SmallMarkdown

A Markdown editor and viewer for GNUstep on Linux, implemented in Objective-C using only GPL/LGPL-compatible C and Objective-C libraries.

Features

• Phase 1 — Core: NSDocument-based file handling, NSTextView editor, basic preferences (NSUserDefaults).
• Phase 2 — Markdown: Integration with libmarkdown (Discount) to convert Markdown to HTML (optional; falls back to <pre>-escaped text).
• Phase 3 — Preview: Split view with editor and preview pane; full HTML rendering via WebKitGTK when available (auto-detected), including dark mode through a WebKit user style sheet.
• Phase 4 — Syntax highlighting: Custom NSTextStorage with NSRegularExpression for headings, bold/italic, inline and fenced code blocks, links, lists.
• Phase 5 — Spell checking: GNU Aspell integration (auto-detected) wired into NSTextView's spell pipeline, with an Ignore context menu on right-click of a marked word.
• Phase 6 — Preferences: Font selection, theme (light/dark), preview refresh behavior, spell-check options.
• Phase 7 — Extras: Export to HTML/PDF/ODT (plus "Export a Copy…"), Print (⌘P), an outline view of headings, and tabs for multiple documents.
• File watching (Linux): the open file is watched via inotify; external changes debounce-reload the editor and preview. Clean documents reload automatically; dirty documents get a Reload / Keep prompt.

Allowed libraries

Purpose	Library	License	Notes
Markdown parsing	Discount (libmarkdown)	BSD	Auto-detected at build
HTML preview	WebKitGTK	LGPL	Auto-detected at build
Spell checking	Aspell	LGPL	Auto-detected at build
ODT export	libzip	BSD	Auto-detected at build
File watching	inotify	(kernel)	Linux only
Syntax highlighting	Custom Obj-C	Your choice	In-tree

Build (GNUstep on Linux)

Prerequisites

• GNUstep Make (gnustep-make), Base and GUI (gnustep-base, gnustep-gui)
• Optional: libmarkdown (Discount) — auto-detected; enables Markdown→HTML rendering
• Optional: Aspell (libaspell-dev) — auto-detected; enables real spell checking
• Optional: WebKitGTK (libwebkit2gtk-4.1-dev) — auto-detected; enables the real HTML preview
• Optional: libzip (libzip-dev) — auto-detected; enables ODT export

Compile

1. Build SmallStepLib first (used for app lifecycle):

   cd ../SmallStepLib && make

2. Build the app:

   . /usr/share/GNUstep/Makefiles/GNUstep.sh   # or your installation path
   make

WebKitGTK, Aspell, libzip and libmarkdown are detected automatically via pkg-config (plus a few common fallback paths), so no manual flag changes are needed:

• WebKitGTK → HAVE_WEBKIT; the preview pane then embeds a real WebKitWebView.
• Aspell → HAVE_ASPELL; SMAspellSpellChecker backs the editor's spell pipeline.
• libzip → HAVE_LIBZIP; SMExportODT writes real ODT archives.
• libmarkdown (Discount) → HAVE_MKDIO_H; MarkdownRenderer converts Markdown to real HTML.

Without these libraries the app still builds and runs: the preview falls back to a plain-text pane, spell checking degrades to the stub checker, ODT export is disabled, and MarkdownRenderer falls back to <pre>-escaped text.

libmarkdown (Discount)

Install the library (package name is libmarkdown2-dev on Debian/Ubuntu, or build from Discount); it is then auto-detected like WebKit/Aspell/libzip. The GNUmakefile probes pkg-config libmarkdown and common mkdio.h locations (including Debian's multiarch subdirectory), and links -lmarkdown — falling back to -ldiscount where the library is installed as libdiscount (e.g. macOS/Homebrew).

Run

./SmallMarkdown.app/SmallMarkdown

Or open from the GNUstep menu. You can create new documents or open .md / .markdown files. Each open document becomes a tab in the shared window (labeled with the document name, kept in sync on Save As); the left pane lists headings from the current document — click one to jump to it in the editor.

Testing

Implementation status vs plan: see PLAN_REVIEW.md.

Build and run the unit and UI suites:

make test

or manually:

make -C Tests CC=clang all
./Tests/obj/SmallMarkdownUnitTests
./Tests/obj/SmallMarkdownUITests

On a headless machine use a virtual display, e.g. xvfb-run ./Tests/obj/SmallMarkdownUITests.

• Unit tests cover: MarkdownRenderer (render/wrap, empty/nil input, theme), MarkdownTextStorage (replace, attributes, fenced-code highlighting), SMOutlineItem (heading parsing), SMDocument (content, dataOfType:, readFromData:), SMSpellChecker (enable/suggest/check).
• UI tests verify the document window structure (tabbed window: outline table, editor, preview) and the preferences window.

Project layout

• Main.m, SMAppDelegate — application entry, preferences registration, and the menu (File: New/Open/Save/Save As, Export HTML/PDF/ODT, Export a Copy…, Print, Close; Edit: Check Spelling).
• SMDocument, SMWindowController — document and window; tabbed window with outline + editor + preview in a split view; inotify file watching; print via NSPrintOperation.
• MarkdownRenderer — Markdown→HTML via libmarkdown (Discount), plus a cached HTML preview template with theme CSS.
• SMWebKitPreviewView — X11-embedded WebKitWebView preview (when HAVE_WEBKIT); dark mode via a WebKitUserStyleSheet.
• SMPreviewView — preview pane (plain-text fallback).
• MarkdownTextStorage — syntax highlighting in the editor.
• SMSpellChecker, SMAspellSpellChecker — Aspell-backed NSSpellChecker replacement with ignore-word support.
• SMOutlineItem — heading model for the outline pane.
• SMExportODT — ODT (libzip) exporter.
• SMPreferencesController — font, theme, preview refresh, spell-check options.

License

This project is under the GNU Affero General Public License v3 or later. See LICENSE.

Libraries used (Discount, Aspell, WebKitGTK, libzip) have their own licenses (BSD, LGPL, …) and are GPL/LGPL-compatible.