FactoryMaker.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Core / CSharp / System / Windows / Media / FactoryMaker.cs / 1305600 / FactoryMaker.cs
                        
                        
                            //------------------------------------------------------------------------------ 
//  Microsoft Avalon
//  Copyright (c) Microsoft Corporation, 2003
//
//  File:       FactoryMaker.cs 
//
//----------------------------------------------------------------------------- 
using System; 
using System.Security;
using System.Security.Permissions; 
using System.Diagnostics;
using MS.Internal;
using MS.Win32;
using System.Windows.Media.Composition; 
using Microsoft.Internal;
 
using SR=MS.Internal.PresentationCore.SR; 
using SRID=MS.Internal.PresentationCore.SRID;
using UnsafeNativeMethods=MS.Win32.PresentationCore.UnsafeNativeMethods; 

namespace System.Windows.Media
{
    ///  
    /// This is a internal class which is used by non context affinity objects
    /// to get access to a MIL factory object. 
    ///  
    internal class FactoryMaker: IDisposable
    { 

        private bool _disposed = false;
        /// 
        /// Critical - Create unmanaged critical resource 
        /// 
        [SecurityCritical] 
        internal FactoryMaker() 
        {
            lock (s_factoryMakerLock) 
            {
                // If we haven't have a factory, create one

                if (s_pFactory == IntPtr.Zero) 
                {
                    // Create the Core MIL factory. 
                    // Note: the call below might throw exception. The caller 
                    // should catch it. We won't add ref counter here if this
                    // happens. 

                    HRESULT.Check(UnsafeNativeMethods.MILFactory2.CreateFactory(out s_pFactory, MS.Internal.Composition.Version.MilSdkVersion));
                }
 
                s_cInstance++;
                _fValidObject = true; 
            } 
        }
 
        ~FactoryMaker()
        {
            Dispose(false);
        } 

        ///  
        /// Dispose of any resources 
        /// 
        public void Dispose() 
        {
                Dispose(true);
        }
 
        ///
        ///     Critical - performs an elevation to call MILUnknown.ReleaseInterface. 
        ///     TreatAsSafe - this function elevates to call release ( on an object we own). 
        ///                          net effect is a shutdown of the FactoryMaker. Considered safe.
        /// 
        [SecurityCritical, SecurityTreatAsSafe]
        protected virtual void Dispose(bool fDisposing)
        {
                if (!_disposed) 
                {
                    if (_fValidObject == true) 
                    { 
                        lock (s_factoryMakerLock)
                        { 
                            s_cInstance--;

                            // Make sure we don't dispose twice
                            _fValidObject = false; 

                            // If there is no FactoryMaker object out there, release 
                            // factory object 

                            if (s_cInstance == 0) 
                            {
                                UnsafeNativeMethods.MILUnknown.ReleaseInterface(ref s_pFactory);

                                if (s_pImagingFactory != IntPtr.Zero) 
                                {
                                    UnsafeNativeMethods.MILUnknown.ReleaseInterface(ref s_pImagingFactory); 
                                } 

                                s_pFactory = IntPtr.Zero; 
                                s_pImagingFactory = IntPtr.Zero;
                            }
                        }
                    } 

 
                // Set the sentinel. 
                _disposed = true;
 
                // Suppress finalization of this disposed instance.
                if (fDisposing)
                {
                    GC.SuppressFinalize(this); 
                }
                } 
        } 

        ///  
        /// Critical - returns critical resource created under an assert
        /// 
        internal IntPtr FactoryPtr
        { 
            [SecurityCritical]
            get 
            { 
                Debug.Assert(s_pFactory != IntPtr.Zero);
                return s_pFactory; 
            }
        }

        ///  
        /// Critical - calls unmanaged code, returns unmanaged pointer
        ///  
        internal IntPtr ImagingFactoryPtr 
        {
            [SecurityCritical] 
            get
            {
                if (s_pImagingFactory == IntPtr.Zero)
                { 
                    lock (s_factoryMakerLock)
                    { 
                        HRESULT.Check(UnsafeNativeMethods.WICCodec.CreateImagingFactory(UnsafeNativeMethods.WICCodec.WINCODEC_SDK_VERSION, out s_pImagingFactory)); 
                    }
                } 
                Debug.Assert(s_pImagingFactory != IntPtr.Zero);
                return s_pImagingFactory;
            }
        } 

        ///  
        /// Critical - this is a pointer to an unmanaged object that methods are called directly on 
        /// 
        [SecurityCritical] 
        private static IntPtr s_pFactory;
        /// 
        /// Critical - this is a pointer to an unmanaged object that methods are called directly on
        ///  
        [SecurityCritical]
        private static IntPtr s_pImagingFactory; 
 
        /// 
        /// Keeps track of how many instance of current object have been passed out 
        /// 
        private static int s_cInstance = 0;

        ///  
        /// "FactoryMaker" is free threaded. This lock is used to synchronize
        /// access to the FactoryMaker. 
        ///  
        private static object s_factoryMakerLock = new object();
        private bool _fValidObject; 
    }
}


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