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

   1 /**
   2  * Namespace: System.Web.UI.WebControls
   3  * Class:     CheckBox
   4  *
   5  * Author:  Gaurav Vaish
   6  * Maintainer: gvaish@iitk.ac.in
   7  * Contact: <my_scripts2001@yahoo.com>, <gvaish@iitk.ac.in>
   8  * Implementation: yes
   9  * Status:  100%
  10  *
  11  * (C) Gaurav Vaish (2001)
  12  * Thanks to Leen Toelen (toelen@hotmail.com)'s classes that helped me
  13  * to write the contents of the function LoadPostData(...)
  14  */
  15
  16 using System;
  17 using System.Collections;
  18 using System.Collections.Specialized;
  19 using System.Globalization;
  20 using System.Web;
  21 using System.Web.UI;
  22 using System.ComponentModel;
  23
  24 namespace System.Web.UI.WebControls
  25 {
  26         [DefaultEvent("CheckedChanged")]
  27         [DefaultProperty("Text")]
  28         //[DataBindingHanlder("??")]
  29         //[Designer("??")]
  30         public class CheckBox : WebControl, IPostBackDataHandler
  31         {
  32                 private static readonly object CheckedChangedEvent = new object();
  33
  34                 public CheckBox(): base(HtmlTextWriterTag.Input)
  35                 {
  36                 }
  37
  38                 public virtual bool AutoPostBack
  39                 {
  40                         get {
  41                                  object o = ViewState ["AutoPostBack"];
  42                                  return (o == null) ? false : (bool) o;
  43                         }
  44
  45                         set { ViewState ["AutoPostBack"] = value; }
  46                 }
  47
  48                 public virtual bool Checked
  49                 {
  50                         get {
  51                                 object o = ViewState ["Checked"];
  52                                 return (o == null) ? false : (bool) o;
  53                         }
  54
  55                         set { ViewState ["Checked"] = value; }
  56                 }
  57
  58                 public virtual string Text
  59                 {
  60                         get {
  61                                 object o = ViewState ["Text"];
  62                                 return (o == null) ? String.Empty : (string) o;
  63                         }
  64
  65                         set { ViewState ["Text"] = value; }
  66                 }
  67
  68                 private bool SaveCheckedViewState
  69                 {
  70                         get {
  71                                 if (Events [CheckedChangedEvent] != null){
  72                                         if (!Enabled)
  73                                                 return true;
  74
  75                                         Type type = GetType ();
  76                                         if (type == typeof (CheckBox))
  77                                                 return false;
  78
  79                                         if (type == typeof (RadioButton))
  80                                                 return false;
  81                                 }
  82                                 return true;
  83                         }
  84                 }
  85
  86                 public virtual TextAlign TextAlign
  87                 {
  88                         get {
  89                                 object o = ViewState ["TextAlign"];
  90                                 return (o == null) ? TextAlign.Right : (TextAlign) o;
  91                         }
  92
  93                         set {
  94                                 if (!System.Enum.IsDefined (typeof (TextAlign), value))
  95                                         throw new ArgumentException ();
  96                                 ViewState ["TextAlign"] = value;
  97                         }
  98                 }
  99
 100                 public event EventHandler CheckedChanged
 101                 {
 102                         add { Events.AddHandler (CheckedChangedEvent, value); }
 103                         remove { Events.RemoveHandler (CheckedChangedEvent, value); }
 104                 }
 105
 106                 protected virtual void OnCheckedChanged(EventArgs e)
 107                 {
 108                         if(Events != null){
 109                                 EventHandler eh = (EventHandler) (Events [CheckedChangedEvent]);
 110                                 if(eh != null)
 111                                         eh (this, e);
 112                         }
 113                 }
 114
 115                 protected override void OnPreRender(EventArgs e)
 116                 {
 117                         if (Page != null && Enabled)
 118                                 Page.RegisterRequiresPostBack (this);
 119
 120                         if (SaveCheckedViewState)
 121                                 ViewState.SetItemDirty ("checked", false);
 122                 }
 123
 124                 protected override void Render (HtmlTextWriter writer)
 125                 {
 126                         bool hasBeginRendering = false;
 127                         if(ControlStyleCreated && !ControlStyle.IsEmpty){
 128                                 hasBeginRendering = true;
 129                                 ControlStyle.AddAttributesToRender (writer, this);
 130                         }
 131
 132                         if (!Enabled){
 133                                 hasBeginRendering = true;
 134                                 writer.AddAttribute (HtmlTextWriterAttribute.Disabled, "disabled");
 135                         }
 136
 137                         if (ToolTip.Length > 0){
 138                                 hasBeginRendering = true;
 139                                 writer.AddAttribute (HtmlTextWriterAttribute.Title, ToolTip);
 140                         }
 141
 142                         if (Attributes.Count > 0){
 143                                 string val = Attributes ["value"];
 144                                 Attributes.Remove ("value");
 145                                 if (Attributes.Count > 0){
 146                                         hasBeginRendering = true;
 147                                         Attributes.AddAttributes (writer);
 148                                 }
 149
 150                                 if (val != null)
 151                                         Attributes ["value"] = val;
 152                         }
 153
 154                         if (hasBeginRendering)
 155                                 writer.RenderBeginTag (HtmlTextWriterTag.Span);
 156
 157                         if (Text.Length > 0){
 158                                 TextAlign ta = TextAlign;
 159                                 if(ta == TextAlign.Right)
 160                                         RenderInputTag (writer, ClientID);
 161                                 writer.AddAttribute (HtmlTextWriterAttribute.For, ClientID);
 162                                 writer.RenderBeginTag (HtmlTextWriterTag.Label);
 163                                 writer.Write (Text);
 164                                 writer.RenderEndTag ();
 165                                 if(ta == TextAlign.Left)
 166                                         RenderInputTag (writer, ClientID);
 167                         }
 168                         else
 169                                 RenderInputTag (writer, ClientID);
 170
 171                         if (hasBeginRendering)
 172                                 writer.RenderEndTag ();
 173                 }
 174
 175                 internal virtual void RenderInputTag (HtmlTextWriter writer, string clientId)
 176                 {
 177                         writer.AddAttribute (HtmlTextWriterAttribute.Id, clientId);
 178                         writer.AddAttribute( HtmlTextWriterAttribute.Type, "checkbox");
 179                         writer.AddAttribute (HtmlTextWriterAttribute.Name, UniqueID);
 180                         if (Checked)
 181                                 writer.AddAttribute (HtmlTextWriterAttribute.Checked, "checked");
 182
 183                         if (AutoPostBack){
 184                                 writer.AddAttribute (HtmlTextWriterAttribute.Onclick,
 185                                                      Page.GetPostBackClientEvent (this, String.Empty));
 186                                 writer.AddAttribute ("language", "javascript");
 187                         }
 188
 189                         if (AccessKey.Length > 0)
 190                                 writer.AddAttribute (HtmlTextWriterAttribute.Accesskey, AccessKey);
 191
 192                         if (TabIndex != 0)
 193                                 writer.AddAttribute (HtmlTextWriterAttribute.Tabindex,
 194                                                      TabIndex.ToString (NumberFormatInfo.InvariantInfo));
 195
 196                         writer.RenderBeginTag (HtmlTextWriterTag.Input);
 197                         writer.RenderEndTag ();
 198                 }
 199
 200                 bool IPostBackDataHandler.LoadPostData (string postDataKey, NameValueCollection postCollection)
 201                 {
 202                         string postedVal = postCollection [postDataKey];
 203                         bool   postChecked = false;
 204                         if(postedVal != null)
 205                                 postChecked = postedVal.Length > 0;
 206                         Checked = postChecked;
 207                         return (postChecked == false);
 208                 }
 209
 210                 void IPostBackDataHandler.RaisePostDataChangedEvent()
 211                 {
 212                         OnCheckedChanged (EventArgs.Empty);
 213                 }
 214         }
 215 }