HtmlHead.cs source code in C# .NET

                        
Code:
                         / FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / xsp / System / Web / UI / HtmlControls / HtmlHead.cs / 1 / HtmlHead.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Web.UI.HtmlControls { 
    using System; 
    using System.Collections;
    using System.Collections.Specialized; 
    using System.ComponentModel;
    using System.Globalization;
    using System.Web;
    using System.Web.UI; 
    using System.Web.UI.WebControls;
    using System.Security.Permissions; 
 
    [AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)]
    [AspNetHostingPermission(SecurityAction.InheritanceDemand, Level=AspNetHostingPermissionLevel.Minimal)] 
    public class HtmlHeadBuilder : ControlBuilder {


        public override Type GetChildControlType(string tagName, IDictionary attribs) { 
            if (String.Equals(tagName, "title", StringComparison.OrdinalIgnoreCase))
                return typeof(HtmlTitle); 
 
            if (String.Equals(tagName, "link", StringComparison.OrdinalIgnoreCase))
                return typeof(HtmlLink); 

            if (String.Equals(tagName, "meta", StringComparison.OrdinalIgnoreCase))
                return typeof(HtmlMeta);
 
            return null;
        } 
 

        public override bool AllowWhitespaceLiterals() { 
            return false;
        }
    }
 
    /// 
    /// Represents the HEAD element. 
    ///  
    [
    ControlBuilderAttribute(typeof(HtmlHeadBuilder)), 
    AspNetHostingPermission(SecurityAction.LinkDemand, Level=AspNetHostingPermissionLevel.Minimal)
    ]
    public sealed class HtmlHead : HtmlGenericControl {
 
        private StyleSheetInternal _styleSheet;
        private HtmlTitle _title; 
        private String _cachedTitleText; 

        ///  
        /// Initializes an instance of an HtmlHead class.
        /// 
        public HtmlHead() : base("head") {
        } 

        public HtmlHead(string tag) : base(tag) { 
            if (tag == null) { 
                tag = String.Empty;
            } 
            _tagName = tag;
        }

        public IStyleSheet StyleSheet { 
            get {
                if (_styleSheet == null) { 
                    _styleSheet = new StyleSheetInternal(this); 
                }
 
                return _styleSheet;
            }
        }
 
        public String Title {
            get { 
                if (_title == null) { 
                    return _cachedTitleText;
                } 

                return _title.Text;
            }
            set { 
                if (_title == null) {
                    // Side effect of adding a title to the control assigns _title 
                    _cachedTitleText = value; 
                }
                else { 
                    _title.Text = value;
                }
            }
        } 

        protected internal override void AddedControl(Control control, int index) { 
            base.AddedControl(control, index); 

            if (control is HtmlTitle) { 
                if (_title != null) {
                    throw new HttpException(SR.GetString(SR.HtmlHead_OnlyOneTitleAllowed));
                }
 
                _title = (HtmlTitle)control;
            } 
        } 

        ///  
        /// 
        /// Allows the HEAD element to register itself with the page.
        /// 
        protected internal override void OnInit(EventArgs e) { 
            base.OnInit(e);
 
            Page p = Page; 
            if (p == null) {
                throw new HttpException(SR.GetString(SR.Head_Needs_Page)); 
            }
            if (p.Header != null) {
                throw new HttpException(SR.GetString(SR.HtmlHead_OnlyOneHeadAllowed));
            } 
            p.SetHeader(this);
        } 
 
        internal void RegisterCssStyleString(string outputString) {
            ((StyleSheetInternal)StyleSheet).CSSStyleString = outputString; 
        }

        protected internal override void RemovedControl(Control control) {
            base.RemovedControl(control); 

            if (control is HtmlTitle) { 
                _title = null; 
            }
        } 

        /// 
        /// 
        /// Notifies the Page when the HEAD is being rendered. 
        /// 
        protected internal override void RenderChildren(HtmlTextWriter writer) { 
            base.RenderChildren(writer); 

            if (_title == null) { 
                // Always render out a