mcs/class/referencesource/System.Activities.Presentation/System.Activities.Presentation/System/Activities/Presentation/Base/Core/Internal/PropertyEditing/Editors/PropertyValueToStandardValuesConverter.cs

   1 //----------------------------------------------------------------
   2 // Copyright (c) Microsoft Corporation.  All rights reserved.
   3 //----------------------------------------------------------------
   4 namespace System.Activities.Presentation.Internal.PropertyEditing.Editors
   5 {
   6     using System;
   7     using System.Collections;
   8     using System.ComponentModel;
   9     using System.Diagnostics;
  10     using System.Diagnostics.CodeAnalysis;
  11     using System.Globalization;
  12     using System.Windows.Data;
  13
  14     using System.Runtime;
  15     using System.Activities.Presentation;
  16     using System.Activities.Presentation.PropertyEditing;
  17     using System.Activities.Presentation.Internal.Properties;
  18     using System.Activities.Presentation.Internal.PropertyEditing.Model;
  19
  20     // <summary>
  21     // Retrieves StandardValues from a passed in PropertyValue, making sure that if a TypeConverter
  22     // exists and if it supports ConvertToString() method, it will be called on each value contained
  23     // in the StandardValues collection.
  24     // This class is instantiated through XAML
  25     // </summary>
  26     [SuppressMessage("Microsoft.Performance", "CA1812:AvoidUninstantiatedInternalClasses")]
  27     internal class PropertyValueToStandardValuesConverter : IValueConverter
  28     {
  29         // IValueConverter Members
  30
  31         public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
  32         {
  33
  34             Fx.Assert(typeof(IEnumerable).IsAssignableFrom(targetType), "Expecting IEnumerable as the targetType");
  35
  36             PropertyValue propertyValue = value as PropertyValue;
  37             if (propertyValue == null)
  38             {
  39                 return null;
  40             }
  41
  42             ModelPropertyEntryBase parentProperty = (ModelPropertyEntryBase)propertyValue.ParentProperty;
  43             return new ConvertedStandardValuesCollection(parentProperty, culture);
  44         }
  45
  46         public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
  47         {
  48             throw FxTrace.Exception.AsError(new InvalidOperationException());
  49         }
  50
  51
  52         // <summary>
  53         // An implementation of ICollection that defers access to the standard
  54         // values collection.  Accessing the StandardValues collection may be
  55         // expensive, so we defer it until we absolutely need it.
  56         // </summary>
  57         private class ConvertedStandardValuesCollection : ICollection
  58         {
  59
  60             private ModelPropertyEntryBase _property;
  61             private CultureInfo _culture;
  62             private ICollection _contents;
  63
  64             internal ConvertedStandardValuesCollection(ModelPropertyEntryBase property, CultureInfo culture)
  65             {
  66                 _property = property;
  67                 _culture = culture;
  68             }
  69
  70             public int Count
  71             {
  72                 get { return Contents.Count; }
  73             }
  74
  75             public bool IsSynchronized
  76             {
  77                 get { return false; }
  78             }
  79
  80             public object SyncRoot
  81             {
  82                 get { return Contents.SyncRoot; }
  83             }
  84
  85         // IEnumerable Members
  86
  87             private ICollection Contents
  88             {
  89                 get {
  90                     if (_contents == null)
  91                     {
  92                         ICollection standardValues = _property.StandardValues;
  93                         TypeConverter converter = _property.Converter;
  94
  95                         if (standardValues != null && (converter == null || !converter.CanConvertTo(typeof(string))))
  96                         {
  97                             _contents = standardValues;
  98                         }
  99                         else
 100                         {
 101                             ArrayList convertedStandardValues = new ArrayList(standardValues == null ? 0 : standardValues.Count);
 102                             if (standardValues != null)
 103                             {
 104                                 foreach (object standardValue in standardValues)
 105                                 {
 106                                     convertedStandardValues.Add(converter.ConvertToString(null, _culture, standardValue));
 107                                 }
 108                             }
 109                             _contents = convertedStandardValues;
 110                         }
 111
 112                         // PS 107537: Special-case handling for nullable enum types
 113                         if (EditorUtilities.IsNullableEnumType(_property.PropertyType))
 114                         {
 115                             ArrayList filteredStandardValues = new ArrayList();
 116                             filteredStandardValues.Add(EditorUtilities.NullString);
 117                             foreach (var i in (ArrayList)_contents)
 118                             {
 119                                 if (i != null)
 120                                 {
 121                                     filteredStandardValues.Add(i);
 122                                 }
 123                             }
 124                             _contents = filteredStandardValues;
 125                         }
 126                     }
 127
 128                     return _contents;
 129                 }
 130             }
 131
 132         // ICollection Members
 133
 134             public void CopyTo(Array array, int index)
 135             {
 136                 Contents.CopyTo(array, index);
 137             }
 138
 139             public IEnumerator GetEnumerator()
 140             {
 141                 return Contents.GetEnumerator();
 142             }
 143
 144         }
 145     }
 146 }