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 //\r
  11 \r
  12 using System;\r
  13 using System.Collections.Specialized;\r
  14 using System.ComponentModel;\r
  15 using System.Drawing;\r
  16 using System.Web;\r
  17 using System.Web.UI;\r
  18 \r
  19 namespace System.Web.UI.WebControls\r
  20 {\r
  21         [ValidationProperty("SelectedItem")]\r
  22         public class DropDownList : ListControl, IPostBackDataHandler\r
  23         {\r
  24                 public DropDownList(): base()\r
  25                 {\r
  26                 }\r
  27
  28                 [Browsable (false)]\r
  29                 public override Color BorderColor\r
  30                 {\r
  31                         get\r
  32                         {\r
  33                                 return base.BorderColor;\r
  34                         }\r
  35                         set\r
  36                         {\r
  37                                 base.BorderColor = value;\r
  38                         }\r
  39                 }\r
  40
  41                 [Browsable (false)]\r
  42                 public override BorderStyle BorderStyle\r
  43                 {\r
  44                         get\r
  45                         {\r
  46                                 return base.BorderStyle;\r
  47                         }\r
  48                         set\r
  49                         {\r
  50                                 base.BorderStyle = value;\r
  51                         }\r
  52                 }\r
  53
  54                 [Browsable (false)]\r
  55                 public override Unit BorderWidth\r
  56                 {\r
  57                         get\r
  58                         {\r
  59                                 return base.BorderWidth;\r
  60                         }\r
  61                         set\r
  62                         {\r
  63                                 base.BorderWidth = value;\r
  64                         }\r
  65                 }\r
  66
  67                 [DefaultValue (0), WebCategory ("Misc")]
  68                 [DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
  69                 [WebSysDescription ("The index number of the currently selected ListItem.")]\r
  70                 public override int SelectedIndex\r
  71                 {\r
  72                         get\r
  73                         {\r
  74                                 int index  = base.SelectedIndex;\r
  75                                 if (index < 0 && Items.Count > 0) {\r
  76                                         index = 0;\r
  77                                         Items [0].Selected = true;\r
  78                                 }\r
  79                                 return index;\r
  80                         }\r
  81                         set\r
  82                         {\r
  83                                 base.SelectedIndex = value;\r
  84                         }\r
  85                 }\r
  86
  87                 [Browsable (false), DesignerSerializationVisibility (DesignerSerializationVisibility.Hidden)]
  88                 [Bindable (false), EditorBrowsable (EditorBrowsableState.Never)]\r
  89                 public override string ToolTip\r
  90                 {\r
  91                         // MS ignores the tooltip for this one\r
  92                         get {\r
  93                                 return String.Empty;\r
  94                         }\r
  95                         set {\r
  96                         }\r
  97                 }\r
  98 \r
  99                 protected override void AddAttributesToRender(HtmlTextWriter writer)\r
 100                 {\r
 101                         if(Page != null)\r
 102                         {\r
 103                                 Page.VerifyRenderingInServerForm(this);\r
 104                         }\r
 105                         writer.AddAttribute(HtmlTextWriterAttribute.Name, UniqueID);\r
 106                         base.AddAttributesToRender(writer);\r
 107 \r
 108                         if(AutoPostBack && Page != null)\r
 109                         {\r
 110                                 writer.AddAttribute(HtmlTextWriterAttribute.Onchange, Page.GetPostBackClientEvent(this,""));\r
 111                                 writer.AddAttribute("language", "javascript");\r
 112                         }\r
 113                 }\r
 114 \r
 115                 protected override ControlCollection CreateControlCollection()\r
 116                 {\r
 117                         return new EmptyControlCollection(this);\r
 118                 }\r
 119 \r
 120                 protected override void RenderContents(HtmlTextWriter writer)\r
 121                 {\r
 122                         if(Items != null)\r
 123                         {\r
 124                                 bool selected = false;\r
 125                                 foreach(ListItem current in Items)\r
 126                                 {\r
 127                                         writer.WriteBeginTag("option");\r
 128                                         if(current.Selected)\r
 129                                         {\r
 130                                                 if(selected)\r
 131                                                 {\r
 132                                                         throw new HttpException(HttpRuntime.FormatResourceString("Cannot_Multiselect_In_DropDownList"));\r
 133                                                 }\r
 134                                                 selected = true;\r
 135                                                 writer.WriteAttribute("selected", "selected", false);\r
 136                                         }\r
 137                                         writer.WriteAttribute("value", current.Value, true);\r
 138                                         writer.Write('>');\r
 139                                         HttpUtility.HtmlEncode(current.Text, writer);\r
 140                                         writer.WriteEndTag("option");\r
 141                                         writer.WriteLine();\r
 142                                 }\r
 143                         }\r
 144                 }\r
 145 \r
 146                 bool IPostBackDataHandler.LoadPostData(string postDataKey, NameValueCollection postCollection)\r
 147                 {\r
 148                         string[] vals = postCollection.GetValues(postDataKey);\r
 149                         if(vals != null)\r
 150                         {\r
 151                                 int index = Items.FindByValueInternal(vals[0]);\r
 152                                 if(index != SelectedIndex)\r
 153                                 {\r
 154                                         SelectedIndex = index;\r
 155                                         return true;\r
 156                                 }\r
 157                         }\r
 158                         return false;\r
 159                 }\r
 160 \r
 161                 void IPostBackDataHandler.RaisePostDataChangedEvent()\r
 162                 {\r
 163                         OnSelectedIndexChanged(EventArgs.Empty);\r
 164                 }\r
 165         }\r
 166 }\r