Html32TextWriter クラス
アセンブリ: System.Web (system.web.dll 内)


Html32TextWriter クラスは、HtmlTextWriter クラスの代替クラスです。HTML 4.0 のスタイル属性を HTML 3.2 の等価のタグと属性に変換します。このクラスは、HTML テーブルを使用して、色やフォントなどの属性の反映を標準化したものです。ASP.NET は、HttpBrowserCapabilities クラスの TagWriter プロパティをチェックして、HTML 3.2 以前のブラウザに対してこのクラスを自動的に使用します。HTML 3.2 マークアップを使用するデバイスをターゲットとするカスタム ページ アダプタまたはカスタム コントロール アダプタを作成しない場合には、Html32TextWriter クラスのインスタンスを明示的に作成する必要はありません。
ページとコントロールのレンダリングをカスタマイズする方法の詳細については、「チュートリアル : カスタム サーバー コントロールの開発と使用」を参照してください。

Html32TextWriter クラスから派生した CustomHtml32TextWriter という名前のクラスを使用する方法を次のコード例に示します。CustomHtml32TextWriter は、HtmlTextWriter クラスによって作成されるパターンに従った 2 つのコンストラクタを作成し、RenderBeforeContent、RenderAfterContent、RenderBeforeTag、および RenderAfterTag の各メソッドをオーバーライドしています。
' Create a custom HtmlTextWriter class that overrides ' the RenderBeforeContent and RenderAfterContent methods. Imports System Imports System.IO Imports System.Web.UI Namespace Examples.AspNet Public Class CustomHtml32TextWriter Inherits Html32TextWriter ' Create a constructor for the class ' that takes a TextWriter as a parameter. Public Sub New(ByVal writer As TextWriter) Me.New(writer, DefaultTabString) End Sub ' Create a constructor for the class that takes ' a TextWriter and a string as parameters. Public Sub New(ByVal writer As TextWriter, ByVal tabString As String) MyBase.New(writer, tabString) End Sub ' Override the RenderBeforeContent method to render ' styles before rendering the content of a <th> element. Protected Overrides Function RenderBeforeContent() As String ' Check the TagKey property. If its value is ' HtmlTextWriterTag.TH, check the value of the ' SupportsBold property. If true, return the ' opening tag of a <b> element; otherwise, render ' the opening tag of a <font> element with a color ' attribute set to the hexadecimal value for red. If TagKey = HtmlTextWriterTag.Th Then If (SupportsBold) Then Return "<b>" Else Return "<font color=""FF0000"">" End If End If ' Check whether the element being rendered ' is an <H4> element. If it is, check the ' value of the SupportsItalic property. ' If true, render the opening tag of the <i> element ' prior to the <H4> element's content; otherwise, ' render the opening tag of a <font> element ' with a color attribute set to the hexadecimal ' value for navy blue. If TagKey = HtmlTextWriterTag.H4 Then If (SupportsItalic) Then Return "<i>" Else Return "<font color=""000080"">" End If End If ' Call the base method. Return MyBase.RenderBeforeContent() End Function ' Override the RenderAfterContent method to close ' styles opened during the call to the RenderBeforeContent ' method. Protected Overrides Function RenderAfterContent() As String ' Check whether the element being rendered is a <th> element. ' If so, and the requesting device supports bold formatting , ' render the closing tag of the <b> element. If not , ' render the closing tag of the <font> element. If TagKey = HtmlTextWriterTag.Th Then If SupportsBold Then Return "</b>" Else Return "</font>" End If End If ' Check whether the element being rendered is an <H4>. ' element. If so, and the requesting device supports italic ' formatting, render the closing tag of the <i> element. ' If not, render the closing tag of the <font> element. If TagKey = HtmlTextWriterTag.H4 Then If (SupportsItalic) Then Return "</i>" Else Return "</font>" End If End If ' Call the base method. Return MyBase.RenderAfterContent() End Function ' Override the RenderBeforeTag method to render the ' opening tag of a <small> element to modify the text size of ' any <a> elements that this writer encounters. Protected Overrides Function RenderBeforeTag() As String ' Check whether the element being rendered is an ' <a> element. If so, render the opening tag ' of the <small> element; otherwise, call the base method. If TagKey = HtmlTextWriterTag.A Then Return "<small>" End If Return MyBase.RenderBeforeTag() End Function ' Override the RenderAfterTag method to render ' close any elements opened in the RenderBeforeTag ' method call. Protected Overrides Function RenderAfterTag() As String ' Check whether the element being rendered is an ' <a> element. If so, render the closing tag of the ' <small> element; otherwise, call the base method. If TagKey = HtmlTextWriterTag.A Then Return "</small>" End If Return MyBase.RenderAfterTag() End Function End Class End Namespace
using System.IO; using System.Web.UI; namespace Examples.AspNet { public class CustomHtml32TextWriter : Html32TextWriter { // Create a constructor for the class // that takes a TextWriter as a parameter. public CustomHtml32TextWriter(TextWriter writer) : this(writer, DefaultTabString) { } // Create a constructor for the class that takes // a TextWriter and a string as parameters. public CustomHtml32TextWriter(TextWriter writer, String tabString) : base(writer, tabString) { } // Override the RenderBeforeContent method to render // styles before rendering the content of a <th> element. protected override string RenderBeforeContent() { // Check the TagKey property. If its value is // HtmlTextWriterTag.TH, check the value of the // SupportsBold property. If true, return the // opening tag of a <b> element; otherwise, render // the opening tag of a <font> element with a color // attribute set to the hexadecimal value for red. if (TagKey == HtmlTextWriterTag.Th) { if (SupportsBold) return "<b>"; else return "<font color=\"FF0000\">"; } // Check whether the element being rendered // is an <H4> element. If it is, check the // value of the SupportsItalic property. // If true, render the opening tag of the <i> element // prior to the <H4> element's content; otherwise, // render the opening tag of a <font> element // with a color attribute set to the hexadecimal // value for navy blue. if (TagKey == HtmlTextWriterTag.H4) { if (SupportsItalic) return "<i>"; else return "<font color=\"000080\">"; } // Call the base method. return base.RenderBeforeContent(); } // Override the RenderAfterContent method to close // styles opened during the call to the RenderBeforeContent // method. protected override string RenderAfterContent() { // Check whether the element being rendered is a <th> element. // If so, and the requesting device supports bold formatting , // render the closing tag of the <b> element. If not , // render the closing tag of the <font> element. if (TagKey == HtmlTextWriterTag.Th) { if (SupportsBold) return "</b>"; else return "</font>"; } // Check whether the element being rendered is an <H4>. // element. If so, and the requesting device supports italic // formatting, render the closing tag of the <i> element. // If not, render the closing tag of the <font> element. if (TagKey == HtmlTextWriterTag.H4) { if (SupportsItalic) return "</i>"; else return "</font>"; } // Call the base method return base.RenderAfterContent(); } // Override the RenderBeforeTag method to render the // opening tag of a <small> element to modify the text size of // any <a> elements that this writer encounters. protected override string RenderBeforeTag() { // Check whether the element being rendered is an // <a> element. If so, render the opening tag // of the <small> element; otherwise, call the base method. if (TagKey == HtmlTextWriterTag.A) return "<small>"; return base.RenderBeforeTag(); } // Override the RenderAfterTag method to render // close any elements opened in the RenderBeforeTag // method call. protected override string RenderAfterTag() { // Check whether the element being rendered is an // <a> element. If so, render the closing tag of the // <small> element; otherwise, call the base method. if (TagKey == HtmlTextWriterTag.A) return "</small>"; return base.RenderAfterTag(); } } }


System.MarshalByRefObject
System.IO.TextWriter
System.Web.UI.HtmlTextWriter
System.Web.UI.Html32TextWriter
System.Web.UI.ChtmlTextWriter


Windows 98, Windows 2000 SP4, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
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