DPCustomTypeDescriptor.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Base / MS / Internal / ComponentModel / DPCustomTypeDescriptor.cs / 1305600 / DPCustomTypeDescriptor.cs
                        
                        
                             
namespace MS.Internal.ComponentModel
{
    using System;
    using System.Collections; 
    using System.Collections.Generic;
    using System.ComponentModel; 
    using System.Diagnostics; 
    using System.Reflection;
    using System.Windows; 
    using System.Windows.Markup;
    using System.Text;

 
    /// 
    ///     This class is a custom type descriptor for dependency properties.  We could simply 
    ///     derive from the CustomTypeDescriptor class, but because these are allocated a lot 
    ///     we make them a struct so they are not on the heap.
    ///  
    internal struct DPCustomTypeDescriptor : ICustomTypeDescriptor {

        //------------------------------------------------------
        // 
        //  Constructors
        // 
        //----------------------------------------------------- 

        #region Constructors 

        /// 
        ///     Creates a new DPCustomTypeDescriptor.  We pass in the custom type descriptor of
        ///     our base provider, which provides is with a default implementation of everything 
        ///     we don't override.  for us, we want to override only the property mechanism.
        ///  
        internal DPCustomTypeDescriptor(ICustomTypeDescriptor parent, Type objectType, object instance) 
        {
            _parent = parent; 
            _objectType = objectType;
            _instance = instance;
        }
 
        #endregion Constructors
 
        //----------------------------------------------------- 
        //
        //  Public Methods 
        //
        //-----------------------------------------------------

        #region Public Methods 

        ///  
        ///     Returns the component name.  To do this, we try to find the 
        ///     RuntimeNamePropertyAttribute on the type.  If we find
        ///     the attribute, we will try to invoke the property to retrieve 
        ///     the component name.  If any of these fail, we defer to the
        ///     parent implementation.
        /// 
        public string GetComponentName() 
        {
            if (_instance != null) 
            { 
                RuntimeNamePropertyAttribute nameAttr = GetAttributes()[typeof(RuntimeNamePropertyAttribute)] as RuntimeNamePropertyAttribute;
                if (nameAttr != null && nameAttr.Name != null) 
                {
                    PropertyDescriptor nameProp = GetProperties()[nameAttr.Name];
                    if (nameProp != null)
                    { 
                        return nameProp.GetValue(_instance) as string;
                    } 
                } 
            }
 
            return _parent.GetComponentName();
        }

        ///  
        ///     Returns a collection of properties for our object.
        ///  
        public PropertyDescriptorCollection GetProperties() 
        {
            return GetProperties(null); 
        }

        /// 
        ///     Returns a collection of properties for our object.  We first rely on base 
        ///     CLR properties and then we attempt to match these with dependency properties.
        ///  
        public PropertyDescriptorCollection GetProperties(Attribute[] attributes) 
        {
            // We have two code paths here based on filtered attributes.  An attribute 
            // filter is just a notificaiton of a filter, it doesn't actually perform
            // the filter.  Because the default PropertyFilterAttribute is PropertyFilter.All,
            // it acts as a nice "don't care" in later filtering stages that TypeDescriptor
            // may apply.  That means that regardless of the filter value, we don't have 
            // to fiddle with adding the attribute to the property descriptor.
 
            PropertyFilterOptions filter = PropertyFilterOptions.Valid | PropertyFilterOptions.SetValues; 

            if (attributes != null) 
            {
                foreach (Attribute attr in attributes)
                {
                    PropertyFilterAttribute filterAttr = attr as PropertyFilterAttribute; 
                    if (filterAttr != null)
                    { 
                        filter = filterAttr.Filter; 
                        break;
                    } 
                }
            }

            // If no filter is set, or if the only filter is for "invalid" properties, 
            // there's no work to do.
 
            if (filter == PropertyFilterOptions.None || filter == PropertyFilterOptions.Invalid) 
            {
                return PropertyDescriptorCollection.Empty; 
            }

            // Value used during filtering.  Because direct properties are always
            // returned for .Valid and .All, the only case we're directly interested 
            // in is when filter exactly equals SetValues.
            DependencyObject filterValue; 
            if (filter == PropertyFilterOptions.SetValues) 
            {
                if (_instance == null) return PropertyDescriptorCollection.Empty; 
                filterValue = (DependencyObject)TypeDescriptor.GetAssociation(_objectType, _instance);
            }
            else
            { 
                filterValue = null;
            } 
 
            // Note:  For a property filter of "SetValues" it would be ideal if we could use
            // DependencyObject's GetLocalValueEnumerator.  Unfortunately, we can't: 
            //
            // * We still need to scan properties to get the property descriptor that
            //   matches the DP.
            // 
            // * The enumerator would skip CLR properties that have no backing DP.
            // 
            // We can still do some optimizations. 

            // First, have we already discovered properties for this type? 

            PropertyDescriptorCollection properties = (PropertyDescriptorCollection)_typeProperties[_objectType];

            if (properties == null) 
            {
                properties = CreateProperties(); 
 
                lock (_typeProperties)
                { 
                    _typeProperties[_objectType] = properties;
                }
            }
 
            // Check bit combinations that would yield true in
            // any case.  For non-attached properties, they're all valid, so if 
            // the valid bit is set, we're done. 

 
            if ((filter & _anySet) == _anySet || (filter & _anyValid) == _anyValid)
            {
                return properties;
            } 

            // The filter specifies either set or unset values. 
 
            Debug.Assert((filter & _anySet) == filter, "There is a filtering case we did not account for");
 
            List newDescriptors = null;

            int cnt = properties.Count;
            for(int idx = 0; idx < cnt; idx++) 
            {
                PropertyDescriptor prop = properties[idx]; 
                bool shouldSerialize = prop.ShouldSerializeValue(filterValue); 
                bool addProp = shouldSerialize ^ ((filter & _anySet) == PropertyFilterOptions.UnsetValues);
 
                if (!addProp)
                {
                    // Property should be removed.  Make sure our newDescriptors array is
                    // up to date for where we need to be 
                    if (newDescriptors == null)
                    { 
                        newDescriptors = new List(cnt); 
                        for (int i = 0; i < idx; i++)
                        { 
                            newDescriptors.Add(properties[i]);
                        }
                    }
                } 
                else if (newDescriptors != null)
                { 
                    newDescriptors.Add(prop); 
                }
            } 

            if (newDescriptors != null)
            {
                properties = new PropertyDescriptorCollection(newDescriptors.ToArray(), true); 
            }
 
            return properties; 
        }
 
        //
        // All methods below simply forward to the parent descriptor.
        //
 
        public AttributeCollection GetAttributes() { return _parent.GetAttributes(); }
        public string GetClassName() { return _parent.GetClassName(); } 
 
        public TypeConverter GetConverter()
        { 
            // We only support public type converters, in order to avoid asserts.
            TypeConverter typeConverter = _parent.GetConverter();
            if( typeConverter.GetType().IsPublic )
            { 
                return typeConverter;
            } 
            else 
            {
                return new TypeConverter(); 
            }
        }

        public EventDescriptor GetDefaultEvent() { return _parent.GetDefaultEvent(); } 
        public PropertyDescriptor GetDefaultProperty() { return _parent.GetDefaultProperty(); }
        public object GetEditor(Type editorBaseType) { return _parent.GetEditor(editorBaseType); } 
        public EventDescriptorCollection GetEvents() { return _parent.GetEvents(); } 
        public EventDescriptorCollection GetEvents(Attribute[] attributes) { return _parent.GetEvents(attributes); }
        public object GetPropertyOwner(PropertyDescriptor property) { return _parent.GetPropertyOwner(property); } 

        #endregion Public Methods

        //------------------------------------------------------ 
        //
        //  Internal Methods 
        // 
        //-----------------------------------------------------
 
        #region Internal Methods

        /// 
        ///     This method is called when we should clear our cached state.  The cache 
        ///     may become invalid if someone adds additional type description providers.
        ///  
        internal static void ClearCache() 
        {
            lock (_propertyMap) 
            {
                _propertyMap.Clear();
            }
 
            lock(_typeProperties)
            { 
                _typeProperties.Clear(); 
            }
        } 

        #endregion Internal Methods

        //------------------------------------------------------ 
        //
        //  Private Methods 
        // 
        //------------------------------------------------------
 
        #region Private Methods

        //
        // Creates the property descriptor collection for this type.  The return 
        // value is all properties that are exposed on this type.
        // 
        private PropertyDescriptorCollection CreateProperties() 
        {
            PropertyDescriptorCollection baseProps = _parent.GetProperties(); 
            List newDescriptors = new List(baseProps.Count);

            for (int idx = 0; idx < baseProps.Count; idx++)
            { 
                PropertyDescriptor prop = baseProps[idx];
 
                DependencyObjectPropertyDescriptor dpProp; 
                DependencyProperty dp = null;
 
                bool inMap;

                lock(_propertyMap)
                { 
                    inMap = _propertyMap.TryGetValue(prop, out dpProp);
                } 
 
                if (inMap && dpProp != null)
                { 
                    // We need to verify that this property descriptor contains the correct DP.
                    // We can get the wrong one if a descendant of the type introducing the
                    // CLR property associates a different DP to itself with the same name.
 
                    dp = DependencyProperty.FromName(prop.Name, _objectType);
                    if (dp != dpProp.DependencyProperty) 
                    { 
                        dpProp = null;
                    } 
                    else
                    {
                        // We also need to verify that the property metadata for dpProp matches
                        // our object type's metadata 

                        if (dpProp.Metadata != dp.GetMetadata(_objectType)) 
                        { 
                            dpProp = null;
                        } 
                    }
                }

                if (dpProp == null) 
                {
                    // Either the property wasn't in the map or the one that was in there 
                    // can't work for this type.  Make a new property if this property is 
                    // backed by a DP.  Since we only care about direct dependency properties
                    // we can short circuit FromName for all properties on types that do 
                    // not derive from DependencyObject.  Also, if we already got a DP out of
                    // the map we can skip the dependency object check on the property, since
                    // the fact that we got a dp means that there used to be something in the map
                    // so the component type is already a DependencyObject. 

                    if (dp != null || typeof(DependencyObject).IsAssignableFrom(prop.ComponentType)) 
                    { 
                        if (dp == null)
                        { 
                            dp = DependencyProperty.FromName(prop.Name, _objectType);
                        }

                        if (dp != null) 
                        {
                            dpProp = new DependencyObjectPropertyDescriptor(prop, dp, _objectType); 
                        } 
                    }
 
                    // Now insert the new property in our map.  Note that we will
                    // insert a null value into the map if this property descriptor
                    // had no backing DP so we don't go through this work twice.
 
                    if (!inMap)
                    { 
                        lock(_propertyMap) 
                        {
                            _propertyMap[prop] = dpProp; 
                        }
                    }
                }
 

                // If we found a dependency property desecriptor for this property, 
                // use it as our new property. 

                if (dpProp != null) 
                {
                    prop = dpProp;
                }
 
                newDescriptors.Add(prop);
            } 
 
            return new PropertyDescriptorCollection(newDescriptors.ToArray(), true);
        } 

        #endregion Private Methods

        //----------------------------------------------------- 
        //
        //  Private Fields 
        // 
        //------------------------------------------------------
 
        #region Private Fields

        private ICustomTypeDescriptor _parent;
        private Type _objectType; 
        private object _instance;
 
        // Synchronized by "_propertyMap" 
        private static Dictionary _propertyMap =
            new Dictionary(new PropertyDescriptorComparer()); 

        // Synchronized by "_typeProperties"
        private static Hashtable _typeProperties = new Hashtable();
 
        private const PropertyFilterOptions _anySet = PropertyFilterOptions.SetValues | PropertyFilterOptions.UnsetValues;
        private const PropertyFilterOptions _anyValid = PropertyFilterOptions.Valid; 
 
        #endregion Private Fields
 
    }
}


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

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