LeXtudio.RichText

UnoRichText

UnoRichText is a rich text layout library for Uno Platform, providing RichTextBlock and the associated document model types that are missing or incomplete in Uno's current implementation.

It is backed by PretextSharp for cross-platform text measurement and layout, and mirrors the WinUI 3 / WPF namespace conventions so it can be used as a drop-in replacement with minimal code changes.

Why

Uno Platform's built-in RichTextBlock has several gaps:

• Styling properties (FontFamily, FontSize, Foreground, etc.) are not applied.
• InlineUIContainer — used to embed arbitrary UI elements inline with text — is not implemented.
• Nested RichTextBlock inside containers (borders, grids, etc.) often renders no text at all.

UnoRichText replaces these types with a fully custom implementation that works correctly on all Uno Skia Desktop targets.

Supported Platforms

• Windows 11 (Uno Skia Desktop)
• macOS, 3 most recent versions
• Ubuntu latest LTS (other Linux distributions may work but are not primary targets)

For support of additional platforms or business sponsorship enquiries, please reach out at lextudio.com.

Get Started

Install the NuGet package:

dotnet add package LeXtudio.RichText

Provided types

Usage

The API mirrors WinUI 3's RichTextBlock:

using LeXtudio.UI.Xaml.Controls;
using LeXtudio.UI.Xaml.Documents;

var block = new RichTextBlock
{
    FontSize = 14,
    TextWrapping = TextWrapping.WrapWholeWords
};

var paragraph = new Paragraph();
paragraph.Inlines.Add(new Run { Text = "Hello, " });
paragraph.Inlines.Add(new Bold { Inlines = { new Run { Text = "world" } } });
block.Blocks.Add(paragraph);

Bridging from WinUI 3 code

If you have existing WinUI 3 code that uses the native RichTextBlock and related types, you can redirect unqualified names to UnoRichText on Uno targets using global using aliases in a single file:

#if !WINDOWS_APP_SDK
global using RichTextBlock     = LeXtudio.UI.Xaml.Controls.RichTextBlock;
global using InlineCollection  = LeXtudio.UI.Xaml.Documents.InlineCollection;
global using Paragraph         = LeXtudio.UI.Xaml.Documents.Paragraph;
global using Run               = LeXtudio.UI.Xaml.Documents.Run;
global using Bold              = LeXtudio.UI.Xaml.Documents.Bold;
global using Italic            = LeXtudio.UI.Xaml.Documents.Italic;
global using Span              = LeXtudio.UI.Xaml.Documents.Span;
global using LineBreak         = LeXtudio.UI.Xaml.Documents.LineBreak;
global using InlineUIContainer = LeXtudio.UI.Xaml.Documents.InlineUIContainer;
global using Hyperlink         = LeXtudio.UI.Xaml.Documents.Hyperlink;
#endif

No other changes to the consuming code are needed.

License

MIT — see LICENSE.