Tittle

A native, cross-platform desktop markdown & code viewer — Avalonia + Skia, no WebView.

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Status: feature-complete v0.x. Milestones M1–M15 shipped — rendering, TOC, search, live-reload, math, export, 14 themes, in-place editing. The full feature port from the original HTML/WebView viewer is closed (diagrams excepted — see BACKLOG.md).

A deliberate rewrite of an HTML/WebView markdown viewer as a native app: it renders through Skia, not a browser engine — so it starts instantly, stays light, and reads the same on Windows, Linux and macOS.

_{Dark · Deep Blue · Dracula · Solarized Light — 4 of 14 built-in themes}

Contents

• Features
• Tech stack
• Project layout
• Build & run
• Contributing
• License

Features

Markdown — GFM preview (tables · task lists · footnotes · admonitions/alerts · emoji), block math (native CSharpMath, $$…$$ / \[…\]), YAML front-matter panel, wiki-links ([[name]] opens the sibling note), collapsible sections, click-to-sort tables, copy buttons on code blocks, image lightbox, checkbox click-to-toggle (writes back to the file).

Navigation — TOC sidebar with active-heading scroll-spy, unread marks and ☆ bookmarks; heading breadcrumbs (markdown and code symbols); position-preserving preview↔source toggle; in-document find (Ctrl+F, regex/case); go-to-line; Ctrl+K command palette; back-to-top; reading-width presets.

Code & text files — TextMate syntax highlighting, cv-* token decorations (timestamps, UUIDs, IPs, hashes, TODOs, log levels, units, dates — with resolved-value hover tooltips), indent guides, code minimap, symbol/text outlines, section folding, CSV/TSV as a sortable table, JSON/XML/NDJSON pretty-print, TOML/INI/.env as a key/value table, smart typography for plain text, document statistics (RU-adapted Flesch).

PDF — an in-app page-by-page viewer (PDFium via Skia, no WebView): fit-width rendering, lazy/virtualized pages, Ctrl+± zoom; falls back to the OS viewer if the native engine is unavailable.

Images — raster (PNG/JPEG/WebP/BMP/GIF/ICO) and SVG files viewed in-app: fit-to-window, Ctrl+± zoom; raster decoded natively via Skia, SVG rendered vectorially.

Diagrams — ```mermaid/```plantuml/```dot (and every other Kroki type) rendered in the preview via a Kroki server (Mermaid → PNG, the rest → SVG). Opt-in and off by default — the diagram text is sent to the configured server (public or self-hosted); enable it in Настройки ▸ Раскладка.

Shell — tabs (drag-reorder, context menu, kept-alive content), single-instance file forwarding, live-reload with a "changed on disk" dot and position-preserving refresh, session restore, split view with live mutual scroll, 14 themes (Dark/Light + Midnight, Ocean, Deep Blue, Nord, Dracula, Solarized ×3, Gruvbox ×2, Sepia, High-Contrast), settings import/export, F1 help.

Editing — edit in the source view, Ctrl+S saves (UTF-8); an unsaved-changes ● marker on the tab.

Export — self-contained themed HTML (Markdig), copy-as-rich-text (CF_HTML), print / save-as-PDF via the browser.

Tech stack

Area	Choice
UI	Avalonia 11.3 (FluentAvaloniaUI v2, Mica/Acrylic)
Markdown	Markdown.Avalonia (preview) · Markdig (export)
Editor	AvaloniaEdit + TextMate (TextMateSharp grammars)
Math	Sylinko.CSharpMath.Avalonia (native, no JS)
PDF	PDFtoImage 4.x (PDFium, native, no WebView)
Images	Avalonia/Skia (raster) · Avalonia.Svg.Skia (SVG)
MVVM	CommunityToolkit.Mvvm
DI	Microsoft.Extensions.DependencyInjection
Tests	xUnit + Avalonia.Headless (840+)
Packages	Central Package Management (Directory.Packages.props)

Why Avalonia 11, not 12? The viewer ecosystem we depend on is not yet stable on 12 (Markdown.Avalonia 12 is alpha, FluentAvaloniaUI 3 is preview). Migration is planned once both ship stable 12 builds.

Project layout

src/Tittle         UI (Avalonia, feature slices, services, themes)
src/Tittle.Core    pure .NET 9 library (abstractions + logic, no Avalonia)
tests/Tittle.Tests xUnit + Avalonia.Headless

Core has no Avalonia dependency: UI concerns (dialogs, theming, clipboard) live behind interfaces in Core with implementations in Tittle. See ARCHITECTURE.md.

Build & run

Requires the .NET 9 SDK.

dotnet build Tittle.sln -c Release
dotnet run --project src/Tittle            # or: Tittle <path-to-file>
dotnet test Tittle.sln                     # unit + Headless UI tests

Windows portable build: build.ps1 / build.bat → dist/Tittle.exe; combined build: build_all.ps1 / build_all.bat → test gate + dist/win-x64/ + dist/win-arm64/ + build-manifest.json; per-user file association via install-fileassoc.ps1.

Contributing

Issues and PRs welcome. The codebase keeps a strict boundary: Tittle.Core must not reference Avalonia; UI concerns live behind interfaces in Core with implementations in Tittle. See ARCHITECTURE.md and BACKLOG.md.

License

Apache-2.0.