mcs/class/System.Web/System.Web.UI.HtmlControls/HtmlHead.cs

   1 //
   2 // System.Web.UI.HtmlControls.HtmlHead
   3 //
   4 // Authors:
   5 //      Lluis Sanchez Gual (lluis@novell.com)
   6 //
   7 // Copyright (C) 2004-2010 Novell, Inc (http://www.novell.com)
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 using System.ComponentModel;
  30 using System.Collections;
  31 using System.Security.Permissions;
  32 using System.Web.UI.WebControls;
  33
  34 namespace System.Web.UI.HtmlControls
  35 {
  36         // CAS - no InheritanceDemand here as the class is sealed
  37         [AspNetHostingPermission (SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
  38         // attributes
  39         [ControlBuilder (typeof(HtmlHeadBuilder))]
  40         public sealed class HtmlHead: HtmlGenericControl, IParserAccessor
  41         {
  42                 string descriptionText;
  43                 string keywordsText;
  44                 HtmlMeta descriptionMeta;
  45                 HtmlMeta keywordsMeta;
  46                 string titleText;
  47                 HtmlTitle title;
  48                 //Hashtable metadata;
  49                 StyleSheetBag styleSheet;
  50
  51                 public HtmlHead(): base("head") {}
  52
  53                 public HtmlHead (string tag) : base (tag)
  54                 {
  55                 }
  56
  57                 protected internal override void OnInit (EventArgs e)
  58                 {
  59                         base.OnInit (e);
  60                         Page page = Page;
  61
  62                         if (page == null)
  63                                 throw new HttpException ("The <head runat=\"server\"> control requires a page.");
  64
  65                         //You can only have one <head runat="server"> control on a page.
  66                         if(page.Header != null)
  67                                 throw new HttpException ("You can only have one <head runat=\"server\"> control on a page.");
  68                         page.SetHeader (this);
  69                 }
  70
  71                 protected internal override void RenderChildren (HtmlTextWriter writer)
  72                 {
  73                         base.RenderChildren (writer);
  74                         if (title == null) {
  75                                 writer.RenderBeginTag (HtmlTextWriterTag.Title);
  76                                 if (!String.IsNullOrEmpty (titleText))
  77                                         writer.Write (titleText);
  78                                 writer.RenderEndTag ();
  79                         }
  80                         if (descriptionMeta == null && descriptionText != null) {
  81                                 writer.AddAttribute ("name", "description");
  82                                 writer.AddAttribute ("content", HttpUtility.HtmlAttributeEncode (descriptionText));
  83                                 writer.RenderBeginTag (HtmlTextWriterTag.Meta);
  84                                 writer.RenderEndTag ();
  85                         }
  86
  87                         if (keywordsMeta == null && keywordsText != null) {
  88                                 writer.AddAttribute ("name", "keywords");
  89                                 writer.AddAttribute ("content", HttpUtility.HtmlAttributeEncode (keywordsText));
  90                                 writer.RenderBeginTag (HtmlTextWriterTag.Meta);
  91                                 writer.RenderEndTag ();
  92                         }
  93                         if (styleSheet != null)
  94                                 styleSheet.Render (writer);
  95                 }
  96
  97                 protected internal override void AddedControl (Control control, int index)
  98                 {
  99                         //You can only have one <title> element within the <head> element.
 100                         HtmlTitle t = control as HtmlTitle;
 101                         if (t != null) {
 102                                 if (title != null)
 103                                         throw new HttpException ("You can only have one <title> element within the <head> element.");
 104                                 title = t;
 105                         }
 106
 107                         HtmlMeta meta = control as HtmlMeta;
 108                         if (meta != null) {
 109                                 if (String.Compare ("keywords", meta.Name, StringComparison.OrdinalIgnoreCase) == 0)
 110                                         keywordsMeta = meta;
 111                                 else if (String.Compare ("description", meta.Name, StringComparison.OrdinalIgnoreCase) == 0)
 112                                         descriptionMeta = meta;
 113                         }
 114                         base.AddedControl (control, index);
 115                 }
 116
 117                 protected internal override void RemovedControl (Control control)
 118                 {
 119                         if (title == control)
 120                                 title = null;
 121
 122                         if (keywordsMeta == control)
 123                                 keywordsMeta = null;
 124                         else if (descriptionMeta == control)
 125                                 descriptionMeta = null;
 126                         base.RemovedControl (control);
 127                 }
 128                 public string Description {
 129                         get {
 130                                 if (descriptionMeta != null)
 131                                         return descriptionMeta.Content;
 132                                 return descriptionText;
 133                         }
 134
 135                         set {
 136                                 if (descriptionMeta != null)
 137                                         descriptionMeta.Content = value;
 138                                 else
 139                                         descriptionText = value;
 140                         }
 141                 }
 142
 143                 public string Keywords {
 144                         get {
 145                                 if (keywordsMeta != null)
 146                                         return keywordsMeta.Content;
 147                                 return keywordsText;
 148                         }
 149
 150                         set {
 151                                 if (keywordsMeta != null)
 152                                         keywordsMeta.Content = value;
 153                                 else
 154                                         keywordsText = value;
 155                         }
 156                 }
 157
 158                 public IStyleSheet StyleSheet {
 159                         get {
 160                                 if (styleSheet == null) styleSheet = new StyleSheetBag ();
 161                                 return styleSheet;
 162                         }
 163                 }
 164
 165                 public string Title {
 166                         get {
 167                                 if (title != null)
 168                                         return title.Text;
 169                                 else
 170                                         return titleText;
 171                         }
 172                         set {
 173                                 if (title != null)
 174                                         title.Text = value;
 175                                 else
 176                                         titleText = value;
 177                         }
 178                 }
 179         }
 180
 181         internal class StyleSheetBag: IStyleSheet
 182         {
 183                 ArrayList entries = new ArrayList ();
 184
 185                 internal class StyleEntry
 186                 {
 187                         public Style Style;
 188                         public string Selection;
 189                         public IUrlResolutionService UrlResolver;
 190                 }
 191
 192                 public StyleSheetBag ()
 193                 {
 194                 }
 195
 196                 public void CreateStyleRule (Style style, IUrlResolutionService urlResolver, string selection)
 197                 {
 198                         StyleEntry entry = new StyleEntry ();
 199                         entry.Style = style;
 200                         entry.UrlResolver = urlResolver;
 201                         entry.Selection = selection;
 202                         entries.Add (entry);
 203                 }
 204
 205                 public void RegisterStyle (Style style, IUrlResolutionService urlResolver)
 206                 {
 207                         for (int n=0; n<entries.Count; n++) {
 208                                 if (((StyleEntry)entries[n]).Style == style)
 209                                         return;
 210                         }
 211
 212                         string name = "aspnet_" + entries.Count;
 213                         style.SetRegisteredCssClass (name);
 214                         CreateStyleRule (style, urlResolver, "." + name);
 215                 }
 216
 217                 public void Render (HtmlTextWriter writer)
 218                 {
 219                         writer.AddAttribute ("type", "text/css", false);
 220                         writer.RenderBeginTag (HtmlTextWriterTag.Style);
 221
 222                         foreach (StyleEntry entry in entries) {
 223                                 CssStyleCollection sts = entry.Style.GetStyleAttributes (entry.UrlResolver);
 224                                 writer.Write ("\n" + entry.Selection + " {" + sts.Value + "}");
 225                         }
 226
 227                         writer.RenderEndTag ();
 228                 }
 229         }
 230 }
 231