Fumen Language Support

English | 日本語

Write Fumen chord charts in VS Code with syntax highlighting, contextual completion, snippets and offline live previews. Keep English and Japanese notation guides close at hand, without chord-name suggestions getting in your way.

日本語: .fumen の譜面作成を、構文の色分け・設定や記号の補完・スニペット・オフラインのリアルタイムプレビューで支援します。コード名の補完は行いません。詳しくは 日本語の説明をご覧ください。

English is the default. With a Japanese VS Code display language, commands, settings descriptions, completion/hover explanations, diagnostics, preview controls and bundled help appear in Japanese. Each help document includes 日本語 / English links, so you can read either language without changing VS Code's display language.

Edit notation and see the score beside it. Try the English sample shown above.

Install

Requires VS Code 1.90 or later. No separate Node.js, Fumen or font installation is needed to use the extension.

1. Open the Extensions view in VS Code.
2. Search for @id:kawato3.fumen-language-support.
3. Select Fumen Language Support by Katsushi Kawato and click Install.
4. Open a .fumen file or run Fumen: New Score from the Command Palette.

Features

• Syntax highlighting for settings, chords, bar lines, sections, durations, annotations and lyrics.
• Bracket/quote pairing and Tab-based snippets for common structures.
• Contextual completion for settings, fixed values, navigation signs and durations.
• A native, searchable notation picker for score structure, signs, rhythm, text and common score settings.
• Hover explanations, a direct link to the bundled cheat sheet and basic checks for malformed settings or missing delimiters.
• Live, side-by-side previews using the bundled Fumen 1.3.3 renderer, including unsaved edits.
• Extension-specific chord labels and layout: choose symbols or text such as Am7, AM7, Cdim, Cm7-5 and Caug, in a compact or full-size inline layout. These settings are separate from upstream Fumen settings in the cheat sheet.
• Offline cheat sheets and user guides in English and Japanese, with links to the official reference.
• Conservative whitespace and setting-order formatting through VS Code's standard Format Document command.
• A vector-friendly print view in Google Chrome, using Chrome's Save as PDF without a PDF library in the extension.

The extension does not suggest chord names, judge chord progressions or validate beat counts. Fumen word-based suggestions are disabled by default to keep arbitrary chord names from being suggested. Your settings or other extensions may override this.

Commands and shortcuts

Open the Command Palette with Cmd+Shift+P on macOS or Ctrl+Shift+P on Windows/Linux, then search for Fumen:

The notation picker, preview and cheat sheet are also available from a Fumen editor's right-click menu. The preview and cheat sheet also have top-right buttons. Reopening the cheat sheet reuses its tab. Each document's language links work even in an English-only VS Code installation; reopening via the command follows the display language again.

The preview uses Markdown's familiar shortcut: Cmd+K, then V on macOS, or Ctrl+K, then V on Windows/Linux. Release the first keys before pressing V. It applies only while editing Fumen source text.

Other Fumen commands have no default key binding. Open Keyboard Shortcuts (Cmd+K, then Cmd+S on macOS; Ctrl+K, then Ctrl+S elsewhere), search for Fumen, and double-click a command to assign a key. User bindings override defaults; this extension never edits your keybindings.json.

Format the document

Right-click in a Fumen editor and choose Format Document, or use the Command Palette. The standard shortcut is Shift+Option+F on macOS, Shift+Alt+F on Windows, and Ctrl+Shift+I on Linux. These are simultaneous key combinations, not the preview's two-step shortcut.

Formatting adds spaces around bar lines, reduces spaces/tabs between notation tokens to one space, removes trailing whitespace and normalizes setting assignments to %NAME=value. Runs of blank lines become one blank line; a single blank line is kept. Blank lines inside text/labels and immediately after a \ line continuation are preserved, because changing them can affect the score. Other line breaks, line-ending style, indentation, chord spelling, lyrics, annotations and labels are unchanged. It does not align bar columns or format a selection.

Consecutive setting lines and top-level %PARAM fields follow a fixed order. Settings never move across blank lines, sections, measures or other notation. Missing settings are not added; unlisted names follow the listed ones in their original relative order. Values retain their original spelling, including numbers, escapes and nested JSON. Runs containing invalid or duplicate assignments are not reordered; duplicate JSON keys prevent reordering that object.

Use normal Undo to revert the entire format. Unclosed text delimiters cause formatting to be skipped; invalid JSON settings are left alone. Documents above 500,000 characters are not formatted.

The extension does not enable automatic formatting or change your default formatter. If you already use Editor: Format On Save, that setting applies to Fumen too. With multiple Fumen formatters installed, use Format Document With… → Configure Default Formatter… to choose one. See VS Code's formatting documentation.

Preview behavior and limits

The preview updates after about 300 ms without typing. It follows the document from which it was opened and supports multiple pages, zoom and fit-to-width. While the source is incomplete, the last valid image remains visible with an error message. Close the preview to stop rendering; use Reload if necessary.

Rendering is local and uses no network service. Source text is sent to a sandboxed webview as data, never interpolated into HTML. The bundled renderer and licenses are version/hash pinned. The A4 preset is the default; %PARAM can override it within safety limits.

The bundled renderer is based on Fumen 1.3.3 with extension-specific display settings: minor_label, major_label, diminished_label, half_diminished_label, augmented_label and chord_suffix_style. They select labels by chord quality and either a compact or ordinary-size inline layout. This standardizes labels rather than preserving input spelling: selecting "aug" displays both Caug and C+ as Caug. It does not add new input notation, and omitted settings retain the original compact appearance. These are not published Fumen 1.3.3 parameters; another Fumen tool may ignore them. The cheat sheet's extension-specific section explains the visual difference, exact defaults and portable-sharing caveat.

Very large scores or extreme rendering parameters may exceed safety limits and show an error instead of rendering. Split unusually large scores into smaller files.

Editing by clicking the score and synchronized source/preview scrolling are not included. Upstream renderer error details are shown as received, while the extension's own messages follow the display language.

With %PARAM={"bar_number":"on"}, small performance-order bar numbers appear at each row start, including repeat visits such as 11,19. The default is off. The starting number defaults to 1; add "bar_start":0 to the initial PARAM to count a pickup as bar 0. This is also an extension-specific renderer feature. Indefinite repeats or an unclear performance order stop numbering, not score rendering; see the rules and limitations.

Print or save as PDF

Requires Google Chrome and local desktop VS Code. Chrome is needed only for printing; it is not bundled. Remote SSH, WSL, containers and browser-based VS Code are not supported for this feature.

1. Choose Fumen: Open Print View in Chrome from the Command Palette or the Fumen editor's right-click menu. You can also use Print / PDF in a successfully rendered preview.
2. Wait for the print view to finish loading, then click Print / Save as PDF.
3. In Chrome, choose Save as PDF, A4, no margins, and turn headers and footers off. Choose where to save the PDF yourself.

The page is a snapshot of the source, including unsaved edits. Editing in VS Code does not update an already-open print page: open a new one after changes. Invalid scores do not fall back to an older preview image. Custom Fumen page sizes are fitted proportionally inside A4.

The print view preserves vector notation and searchable text where Chrome and the available fonts support them. Search and font behavior can vary by browser version and OS. Short scores may be larger than image-based PDFs because of embedded fonts.

Rendering uses only bundled assets, without uploading the score. The extension launches Chrome without a shell and creates private local HTML snapshots in its VS Code storage. These contain the source text and third-party notices. They are removed when the extension shuts down; after a crash, snapshots older than 24 hours are removed on the next print request. Save the PDF before closing VS Code. Your own Chrome extensions, browser settings and chosen print destination remain outside this extension's control.

If Chrome is installed in a nonstandard location, set fumen.print.chromePath to its executable's absolute path in User Settings. This machine-only setting does not accept command-line arguments or workspace overrides. Printing has no default shortcut; you may assign one in Keyboard Shortcuts.

Settings and snippets

• fumen.diagnostics.enabled: enable basic setting/delimiter checks (default: true).
• fumen.diagnostics.delay: milliseconds after typing stops (default: 700; range: 200–5000).
• fumen.print.chromePath: optional absolute Chrome executable path (default: detect a standard installation).

Snippets use English names and stable fumen- prefixes in all display languages: fumen-new, fumen-4bars, fumen-8bars, fumen-section, fumen-repeat, fumen-endings, fumen-note, fumen-lyric. Use Snippets: Insert Snippet or invoke completion manually. Template placeholders and notation examples stay in English; existing score content is never translated.

Feedback

Report bugs and request features through GitHub Issues. English and Japanese are both welcome. For bug reports, include your VS Code and extension versions and a small example you can share publicly.

License and acknowledgments

MIT License — Copyright (c) 2026 Katsushi Kawato. See LICENSE for the full terms.

This is an independent extension, not an official Fumen product. Rendering is provided by hbjpn/fumen, created by Hiroyuki Baba. Bundled third-party code, documentation and music symbols retain their own MIT/OFL licenses and copyright notices; see third-party notices and bundled licenses.

Changelog

Release notes are maintained in CHANGELOG.md.