RichTextViewer.Avalonia 1.0.0

RichTextViewer.Avalonia

A read-only rich text viewer control for Avalonia applications that enhances plain text with clickable hyperlinks, limited inline Markdown formatting, quote styling, and find-and-highlight — without the overhead of a full HTML or Markdown renderer.

The control displaying quoted text at multiple depths, inline Markdown formatting, and highlighted find matches.

Features

• Inline Markdown detection — bold (**text**), italic (*text* / _text_), bold-italic (***text***), strikethrough (~~text~~), and inline code (`code`).
• Clickable hyperlinks — HTTP, HTTPS, FTP, and mailto: links detected automatically; scheme allowlist and blocklist enforced at both detection time and click time.
• Multi-level quote styling — lines prefixed with > are coloured and indented by quote depth, up to three levels; configurable depth colours via Avalonia resource keys.
• Extended quote detection — initials-style markers (AG>, pF>>), dash-prefix markers (->, ->>), empty quote line collapsing, and decorative-divider detection.
• Find and highlight — case-insensitive search with a 150ms debounce; matches highlighted with configurable brush colours.
• Preformatted line support — lines beginning with a single leading space can be rendered in a monospace font (Gopher convention).
• Custom span detectors — plug-in ISpanDetector implementations to detect domain-specific syntax not handled by the built-in pipeline.
• Custom span renderers — plug-in ISpanRenderer implementations to apply custom styling to any SpanType.
• Theming via Avalonia resource keys — override any of the six named brush resources from the host application's resource dictionary.
• Word-wrap toggle — switch between wrapping and horizontal scrolling at runtime.

Installation

dotnet add package RichTextViewer.Avalonia

Minimal Usage

Add the control to a window or user control:

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:rtv="clr-namespace:RichTextViewer.Avalonia.Controls;assembly=RichTextViewer.Avalonia"
        x:Class="MyApp.MainWindow">

  <rtv:RichTextViewer Text="Hello, **world**! Visit https://avaloniaui.net" />

</Window>

The control embeds its own default styles and works without any additional setup in App.axaml. If you want to override the library's named brush resources (such as RichTextViewer.QuoteDepth1Brush), see https://github.com/57951/RichTextViewer.Avalonia/blob/main/docs/theming.md for the required StyleInclude entry.

Equivalent C# code-behind:

RichTextViewer viewer = new RichTextViewer
{
  Text = "Hello, **world**! Visit https://avaloniaui.net"
};

Documentation

• https://github.com/57951/RichTextViewer.Avalonia/blob/main/docs/getting-started.md — installation, prerequisites, and first steps.
• https://github.com/57951/RichTextViewer.Avalonia/blob/main/docs/configuration.md — all properties, defaults, and examples.
• https://github.com/57951/RichTextViewer.Avalonia/blob/main/docs/custom-detectors.md — implementing and registering ISpanDetector.
• https://github.com/57951/RichTextViewer.Avalonia/blob/main/docs/custom-renderers.md — implementing and registering ISpanRenderer.
• https://github.com/57951/RichTextViewer.Avalonia/blob/main/docs/theming.md — overriding brush resource keys and dark-theme support.
• https://github.com/57951/RichTextViewer.Avalonia/blob/main/docs/find.md — find-and-highlight, debounce, and known limitations.
• https://github.com/57951/RichTextViewer.Avalonia/blob/main/docs/security.md — scheme allowlist, blocklist, and threat model.
• https://github.com/57951/RichTextViewer.Avalonia/blob/main/docs/known-limitations.md — deliberate design constraints.

License

RichTextViewer.Avalonia is released under the GNU Affero General Public License v3.0.