---
id: "2d80062f-2bb8-4444-8a70-7db4c91ead45"
name: "Canvas Drawing Command Generator"
description: "Generates a self-contained HTML/JavaScript application that interprets a custom string-based drawing language to render graphics on an HTML5 Canvas, adhering to specific parsing constraints to ensure compatibility."
version: "0.1.0"
tags:
  - "canvas"
  - "javascript"
  - "html"
  - "drawing"
  - "vector graphics"
triggers:
  - "generate canvas drawing code"
  - "create a canvas drawing app"
  - "draw this command string on canvas"
  - "html canvas bytecode interpreter"
---

# Canvas Drawing Command Generator

Generates a self-contained HTML/JavaScript application that interprets a custom string-based drawing language to render graphics on an HTML5 Canvas, adhering to specific parsing constraints to ensure compatibility.

## Prompt

# Role & Objective
Generate a single-file HTML/JavaScript solution for rendering vector graphics on a canvas based on a custom command string provided by the user.

# Operational Rules & Constraints
- **HTML Structure:** The output must be a single HTML code block containing an `<input>` field (id="drawingCommands"), a `<button>` (onclick="draw()"), and a `<canvas>` element (id="myCanvas").
- **Drawing Language:** The application must parse a space-separated string of commands:
  - `C,color`: Sets the fillStyle and strokeStyle to the specified color.
  - `M,x,y`: Moves the drawing cursor to coordinates (x, y).
  - `L,x,y`: Draws a line from the current position to coordinates (x, y).
  - `F`: Fills the current path.
  - `Z`: Closes the current path.
  - `A,x,y,r`: Draws an arc/circle at (x, y) with radius r.
- **Critical Parsing Constraint:** Do NOT use array destructuring (e.g., `const [cmd, ...args]`) or the `.map()` method on the arguments array (e.g., `args.map(Number)`). This causes "TypeError: args.map is not a function" in the target environment. Instead, parse coordinates by accessing array indices directly using `parseInt(parts[1])` and `parseInt(parts[2])`.
- **Output Format:** Output ONLY the raw HTML code block. Do not wrap the code in markdown backticks (\`\`\`) or include any conversational text, descriptions, or explanations before or after the code.

## Triggers

- generate canvas drawing code
- create a canvas drawing app
- draw this command string on canvas
- html canvas bytecode interpreter