class/WindowsBase/System.Windows/PropertyMetadata.cs

   1 // Permission is hereby granted, free of charge, to any person obtaining
   2 // a copy of this software and associated documentation files (the
   3 // "Software"), to deal in the Software without restriction, including
   4 // without limitation the rights to use, copy, modify, merge, publish,
   5 // distribute, sublicense, and/or sell copies of the Software, and to
   6 // permit persons to whom the Software is furnished to do so, subject to
   7 // the following conditions:
   8 //
   9 // The above copyright notice and this permission notice shall be
  10 // included in all copies or substantial portions of the Software.
  11 //
  12 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  13 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  14 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  15 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  16 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  17 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  18 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  19 //
  20 // (C) 2005 Iain McCoy
  21 //
  22 // Copyright (c) 2007 Novell, Inc. (http://www.novell.com)
  23 //
  24 // Authors:
  25 //   Iain McCoy (iain@mccoy.id.au)
  26 //   Chris Toshok (toshok@ximian.com)
  27 //
  28
  29 namespace System.Windows {
  30         public class PropertyMetadata {
  31                 private object defaultValue;
  32                 private bool isSealed;
  33                 private PropertyChangedCallback propertyChangedCallback;
  34                 private CoerceValueCallback coerceValueCallback;
  35
  36                 protected bool IsSealed {
  37                         get { return isSealed; }
  38                 }
  39
  40                 public object DefaultValue {
  41                         get { return defaultValue; }
  42                         set {
  43                                 if (IsSealed)
  44                                         throw new InvalidOperationException ("Cannot change metadata once it has been applied to a property");
  45                                 if (value == DependencyProperty.UnsetValue)
  46                                         throw new ArgumentException ("Cannot set property metadata's default value to 'Unset'");
  47
  48                                 defaultValue = value;
  49                         }
  50                 }
  51
  52                 public PropertyChangedCallback PropertyChangedCallback {
  53                         get { return propertyChangedCallback; }
  54                         set {
  55                                 if (IsSealed)
  56                                         throw new InvalidOperationException ("Cannot change metadata once it has been applied to a property");
  57                                 propertyChangedCallback = value;
  58                         }
  59                 }
  60
  61                 public CoerceValueCallback CoerceValueCallback {
  62                         get { return coerceValueCallback; }
  63                         set {
  64                                 if (IsSealed)
  65                                         throw new InvalidOperationException ("Cannot change metadata once it has been applied to a property");
  66                                 coerceValueCallback = value;
  67                         }
  68                 }
  69
  70                 public PropertyMetadata()
  71                         : this (null, null, null)
  72                 {
  73                 }
  74
  75                 public PropertyMetadata(object defaultValue)
  76                         : this (defaultValue, null, null)
  77                 {
  78                 }
  79
  80                 public PropertyMetadata (PropertyChangedCallback propertyChangedCallback)
  81                         : this (null, propertyChangedCallback, null)
  82                 {
  83                 }
  84
  85                 public PropertyMetadata (object defaultValue, PropertyChangedCallback propertyChangedCallback)
  86                         : this (defaultValue, propertyChangedCallback, null)
  87                 {
  88                 }
  89
  90                 public PropertyMetadata (object defaultValue, PropertyChangedCallback propertyChangedCallback, CoerceValueCallback coerceValueCallback)
  91                 {
  92                         if (defaultValue == DependencyProperty.UnsetValue)
  93                                 throw new ArgumentException ("Cannot initialize property metadata's default value to 'Unset'");
  94
  95                         this.defaultValue = defaultValue;
  96                         this.propertyChangedCallback = propertyChangedCallback;
  97                         this.coerceValueCallback = coerceValueCallback;
  98                 }
  99
 100                 protected virtual void Merge (PropertyMetadata baseMetadata, DependencyProperty dp)
 101                 {
 102                         if (defaultValue == null)
 103                                 defaultValue = baseMetadata.defaultValue;
 104                         if (propertyChangedCallback == null)
 105                                 propertyChangedCallback = baseMetadata.propertyChangedCallback;
 106                         if (coerceValueCallback == null)
 107                                 coerceValueCallback = baseMetadata.coerceValueCallback;
 108                 }
 109
 110                 protected virtual void OnApply (DependencyProperty dp, Type targetType)
 111                 {
 112                 }
 113
 114                 internal void DoMerge (PropertyMetadata baseMetadata, DependencyProperty dp, Type targetType)
 115                 {
 116                         Merge (baseMetadata, dp);
 117                         OnApply (dp, targetType);
 118                         isSealed = true;
 119                 }
 120         }
 121 }