mcs/class/System.Web/System.Web.UI.WebControls/HiddenField.cs

   1 //
   2 // System.Web.UI.WebControls.HiddenField.cs
   3 //
   4 // Authors:
   5 //  Lluis Sanchez Gual (lluis@novell.com)
   6 //
   7 // (C) 2005 Novell, Inc. (http://www.novell.com)
   8 //
   9
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30
  31 #if NET_2_0
  32 using System.Web.UI;
  33 using System.ComponentModel;
  34
  35 namespace System.Web.UI.WebControls
  36 {
  37         public class HiddenField : Control, IPostBackDataHandler
  38         {
  39
  40                 static readonly object ValueChangedEvent = new object ();
  41
  42                 public event EventHandler ValueChanged
  43                 {
  44                         add { Events.AddHandler (ValueChangedEvent, value); }
  45                         remove { Events.RemoveHandler (ValueChangedEvent, value); }
  46                 }
  47
  48                 [Bindable (true)]
  49                 public virtual string Value {
  50                         get {
  51                                 return ViewState.GetString ("Value", "");
  52                         }
  53                         set {
  54                                 ViewState ["Value"] = value;
  55                         }
  56                 }
  57
  58                 public override bool EnableTheming {
  59                         get {
  60                                 return false;
  61                         }
  62                         set {
  63                                 throw new NotSupportedException ();
  64                         }
  65                 }
  66
  67                 public override string SkinID {
  68                         get {
  69                                 return String.Empty;
  70                         }
  71                         set {
  72                                 throw new NotSupportedException ();
  73                         }
  74                 }
  75
  76                 public override void Focus ()
  77                 {
  78                         throw new NotSupportedException ();
  79                 }
  80
  81                 protected virtual void OnValueChanged (EventArgs e)
  82                 {
  83                         EventHandler h = (EventHandler) Events [ValueChangedEvent];
  84                         if (h != null)
  85                                 h (this, e);
  86                 }
  87
  88                 protected virtual bool LoadPostData (string postDataKey, System.Collections.Specialized.NameValueCollection postCollection)
  89                 {
  90                         if (Value != postCollection [postDataKey]) {
  91                                 Value = postCollection [postDataKey];
  92                                 return true;
  93                         }
  94                         return false;
  95                 }
  96
  97                 protected virtual void RaisePostDataChangedEvent ()
  98                 {
  99                         ValidateEvent (UniqueID, String.Empty);
 100                         OnValueChanged (EventArgs.Empty);
 101                 }
 102
 103                 protected override ControlCollection CreateControlCollection ()
 104                 {
 105                         return new System.Web.UI.EmptyControlCollection (this);
 106                 }
 107
 108                 protected internal override void OnPreRender (EventArgs e)
 109                 {
 110                         base.OnPreRender (e);
 111                 }
 112
 113                 protected internal override void Render (HtmlTextWriter writer)
 114                 {
 115                         Page page = Page;
 116                         string uniqueid = UniqueID;
 117                         if (page != null)
 118                                 page.ClientScript.RegisterForEventValidation (uniqueid);
 119
 120                         writer.AddAttribute (HtmlTextWriterAttribute.Type, "hidden", false);
 121
 122                         if (!String.IsNullOrEmpty (ClientID))
 123                                 writer.AddAttribute (HtmlTextWriterAttribute.Id, ClientID);
 124
 125                         if (!String.IsNullOrEmpty (uniqueid))
 126                                 writer.AddAttribute (HtmlTextWriterAttribute.Name, uniqueid);
 127
 128                         if (!String.IsNullOrEmpty (Value))
 129                                 writer.AddAttribute (HtmlTextWriterAttribute.Value, Value);
 130
 131                         writer.RenderBeginTag (HtmlTextWriterTag.Input);
 132                         writer.RenderEndTag ();
 133                 }
 134
 135                 #region IPostBackDataHandler Members
 136
 137                 bool IPostBackDataHandler.LoadPostData (string postDataKey, System.Collections.Specialized.NameValueCollection postCollection)
 138                 {
 139                         return LoadPostData (postDataKey, postCollection);
 140                 }
 141
 142                 void IPostBackDataHandler.RaisePostDataChangedEvent ()
 143                 {
 144                         RaisePostDataChangedEvent ();
 145                 }
 146
 147                 #endregion
 148         }
 149 }
 150 #endif