# open-fcm

TypeScript parser and encoder for Brother ScanNCut FCM/VCM files.

## What's an FCM file?

FCM (and VCM) files are the native format for Brother ScanNCut cutting machines. They contain vector cut paths, thumbnails, and metadata. VCM files are specifically for print-and-cut workflows with registration marks.

## Quick Start

```typescript
import { readFcmFile, writeFcmFile } from "open-fcm";

// Parse an FCM file
const data = new Uint8Array(/* file bytes */);
const fcm = readFcmFile(data);

console.log(fcm.file_header.variant);  // "FCM" or "VCM"
console.log(fcm.cut_data.file_type);   // "Cut" or "PrintAndCut"
console.log(fcm.piece_table.pieces.length);

// Modify and re-encode
const output = writeFcmFile(fcm);
```

### SVG Path Conversion

```typescript
import { SvgPathParser, PathTool } from "open-fcm";

const parser = new SvgPathParser({ dpi: 72 });
const shapes = parser.parse("M 0,0 L 100,0 L 100,100 L 0,100 Z");

// Use shapes to build FCM paths
const path = {
  tool: PathTool.TOOL_CUT,
  shape: shapes[0],
  rhinestone_diameter: null,
  rhinestones: [],
};
```

### Registration Marks (Print-and-Cut)

```typescript
import { PageSizes, getFcmAlignmentMarks, generateRegistrationMarksSvg } from "open-fcm";

// Get mark positions for FCM alignment data
const marks = getFcmAlignmentMarks(PageSizes.LETTER);

// Generate SVG with registration marks for printing
const svg = generateRegistrationMarksSvg(PageSizes.LETTER);
```

### Thumbnail Generation

```typescript
import { generateThumbnail, generateBlankThumbnail } from "open-fcm";

// Generate thumbnail from paths (prevents machine reboots from invalid BMPs)
const thumbnail = generateThumbnail(paths);

// Or a blank white thumbnail
const blank = generateBlankThumbnail();
```

## API Overview

| Module | Purpose |
|--------|---------|
| `readFcmFile` / `writeFcmFile` | Parse and encode complete FCM files |
| `SvgPathParser` | Convert SVG path `d` attributes to FCM format |
| `generateThumbnail` | Create valid 88×88 monochrome BMP thumbnails |
| `getFcmAlignmentMarks` | Registration mark positions for print-and-cut |
| `generateRegistrationMarksSvg` | SVG output with Brother-compatible marks |

## Attribution

This is a TypeScript port inspired by the original Rust library:

- **[fcmlib](https://crates.io/crates/fcmlib)** by [justjanne](https://github.com/justjanne/fcmlib) — MPL 2.0 licensed, comprehensive FCM parser with examples
- **[fcmlib fork](https://github.com/markuryy/fcmlib)** — Adds SVG path parsing, registration marks, and a sticker sheet example for print-and-cut workflows

The original Rust implementation is more mature and battle-tested.

## Disclaimer

"Brother" and "ScanNCut" are trademarks of Brother Industries, Ltd. This project is not affiliated with, endorsed by, or sponsored by Brother. The FCM/VCM file format was reverse-engineered for interoperability purposes.

## See Also

- [Brother ScanNCut](https://www.brother-usa.com/scanNcut) — The cutting machines that use FCM files
- `scripts/make-sticker-sheet.ts` — Example script for generating print-and-cut files