在寫ASP.NET.NET MVC的網站時, 常會用到 @Html. 這個
這篇是自訂原本 @Html. 裡面所沒有的功能, 依此類推

*參考資料
** System.Web.Mvc.Html Namespace
** HTML5

回目錄
* 檔案 HtmlHelperExtensions.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;

namespace System.Web.Mvc.Html
{
    public static class HtmlHelperExtensions
    {
        public static MvcHtmlString Image(this HtmlHelper helper,
                               string url,
                               string altText = "",
                               object htmlAttributes = null)
        {
            TagBuilder builder = new TagBuilder("img");
            builder.Attributes.Add("src", url);

            if (altText != "")
                builder.Attributes.Add("alt", altText);

            if (htmlAttributes != null)
            {
                builder.MergeAttributes(new RouteValueDictionary(htmlAttributes));
            }

            return MvcHtmlString.Create(builder.ToString(TagRenderMode.SelfClosing));
        }

        public MvcHtmlString Video(this HtmlHelper helper, 
            string [] source,
            string notSupportedMessage = null,
            object htmlAttributes = null)
        {
            TagBuilder builder = new TagBuilder("video");
           
            if (htmlAttributes != null)
            {
                builder.MergeAttributes(new RouteValueDictionary(htmlAttributes));
            }

            StringBuilder sb = new StringBuilder();
            foreach (string url in source) 
            {
                string fileExt = System.IO.Path.GetExtension(url).ToLower();
                string type = null;

                switch (fileExt)
                {
                    case ".mp4":
                        type = "video/mp4";
                        break;
                    case ".ogg":
                        type = "video/ogg";
                        break;
                    case ".webm":
                        type = "video/webm";
                        break;
                }
                if (type != null)
                {
                    TagBuilder builder2 = new TagBuilder("source");
                    builder2.Attributes.Add("src", url);
                    builder2.Attributes.Add("type", type);
                    sb.Append(builder2.ToString(TagRenderMode.SelfClosing));
                }
            }
            builder.InnerHtml = sb.ToString();
            if (notSupportedMessage != null)
                builder.InnerHtml = notSupportedMessage;
            else
                builder.InnerHtml = "這個瀏覽器不支援HTML5的video語法";

            return MvcHtmlString.Create(builder.ToString(TagRenderMode.Normal));
        }

        public MvcHtmlString Audio(this HtmlHelper helper,
           string[] source,
           string notSupportedMessage = null,
           object htmlAttributes = null)
        {
            TagBuilder builder = new TagBuilder("audio");

            if (htmlAttributes != null)
            {
                builder.MergeAttributes(new RouteValueDictionary(htmlAttributes));
            }

            StringBuilder sb = new StringBuilder();
            foreach (string url in source)
            {
                string fileExt = System.IO.Path.GetExtension(url).ToLower();
                string type = null;

                switch (fileExt)
                {
                    case ".mp3":
                        type = "audio/mpeg";
                        break;
                    case ".ogg":
                        type = "audio/ogg";
                        break;
                    case ".wav":
                        type = "audio/wav";
                        break;
                }
                if (type != null)
                {
                    TagBuilder builder2 = new TagBuilder("source");
                    builder2.Attributes.Add("src", url);
                    builder2.Attributes.Add("type", type);
                    sb.Append(builder2.ToString(TagRenderMode.SelfClosing));
                }
            }

            builder.InnerHtml = sb.ToString();
            if (notSupportedMessage != null)
                builder.InnerHtml = notSupportedMessage;
            else
                builder.InnerHtml = "這個瀏覽器不支援HTML5的audio語法";

            return MvcHtmlString.Create(builder.ToString(TagRenderMode.Normal));
        }
    }
}

*就這樣了, 休息