SafeMILHandle.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Core / CSharp / System / Windows / Media / SafeMILHandle.cs / 1305600 / SafeMILHandle.cs
                        

                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// 
// Description: 
//      A safe way to deal with unmanaged MIL interface pointers.
//--------------------------------------------------------------------------- 

using System;
using System.Security;
using Microsoft.Win32.SafeHandles; 

using UnsafeNativeMethods = MS.Win32.PresentationCore.UnsafeNativeMethods; 
 
namespace System.Windows.Media
{ 
    internal class SafeMILHandle : SafeHandleZeroOrMinusOneIsInvalid
    {
        /// 
        /// Use this constructor if the handle isn't ready yet and later 
        /// set the handle with SetHandle. SafeMILHandle owns the release
        /// of the handle. 
        ///  
        /// 
        ///    Critical: This derives from a class that has a link demand and inheritance demand 
        ///    TreatAsSafe: Ok to call constructor
        ///  
        [SecurityCritical,SecurityTreatAsSafe]
        internal SafeMILHandle() : base(true) 
        {
        } 
 
        /// 
        /// Use this constructor if the handle exists at construction time. 
        /// SafeMILHandle owns the release of the parameter.
        /// 
        /// 
        ///    Critical: This derives from a class that has a link demand and inheritance demand 
        ///  
        [SecurityCritical] 
        internal SafeMILHandle(IntPtr handle) : base(true) 
        {
            SetHandle(handle); 
        }

        /// 
        /// Change our size to the new size specified 
        /// 
        ///  
        ///    Critical: This code calls into AddMemoryPressure and RemoveMemoryPressure 
        ///                 both of which have link demands. It is used to keep memory around
        ///   
        [SecurityCritical]
        internal void UpdateEstimatedSize(long estimatedSize)
        {
            if (_gcPressure != null) 
            {
                _gcPressure.Release(); 
            } 

            // 
            // estimatedSize may be 0 for small images with fewer than 8 bits per pixel,
            // attempting to call GC.AddMemoryPressure with a pressure of 0 will cause it to
            // throw, so don't add memory pressure if estimatedSize is 0.
            // 
            if (estimatedSize > 0)
            { 
                _gcPressure = new SafeMILHandleMemoryPressure(estimatedSize); 
                _gcPressure.AddRef();
            } 
        }

        internal void CopyMemoryPressure(SafeMILHandle original)
        { 
            _gcPressure = original._gcPressure;
            if (_gcPressure != null) 
            { 
                _gcPressure.AddRef();
            } 
        }

        /// 
        /// Critical - calls unmanaged code, not treat as safe because you must 
        ///            validate that handle is a valid COM object.
        ///  
        [SecurityCritical] 
        protected override bool ReleaseHandle()
        { 
            UnsafeNativeMethods.MILUnknown.ReleaseInterface(ref handle);

            if (_gcPressure != null)
            { 
                _gcPressure.Release();
                _gcPressure = null; 
            } 

            return true; 
        }

        // Estimated size of the unmanaged memory
        private SafeMILHandleMemoryPressure _gcPressure; 
    }
} 
 

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

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