HwndStylusInputProvider.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Core / CSharp / System / Windows / InterOp / HwndStylusInputProvider.cs / 1305600 / HwndStylusInputProvider.cs
                        
                        
                            using System.Runtime.InteropServices; 
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Threading;
using System.Diagnostics; 
using MS.Win32;
using MS.Internal; 
using MS.Internal.Interop; 
using MS.Internal.PresentationCore;                        // SecurityHelper
using MS.Utility; 
using System.Security;
using System.Security.Permissions;

using SR=MS.Internal.PresentationCore.SR; 
using SRID=MS.Internal.PresentationCore.SRID;
 
namespace System.Windows.Interop 
{
    ///////////////////////////////////////////////////////////////////////// 

    internal sealed class HwndStylusInputProvider : DispatcherObject, IInputProvider, IDisposable
    {
        private const uint TABLET_PRESSANDHOLD_DISABLED = 0x00000001; 
        private const uint TABLET_TAPFEEDBACK_DISABLED  = 0x00000008;
        private const uint TABLET_TOUCHUI_FORCEON       = 0x00000100; 
        private const uint TABLET_TOUCHUI_FORCEOFF      = 0x00000200; 
        private const uint TABLET_FLICKS_DISABLED       = 0x00010000;
 
        private const int MultiTouchEnabledFlag         = 0x01000000;

        /////////////////////////////////////////////////////////////////////
        ///  
        ///     Accesses and stores critical data (_site, _source, _stylusLogic).
        ///  
        [SecurityCritical] 
        internal HwndStylusInputProvider(HwndSource source)
        { 
            InputManager inputManager = InputManager.Current;
            StylusLogic stylusLogic = inputManager.StylusLogic;

            IntPtr sourceHandle; 

            (new UIPermission(PermissionState.Unrestricted)).Assert(); 
            try //Blessed Assert this is for RegisterInputManager and RegisterHwndforinput 
            {
                // Register ourselves as an input provider with the input manager. 
                _site = new SecurityCriticalDataClass(inputManager.RegisterInputProvider(this));

                sourceHandle = source.Handle;
            } 
            finally
            { 
                UIPermission.RevertAssert(); 
            }
 
            stylusLogic.RegisterHwndForInput(inputManager, source);
            _source = new SecurityCriticalDataClass(source);
            _stylusLogic = new SecurityCriticalDataClass(stylusLogic);
 
            // Enables multi-touch input
            UnsafeNativeMethods.SetProp(new HandleRef(this, sourceHandle), "MicrosoftTabletPenServiceProperty", new HandleRef(null, new IntPtr(MultiTouchEnabledFlag))); 
        } 

        ///////////////////////////////////////////////////////////////////// 


        /// 
        ///     Critical:This class accesses critical data, _site 
        ///     TreatAsSafe: This class does not expose the critical data.
        ///  
        [SecurityCritical,SecurityTreatAsSafe] 
        public void Dispose()
        { 
            if(_site != null)
            {
                _site.Value.Dispose();
                _site = null; 

                _stylusLogic.Value.UnRegisterHwndForInput(_source.Value); 
                _stylusLogic = null; 
                _source = null;
            } 
        }

        /////////////////////////////////////////////////////////////////////
        ///  
        ///     Critical: This method acceses critical data hwndsource
        ///     TreatAsSafe:Information about whether a given input provider services 
        ///     a visual is safe to expose. This method does not expose the critical data either. 
        /// 
        [SecurityCritical,SecurityTreatAsSafe] 
        bool IInputProvider.ProvidesInputForRootVisual(Visual v)
        {
            Debug.Assert( null != _source );
            return _source.Value.RootVisual == v; 
        }
 
        void IInputProvider.NotifyDeactivate() {} 

        ///////////////////////////////////////////////////////////////////// 
        //[CodeAnalysis("AptcaMethodsShouldOnlyCallAptcaMethods")] //Tracking Bug: 29647
        /// 
        ///     Critical: This code is critical since it handles all stylus messages and could be used to spoof input
        ///  
        [SecurityCritical]
        internal IntPtr FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, ref bool handled) 
        { 
            IntPtr result = IntPtr.Zero ;
 
            // It is possible to be re-entered during disposal.  Just return.
            if(null == _source || null == _source.Value)
            {
                return result; 
            }
 
            switch(msg) 
            {
                case WindowMessage.WM_ENABLE: 
                    _stylusLogic.Value.OnWindowEnableChanged(hwnd, (int)NativeMethods.IntPtrToInt32(wParam) == 0);
                    break;

                case WindowMessage.WM_TABLET_QUERYSYSTEMGESTURESTATUS: 
                    handled = true;
 
                    NativeMethods.POINT pt1 = new NativeMethods.POINT( 
                                            NativeMethods.SignedLOWORD(lParam),
                                            NativeMethods.SignedHIWORD(lParam)); 
                    SafeNativeMethods.ScreenToClient(new HandleRef(this, hwnd), pt1);
                    Point ptClient1 = new Point(pt1.x, pt1.y);

                    IInputElement inputElement = StylusDevice.LocalHitTest(_source.Value, ptClient1); 
                    if (inputElement != null)
                    { 
                        // walk up the parent chain 
                        DependencyObject elementCur = (DependencyObject)inputElement;
                        bool isPressAndHoldEnabled = Stylus.GetIsPressAndHoldEnabled(elementCur); 
                        bool isFlicksEnabled = Stylus.GetIsFlicksEnabled(elementCur);
                        bool isTapFeedbackEnabled = Stylus.GetIsTapFeedbackEnabled(elementCur);
                        bool isTouchFeedbackEnabled = Stylus.GetIsTouchFeedbackEnabled(elementCur);
 
                        uint flags = 0;
 
                        if (!isPressAndHoldEnabled) 
                        {
                            flags |= TABLET_PRESSANDHOLD_DISABLED; 
                        }

                        if (!isTapFeedbackEnabled)
                        { 
                            flags |= TABLET_TAPFEEDBACK_DISABLED;
                        } 
 
                        if (isTouchFeedbackEnabled)
                        { 
                            flags |= TABLET_TOUCHUI_FORCEON;
                        }
                        else
                        { 
                            flags |= TABLET_TOUCHUI_FORCEOFF;
                        } 
 
                        if (!isFlicksEnabled)
                        { 
                            flags |= TABLET_FLICKS_DISABLED;
                        }

                        result = new IntPtr(flags); 
                    }
                    break; 
 
                case WindowMessage.WM_TABLET_FLICK:
                    handled = true; 

                    int flickData = NativeMethods.IntPtrToInt32(wParam);

                    // We always handle any scroll actions if we are enabled.  We do this when we see the SystemGesture Flick come through. 
                    // Note: Scrolling happens on window flicked on even if it is not the active window.
                    if(_stylusLogic != null && _stylusLogic.Value.Enabled && (StylusLogic.GetFlickAction(flickData) == 1)) 
                    { 
                        result = new IntPtr(0x0001); // tell UIHub the flick has already been handled.
                    } 
                    break;
            }

            if (handled && EventTrace.IsEnabled(EventTrace.Keyword.KeywordInput | EventTrace.Keyword.KeywordPerf, EventTrace.Level.Info)) 
            {
                EventTrace.EventProvider.TraceEvent(EventTrace.Event.WClientInputMessage, EventTrace.Keyword.KeywordInput | EventTrace.Keyword.KeywordPerf, EventTrace.Level.Info, 
                                                    (_source.Value.CompositionTarget != null ? _source.Value.CompositionTarget.Dispatcher.GetHashCode() : 0), 
                                                     hwnd.ToInt64(),
                                                     msg, 
                                                     (int)wParam,
                                                     (int)lParam);
            }
 
            return result;
        } 
 
        /////////////////////////////////////////////////////////////////////
 
        private SecurityCriticalDataClass        _stylusLogic;
        /// 
        ///     Critical: This is the HwndSurce object , not ok to expose
        ///  
        private SecurityCriticalDataClass        _source;
        ///  
        ///     This data is critical and should never be exposed 
        /// 
        private SecurityCriticalDataClass _site; 
    }
}

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

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