeyboardSinkMustBeAnElement, "sink");
}
_source = source;
_sink = sink;
_sink.KeyboardInputSite = this;
_sinkElement = sink as UIElement;
}
#region IKeyboardInputSite
/// <summary>
/// Unregisters a child KeyboardInputSink from this sink.
/// </summary>
/// <remarks>
/// Requires unmanaged code permission.
/// </remarks>
void IKeyboardInputSite.Unregister()
{
CriticalUnregister();
}
/// <summary>
/// Unregisters a child KeyboardInputSink from this sink.
/// </summary>
internal void CriticalUnregister()
{
if(_source != null && _sink != null)
{
_source.CriticalUnregisterKeyboardInputSink(this);
_sink.KeyboardInputSite = null;
}
_source = null;
_sink = null;
}
/// <summary>
/// Returns the sink associated with this site (the "child", not
/// the "parent" sink that owns the site). There's no way of
/// getting from the site to the parent sink.
/// </summary>
IKeyboardInputSink IKeyboardInputSite.Sink
{
get
{
return _sink;
}
}
/// <summary>
/// Components call this when they want to move focus ("tab") but
/// have nowhere further to tab within their own component. Return
/// value is true if the site moved focus, false if the calling
/// component still has focus and should wrap around.
/// </summary>
bool IKeyboardInputSite.OnNoMoreTabStops(TraversalRequest request)
{
bool traversed = false;
if(_sinkElement != null)
{
traversed = _sinkElement.MoveFocus(request);
}
return traversed;
}
#endregion IKeyboardInputSite
private HwndSource _source;
private IKeyboardInputSink _sink;
private UIElement _sinkElement;
}
}
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