HwndPanningFeedback.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Core / CSharp / System / Windows / InterOp / HwndPanningFeedback.cs / 1305600 / HwndPanningFeedback.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// 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 
{ 
    /// 
    ///     Helper class to provide window feedback that panning has hit an edge. 
    /// 
    internal class HwndPanningFeedback
    {
        ///  
        ///     Instantiates a new instance of this class.
        ///  
        /// The HWND on which to provide feedback. 
        /// 
        ///     SecurityCritical: Accesses HwndSource. 
        ///     TreatAsSafe: Information is not given out.
        /// 
        [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); 
            }
        }

        ///  
        ///     Returns the handle of the current window.
        ///  
        ///  
        ///     SecurityCritical: Handles _hwndSource
        ///     SecurityCritical: Handles and exposes HwndSource.Handle 
        /// 
        private HandleRef Handle
        {
            [SecurityCritical] 
            get
            { 
                if (_hwndSource != null) 
                {
                    IntPtr handle = _hwndSource.CriticalHandle; 
                    if (handle != IntPtr.Zero)
                    {
                        return new HandleRef(_hwndSource, handle);
                    } 
                }
 
                return new HandleRef(); 
            }
        } 

        /// 
        ///     Moves the window by the offset.
        ///     Used to provide feedback that panning has hit an edge. 
        /// 
        /// The total offset relative to the original location. 
        /// Whether the edge was hit due to inertia or the user panning. 
        /// 
        ///     SecurityCritical: Changes the on-screen position of a window. 
        ///     SecurityCritical: Accesses Handle.
        /// 
        [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); 
                    } 
                }
            } 
        }

        /// 
        ///     SecurityCritical: Changes the on-screen position of a window. 
        ///     SecurityCritical: Accesses Handle.
        ///  
        [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;

        /// 
        ///     Moves the window back to its original position. 
        ///     Used to provide feedback that panning has hit an edge.
        ///  
        /// Whether to animate or snap back to the original position 
        /// 
        ///     SecurityCritical: Changes the on-screen position of a window. 
        ///     SecurityCritical: Accesses _handle.
        ///     TreatAsSafe: Returns the window to its original position, which is safe.
        /// 
        [SecurityCritical, SecurityTreatAsSafe] 
        public void EndPanningFeedback(bool animateBack)
        { 
            if (_hwndSource != null && _isProvidingPanningFeedback) 
            {
                _isProvidingPanningFeedback = false; 
                if (_updatePanningOperation != null)
                {
                    _updatePanningOperation.Abort();
                    _updatePanningOperation = null; 
                }
                UnsafeNativeMethods.EndPanningFeedback(Handle, animateBack); 
            } 
        }
 
        /// 
        ///     Whether panning feedback is currently in progress.
        /// 
        private bool _isProvidingPanningFeedback; 

        ///  
        ///     The HwndSource being manipulated. 
        /// 
        ///  
        ///     SecurityCritical: Access to the window.
        /// 
        [SecurityCritical]
        private HwndSource _hwndSource; 
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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HwndPanningFeedback.cs source code in C# .NET

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