ChildDocumentBlock.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / Documents / ChildDocumentBlock.cs / 1305600 / ChildDocumentBlock.cs
                        
                        
                            //---------------------------------------------------------------------------- 
// 
//      Copyright (C) 2004 by Microsoft Corporation.  All rights reserved.
// 
// 
// Description:
//      Represent a node in the doubly linked list a DocumentSequenceTextContainer 
//      maintains for the child-TextContainers it aggregates.  Each child-TextContainer 
//      would have a corresponding entry in the list.
// 
// History:
//      07/14/2004 - Zhenbin Xu (ZhenbinX) - Created.
//
//--------------------------------------------------------------------------- 
namespace System.Windows.Documents
{ 
    using MS.Internal.Documents; 
    using System;
    using System.Diagnostics; 


    //=====================================================================
    ///  
    /// Represent a node in the doubly linked list a DocumentSequenceTextContainer
    /// maintains for the child-TextContainers it aggregates.  Each child-TextContainer 
    /// would have a corresponding entry in the list. 
    /// 
    internal sealed class ChildDocumentBlock 
    {
        //-------------------------------------------------------------------
        //
        // Enum 
        //
        //---------------------------------------------------------------------- 
 
        [Flags()]
        internal enum BlockStatus 
        {
            None = 0,
            UnloadedBlock = 1,          // Child block has not been loaded
        } 

        //------------------------------------------------------------------- 
        // 
        // Connstructors
        // 
        //----------------------------------------------------------------------


        #region Ctors 
        internal ChildDocumentBlock(DocumentSequenceTextContainer aggregatedContainer, ITextContainer childContainer)
        { 
            Debug.Assert(childContainer != null); 
            _aggregatedContainer = aggregatedContainer;
            _container = childContainer; 
        }

        internal ChildDocumentBlock(DocumentSequenceTextContainer aggregatedContainer, DocumentReference docRef)
        { 
            Debug.Assert(docRef != null);
            _aggregatedContainer = aggregatedContainer; 
            _docRef = docRef; 
            _SetStatus(BlockStatus.UnloadedBlock);
        } 
        #endregion Ctors


        //-------------------------------------------------------------------- 
        //
        // Internal Properties 
        // 
        //---------------------------------------------------------------------
        #region Internal Methods 

        // Insert a new node into this list.
        internal ChildDocumentBlock InsertNextBlock(ChildDocumentBlock newBlock)
        { 
            Debug.Assert(newBlock != null);
 
            // Setup the new block correctly 
            newBlock._nextBlock     = this._nextBlock;
            newBlock._previousBlock = this; 

            // Link old next block to the new block
            if (this._nextBlock != null)
            { 
                this._nextBlock._previousBlock = newBlock;
            } 
 
            // Link this block to new block
            this._nextBlock = newBlock; 

            return newBlock;
        }
 
        #endregion Internal Methods
 
        //-------------------------------------------------------------------- 
        //
        // Internal Properties 
        //
        //---------------------------------------------------------------------

        #region Internal Properties 
        // The AggregatedContainer that holds the list of ChildDocumentBlock.
        internal DocumentSequenceTextContainer AggregatedContainer 
        { 
            get
            { 
                return _aggregatedContainer;
            }
        }
 
        // Reference to the child TextContainer
        internal ITextContainer ChildContainer 
        { 
            get
            { 
                _EnsureBlockLoaded();
                return _container;
            }
        } 

        // The highlight layer used to notify child TextContainer 
        // about TextSelection highlight change. 
        internal DocumentSequenceHighlightLayer ChildHighlightLayer
        { 
            get
            {
                if (_highlightLayer == null)
                { 
                    _highlightLayer = new DocumentSequenceHighlightLayer(_aggregatedContainer);
                    Debug.Assert(ChildContainer.Highlights.GetLayer(typeof(TextSelection)) == null); 
                    ChildContainer.Highlights.AddLayer(_highlightLayer); 
                }
                return _highlightLayer; 
            }
        }

 
        // Reference to the DocumentReference
        internal DocumentReference DocRef 
        { 
            get
            { 
                return _docRef;
            }
        }
 
        // End TextPointer of the child container
        internal ITextPointer End 
        { 
            get
            { 
                return ChildContainer.End;
            }
        }
 
#if DEBUG
        // Get if this entry is non-head/tail block in the linked list 
        internal bool IsInsideBlock 
        {
            get 
            {
                return (this._previousBlock != null && this._nextBlock != null);
            }
        } 
#endif
 
        // Get if this entry is Head of list 
        internal bool IsHead
        { 
            get
            {
                return (this._previousBlock == null);
            } 
        }
 
 
        // Get if this entry is Tail of list
        internal bool IsTail 
        {
            get
            {
                return (this._nextBlock == null); 
            }
        } 
 

        // Previous container entry in the link list 
        internal ChildDocumentBlock PreviousBlock
        {
            get
            { 
                return _previousBlock;
            } 
        } 

        // Next container entry in the link list 
        internal ChildDocumentBlock NextBlock
        {
            get
            { 
                return _nextBlock;
            } 
        } 

#if DEBUG 
        internal uint DebugId
        {
            get
            { 
                return _debugId;
            } 
        } 
#endif
        #endregion Internal Properties 

        //-------------------------------------------------------------------
        //
        // Private Methods 
        //
        //--------------------------------------------------------------------- 
 
        #region Private Methods
        private void _EnsureBlockLoaded() 
        {
            if (_HasStatus(BlockStatus.UnloadedBlock))
            {
                _ClearStatus(BlockStatus.UnloadedBlock); 

                DocumentsTrace.FixedDocumentSequence.TextOM.Trace("Loading TextContainer " + _docRef.ToString()); 
                // Load the TextContainer 
                IDocumentPaginatorSource idp = _docRef.GetDocument(false /*forceReload*/);
                IServiceProvider isp = idp as IServiceProvider; 
                if (isp != null)
                {
                    ITextContainer tc = isp.GetService(typeof(ITextContainer)) as ITextContainer;
                    if (tc != null) 
                    {
                        _container = tc; 
                        DocumentsTrace.FixedDocumentSequence.TextOM.Trace("Got ITextContainer"); 
                    }
                } 

                if (_container == null)
                {
                    _container = new NullTextContainer(); 
                }
            } 
        } 

 
        private bool _HasStatus(BlockStatus flags)
        {
            return ((_status & flags) == flags);
        } 

        private void _SetStatus(BlockStatus flags) 
        { 
            _status |= flags;
        } 

        private void _ClearStatus(BlockStatus flags)
        {
            _status &= (~flags); 
        }
        #endregion Private Methods 
 
        //--------------------------------------------------------------------
        // 
        // Private Fields
        //
        //---------------------------------------------------------------------
 
        #region Private Fields
        private readonly DocumentSequenceTextContainer _aggregatedContainer; 
        private readonly DocumentReference _docRef;          // Reference to the sub-document 
        private ITextContainer _container;           // Child TextContainer
        private DocumentSequenceHighlightLayer  _highlightLayer;  // Highlight layer used to notify child TextContainer highlight changes. 
        private BlockStatus _status;                // Status of this block, such as Loaded, etc.
        private ChildDocumentBlock _previousBlock;  // Link to previous block
        private ChildDocumentBlock _nextBlock;      // Link to next block
 
#if DEBUG
        private uint _debugId = (_debugIdCounter++); 
        private static uint _debugIdCounter = 0; 
#endif
        #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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