Piet Editor

by Galacticica

Repository: https://github.com/Galacticica/vscode-piet

Create, edit, debug, and run Piet programs inside VS Code.

A .piet file is a PNG image stored at one pixel per codel. Opening one shows a paintable color grid instead of an image preview.

Features

• Grid editor for .piet files: pencil (click/drag) and paint-bucket (fill a block) tools with the 20 Piet colors; right-click picks up a color from the grid.
• Configurable grid size — resize the grid at any time from the toolbar (content is preserved).
• Authoring aids — palette swatches are labeled with the command each color gives relative to the selected color; the 👁 toggle draws those labels on the grid itself; the status bar shows the hovered block's size (the value push would push).
• Built-in debugger (DEBUGGER tab on the right edge): run animated at three speeds, pause, single-step, run to completion, stop; live view of the DP/CC, the stack, the last command, and program output; input can be entered before running; the current color block and codel are highlighted on the canvas. Set breakpoints with the 📌 tool — execution pauses when flow enters a marked cell's block. Arithmetic uses BigInt, so values never overflow.
• Import / Export toolbar buttons: load any Piet image into the grid (any codel size — it is normalized to one pixel per codel), or export a scaled PNG for sharing.
• ▶ Run in terminal via the editor title bar — programs run in a terminal tab on the extension's own interpreter (no Python or other tools needed), with interactive input: when the program executes in(num)/in(char) you type the value right in the terminal. Ctrl+C stops endless programs. Set piet.runCommand (e.g. uv run python piet/piet.py {file}) to use an external interpreter instead.
• Piet: New Piet File — create a blank grid of any size.
• Piet: Import PNG as .piet — convert an existing Piet image to a .piet file.

Building

npm install
npm run compile
npm run package        # produces piet-editor-<version>.vsix
code --install-extension piet-editor-0.3.3.vsix

Or open this folder in VS Code and press F5 for a development host.

Tests

npm test

Runs the suite under Node's built-in test runner (no extra dependencies):

• test/interpreter.test.js — PietVM semantics: every arithmetic/stack command (with sign edge cases), BigInt precision, termination rules, interactive input, and full runs of the bundled hi/fibonnaci programs (checked through fib(100)).
• test/png.test.js — PNG codec: encode/decode round trips at several codel sizes, plus decoding of Pillow-generated fixtures (filtered RGB, 8-bit and 4-bit palette, grayscale) verified pixel-for-pixel against Pillow's own output.
• test/runner.test.js — the terminal runner with a stubbed VS Code API: codel-size detection, program completion, output throttling, interactive input echo, and Ctrl+C handling.