ImagingCache.cs source code in C# .NET

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                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Core / System / Windows / Media / Imaging / ImagingCache.cs / 1 / ImagingCache.cs
                        
                        
                            //------------------------------------------------------------------------------ 
//  Microsoft Avalon
//  Copyright (c) Microsoft Corporation
//
//  File: ImagingCache.cs 
//
//----------------------------------------------------------------------------- 
 
using System;
using System.IO; 
using System.Collections;
using System.ComponentModel;
using System.ComponentModel.Design.Serialization;
using System.Reflection; 
using MS.Internal;
using System.Diagnostics; 
using System.Windows.Media; 
using System.Globalization;
using System.Security; 
using System.Security.Permissions;
using System.Runtime.InteropServices;
using System.Windows.Media.Animation;
using System.Windows.Media.Composition; 
using System.Windows.Media.Imaging;
using MS.Win32; 
using SR=MS.Internal.PresentationCore.SR; 
using SRID=MS.Internal.PresentationCore.SRID;
 
namespace System.Windows.Media.Imaging
{
    #region ImagingCache
 
    ///
    /// ImagingCache provides caching for different Imaging objects 
    /// Caches are thread-safe. 
    ///
    internal static class ImagingCache 
    {
        #region Methods

        /// Adds an object to the image cache 
        internal static void AddToImageCache(Uri uri, object obj)
        { 
            AddToCache(uri, obj, _imageCache); 
        }
 
        /// Removes an object from the image cache
        internal static void RemoveFromImageCache(Uri uri)
        {
            RemoveFromCache(uri, _imageCache); 
        }
 
        /// Get object from the image cache 
        internal static object CheckImageCache(Uri uri)
        { 
            return CheckCache(uri, _imageCache);
        }

        /// Adds an object to the decoder cache 
        internal static void AddToDecoderCache(Uri uri, object obj)
        { 
            AddToCache(uri, obj, _decoderCache); 
        }
 
        /// Removes an object from the decoder cache
        internal static void RemoveFromDecoderCache(Uri uri)
        {
            RemoveFromCache(uri, _decoderCache); 
        }
 
        /// Get object from the image cache 
        internal static object CheckDecoderCache(Uri uri)
        { 
            return CheckCache(uri, _decoderCache);
        }

        /// Adds an object to a given table 
        private static void AddToCache(Uri uri, object obj, Hashtable table)
        { 
            lock(table) 
            {
                // if entry is already there, exit 
                if (table.Contains(uri))
                {
                    return;
                } 

                // if the table has reached the max size, try to see if we can reduce its size 
                if (table.Count == MAX_CACHE_SIZE) 
                {
                    ArrayList al = new ArrayList(); 
                    foreach (DictionaryEntry de in table)
                    {
                        // if the value is a WeakReference that has been GC'd, remove it
                        WeakReference weakRef = de.Value as WeakReference; 
                        if ((weakRef != null) && (weakRef.Target == null))
                        { 
                            al.Add(de.Key); 
                        }
                    } 

                    foreach (object o in al)
                    {
                        table.Remove(o); 
                    }
                } 
 
                // if table is still maxed out, exit
                if (table.Count == MAX_CACHE_SIZE) 
                {
                    return;
                }
 
                // add it
                table[uri] = obj; 
            } 
        }
 
        /// Removes an object from a given table
        private static void RemoveFromCache(Uri uri, Hashtable table)
        {
            lock(table) 
            {
                // if entry is there, remove it 
                if (table.Contains(uri)) 
                {
                    table.Remove(uri); 
                }
            }
        }
 
        /// Return an object from a given table
        private static object CheckCache(Uri uri, Hashtable table) 
        { 
            lock(table)
            { 
                return table[uri];
            }
        }
 
        #endregion
 
        #region Data Members 

        /// image cache 
        private static Hashtable _imageCache = new Hashtable();

        /// decoder cache
        private static Hashtable _decoderCache = new Hashtable(); 

        /// max size to limit the cache 
        private static int MAX_CACHE_SIZE = 300; 

        #endregion 
    }

    #endregion
} 


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

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