mcs/class/referencesource/System.Activities.Presentation/System.Activities.Presentation/System/Activities/Presentation/Model/XamlUtilities.cs

   1 //----------------------------------------------------------------
   2 // Copyright (c) Microsoft Corporation.  All rights reserved.
   3 //----------------------------------------------------------------
   4
   5
   6 namespace System.Activities.Presentation.Model
   7 {
   8
   9     using System;
  10     using System.Collections;
  11     using System.ComponentModel;
  12     using System.Reflection;
  13
  14
  15     internal static class XamlUtilities
  16     {
  17
  18         static Hashtable converterCache;
  19         static object converterCacheSyncObject = new object();
  20
  21         public static TypeConverter GetConverter(Type itemType)
  22         {
  23             TypeConverter converter = TypeDescriptor.GetConverter(itemType);
  24
  25             if (converter == null || converter.GetType() == typeof(TypeConverter))
  26             {
  27
  28                 // We got an invalid converter.  WPF will do this if the converter
  29                 // is internal, but we use internal converters all over the place
  30                 // at design time.  Detect this and build the converter ourselves.
  31
  32                 if (converterCache != null)
  33                 {
  34                     converter = (TypeConverter)converterCache[itemType];
  35                     if (converter != null)
  36                     {
  37                         return converter;
  38                     }
  39                 }
  40
  41                 AttributeCollection attrs = TypeDescriptor.GetAttributes(itemType);
  42                 TypeConverterAttribute tca = attrs[typeof(TypeConverterAttribute)] as TypeConverterAttribute;
  43                 if (tca != null && tca.ConverterTypeName != null)
  44                 {
  45                     Type type = Type.GetType(tca.ConverterTypeName);
  46                     if (type != null && !type.IsPublic && typeof(TypeConverter).IsAssignableFrom(type))
  47                     {
  48                         ConstructorInfo ctor = type.GetConstructor(new Type[] { typeof(Type) });
  49                         if (ctor != null)
  50                         {
  51                             converter = (TypeConverter)ctor.Invoke(new object[] { itemType });
  52                         }
  53                         else
  54                         {
  55                             converter = (TypeConverter)Activator.CreateInstance(type);
  56                         }
  57
  58                         lock (converterCacheSyncObject)
  59                         {
  60                             if (converterCache == null)
  61                             {
  62                                 converterCache = new Hashtable();
  63
  64                                 // Listen to type changes and clear the cache.
  65                                 // This allows new metadata tables to be installed
  66
  67                                 TypeDescriptor.Refreshed += delegate(RefreshEventArgs args)
  68                                 {
  69                                     converterCache.Remove(args.TypeChanged);
  70                                 };
  71                             }
  72
  73                             converterCache[itemType] = converter;
  74                         }
  75                     }
  76                 }
  77             }
  78
  79             return converter;
  80         }
  81     }
  82 }