StaticResourceExtension.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Framework / System / Windows / StaticResourceExtension.cs / 1 / StaticResourceExtension.cs
                        
                        
                            /****************************************************************************\ 
*
* File: StaticResourceExtension.cs
*
*  Class for Xaml markup extension for static resource references. 
*
* Copyright (C) 2004 by Microsoft Corporation.  All rights reserved. 
* 
\***************************************************************************/
 
using System;
using System.Collections;
using System.Diagnostics;
using System.Windows; 
using System.Windows.Documents;
using System.Windows.Markup; 
using System.Reflection; 
using MS.Internal;
 
namespace System.Windows
{
    /// 
    ///  Class for Xaml markup extension for static resource references. 
    /// 
    [MarkupExtensionReturnType(typeof(object))] 
    [Localizability(LocalizationCategory.NeverLocalize)] // cannot be localized 
    public class StaticResourceExtension : MarkupExtension
    { 
        /// 
        ///  Constructor that takes no parameters
        /// 
        public StaticResourceExtension() 
        {
        } 
 
        /// 
        ///  Constructor that takes the resource key that this is a static reference to. 
        /// 
        public StaticResourceExtension(
            object resourceKey)
        { 
            if (resourceKey == null)
            { 
                throw new ArgumentNullException("resourceKey"); 
            }
            _resourceKey = resourceKey; 
        }

        /// 
        ///  Return an object that should be set on the targetObject's targetProperty 
        ///  for this markup extension.  For StaticResourceExtension, this is the object found in
        ///  a resource dictionary in the current parent chain that is keyed by ResourceKey 
        ///  
        /// Object that can provide services for the markup extension.
        ///  
        ///  The object to set on this property.
        /// 
        public override object ProvideValue(IServiceProvider serviceProvider)
        { 
            IProvideValueTarget provideValueTarget = null;
            IBamlReader bamlReader = null; 
 
            if( serviceProvider != null )
            { 
                provideValueTarget = serviceProvider.GetService(typeof(IProvideValueTarget)) as IProvideValueTarget;
                bamlReader = serviceProvider.GetService(typeof(IBamlReader)) as IBamlReader;
            }
 
            if( bamlReader == null )
            { 
                throw new InvalidOperationException((SR.Get(SRID.StaticResourceInXamlOnly))); 
            }
 
            if( provideValueTarget == null )
            {
                throw new InvalidOperationException( SR.Get(SRID.MarkupExtensionNoContext, GetType().Name, "IProvideValueTarget" ));
            } 

            return ProvideValueInternal( 
                            bamlReader, 
                            provideValueTarget.TargetObject,
                            provideValueTarget.TargetProperty, 
                            false /*allowDeferredReference*/);
        }

 
        internal object ProvideValueInternal(
            IBamlReader bamlReader, 
            object targetObject, 
            object targetProperty,
            bool   allowDeferredReference) 
        {

            if (ResourceKey == null)
            { 
                throw new InvalidOperationException(SR.Get(SRID.MarkupExtensionResourceKey));
            } 
 
            // Return a DeferredReference when set on a DependencyProperty in a Style
            bool deferReference = allowDeferredReference && 
                (targetObject is FrameworkElementFactory || targetObject is Setter || targetObject is SharedDp);

            // Get prefetchedValue
            DeferredResourceReference prefetchedValue = PrefetchedValue; 
            bool isValidPrefetchedValue = prefetchedValue != null && !prefetchedValue.IsUnset;
 
            // Find value 
            BamlRecordReader bamlRecordReader = bamlReader.GetBamlReader() as BamlRecordReader;
            object value; 

            if (prefetchedValue != null)
            {
                // If we have a prefetched value then we we need to look only in the parser stack not in the App or the theme. 
                value = bamlRecordReader.FindResourceInParserStack(ResourceKey, deferReference, false/*mustReturnDeferredResourceReference*/);
            } 
            else 
            {
                // If we do not have a prefetched value it is a regular staticresource lookup and hence we must look in the parser stack and the app and the theme. 
                value = bamlRecordReader.FindResourceInParentChain(ResourceKey, deferReference, false /*mustReturnDeferredResourceReference*/);
            }

            if (value == DependencyProperty.UnsetValue) 
            {
                // If both the currently fetched value and the previously fetched value indicate that the 
                // resource has not been found then it is time to throw an exception. 
                if (!isValidPrefetchedValue)
                { 
                    bamlRecordReader.ThrowException(SRID.ParserNoResource , "{" + ResourceKey.ToString() + "}");
                }
                else
                { 
                    if (!deferReference)
                    { 
                        // Inflate the prefetched deferred resource reference, because the 
                        // current context does not support using deferred references.
                        value = prefetchedValue.GetValue(BaseValueSourceInternal.Unknown); 
                    }
                    else
                    {
                        // Use the prefetched value as is 
                        value = prefetchedValue;
                    } 
                } 
            }
 
            return value;
        }

        ///  
        ///  The key in a Resource Dictionary used to find the object refered to by this
        ///  Markup Extension. 
        ///  
        [ConstructorArgument("resourceKey")]
        public object ResourceKey 
        {
            get { return _resourceKey; }
            set
            { 
                if (value == null)
                { 
                    throw new ArgumentNullException("value"); 
                }
                _resourceKey = value; 
            }
        }

        ///  
        /// This value is used to resolved StaticResourceIds
        ///  
        internal virtual DeferredResourceReference PrefetchedValue 
        {
            get { return null; } 
        }

        private object _resourceKey;
    } 
}
 

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

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