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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.Media;
using System.Windows.Input.StylusPlugIns;
namespace System.Windows.Input.StylusWisp
{
/// <summary>
/// Collection of StylusPlugIn objects
/// </summary>
/// <remarks>
/// The collection order is based on the order that StylusPlugIn objects are
/// added to the collection via the IList interfaces. The order of the StylusPlugIn
/// objects in the collection is modifiable.
/// Some of the methods are designed to be called from both the App thread and the Pen thread,
/// but some of them are supposed to be called from one thread only. Please look at the
/// comments of each method for such an information.
/// </remarks>
internal class WispStylusPlugInCollection : StylusPlugInCollectionBase
{
#region Properties
/// <summary>
/// Get the current rect for the Element that the StylusPlugInCollection is attached to.
/// May be empty rect if plug in is not in tree.
/// </summary>
internal override bool IsActiveForInput
{
get
{
return _penContexts != null;
}
}
internal override object SyncRoot
{
get
{
return _penContexts != null ? _penContexts.SyncRoot : null;
}
}
internal PenContexts PenContexts
{
get
{
return _penContexts;
}
}
#endregion
#region Private APIs
internal override void UpdateState(UIElement element)
{
bool unhookPenContexts = true;
// Disable processing of the queue during blocking operations to prevent unrelated reentrancy
// which a call to Lock() can cause.
using (element.Dispatcher.DisableProcessing())
{
// See if we should be enabled
if (element.IsVisible && element.IsEnabled && element.IsHitTestVisible)
{
PresentationSource presentationSource = PresentationSource.CriticalFromVisual(element as Visual);
if (presentationSource != null)
{
unhookPenContexts = false;
// Are we currently hooked up? If not then hook up.
if (_penContexts == null)
{
InputManager inputManager = (InputManager)element.Dispatcher.InputManager;
PenContexts penContexts = StylusLogic.GetCurrentStylusLogicAs<WispLogic>().GetPenContextsFromHwnd(presentationSource);
// _penContexts must be non null or don't do anything.
if (penContexts != null)
{
_penContexts = penContexts;
lock (penContexts.SyncRoot)
{
penContexts.AddStylusPlugInCollection(Wrapper);
foreach (StylusPlugIn spi in Wrapper)
{
spi.InvalidateIsActiveForInput(); // Uses _penContexts being set to determine active state.
}
// Normally the Rect will be updated when we receive the LayoutUpdate.
// However there could be a race condition which the LayoutUpdate gets received
// before the properties like IsVisible being set.
// So we should always force to call OnLayoutUpdated whenever the input is active.
Wrapper.OnLayoutUpdated(this.Wrapper, EventArgs.Empty);
}
}
}
}
}
if (unhookPenContexts)
{
Unhook();
}
}
}
internal override void Unhook()
{
// Are we currently unhooked? If not then unhook.
if (_penContexts != null)
{
lock (_penContexts.SyncRoot)
{
_penContexts.RemoveStylusPlugInCollection(Wrapper);
// Can't recieve any more input now!
_penContexts = null;
// Notify after input is disabled to the PlugIns.
foreach (StylusPlugIn spi in Wrapper)
{
spi.InvalidateIsActiveForInput();
}
}
}
}
#endregion
#region Fields
// Note that this is only set when the Element is in a state to receive input (visible,enabled,in tree).
private PenContexts _penContexts;
#endregion
}
}
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