TextLineBreak.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Core / CSharp / System / Windows / Media / textformatting / TextLineBreak.cs / 1305600 / TextLineBreak.cs
                        
                        
                            //------------------------------------------------------------------------ 
//
//  Microsoft Windows Client Platform
//  Copyright (C) Microsoft Corporation
// 
//  File:      TextLineBreak.cs
// 
//  Contents:  Text properties and state at the point where text is broken 
//             by the line breaking process, which may need to be carried over
//             when formatting the next line. 
//
//  Spec:      http://team/sites/Avalon/Specs/Text%20Formatting%20API.doc
//
//  Created:   12-5-2004 Niklas Borson (niklasb) 
//
//----------------------------------------------------------------------- 
 
using System;
using System.Security; 
using System.Collections;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Media; 
using MS.Internal;
using MS.Internal.TextFormatting; 
 
using SR = MS.Internal.PresentationCore.SR;
using SRID = MS.Internal.PresentationCore.SRID; 


namespace System.Windows.Media.TextFormatting
{ 
    /// 
    /// Text properties and state at the point where text is broken 
    /// by the line breaking process. 
    /// 
    public sealed class TextLineBreak : IDisposable 
    {
        private TextModifierScope                   _currentScope;
        private SecurityCriticalDataForSet  _breakRecord;
 
        #region Constructors
 
        ///  
        /// Internallly construct the line break
        ///  
        internal TextLineBreak(
            TextModifierScope                   currentScope,
            SecurityCriticalDataForSet  breakRecord
            ) 
        {
            _currentScope = currentScope; 
            _breakRecord = breakRecord; 

            if (breakRecord.Value == IntPtr.Zero) 
            {
                // this object does not hold unmanaged resource,
                // remove it from the finalizer queue.
                GC.SuppressFinalize(this); 
            }
        } 
 
        #endregion
 

        /// 
        /// Finalize the line break
        ///  
        ~TextLineBreak()
        { 
            DisposeInternal(true); 
        }
 

        /// 
        /// Dispose the line break
        ///  
        public void Dispose()
        { 
            DisposeInternal(false); 
            GC.SuppressFinalize(this);
        } 


        /// 
        /// Clone a new instance of TextLineBreak 
        /// 
        ///  
        /// Critical - as this calls unmanaged API LoCloneBreakRecord. 
        /// PublicOK - as it takes no parameter and retain no additional unmanaged resource.
        ///  
        [SecurityCritical]
        public TextLineBreak Clone()
        {
            IntPtr pbreakrec = IntPtr.Zero; 

            if (_breakRecord.Value != IntPtr.Zero) 
            { 
                LsErr lserr = UnsafeNativeMethods.LoCloneBreakRecord(_breakRecord.Value, out pbreakrec);
 
                if (lserr != LsErr.None)
                {
                    TextFormatterContext.ThrowExceptionFromLsError(SR.Get(SRID.CloneBreakRecordFailure, lserr), lserr);
                } 
            }
 
            return new TextLineBreak(_currentScope, new SecurityCriticalDataForSet(pbreakrec)); 
        }
 

        /// 
        /// Destroy LS unmanaged break records object inside the line break
        /// managed object. The parameter flag indicates whether the call is 
        /// from finalizer thread or the main UI thread.
        ///  
        ///  
        /// Critical - as this calls the setter of _breakRecord.Value which is type SecurityCriticalDataForSet.
        ///            _breakRecord is the value received from call to LoCreateBreaks and being passed back in 
        ///            when building the next break. No code should have access to set it otherwise.
        /// Safe - as this does not take any parameter that it passes directly to the critical function.
        /// 
        [SecurityCritical, SecurityTreatAsSafe] 
        private void DisposeInternal(bool finalizing)
        { 
            if (_breakRecord.Value != IntPtr.Zero) 
            {
                UnsafeNativeMethods.LoDisposeBreakRecord(_breakRecord.Value, finalizing); 

                _breakRecord.Value = IntPtr.Zero;
                GC.KeepAlive(this);
            } 
        }
 
 
        /// 
        /// Current text modifier scope, which can be null. 
        /// 
        internal TextModifierScope TextModifierScope
        {
            get { return _currentScope; } 
        }
 
 
        /// 
        /// Unmanaged pointer to LS break records structure 
        /// 
        internal SecurityCriticalDataForSet BreakRecord
        {
            get { return _breakRecord; } 
        }
    } 
} 

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

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