PropertyGroupDescription.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Framework / System / Windows / Data / PropertyGroupDescription.cs / 1 / PropertyGroupDescription.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) 2003 by Microsoft Corporation.  All rights reserved.
//  
//
// 
// Description: Description of grouping based on a property value. 
//
// See spec at [....]/connecteddata/Specs/Grouping.mht 
//
//---------------------------------------------------------------------------

using System;                   // StringComparison 
using System.ComponentModel;    // [DefaultValue]
using System.Globalization;     // CultureInfo 
using System.Reflection;        // PropertyInfo 
using System.Windows;           // SR
using System.Xml;               // XmlNode 
using MS.Internal;              // XmlHelper

namespace System.Windows.Data
{ 
    /// 
    /// Description of grouping based on a property value. 
    ///  
    public class PropertyGroupDescription : GroupDescription
    { 
        #region Constructors

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

        ///  
        /// Initializes a new instance of PropertyGroupDescription.
        /// 
        public PropertyGroupDescription()
        { 
        }
 
        ///  
        /// Initializes a new instance of PropertyGroupDescription.
        ///  
        /// 
        /// The name of the property whose value is used to determine which group(s)
        /// an item belongs to.
        /// If PropertyName is null, the item itself is used. 
        /// 
        public PropertyGroupDescription(string propertyName) 
        { 
            UpdatePropertyName(propertyName);
        } 

        /// 
        /// Initializes a new instance of PropertyGroupDescription.
        ///  
        /// 
        /// The name of the property whose value is used to determine which group(s) 
        /// an item belongs to. 
        /// If PropertyName is null, the item itself is used.
        ///  
        /// 
        /// This converter is applied to the property value (or the item) to
        /// produce the final value used to determine which group(s) an item
        /// belongs to. 
        /// If the delegate returns an ICollection, the item is added to
        /// multiple groups - one for each member of the collection. 
        ///  
        public PropertyGroupDescription(string propertyName,
                                        IValueConverter converter) 
        {
            UpdatePropertyName(propertyName);
            _converter = converter;
        } 

        ///  
        /// Initializes a new instance of PropertyGroupDescription. 
        /// 
        ///  
        /// The name of the property whose value is used to determine which group(s)
        /// an item belongs to.
        /// If PropertyName is null, the item itself is used.
        ///  
        /// 
        /// This converter is applied to the property value (or the item) to 
        /// produce the final value used to determine which group(s) an item 
        /// belongs to.
        /// If the delegate returns an ICollection, the item is added to 
        /// multiple groups - one for each member of the collection.
        /// 
        /// 
        /// This governs the comparison between an item's value (as determined 
        /// by PropertyName and Converter) and a group's name.
        /// It is ignored unless both comparands are strings. 
        /// The default value is StringComparison.Ordinal. 
        /// 
        public PropertyGroupDescription(string propertyName, 
                                        IValueConverter converter,
                                        StringComparison stringComparison)
        {
            UpdatePropertyName(propertyName); 
            _converter = converter;
            _stringComparison = stringComparison; 
        } 

        #endregion Constructors 

        #region Public Properties

        //------------------------------------------------------ 
        //
        //  Public Properties 
        // 
        //-----------------------------------------------------
 
        /// 
        /// The name of the property whose value is used to determine which group(s)
        /// an item belongs to.
        /// If PropertyName is null, the item itself is used. 
        /// 
        [DefaultValue(null)] 
        public string PropertyName 
        {
            get { return _propertyName; } 
            set
            {
                UpdatePropertyName(value);
                OnPropertyChanged("PropertyName"); 
            }
        } 
 
        /// 
        /// This converter is applied to the property value (or the item) to 
        /// produce the final value used to determine which group(s) an item
        /// belongs to.
        /// If the delegate returns an ICollection, the item is added to
        /// multiple groups - one for each member of the collection. 
        /// 
        [DefaultValue(null)] 
        public IValueConverter Converter 
        {
            get { return _converter; } 
            set { _converter = value; OnPropertyChanged("Converter"); }
        }

        ///  
        /// This governs the comparison between an item's value (as determined
        /// by PropertyName and Converter) and a group's name. 
        /// It is ignored unless both comparands are strings. 
        /// The default value is StringComparison.Ordinal.
        ///  
        [DefaultValue(StringComparison.Ordinal)]
        public StringComparison StringComparison
        {
            get { return _stringComparison; } 
            set { _stringComparison = value; OnPropertyChanged("StringComparison"); }
        } 
 
        #endregion Public Properties
 
        #region Public Methods

        //------------------------------------------------------
        // 
        //  Public Methods
        // 
        //------------------------------------------------------ 

        ///  
        /// Return the group name(s) for the given item
        /// 
        public override object GroupNameFromItem(object item, int level, CultureInfo culture)
        { 
            object value;
 
            // get the property value 
            if (String.IsNullOrEmpty(PropertyName))
            { 
                value = item;
            }
            else if (XmlHelper.IsXmlNode(item))
            { 
                value = GetValueFromXmlNode(item);
            } 
            else if (item != null) 
            {
                using (_propertyPath.SetContext(item)) 
                {
                    value = _propertyPath.GetValue();
                }
            } 
            else
            { 
                value = null; 
            }
 
            // apply the converter to the value
            if (Converter != null)
            {
                value = Converter.Convert(value, typeof(object), level, culture); 
            }
 
            return value; 
        }
 
        /// 
        /// Return true if the names match (i.e the item should belong to the group).
        /// 
        public override bool NamesMatch(object groupName, object itemName) 
        {
            string s1 = groupName as string; 
            string s2 = itemName as string; 

            if (s1 != null && s2 != null) 
            {
                return String.Equals(s1, s2, StringComparison);
            }
            else 
            {
                return Object.Equals(groupName, itemName); 
            } 
        }
 
        #endregion Public Methods

        #region Private Methods
 
        private void UpdatePropertyName(string propertyName)
        { 
            _propertyName = propertyName; 
            _propertyPath = !String.IsNullOrEmpty(propertyName) ? new PropertyPath(propertyName) : null;
        } 

        private void OnPropertyChanged(string propertyName)
        {
            OnPropertyChanged(new PropertyChangedEventArgs(propertyName)); 
        }
 
        #endregion Private Methods 

        // separate method to avoid JIT of System.Xml 
        private object GetValueFromXmlNode(object item)
        {
            return XmlHelper.SelectStringValue((XmlNode)item, PropertyName);
        } 

        #region Private Fields 
 
        //-----------------------------------------------------
        // 
        //  Private Fields
        //
        //------------------------------------------------------
 
        string              _propertyName;
        PropertyPath        _propertyPath; 
        IValueConverter     _converter; 
        StringComparison    _stringComparison = StringComparison.Ordinal;
 
        #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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