Code4Delphi — Delphi Language Support for Visual Studio Code

Code4Delphi — Modern, high-quality Delphi / Object Pascal language support for Visual Studio Code, covering the latest Delphi language features (through Delphi 13.1 and all older versions back to Delphi 7), plus the code-navigation shortcuts Delphi developers expect from the RAD Studio IDE.

Author: Olaf Monien, Embarcadero MVP · Developer Experts, LLC

Quick Info

Syntax Highlighting, Familiar Keybindings & Form Layout for Delphi in Visual Studio Code — out of the box:

Why Code4Delphi?

There are other Delphi extensions for Visual Studio Code — some of them are very powerful, but they often bundle complex additional features: language servers, project & build tooling, completion engines, dependency analyzers and more. That is great when you need all of it — and heavy when you don't.

Code4Delphi is deliberately lightweight:

• 🎨 just excellent syntax highlighting,
• ⌨️ the familiar Delphi keybindings for fast code navigation, and
• 📐 a form layout visualizer for .dfm / .fmx —
• 🪶 no Language Server (LSP), no build integration, no telemetry, zero runtime dependencies.

Instead of a language server — a separate process with its own runtime and dependencies — Code4Delphi uses a small, built-in static analyser that runs directly in the extension host. It is purely syntax-based (lexical) and needs no external components: nothing to download, no server to start, no extra memory beyond the document itself. That keeps the extension small, fast to install, and instant to activate.

Forms without the full IDE. Opening a form or data module in the Delphi IDE expects every component package used on that form to be installed in the IDE. Missing design-time packages are a common blocker — especially when reviewing legacy code, third-party forms, or AI-generated DFMs, and especially when you are not on Windows. Code4Delphi’s visualizer shows layout, hierarchy and text properties from the form file alone: lightweight, easy, and it works on macOS (and Linux) as well as Windows.

It activates instantly and stays out of your way — the ideal companion when you want to read, review and inspect Delphi code, for example code written by Claude or other AI agents.

Features

Code4Delphi brings the features Delphi developers know from the RAD Studio IDE into Visual Studio Code:

1. High-quality syntax highlighting — a hand-crafted TextMate grammar that covers the complete Delphi 13.1 language and every older version. Unit sections, class/record/interface declarations, generics, attributes, operator overloading, managed records and multi-line string literals are all colored precisely — in any theme. .dfm / .fmx form files get the same schemes (object hierarchy, properties, strings, numbers, collections).

2. Delphi-IDE code navigation — jump from an interface method declaration to its implementation (Ctrl+Shift+↓), back with Ctrl+Shift+↑, and step through methods with Alt+↓ / Alt+↑. Navigation is overload-aware (parameter types are compared, so you always land on the right method) and understands classes, records, helpers, generics and global routines.

3. Selectable color schemes — four syntax schemes for Delphi code: Fancy (the vivid Code4Delphi look), Turbo Pascal (the classic IDE) and the authentic Delphi Light / Delphi Dark colors of Delphi 13.1. The default auto follows your VS Code light/dark theme. Only the Delphi highlighting changes — your global theme is never touched.

4. Code folding — fold unit sections, begin…end blocks, {$REGION} markers and conditional compiler directives (see below).

5. Editor conveniences — comment toggling for // and { }, auto-closing brackets and strings (incl. multi-line '''…''' literals), and correct word selection for identifiers like TMyClass_123.

6. Form layout visualizer — box-model view of .dfm / .fmx with Align simulation (see below).

4. Code folding

A built-in folding provider for Delphi source (.pas, .dpr, …) supplies fold ranges that work with VS Code’s gutter chevrons and fold commands:

{$REGION} folds are tagged as VS Code region folds, so Fold All Regions / Unfold All Regions apply to them. All four kinds default to on and can be disabled independently in settings.

5. Editor conveniences

• Comment toggling for // and { }
• Auto-closing pairs for (), [], {}, strings and multi-line strings
• Proper word boundaries (TMyClass_123 selects as one word)

6. Form layout visualizer (DFM / FMX)

Open any .dfm or .fmx file (or a .pas that has a sibling form) and run Code4Delphi: Show Form Layout (Command Palette, or the editor context menu on Delphi / form files).

Not a design-time renderer.
The visualizer deliberately does not try to paint real VCL/FMX controls. Doing that would require the compiled design-time packages for every component on the form — exactly the heavy, Windows-centric dependency this extension avoids. What you get instead is a structural box model: bounds, Align, ownership tree and text properties parsed from the form file. Enough to understand and edit layout without installing the full component set in an IDE.

A three-pane webview shows the form as a box model:

Interaction

• Click a box or tree node → select it; descendants are highlighted so ownership is obvious.
• Double-click a box or tree node → jump to the corresponding object line in the editor.
• Escape → select the parent control (ignored while typing in an editor field).
• ↑ / ↓ in the tree → move selection among visible (filtered) nodes.
• Label toggles at the bottom: Name, Class, Text (Caption/Text), Align — any combination, including none. Defaults come from settings (see below).
• Zoom from 25 % to 400 %; type a percentage and press Enter to apply.
• PPI / PixelsPerInch — if the form stores a design-time PPI, bounds are scaled to 96 DPI logical pixels for display (default 96 = 1:1).

Property editing

• Click a property value to edit inline; Enter or blur saves, Escape cancels.
• … opens an extended multi-line editor (useful for long captions / scripts).
• Values are treated as plain text (no type checking). Prefer version control.
• Delphi #xyz string encoding is handled on read/write:
  • Decode on load: 'J'#228'nner' → Jänner
  • Encode on save: non-ASCII and control characters become #n codes
  • Line breaks are stored as #13#10 on a single DFM source line
    (e.g. 'Line1'#13#10'Line2'), never as raw newlines in the file.

Align simulation. The visualizer does not only show the raw coordinates written in the file. It runs a lightweight layout pass that approximates Delphi’s Align behaviour:

Align is normalised (alTop → Top, etc.) and can be shown in box labels when the Align toggle is on.

The renderer is pluggable: FormLayoutView owns the shell (tree, inspector, selection, messaging) and delegates the drawing surface to a render provider (IRenderProvider). The current implementation (DomRenderProvider) uses nested absolutely positioned divs; a Canvas or SVG provider can be added by implementing buildCss() / buildClientScript(), without touching the parser or the view host.

Configuration

Everything is configurable through settings (Preferences → Settings → Extensions → Delphi):

To change a shortcut, use Preferences → Keyboard Shortcuts and rebind Delphi: Go to Method Implementation / Interface Section, etc. (or edit keybindings.json).

Requirements

• Visual Studio Code 1.80 or newer. No runtime dependencies; works offline.

Known limitations

• Syntax highlighting is a TextMate grammar, so it is purely lexical (no semantic type resolution) — like every other non-LSP Delphi extension.
• Interface ↔ implementation matching is heuristic and line-based; extremely unusual formatting (e.g. procedure on a different line than the method name) may not be recognised.
• Form layout visualizer:
  • Text DFM/FMX only (binary forms are not parsed).
  • Align simulation covers the common edge + Client cases well; it does not implement full FMX layout managers, per-control Margins/Padding, CustomAlign callbacks, or exact Fit/Scale aspect-ratio math.
  • Property edits are plain text (no type/syntax validation); multi-line string values are written as a single DFM line using #13#10 character codes.
  • DFM source that splits one string across physical lines with trailing + is only partially supported for round-trip editing.
  • Non-visual components without size may be omitted from the drawing (they still appear in the tree).

Development

npm install               # tests: vscode-textmate, vscode-oniguruma, Playwright
npm test                  # unit tests: parser/navigation + grammar + form layout + commands
npm run test:formLayout   # DFM/FMX parser, layout engine, webview host unit tests
npm run test:webview      # Playwright browser tests for the form-layout webview UI
npx playwright install chromium   # once, for test:webview

Press F5 in VS Code to launch the Extension Development Host.

Marketplace publishing (publisher DeveloperExperts, PAT expiry, vsce commands) is documented in docs/publishing.md.

License

MIT — see LICENSE.

Trademarks

Delphi and Embarcadero are trademarks or registered trademarks of Embarcadero Technologies, Inc. or its affiliates in the United States and/or other countries. All other trademarks are the property of their respective owners. This project is not affiliated with, endorsed by, or sponsored by Embarcadero Technologies, Inc.