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//---------------------------------------------------------------------------
//
// Copyright (C) Microsoft Corporation. All rights reserved.
//
//---------------------------------------------------------------------------
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Security;
using System.Windows.Interop;
using System.Windows.Media;
using System.Windows.Threading;
using MS.Win32;
namespace System.Windows.Interop
{
/// <summary>
/// Helper class to provide window feedback that panning has hit an edge.
/// </summary>
internal class HwndPanningFeedback
{
/// <summary>
/// Instantiates a new instance of this class.
/// </summary>
/// <param name="hwndSource">The HWND on which to provide feedback.</param>
/// <SecurityNote>
/// SecurityCritical: Accesses HwndSource.
/// TreatAsSafe: Information is not given out.
/// </SecurityNote>
[SecurityCritical, SecurityTreatAsSafe]
public HwndPanningFeedback(HwndSource hwndSource)
{
if (hwndSource == null)
{
throw new ArgumentNullException("hwndSource");
}
_hwndSource = hwndSource;
}
private static bool IsSupported
{
get
{
return OperatingSystemVersionCheck.IsVersionOrLater(OperatingSystemVersion.Windows7);
}
}
/// <summary>
/// Returns the handle of the current window.
/// </summary>
/// <SecurityNote>
/// SecurityCritical: Handles _hwndSource
/// SecurityCritical: Handles and exposes HwndSource.Handle
/// </SecurityNote>
private HandleRef Handle
{
[SecurityCritical]
get
{
if (_hwndSource != null)
{
IntPtr handle = _hwndSource.CriticalHandle;
if (handle != IntPtr.Zero)
{
return new HandleRef(_hwndSource, handle);
}
}
return new HandleRef();
}
}
/// <summary>
/// Moves the window by the offset.
/// Used to provide feedback that panning has hit an edge.
/// </summary>
/// <param name="totalOverpanOffset">The total offset relative to the original location.</param>
/// <param name="inInertia">Whether the edge was hit due to inertia or the user panning.</param>
/// <SecurityNote>
/// SecurityCritical: Changes the on-screen position of a window.
/// SecurityCritical: Accesses Handle.
/// </SecurityNote>
[SecurityCritical]
public void UpdatePanningFeedback(Vector totalOverpanOffset, bool inInertia)
{
if ((_hwndSource != null) && IsSupported)
{
if (!_isProvidingPanningFeedback)
{
_isProvidingPanningFeedback = UnsafeNativeMethods.BeginPanningFeedback(Handle);
}
if (_isProvidingPanningFeedback)
{
var deviceOffset = _hwndSource.TransformToDevice((Point)totalOverpanOffset);
_deviceOffsetX = (int)deviceOffset.X;
_deviceOffsetY = (int)deviceOffset.Y;
_inInertia = inInertia;
if (_updatePanningOperation == null)
{
_updatePanningOperation = _hwndSource.Dispatcher.BeginInvoke(DispatcherPriority.Background,
new DispatcherOperationCallback(OnUpdatePanningFeedback),
this);
}
}
}
}
/// <SecurityNote>
/// SecurityCritical: Changes the on-screen position of a window.
/// SecurityCritical: Accesses Handle.
/// </SecurityNote>
[SecurityCritical]
private object OnUpdatePanningFeedback(object args)
{
HwndPanningFeedback panningFeedback = (HwndPanningFeedback)args;
_updatePanningOperation = null;
UnsafeNativeMethods.UpdatePanningFeedback(panningFeedback.Handle, panningFeedback._deviceOffsetX, panningFeedback._deviceOffsetY, panningFeedback._inInertia);
return null;
}
private int _deviceOffsetX;
private int _deviceOffsetY;
private bool _inInertia;
private DispatcherOperation _updatePanningOperation;
/// <summary>
/// Moves the window back to its original position.
/// Used to provide feedback that panning has hit an edge.
/// </summary>
/// <param name="animateBack">Whether to animate or snap back to the original position</param>
/// <SecurityNote>
/// SecurityCritical: Changes the on-screen position of a window.
/// SecurityCritical: Accesses _handle.
/// TreatAsSafe: Returns the window to its original position, which is safe.
/// </SecurityNote>
[SecurityCritical, SecurityTreatAsSafe]
public void EndPanningFeedback(bool animateBack)
{
if (_hwndSource != null && _isProvidingPanningFeedback)
{
_isProvidingPanningFeedback = false;
if (_updatePanningOperation != null)
{
_updatePanningOperation.Abort();
_updatePanningOperation = null;
}
UnsafeNativeMethods.EndPanningFeedback(Handle, animateBack);
}
}
/// <summary>
/// Whether panning feedback is currently in progress.
/// </summary>
private bool _isProvidingPanningFeedback;
/// <summary>
/// The HwndSource being manipulated.
/// </summary>
/// <SecurityNote>
/// SecurityCritical: Access to the window.
/// </SecurityNote>
[SecurityCritical]
private HwndSource _hwndSource;
}
}
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