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

   1 //
   2 // System.Web.UI.WebControls.DropDownList.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 //
  11
  12 //
  13 // Permission is hereby granted, free of charge, to any person obtaining
  14 // a copy of this software and associated documentation files (the
  15 // "Software"), to deal in the Software without restriction, including
  16 // without limitation the rights to use, copy, modify, merge, publish,
  17 // distribute, sublicense, and/or sell copies of the Software, and to
  18 // permit persons to whom the Software is furnished to do so, subject to
  19 // the following conditions:
  20 //
  21 // The above copyright notice and this permission notice shall be
  22 // included in all copies or substantial portions of the Software.
  23 //
  24 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  25 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  26 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  27 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  28 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  29 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  30 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  31 //
  32
  33 using System;
  34 using System.Collections.Specialized;
  35 using System.ComponentModel;
  36 using System.Drawing;
  37 using System.Web;
  38 using System.Web.UI;
  39
  40 namespace System.Web.UI.WebControls
  41 {
  42         [ValidationProperty("SelectedItem")]
  43         public class DropDownList : ListControl, IPostBackDataHandler
  44         {
  45                 public DropDownList(): base()
  46                 {
  47                 }
  48
  49                 [Browsable (false)]
  50                 public override Color BorderColor
  51                 {
  52                         get
  53                         {
  54                                 return base.BorderColor;
  55                         }
  56                         set
  57                         {
  58                                 base.BorderColor = value;
  59                         }
  60                 }
  61
  62                 [Browsable (false)]
  63                 public override BorderStyle BorderStyle
  64                 {
  65                         get
  66                         {
  67                                 return base.BorderStyle;
  68                         }
  69                         set
  70                         {
  71                                 base.BorderStyle = value;
  72                         }
  73                 }
  74
  75                 [Browsable (false)]
  76                 public override Unit BorderWidth
  77                 {
  78                         get
  79                         {
  80                                 return base.BorderWidth;
  81                         }
  82                         set
  83                         {
  84                                 base.BorderWidth = value;
  85                         }
  86                 }
  87
  88                 [DefaultValue (0), WebCategory ("Misc")]
  89                 [DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
  90                 [WebSysDescription ("The index number of the currently selected ListItem.")]
  91                 public override int SelectedIndex
  92                 {
  93                         get
  94                         {
  95                                 int index  = base.SelectedIndex;
  96                                 if (index < 0 && Items.Count > 0) {
  97                                         index = 0;
  98                                         Items [0].Selected = true;
  99                                 }
 100                                 return index;
 101                         }
 102                         set
 103                         {
 104                                 base.SelectedIndex = value;
 105                         }
 106                 }
 107
 108                 [Browsable (false), DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
 109                 [Bindable (false), EditorBrowsable (EditorBrowsableState.Never)]
 110                 public override string ToolTip
 111                 {
 112                         // MS ignores the tooltip for this one
 113                         get {
 114                                 return String.Empty;
 115                         }
 116                         set {
 117                         }
 118                 }
 119
 120                 protected override void AddAttributesToRender(HtmlTextWriter writer)
 121                 {
 122                         if(Page != null)
 123                         {
 124                                 Page.VerifyRenderingInServerForm(this);
 125                         }
 126                         writer.AddAttribute(HtmlTextWriterAttribute.Name, UniqueID);
 127                         base.AddAttributesToRender(writer);
 128
 129                         if(AutoPostBack && Page != null)
 130                         {
 131                                 writer.AddAttribute(HtmlTextWriterAttribute.Onchange, Page.GetPostBackClientEvent(this,""));
 132                                 writer.AddAttribute("language", "javascript");
 133                         }
 134                 }
 135
 136                 protected override ControlCollection CreateControlCollection()
 137                 {
 138                         return new EmptyControlCollection(this);
 139                 }
 140
 141                 protected override void RenderContents(HtmlTextWriter writer)
 142                 {
 143                         if(Items != null)
 144                         {
 145                                 bool selected = false;
 146                                 foreach(ListItem current in Items)
 147                                 {
 148                                         writer.WriteBeginTag("option");
 149                                         if(current.Selected)
 150                                         {
 151                                                 if(selected)
 152                                                 {
 153                                                         throw new HttpException(HttpRuntime.FormatResourceString("Cannot_Multiselect_In_DropDownList"));
 154                                                 }
 155                                                 selected = true;
 156                                                 writer.WriteAttribute("selected", "selected", false);
 157                                         }
 158                                         writer.WriteAttribute("value", current.Value, true);
 159                                         writer.Write('>');
 160                                         HttpUtility.HtmlEncode(current.Text, writer);
 161                                         writer.WriteEndTag("option");
 162                                         writer.WriteLine();
 163                                 }
 164                         }
 165                 }
 166
 167                 bool IPostBackDataHandler.LoadPostData(string postDataKey, NameValueCollection postCollection)
 168                 {
 169                         string[] vals = postCollection.GetValues(postDataKey);
 170                         if(vals != null)
 171                         {
 172                                 int index = Items.FindByValueInternal(vals[0]);
 173                                 if(index != SelectedIndex)
 174                                 {
 175                                         SelectedIndex = index;
 176                                         return true;
 177                                 }
 178                         }
 179                         return false;
 180                 }
 181
 182                 void IPostBackDataHandler.RaisePostDataChangedEvent()
 183                 {
 184                         OnSelectedIndexChanged(EventArgs.Empty);
 185                 }
 186         }
 187 }