DocumentReference.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / Documents / DocumentReference.cs / 1305600 / DocumentReference.cs
                        
                        
                            //---------------------------------------------------------------------------- 
// 
//      Copyright (C) 2004 by Microsoft Corporation.  All rights reserved.
// 
// 
// Description:
//      Implements the DocumentReference element 
// 
// History:
//      05/13/2004 - Zhenbin Xu (ZhenbinX) - Created. 
//
//
//---------------------------------------------------------------------------
namespace System.Windows.Documents 
{
    using MS.Internal; 
    using MS.Internal.AppModel; 
    using MS.Internal.Documents;
    using MS.Internal.Utility; 
    using MS.Internal.Navigation;
    using MS.Internal.PresentationFramework; // SecurityHelper
    using System.Reflection;
    using System.Windows;                // DependencyID etc. 
    using System.Windows.Navigation;
    using System.Windows.Markup; 
    using System.Windows.Threading;               // Dispatcher 
    using System;
    using System.ComponentModel; 
    using System.Diagnostics;
    using System.IO;
    using System.IO.Packaging;
    using System.Net; 
    using System.Security;
 
 
    //=====================================================================
    ///  
    /// DocumentReference is the class that references a Document.
    /// Each document
    /// 
    [UsableDuringInitialization(false)] 
    public sealed class DocumentReference : FrameworkElement, IUriContext
    { 
 
        //-------------------------------------------------------------------
        // 
        // Connstructors
        //
        //----------------------------------------------------------------------
 
        #region Constructors
        ///  
        ///     Default DocumentReference constructor 
        /// 
        ///  
        ///     Automatic determination of current Dispatcher. Use alternative constructor
        ///     that accepts a Dispatcher for best performance.
        /// 
        public DocumentReference() : base() 
        {
            _Init(); 
        } 

        #endregion Constructors 

        //-------------------------------------------------------------------
        //
        // Public Methods 
        //
        //---------------------------------------------------------------------- 
 
        #region Public Methods
        ///  
        /// Synchonrously download and parse the document based on the Source specification.
        /// If a document was attached earlier and forceReload == false, the attached
        /// document will be returned.  forceReload == true results in downloading of the referenced
        /// document based on Source specification, any previously attached document is ignored 
        /// in this case.
        /// Regardless of forceReload, the document will be loaded based on Source specification if 
        /// it hasn't been loaded earlier. 
        /// 
        /// Force reloading the document instead of using cached value 
        /// The document tree
        public FixedDocument GetDocument(bool forceReload)
        {
            DocumentsTrace.FixedDocumentSequence.IDF.Trace(string.Format("DocumentReference.GetDocument ({0}, {1})", Source == null ? new Uri("", UriKind.RelativeOrAbsolute) : Source, forceReload)); 
             VerifyAccess();
 
            FixedDocument idp = null; 
            if (_doc != null)
            { 
                idp = _doc;
            }
            else
            { 
                if (!forceReload)
                { 
                     idp = CurrentlyLoadedDoc; 
                }
 
                if (idp == null)
                {
                    FixedDocument idpReloaded = _LoadDocument();
                    if (idpReloaded != null) 
                    {
                        DocumentsTrace.FixedDocumentSequence.IDF.Trace(string.Format("DocumentReference.GetDocument Loaded IDP {0}", idpReloaded.GetHashCode())); 
                        // save the doc's identity 
                        _docIdentity = idpReloaded;
                        idp = idpReloaded; 
                    }
                }
            }
 
            if (idp != null)
            { 
                LogicalTreeHelper.AddLogicalChild(this.Parent, idp); 
            }
            return idp; 
        }

        /// 
        /// Attach a document to this DocumentReference 
        /// You can only attach a document if it is not attached before or it is not created from URI before.
        ///  
        ///  
        public void SetDocument(FixedDocument doc)
        { 
            VerifyAccess();
            _docIdentity = null;
            _doc = doc;
        } 

        #endregion Public Methods 
 

        //-------------------------------------------------------------------- 
        //
        // Public Properties
        //
        //--------------------------------------------------------------------- 

        #region Public Properties 
        ///  
        /// Dynamic Property to reference an external document stream.
        ///  
        public static readonly DependencyProperty SourceProperty =
                DependencyProperty.Register(
                        "Source",
                        typeof(Uri), 
                        typeof(DocumentReference),
                        new FrameworkPropertyMetadata( 
                                (Uri) null, 
                                new PropertyChangedCallback(OnSourceChanged)));
 

        static void OnSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            DocumentsTrace.FixedDocumentSequence.IDF.Trace(string.Format("DocumentReference.Source_Invaidated")); 
            DocumentReference docRef = (DocumentReference)d;
 
            if (!object.Equals(e.OldValue, e.NewValue)) 
            {
                Uri oldSource = (Uri) e.OldValue; 
                Uri newSource = (Uri) e.NewValue;
                DocumentsTrace.FixedDocumentSequence.IDF.Trace(string.Format("====Replace old doc {0} with new {1}",
                    oldSource == null ? "null" : oldSource.ToString(),
                    newSource == null? "null" : newSource.ToString())); 
                // drop loaded document if source changed
                docRef._doc = null; 
                // 
                // #966803: Source change won't be a support scenario.
                // 
            }
        }

 
        /// 
        /// Get/Set Source property that references an external page stream. 
        ///  
        public Uri Source
        { 
            get { return (Uri) GetValue(SourceProperty); }
            set { SetValue(SourceProperty, value); }
        }
        #endregion Public Properties 

        #region IUriContext 
        ///  
        /// 
        ///  
        Uri IUriContext.BaseUri
        {
            get { return (Uri)GetValue(BaseUriHelper.BaseUriProperty); }
            set { SetValue(BaseUriHelper.BaseUriProperty, value); } 
        }
        #endregion IUriContext 
 
        //--------------------------------------------------------------------
        // 
        // Public Events
        //
        //---------------------------------------------------------------------
 
        #region Public Event
        #endregion Public Event 
 

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

        #region Internal Methods 
#if DEBUG 
        internal void Dump()
        { 
            DocumentsTrace.FixedDocumentSequence.Content.Trace(string.Format("     This {0}", this.GetHashCode()));
            DocumentsTrace.FixedDocumentSequence.Content.Trace(string.Format("         Source {0}", this.Source == null ? "null" : this.Source.ToString()));
            DocumentsTrace.FixedDocumentSequence.Content.Trace(string.Format("         _doc   {0}", _doc == null ? 0 : _doc.GetHashCode()));
            DocumentsTrace.FixedDocumentSequence.Content.Trace(string.Format("         _docIdentity {0}", _docIdentity == null ? 0 : _docIdentity.GetHashCode())); 
        }
#endif 
        #endregion Internal Methods 

        //-------------------------------------------------------------------- 
        //
        // Internal Properties
        //
        //--------------------------------------------------------------------- 

        #region Internal Properties 
        // return most recent result of GetDocument, if it is still alive 
        internal FixedDocument CurrentlyLoadedDoc
        { 
            get
            {
                return _docIdentity;
            } 
        }
        #endregion Internal Properties 
 
        //--------------------------------------------------------------------
        // 
        // private Properties
        //
        //----------------------------------------------------------------------
 
        #region Private Properties
        #endregion Private Properties 
 

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

        #region Private Methods 
        private void  _Init() 
        {
            this.InheritanceBehavior = InheritanceBehavior.SkipToAppNow; 
        }


        /// 
       /// Critical as it access the base uri through GetUriToNavigate
       /// 
       [SecurityCritical] 
        private Uri _ResolveUri()
        { 
            Uri uriToNavigate = this.Source;
            if (uriToNavigate != null)
            {
                uriToNavigate = BindUriHelper.GetUriToNavigate(this, ((IUriContext)this).BaseUri, uriToNavigate); 
            }
            return uriToNavigate; 
        } 

 
        // [....] load a document
       ///
       /// Critical as it access the base uri through _resolveUri
       /// TreatAsSafe since it does not disclose this 
       ///
       [SecurityCritical, SecurityTreatAsSafe] 
        private FixedDocument _LoadDocument() 
        {
            FixedDocument idp = null; 
            Uri uriToLoad = _ResolveUri();
            if (uriToLoad != null)
            {
                ContentType mimeType = null; 
                Stream docStream = null;
 
                docStream = WpfWebRequestHelper.CreateRequestAndGetResponseStream(uriToLoad, out mimeType); 
                if (docStream == null)
                { 
                    throw new ApplicationException(SR.Get(SRID.DocumentReferenceNotFound));
                }

                ParserContext pc = new ParserContext(); 

                pc.BaseUri = uriToLoad; 
 
                if (BindUriHelper.IsXamlMimeType(mimeType))
                { 
                    XpsValidatingLoader loader = new XpsValidatingLoader();
                    idp = loader.Load(docStream, ((IUriContext)this).BaseUri, pc, mimeType) as FixedDocument;
                }
                else if (MS.Internal.MimeTypeMapper.BamlMime.AreTypeAndSubTypeEqual(mimeType)) 
                {
                    idp = XamlReader.LoadBaml(docStream, pc, null, true) as FixedDocument; 
                } 
                else
                { 
                    throw new ApplicationException(SR.Get(SRID.DocumentReferenceUnsupportedMimeType));
                }
                idp.DocumentReference = this;
 
            }
 
           return idp; 
        }
        #endregion Private Methods 

        //-------------------------------------------------------------------
        //
        // Private Fields 
        //
        //--------------------------------------------------------------------- 
 
        #region Private Fields
        private FixedDocument _doc; 
        private FixedDocument _docIdentity;     // used to cache the identity of the IDF so the IDF knows where it come from.
        #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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