DeferredReference.cs source code in C# .NET

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Code:

                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Base / System / Windows / DeferredReference.cs / 1 / DeferredReference.cs
                        

                        
                            //---------------------------------------------------------------------------- 
//
// File: DeferredReference.cs
//
// Copyright (C) Microsoft Corporation.  All rights reserved. 
//
// Description: Proxy object passed to the property system to delay load values. 
// 
//---------------------------------------------------------------------------
 
namespace System.Windows
{
    using MS.Internal.WindowsBase;  // FriendAccessAllowed
 
    // Proxy object passed to the property system to delay load values.
    // 
    // The property system will make a GetValue callback (dereferencing the 
    // reference) inside DependencyProperty.GetValue calls, or before
    // coercion callbacks to derived classes. 
    //
    // DeferredReference instances are passed directly to ValidateValue
    // callbacks (which always go to the DependencyProperty owner class),
    // and also to CoerceValue callbacks on the owner class only.  THEREFORE, 
    // IT IS
 
    [FriendAccessAllowed] // Built into Base, also used by Core & Framework. 
    internal abstract class DeferredReference
    { 
        //-----------------------------------------------------
        //
        //  Internal Methods
        // 
        //-----------------------------------------------------
 
        #region Internal Methods 

        // Deferences a property value on demand. 
        internal abstract object GetValue(BaseValueSourceInternal valueSource);

        // Gets the type of the value it represents
        internal abstract Type GetValueType(); 

        #endregion Internal Methods 
    } 

    internal class DeferredMutableDefaultReference : DeferredReference 
    {
        #region Constructor

        internal DeferredMutableDefaultReference(PropertyMetadata metadata, DependencyObject d, DependencyProperty dp) 
        {
            _sourceObject = d; 
            _sourceProperty = dp; 
            _sourceMetadata = metadata;
        } 

        #endregion Constructor

        #region Methods 

        internal override object GetValue(BaseValueSourceInternal valueSource) 
        { 
            return _sourceMetadata.GetDefaultValue(_sourceObject, _sourceProperty);
        } 

        // Gets the type of the value it represents
        internal override Type GetValueType()
        { 
            return _sourceProperty.PropertyType;
        } 
 
        #endregion Methods
 
        #region Properties

        internal PropertyMetadata SourceMetadata
        { 
            get { return _sourceMetadata; }
        } 
 
        protected DependencyObject SourceObject
        { 
            get { return _sourceObject; }
        }

        protected DependencyProperty SourceProperty 
        {
            get { return _sourceProperty; } 
        } 

        #endregion Properties 

        #region Data

        private readonly PropertyMetadata _sourceMetadata; 
        private readonly DependencyObject _sourceObject;
        private readonly DependencyProperty _sourceProperty; 
 
        #endregion Data
    } 


}

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

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