HTML-like Text Formatting

Updated on Nov 11, 2026

Use HTML-like text formatting to display styled text in Telerik UI for WinForms controls that render text through the Telerik Presentation Framework (TPF). Start the text value with the <html> tag, and then apply supported tags to control font styling, links, lists, paragraphs, and images.

Related Video

Enhanced HTML-like Markup Support explains the text rendering tags introduced in the R3 2009 release, shows RadMarkupEditor, and demonstrates how to use it in your applications.

How HTML-like Text Formatting Works

TPF extends the text primitive that Telerik UI for WinForms controls use to render text. As a result, many Telerik controls can display rich text by parsing a limited set of HTML-like tags. This formatting engine is intended for styled text output. It is not a full HTML or CSS renderer.

As of R1 2021, HTML-like formatting supports custom fonts.

To enable HTML-like formatting:

1. Set the text property of a Telerik control to a string that starts with <html>.
2. Add the supported tags that describe the formatting you want.
3. Use <span> when you need to apply color, font family, or font size in a way that is compatible with RadMarkupEditor.

The following example shows the minimum required structure:

HTML

<html><b>Formatted text</b></html>

Supported Tags

Tag	End Tag	Description
<font>	N/A	Sets the font family. Prefer <span> because RadMarkupEditor does not support <font>.
<color>	N/A	Sets the text color. Prefer <span> because RadMarkupEditor does not support <color>.
<size>	N/A	Sets the font size. Prefer <span> because RadMarkupEditor does not support <size>.
<b>, <strong>	</b>, </strong>	Displays bold text.
<i>, <em>	</i>, </em>	Displays italic text.
<u>	</u>	Underlines text.
<br>	N/A	Inserts a line break.
<p>	</p>	Creates a paragraph.
<span>	</span>	Applies limited inline styling through font-family, font-size, color, and background-color. Use this tag when possible.
<ol>	</ol>	Creates an ordered list.
<ul>	</ul>	Creates an unordered list.
<li>	</li>	Creates a list item inside an ordered or unordered list.
<strike>	</strike>	Displays strikethrough text.
<a>	</a>	Creates a hyperlink.
<img>	N/A	Displays an image.

Common Formatting Examples

The examples below cover the most common formatting tasks.

Bold, Italic, and Underline

The following example combines bold, italic, and underlined text:

HTML

<html>
	<b>some <i> text </i></b><u> some text </u>
</html>

Paragraphs

Use <p> to separate text into paragraphs:

HTML

<html>
	<p>First paragraph</p>
	<p>Second paragraph</p>
</html>

Font Color

Set the text color by using a named color such as red or a hexadecimal value such as #0000FF:

HTML

<html>
	<span style="color:red">font color (color name) </span>
	<span style="color:#0000FF">font color (hex color) </span>
</html>

Font Size

You can use relative sizes such as larger and smaller, named absolute sizes such as small or x-large, or point values. The default font size in Windows Forms on most systems is 8.25pt, which is the value returned by SystemFonts.DefaultFont.

HTML

<html>
    <span style="font-size:large">font size(absolute) </span>
	<span style="font-size:12">font size in pt(s) (absolute) </span>
    <span style="font-size:smaller">font size(relative) </span>
</html>

Highlighted Text

Use background-color to highlight text:

HTML

<html><span style="background-color:red">Highlighted Text</span></html>

Font Family

Set the font family through the style attribute of a <span> tag:

HTML

<html><span style="font-family:georgia">Font Family</span></html>

Strikethrough Text

Use <strike> to display strikethrough text:

HTML

<html><strike> Some text </strike></html>

Links and Images

Use hyperlinks when you want formatted text to navigate to another location, and use images when text alone is not enough.

Links

The following example shows the Telerik hyperlink markup that opens an external link:

HTML

<html><a href="<externalLink><linkText>www.telerik.com</linkText><linkUri>http://www.telerik.com</linkUri></externalLink>"> Telerik Corporation</a></html>

Images

Use <img> to display an image in the formatted text:

HTML

<html><img src="ImagePath"></html>

The image path can point to an embedded resource or to a file on disk. To specify a resource, use the res: prefix:

HTML

<img src="res:Telerik.Examples.WinControls.SomeImage.jpg">

To specify a file on disk, provide the full path, for example src="C:\some path\image.png", or use ~ to refer to the current directory, for example src="~\some path\image.gif". All image formats supported by the .NET Image class are supported by the <img> tag.

RadMarkupEditor specifics

RadMarkupEditor and TextPrimitive share much of the same formatting model, but they do not support exactly the same tags. TextPrimitive also supports several non-standard tags.

See the RadMarkupDialog article for the list of supported tags. The font, color, and size tags are rendered by TextPrimitive, but they are not supported by RadMarkupDialog.

You can use <size=[+|-]value> to change the font size, <br> to insert a new line, and the matching opening and closing tags to apply bold, underline, or italic formatting. Set the font family through <font=Family>.

The following code snippet produces the formatted result shown in the screenshot:

RadLabel markup with mixed font styles, colors, sizes, and custom font content

C#

            
this.radLabel1.Text = "<html><size=12>This is RadLabel <br><b><font=Arial>Arial, Bold</b><br><i><color= Red><font=Times New Roman>Times, Italic <u>Underline</u><br><size=9>Size = 9<br><color= 0, 0, 255>Sample Text";

VB.NET

Me.RadLabel1.Text = "<html><size=12>This is RadLabel <br><b><font=Arial>Arial, Bold</b><br><i><color= Red><font=Times New Roman>Times, Italic <u>Underline</u><br><size=9>Size = 9<br><color= 0, 0, 255>Sample Text"

Figure 1: A RadLabel that displays multiple HTML-like text styles

Display Multiple Hyperlinks in RadLabel

RadLabel can display multiple hyperlinks in a single formatted text block. The following example shows how to define several links:

C#

                      
this.radLabel1.Text = "<html><size=12><a href=www.telerik.com>Telerik</a>" + Environment.NewLine +
                      "<a href=www.telerik.com/help/winforms>Documentation</a> " + Environment.NewLine +
                      "<a href=www.telerik.com/forums/winforms>Forum</a> ";

VB.NET

Me.RadLabel1.Text = "<html><size=12><a href=www.telerik.com>Telerik</a>" & Environment.NewLine & _
"<a href=www.telerik.com/help/winforms>Documentation</a> " & Environment.NewLine & _
"<a href=www.telerik.com/forums/winforms>Forum</a> "

The hyperlink colors are controlled by these static properties:

• TinyHTMLParsers.LinkColor: Default hyperlink color.
• TinyHTMLParsers.LinkClickedColor: Visited hyperlink color.

Figure 2: A RadLabel that displays multiple hyperlinks

Controlling Hyperlink Navigation

Links in TPF HTML-formatted text require both HyperlinkHelper.ValidateLinkPattern and HyperlinkHelper.ValidateLinkScheme before automatic navigation. Only absolute http, https, and mailto URIs are accepted by default. In markup, use an explicit scheme such as href=https://www.telerik.com; the bare www. addresses in the formatting example above are not absolute URIs and are not automatically opened.

Telerik.WinControls.TextPrimitiveUtils.FormattedTextBlock.HyperlinkClicked provides a local hook before navigation. Its Telerik.WinControls.Hyperlinks.HyperlinkClickedEventArgs exposes URL, IsTrustedUrl, and Handled. If the local event does not handle the request, HyperlinkHelper.HyperlinkClicked runs next. Only an unhandled request whose final trust state is true is launched.

The following code runs after radLabel1 has been initialized and its formatted text has been assigned. It approves only an exact application-controlled custom-protocol destination. Ensure that the registered protocol handler is trusted.

Approving a Destination in One Formatted Text Block

C#

var htmlText = this.radLabel1.LabelElement.LabelText.Impl
    as Telerik.WinControls.Primitives.TextPrimitiveHtmlImpl;
if (htmlText != null)
{
    htmlText.TextBlock.HyperlinkClicked += (sender, e) =>
    {
        if (string.Equals(e.URL, "contoso-help://help/start",
            System.StringComparison.Ordinal))
        {
            e.IsTrustedUrl = true;
        }
    };
}

Set Handled to true instead when application code handles or rejects the request. The subscription applies to that text block instance; if text changes recreate the block, register the handler on the new block or use the shared event described below.

Applications that rely on formatted-text links opening FTP URLs, UNC/file paths, OneNote links, or custom protocols must explicitly handle or approve those destinations.

Shared Hyperlink Validation

Telerik.WinControls.HyperlinkHelper provides the shared hyperlink API used by TPF formatted text and participating Telerik UI for WinForms controls. Its validation methods serve different purposes:

Method	Validation
ValidateLinkPattern(string)	Recognizes link formats, including HTTP/HTTPS, FTP, mailto, UNC paths, OneNote links, addresses starting with www., and email addresses.
ValidateLinkScheme(string)	Requires an absolute URI whose scheme is http, https, or mailto.

Default external navigation requires both checks to return true. Passing ValidateLinkPattern alone does not mean that a link will open. An FTP URL, for example, can pass the pattern check but fail the scheme check.

Checking a Destination Against the Default Policy

C#

string destination = "https://example.com/help";
bool passesDefaultValidation =
    Telerik.WinControls.HyperlinkHelper.ValidateLinkPattern(destination) &&
    Telerik.WinControls.HyperlinkHelper.ValidateLinkScheme(destination);

Handling Links Across Controls

Subscribe to the static HyperlinkHelper.HyperlinkClicked event to handle requests across participating controls. Its Telerik.WinControls.Hyperlinks.HyperlinkClickedEventArgs provides URL, IsTrustedUrl, and Handled. The destination property is named URL, not Url.

Local handlers run first. A locally handled request does not reach the shared event. An unhandled request can reach it even when IsTrustedUrl is false, allowing an application to approve an otherwise blocked destination. Set IsTrustedUrl to true only after checking the destination against your application's policy. Setting it to false alone does not prevent a later handler from changing it back to true.

Approving an Application Destination Globally

C#

using System;
using System.Windows.Forms;
using Telerik.WinControls;
using Telerik.WinControls.Hyperlinks;

public class MainForm : Form
{
    public MainForm()
    {
        HyperlinkHelper.HyperlinkClicked += this.OnHyperlinkClicked;
    }

    private void OnHyperlinkClicked(object sender, HyperlinkClickedEventArgs e)
    {
        if (string.Equals(e.URL, "contoso-help://help/start", StringComparison.Ordinal))
        {
            e.IsTrustedUrl = true;
        }
    }

    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            HyperlinkHelper.HyperlinkClicked -= this.OnHyperlinkClicked;
        }

        base.Dispose(disposing);
    }
}

Leaving Handled as false allows the originating control to navigate after checking the final trust state. If your application performs navigation itself, set Handled to true to prevent a second launch. To reject a request definitively, set Handled to true without launching anything. Never approve every destination unconditionally or use ValidateLinkPattern alone as your approval policy.

The shared event receives unhandled requests from GridView hyperlink columns, RadMap's HTML renderer, RadPdfViewer URI annotations, RichTextEditor, and Spreadsheet. GridView uses HyperlinkOpeningEventArgs.Cancel for local cancellation; setting it to true stops the request before the shared event.

Detect the Clicked Hyperlink

If a RadLabel contains multiple hyperlinks, you can detect which one the user clicked. The example below inspects the TextPrimitiveHtmlImpl.TextBlock.Lines collection and finds the FormattedText instance under the mouse pointer.

C#

        
private void RadLabel1_MouseDown(object sender, MouseEventArgs e)
{
    TextPrimitiveHtmlImpl text = this.radLabel1.LabelElement.LabelText.Impl as TextPrimitiveHtmlImpl;
    FormattedTextBlock textBlock = text.TextBlock;
    FormattedText clickedLink = IsMouseOverBlock(textBlock, e);
    if (clickedLink != null)
    {
        MessageBox.Show(clickedLink.Text + " pressed");
    }
}
        
private FormattedText IsMouseOverBlock(FormattedTextBlock textBlock, MouseEventArgs e)
{
    Point elementAtPoint = this.radLabel1.LabelElement.PointFromControl(e.Location);
    int linesCount = textBlock.Lines.Count;
    for (int i = 0; i <= linesCount - 1; i++)
    {
        TextLine textLine = textBlock.Lines[i];
        int textLineCount = textLine.List.Count;
        for (int j = 0; j <= textLineCount - 1; j++)
        {
            FormattedText formattedText = textLine.List[j];
            if (formattedText.DrawingRectangle.Contains(elementAtPoint))
            {
                //found link under mouse
                return formattedText;
            }
        }
    }
    
    return null;
}

VB.NET

Private Sub RadLabel1_MouseDown(sender As Object, e As MouseEventArgs)
    Dim text As TextPrimitiveHtmlImpl = TryCast(Me.RadLabel1.LabelElement.LabelText.Impl, TextPrimitiveHtmlImpl)
    Dim textBlock As FormattedTextBlock = text.TextBlock
    Dim clickedLink As FormattedText = IsMouseOverBlock(textBlock, e)
    If clickedLink IsNot Nothing Then
        MessageBox.Show(clickedLink.Text + " pressed")
    End If
End Sub
Private Function IsMouseOverBlock(textBlock As FormattedTextBlock, e As MouseEventArgs) As FormattedText
    Dim elementAtPoint As Point = Me.RadLabel1.LabelElement.PointFromControl(e.Location)
    Dim linesCount As Integer = textBlock.Lines.Count
    For i As Integer = 0 To linesCount - 1
        Dim textLine As TextLine = textBlock.Lines(i)
        Dim textLineCount As Integer = textLine.List.Count
        For j As Integer = 0 To textLineCount - 1
            Dim formattedText As FormattedText = textLine.List(j)
            If formattedText.DrawingRectangle.Contains(elementAtPoint) Then
                'found link under mouse
                Return formattedText
            End If
        Next
    Next
    Return Nothing
End Function

See Also

• Animations
• Dependency Properties
• Handling User Input
• Inherit Themes from RadControls Derivatives
• Microsoft Active Accessibility Support
• Override Theme Settings at Run Time
• RadMarkupDialog