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ASP.NET: HtmlHead ControlAdapters implementation

Here I want to show my implementation of ControlAdapters to render HtmlHead element properly in ASP.NET (at least as far as I can see it :)). For reference see my previous entries on the issue:



And here is original implementation of Control Adapters by Bazile.


So in order to render HtmlHead need to implement the following Control Adapters and register them in Default.browser:


  1. HtmlHeadAdapter
    public class HtmlHeadAdapter : System.Web.UI.Adapters.ControlAdapter
    {
        protected override void Render(HtmlTextWriter writer)
        {
            writer.WriteLine("<head>");
                
            HtmlHead headTag = (HtmlHead)this.Control;
            foreach(Control contrl in headTag.Controls)
            {
                contrl.RenderControl(writer);
            }
    
            writer.WriteLine("</head>");
        }
    } 
    
  2. HtmlTitleAdapter
    public class HtmlTitleAdapter : System.Web.UI.Adapters.ControlAdapter
    {
        protected override void Render(HtmlTextWriter writer)
        {
            // Title
            writer.Write("<title>");
            writer.Write(Page.Title);
            writer.WriteLine("</title>");
        }
    }
    
  3. HtmlMetaAdapter
    public class HtmlMetaAdapter : System.Web.UI.Adapters.ControlAdapter
    {
        protected override void Render(HtmlTextWriter writer)
        {
            HtmlMeta metaTag = (HtmlMeta)this.Control;
    
            writer.Write("<meta");
    
            if (!String.IsNullOrEmpty(metaTag.HttpEquiv))
            {
                writer.Write(" http-equiv=\"");
                writer.Write(metaTag.HttpEquiv);
                writer.Write("\"");
            }
    
            if (!String.IsNullOrEmpty(metaTag.Name))
            {
                writer.Write(" name=\"");
                writer.Write(metaTag.Name);
                writer.Write("\"");
            }
    
            writer.Write(" content=\"");
            writer.Write(metaTag.Content);
            writer.Write("\"");
    
            writer.WriteLine(" />");
        }
    }
    
  4. HtmlLinkAdapter
    public class HtmlLinkAdapter : System.Web.UI.Adapters.ControlAdapter
    {
        protected override void Render(HtmlTextWriter writer)
        {
            HtmlLink linkTag = (HtmlLink)this.Control;
    
            if ((linkTag.Attributes != null) && 
                (linkTag.Attributes.Count > 0))
            {
                writer.Write("<link");
    
                foreach (string key in linkTag.Attributes.Keys)
                {
                    writer.Write(" ");
                    writer.Write(key);
                    writer.Write("=\"");
                    writer.Write(linkTag.Attributes[key]);
                    writer.Write("\"");
                }
    
                writer.WriteLine(" />");
            }
        }
    }
    

Related Posts:

Wednesday, January 31, 2007 1:51 AM

Comments

# re: ASP.NET: HtmlHead ControlAdapters implementation
I found a few bugs in this implementaion:
1) Some html didn't render with nested master pages.
2) ASP.NET theme engine injects <link> tags with application root reference (~/). HtmlLinkAdapter should resolve this links.
3) Styles added to <head> with Page.Header.StyleSheet.CreateStyleRule() dind't render.

All these bugs are fixed with the following implementaion of HtmlHeadAdapter and HtmlLinkAdapter classes.

using System;
using System.Globalization;
using System.Web.UI;
using System.Web.UI.HtmlControls;


public class HtmlHeadAdapter : System.Web.UI.Adapters.ControlAdapter
{
protected override void OnPreRender(EventArgs e)
{
bool hasTitle = false;
foreach (Control cntrl in this.Control.Controls)
{
if (cntrl is HtmlTitle)
{
hasTitle = true;
break;
}
}
if (!hasTitle)
{
HtmlTitle ht = new HtmlTitle();
ht.Text = Page.Title;
Control.Controls.Add(ht);
}
base.OnPreRender(e);
}


protected override void Render(HtmlTextWriter writer)
{
writer.WriteLine("<head>");
RenderChildren(writer);
writer.Write("</head>");
}
}


public class HtmlLinkAdapter : System.Web.UI.Adapters.ControlAdapter
{
protected override void Render(HtmlTextWriter writer)
{
AttributeCollection attributes = ((HtmlLink)this.Control).Attributes;
if (null!=attributes && attributes.Count>0)
{
writer.Write("<link");
foreach (string key in attributes.Keys)
{
writer.Write(" ");
writer.Write(key);
writer.Write("=\"");
if (0 == String.Compare("href", key, true, CultureInfo.InvariantCulture))
writer.Write(this.Control.ResolveUrl(attributes[key]));
else
writer.Write(attributes[key]);
writer.Write("\"");
}
writer.WriteLine(">");
}
}
}

2/15/2008 9:13 AM by Bazile

# ASP.NET "Head" Rendering Issues!
Are you one of &quot;those&quot; ASP.NET web developers that care passionately about not only about writing

5/2/2008 4:06 PM by Jeff Lynch [MVP]

# re: ASP.NET: HtmlHead ControlAdapters implementation
Thank you...

11/25/2008 9:57 AM by rüya tabiri

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