HostVisual.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Core / CSharp / System / Windows / Media / HostVisual.cs / 1407647 / HostVisual.cs
                        
                        
                            //------------------------------------------------------------------------------ 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// Description: 
//     Host visual. 
//
//----------------------------------------------------------------------------- 

namespace System.Windows.Media
{
    using System; 
    using System.Windows.Threading;
    using System.Windows.Media; 
    using System.Windows.Media.Composition; 
    using System.Diagnostics;
    using System.Collections; 
    using System.Collections.Generic;
    using MS.Internal;
    using System.Resources;
    using System.Runtime.InteropServices; 
    using MS.Win32;
    using System.Threading; 
 
    using SR=MS.Internal.PresentationCore.SR;
    using SRID=MS.Internal.PresentationCore.SRID; 

    /// 
    /// Host visual.
    ///  
    public class HostVisual : ContainerVisual
    { 
        //--------------------------------------------------------------------- 
        //
        //  Constructors 
        //
        //---------------------------------------------------------------------

        #region Constructors 

        ///  
        /// 
        /// 
        public HostVisual() 
        {

        }
 
        #endregion Constructors
 
        //---------------------------------------------------------------------- 
        //
        //  Protected Methods 
        //
        //---------------------------------------------------------------------

        #region Protected Methods 

        ///  
        /// HitTestCore 
        /// 
        protected override HitTestResult HitTestCore( 
            PointHitTestParameters hitTestParameters)
        {
            //
            // HostVisual never reports itself as being hit. To change this 
            // behavior clients should derive from HostVisual and override
            // HitTestCore methods. 
            // 
            return null;
        } 

        /// 
        /// HitTestCore
        ///  
        protected override GeometryHitTestResult HitTestCore(
            GeometryHitTestParameters hitTestParameters) 
        { 
            //
            // HostVisual never reports itself as being hit. To change this 
            // behavior clients should derive from HostVisual and override
            // HitTestCore methods.
            //
            return null; 
        }
 
        #endregion Protected Methods 

        //---------------------------------------------------------------------- 
        //
        //  Internal Methods
        //
        //---------------------------------------------------------------------- 

        #region Internal Methods 
 
        /// 
        /// 
        /// 
        internal override Rect GetContentBounds()
        {
            return Rect.Empty; 
        }
 
        ///  
        ///
        ///  
        internal override void RenderContent(RenderContext ctx, bool isOnChannel)
        {
            //
            // Make sure that the visual target is properly hosted. 
            //
 
            EnsureHostedVisualConnected(ctx.Channel); 
        }
 
        /// 
        ///
        /// 
        internal override void FreeContent(DUCE.Channel channel) 
        {
            // 
            // Disconnect hosted visual from this channel. 
            //
 
            using (CompositionEngineLock.Acquire())
            {
                DisconnectHostedVisual(
                    channel, 
                    /* removeChannelFromCollection */ true);
            } 
 
            base.FreeContent(channel);
        } 

        /// 
        ///
        ///  
        internal void BeginHosting(VisualTarget target)
        { 
            // 
            // This method is executed on the visual target thread.
            // 

            Debug.Assert(target != null);
            Debug.Assert(target.Dispatcher.Thread == Thread.CurrentThread);
 
            using (CompositionEngineLock.Acquire())
            { 
                // 
                // Check if another target is already hosted by this
                // visual and throw exception if this is the case. 
                //
                if (_target != null)
                {
                    throw new InvalidOperationException( 
                        SR.Get(SRID.VisualTarget_AnotherTargetAlreadyConnected)
                        ); 
                } 

                _target = target; 

                //
                // If HostVisual and VisualTarget on same thread, then call Invalidate
                // directly. Otherwise post invalidate message to the host visual thread 
                // indicating that content update is required.
                // 
                if (this.CheckAccess()) 
                {
                    Invalidate(); 
                }
                else
                {
                    Dispatcher.BeginInvoke( 
                        DispatcherPriority.Normal,
                        (DispatcherOperationCallback)delegate(object args) 
                        { 
                            Invalidate();
                            return null; 
                        },
                        null
                        );
                } 
            }
        } 
 
        /// 
        /// 
        /// 
        internal void EndHosting()
        {
            // 
            // This method is executed on the visual target thread.
            // 
 
            using (CompositionEngineLock.Acquire())
            { 
                Debug.Assert(_target != null);
                Debug.Assert(_target.Dispatcher.Thread == Thread.CurrentThread);

                DisconnectHostedVisualOnAllChannels(); 

                _target = null; 
            } 
        }
 
        /// 
        /// Should be called from the VisualTarget thread
        /// when it is safe to access the composition node
        /// and out of band channel from the VisualTarget thread 
        /// to allow for the handle duplication/channel commit
        ///  
        internal object DoHandleDuplication(object channel) 
        {
            DUCE.ResourceHandle targetsHandle = DUCE.ResourceHandle.Null; 

            using (CompositionEngineLock.Acquire())
            {
                targetsHandle = _target._contentRoot.DuplicateHandle(_target.OutOfBandChannel, (DUCE.Channel)channel); 

                Debug.Assert(!targetsHandle.IsNull); 
 
                _target.OutOfBandChannel.CloseBatch();
                _target.OutOfBandChannel.Commit(); 
            }

            return targetsHandle;
        } 

        #endregion Internal Methods 
 

        //--------------------------------------------------------------------- 
        //
        //  Private Methods
        //
        //---------------------------------------------------------------------- 

        #region Private Methods 
 
        /// 
        /// Connects the hosted visual on a channel if necessary. 
        /// 
        private void EnsureHostedVisualConnected(DUCE.Channel channel)
        {
            // 
            // Conditions for connecting VisualTarget to Host Visual:-
            // 1. The channel on which we are rendering should not be synchronous. This 
            //    scenario is not supported currently. 
            // 2. VisualTarget should not be null.
            // 3. They should not be already connected. 
            //
            if (!(channel.IsSynchronous)
                && _target != null
                && !_connectedChannels.Contains(channel)) 
            {
                Debug.Assert(IsOnChannel(channel)); 
 
                DUCE.ResourceHandle targetsHandle = DUCE.ResourceHandle.Null;
 
                bool doDuplication = true;

                //
                // If HostVisual and VisualTarget are on same thread, then we just addref 
                // VisualTarget. Otherwise, if on different threads, then we duplicate
                // VisualTarget onto Hostvisual's channel. 
                // 
                if (_target.CheckAccess())
                { 
                    Debug.Assert(_target._contentRoot.IsOnChannel(channel));
                    Debug.Assert(_target.OutOfBandChannel == MediaContext.CurrentMediaContext.OutOfBandChannel);
                    bool created = _target._contentRoot.CreateOrAddRefOnChannel(this, channel, VisualTarget.s_contentRootType);
                    Debug.Assert(!created); 
                    targetsHandle = _target._contentRoot.GetHandle(channel);
                } 
                else 
                {
                    // 
                    // Duplicate the target's handle onto our channel.
                    //
                    // We must wait synchronously for the _targets Dispatcher to call
                    // back and do handle duplication. We can't do handle duplication 
                    // on this thread because access to the _target CompositionNode
                    // is not synchronized. If we duplicated here, we could potentially 
                    // corrupt the _target OutOfBandChannel or the CompositionNode 
                    // MultiChannelResource. We have to wait synchronously because
                    // we need the resulting duplicated handle to hook up as a child 
                    // to this HostVisual.
                    //

                    object returnValue = _target.Dispatcher.Invoke( 
                        DispatcherPriority.Normal,
                        TimeSpan.FromMilliseconds(1000), 
                        new DispatcherOperationCallback(DoHandleDuplication), 
                        channel
                        ); 

                    //
                    // Duplication and flush is complete, we can resume processing
                    // Only if the Invoke succeeded will we have a handle returned. 
                    //
                    if (returnValue != null) 
                    { 
                        targetsHandle = (DUCE.ResourceHandle)returnValue;
                    } 
                    else
                    {
                        // The Invoke didn't complete
                        doDuplication = false; 
                    }
                } 
 
                if (doDuplication)
                { 
                    if (!targetsHandle.IsNull)
                    {
                        using (CompositionEngineLock.Acquire())
                        { 
                            DUCE.CompositionNode.InsertChildAt(
                                _proxy.GetHandle(channel), 
                                targetsHandle, 
                                0,
                                channel); 
                        }

                        _connectedChannels.Add(channel);
 
                        //
                        // Indicate that that content composition root has been 
                        // connected, this needs to be taken into account to 
                        // properly manage children of this visual.
                        // 

                        SetFlags(channel, true, VisualProxyFlags.IsContentNodeConnected);
                    }
                } 
                else
                { 
                    // 
                    // We didn't get a handle, because _target belongs to a
                    // different thread, and the Invoke operation failed. We can't do 
                    // anything except try again in the next render pass. We can't
                    // call Invalidate during the render pass because it pushes up
                    // flags that are being modified within the render pass, so get
                    // the local Dispatcher to do it for us later. 
                    //
                    Dispatcher.BeginInvoke( 
                        DispatcherPriority.Normal, 
                        (DispatcherOperationCallback)delegate(object args)
                        { 
                            Invalidate();
                            return null;
                        },
                        null 
                        );
                } 
            } 
        }
 

        /// 
        /// Disconnects the hosted visual on all channels we have
        /// connected it to. 
        /// 
        private void DisconnectHostedVisualOnAllChannels() 
        { 
            foreach (DUCE.Channel channel in _connectedChannels)
            { 
                DisconnectHostedVisual(
                    channel,
                    /* removeChannelFromCollection */ false);
            } 

            _connectedChannels.Clear(); 
        } 

 
        /// 
        /// Disconnects the hosted visual on a channel.
        /// 
        private void DisconnectHostedVisual( 
            DUCE.Channel channel,
            bool removeChannelFromCollection) 
        { 
            if (_target != null && _connectedChannels.Contains(channel))
            { 
                DUCE.CompositionNode.RemoveChild(
                    _proxy.GetHandle(channel),
                    _target._contentRoot.GetHandle(channel),
                    channel 
                    );
 
                // 
                // Release the targets handle. If we had duplicated the handle,
                // then this removes the duplicated handle, otherwise just decrease 
                // the ref count for VisualTarget.
                //

                _target._contentRoot.ReleaseOnChannel(channel); 

                SetFlags(channel, false, VisualProxyFlags.IsContentNodeConnected); 
 
                if (removeChannelFromCollection)
                { 
                    _connectedChannels.Remove(channel);
                }
            }
        } 

 
        ///  
        /// Invalidate this visual.
        ///  
        private void Invalidate()
        {
            SetFlagsOnAllChannels(true, VisualProxyFlags.IsContentDirty);
 
            PropagateChangedFlags();
        } 
 
        #endregion Private Methods
 

        //---------------------------------------------------------------------
        //
        //  Private Fields 
        //
        //--------------------------------------------------------------------- 
 
        #region Private Fields
 
        /// 
        /// The hosted visual target.
        /// 
        ///  
        /// This field is free-threaded and should be accessed from under a lock.
        ///  
        private VisualTarget _target; 

        ///  
        /// The channels we have marshalled the visual target composition root.
        /// 
        /// 
        /// This field is free-threaded and should be accessed from under a lock. 
        /// 
        private List _connectedChannels = new List(); 
 
        #endregion Private Fields
    } 
}


// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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