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

   1 //
   2 // System.Web.UI.WebControls.CheckBox.cs
   3 //
   4 // Authors:
   5 //   Gaurav Vaish (gvaish@iitk.ac.in)
   6 //   Andreas Nahr (ClassDevelopment@A-SoftTech.com)
   7 //
   8 // (C) Gaurav Vaish (2002)
   9 // (C) 2003 Andreas Nahr
  10 // Thanks to Leen Toelen (toelen@hotmail.com)'s classes that helped me
  11 // to write the contents of the function LoadPostData(...)
  12 //
  13
  14 using System;
  15 using System.Collections;
  16 using System.Collections.Specialized;
  17 using System.Globalization;
  18 using System.Web;
  19 using System.Web.UI;
  20 using System.ComponentModel;
  21 using System.ComponentModel.Design;
  22
  23 namespace System.Web.UI.WebControls
  24 {
  25         [DefaultEvent("CheckedChanged")]
  26         [DefaultProperty("Text")]
  27         [DataBindingHandler("System.Web.UI.Design.TextDataBindingHandler, " + Consts.AssemblySystem_Design)]
  28         [Designer ("System.Web.UI.Design.WebControls.CheckBoxDesigner, " + Consts.AssemblySystem_Design, typeof (IDesigner))]
  29         public class CheckBox : WebControl, IPostBackDataHandler
  30         {
  31                 private static readonly object CheckedChangedEvent = new object();
  32
  33                 public CheckBox(): base(HtmlTextWriterTag.Input)
  34                 {
  35                 }
  36
  37                 [DefaultValue (false), WebCategory ("Behavior")]
  38                 [WebSysDescription ("The control automatically posts back after changing the text.")]
  39                 public virtual bool AutoPostBack
  40                 {
  41                         get {
  42                                  object o = ViewState ["AutoPostBack"];
  43                                  return (o == null) ? false : (bool) o;
  44                         }
  45
  46                         set { ViewState ["AutoPostBack"] = value; }
  47                 }
  48
  49
  50                 [DefaultValue (false), Bindable (true)]
  51                 [WebSysDescription ("Determines if the control is checked.")]
  52                 public virtual bool Checked
  53                 {
  54                         get {
  55                                 object o = ViewState ["Checked"];
  56                                 return (o == null) ? false : (bool) o;
  57                         }
  58
  59                         set { ViewState ["Checked"] = value; }
  60                 }
  61
  62                 [DefaultValue (""), Bindable (true), WebCategory ("Appearance")]
  63                 [WebSysDescription ("The text that this control displays.")]
  64                 public virtual string Text
  65                 {
  66                         get {
  67                                 object o = ViewState ["Text"];
  68                                 return (o == null) ? String.Empty : (string) o;
  69                         }
  70
  71                         set { ViewState ["Text"] = value; }
  72                 }
  73
  74                 private bool SaveCheckedViewState
  75                 {
  76                         get {
  77                                 if (Events [CheckedChangedEvent] != null || !Enabled)
  78                                         return true;
  79
  80                                 Type type = GetType ();
  81                                 return (type != typeof (CheckBox) && type != typeof (RadioButton));
  82                         }
  83                 }
  84
  85
  86                 [DefaultValue (typeof (TextAlign), "Right"), Bindable (true), WebCategory ("Appearance")]
  87                 [WebSysDescription ("The alignment of the text.")]
  88                 public virtual TextAlign TextAlign
  89                 {
  90                         get {
  91                                 object o = ViewState ["TextAlign"];
  92                                 return (o == null) ? TextAlign.Right : (TextAlign) o;
  93                         }
  94
  95                         set {
  96                                 if (!System.Enum.IsDefined (typeof (TextAlign), value))
  97                                         throw new ArgumentException ();
  98                                 ViewState ["TextAlign"] = value;
  99                         }
 100                 }
 101
 102                 [WebCategory ("Action")]
 103                 [WebSysDescription ("Raised when the control is checked or unchecked.")]
 104                 public event EventHandler CheckedChanged
 105                 {
 106                         add { Events.AddHandler (CheckedChangedEvent, value); }
 107                         remove { Events.RemoveHandler (CheckedChangedEvent, value); }
 108                 }
 109
 110                 protected virtual void OnCheckedChanged(EventArgs e)
 111                 {
 112                         if(Events != null){
 113                                 EventHandler eh = (EventHandler) (Events [CheckedChangedEvent]);
 114                                 if(eh != null)
 115                                         eh (this, e);
 116                         }
 117                 }
 118
 119                 protected override void OnPreRender(EventArgs e)
 120                 {
 121                         if (Page != null && Enabled) {
 122                                 Page.RegisterRequiresPostBack (this);
 123                                 if (AutoPostBack)
 124                                         Page.RequiresPostBackScript ();
 125                         }
 126
 127                         if (!SaveCheckedViewState)
 128                                 ViewState.SetItemDirty ("Checked", false);
 129                 }
 130
 131                 protected override void Render (HtmlTextWriter writer)
 132                 {
 133                         bool hasBeginRendering = false;
 134                         if(ControlStyleCreated && !ControlStyle.IsEmpty){
 135                                 hasBeginRendering = true;
 136                                 ControlStyle.AddAttributesToRender (writer, this);
 137                         }
 138
 139                         if (ToolTip.Length > 0){
 140                                 hasBeginRendering = true;
 141                                 writer.AddAttribute (HtmlTextWriterAttribute.Title, ToolTip);
 142                         }
 143
 144                         if (Attributes.Count > 0){
 145                                 string val = Attributes ["value"];
 146                                 Attributes.Remove ("value");
 147                                 if (Attributes.Count > 0){
 148                                         hasBeginRendering = true;
 149                                         Attributes.AddAttributes (writer);
 150                                 }
 151
 152                                 if (val != null)
 153                                         Attributes ["value"] = val;
 154                         }
 155
 156                         if (hasBeginRendering)
 157                                 writer.RenderBeginTag (HtmlTextWriterTag.Span);
 158
 159                         if (Text.Length > 0){
 160                                 TextAlign ta = TextAlign;
 161                                 if(ta == TextAlign.Right)
 162                                         RenderInputTag (writer, ClientID);
 163                                 writer.AddAttribute (HtmlTextWriterAttribute.For, ClientID);
 164                                 writer.RenderBeginTag (HtmlTextWriterTag.Label);
 165                                 writer.Write (Text);
 166                                 writer.RenderEndTag ();
 167                                 if(ta == TextAlign.Left)
 168                                         RenderInputTag (writer, ClientID);
 169                         }
 170                         else
 171                                 RenderInputTag (writer, ClientID);
 172
 173                         if (hasBeginRendering)
 174                                 writer.RenderEndTag ();
 175                 }
 176
 177                 internal virtual void RenderInputTag (HtmlTextWriter writer, string clientId)
 178                 {
 179                         if (!Enabled)
 180                                 writer.AddAttribute (HtmlTextWriterAttribute.Disabled, "disabled");
 181
 182                         writer.AddAttribute (HtmlTextWriterAttribute.Id, clientId);
 183                         writer.AddAttribute( HtmlTextWriterAttribute.Type, "checkbox");
 184                         writer.AddAttribute (HtmlTextWriterAttribute.Name, UniqueID);
 185                         if (Checked)
 186                                 writer.AddAttribute (HtmlTextWriterAttribute.Checked, "checked");
 187
 188                         if (AutoPostBack){
 189                                 writer.AddAttribute (HtmlTextWriterAttribute.Onclick,
 190                                                      Page.GetPostBackClientEvent (this, String.Empty));
 191                                 writer.AddAttribute ("language", "javascript");
 192                         }
 193
 194                         if (AccessKey.Length > 0)
 195                                 writer.AddAttribute (HtmlTextWriterAttribute.Accesskey, AccessKey);
 196
 197                         if (TabIndex != 0)
 198                                 writer.AddAttribute (HtmlTextWriterAttribute.Tabindex,
 199                                                      TabIndex.ToString (NumberFormatInfo.InvariantInfo));
 200
 201                         writer.RenderBeginTag (HtmlTextWriterTag.Input);
 202                         writer.RenderEndTag ();
 203                 }
 204
 205                 bool IPostBackDataHandler.LoadPostData (string postDataKey, NameValueCollection postCollection)
 206                 {
 207                         string postedVal = postCollection [postDataKey];
 208
 209                         if (postedVal == null)
 210                                 return false;
 211
 212                         bool haveData = (postedVal.Length > 0);
 213                         if (haveData == Checked)
 214                                 return false;
 215
 216                         Checked = haveData;
 217                         return true;;
 218                 }
 219
 220                 void IPostBackDataHandler.RaisePostDataChangedEvent()
 221                 {
 222                         OnCheckedChanged (EventArgs.Empty);
 223                 }
 224         }
 225 }