# tc-lib-pdf-font

> Font import, metrics, and stack management utilities for PDF generation.

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---

## Overview

`tc-lib-pdf-font` provides font import and runtime font-stack services used by PDF composition engines.

It bridges static font assets and runtime document composition by handling metrics, encodings, and font program references in a PDF-friendly way. This modular design lets applications evolve font workflows independently from the rest of the rendering stack.

| | |
|---|---|
| **Namespace** | `\Com\Tecnick\Pdf\Font` |
| **Author** | Nicola Asuni <info@tecnick.com> |
| **License** | [GNU LGPL v3](https://www.gnu.org/copyleft/lesser.html) - see [LICENSE](LICENSE) |
| **API docs** | <https://tcpdf.org/docs/srcdoc/tc-lib-pdf-font> |
| **Packagist** | <https://packagist.org/packages/tecnickcom/tc-lib-pdf-font> |

---

## Features

### Font Processing
- Import support for core, Type1, and TrueType sources
- Font metadata extraction and normalization
- Utilities for subset and output dictionary generation
- Optional injectable cache to reuse computed TrueType font subsets

### Runtime Font Stack
- Font stack insertion and switching
- Glyph width/bounding-box helpers
- Character replacement and fallback handling

---

## Requirements

- PHP 8.2 or later
- Extensions: `json`, `pcre`, `zlib`
- Composer

---

## Installation

```bash
composer require tecnickcom/tc-lib-pdf-font
```

---

## Quick Start

```php
<?php

require_once __DIR__ . '/vendor/autoload.php';

$font = new \Com\Tecnick\Pdf\Font\Import('/path/to/font.ttf');
$metrics = $font->getFontMetrics();

var_dump($font->getFontName(), $metrics['type']);
```

For larger examples, refer to `test/OutputTest.php` and the conversion tooling in this repository.

---

## Subset Caching

TrueType font subsetting is computational and memory intensive. When the same
fonts and character sets are embedded repeatedly (for example across many
generated documents), you can inject an optional cache into
`\Com\Tecnick\Pdf\Font\Output` to reuse previously computed subset programs.

Provide any object implementing
`\Com\Tecnick\Pdf\Font\FontSubsetCacheInterface`:

```php
interface FontSubsetCacheInterface
{
    public function get(string $key): ?string;          // null on cache miss
    public function set(string $key, string $subsetFont): void;
}
```

Pass it as the last constructor argument:

```php
$output = new \Com\Tecnick\Pdf\Font\Output(
    $fonts,
    $objectNumber,
    $encrypt,
    $fileHelper,   // or null
    $subsetCache,  // your FontSubsetCacheInterface implementation
);
```

When no cache is supplied (the default), behavior is unchanged and every
subset is recomputed. The library never evicts entries — the injected backend
owns expiration and size limits. The cache key already accounts for the font
program bytes, the cmap-selection metrics, and the requested subset
characters, so distinct inputs never collide.

### Using a PSR-16 cache

No PSR-16 adapter is bundled, because the interface above is intentionally
trivial to wrap around any backend (PSR-16/PSR-6, Symfony Cache, Laravel,
Redis, APCu, …). A correct PSR-16 wrapper is a few lines:

```php
use Com\Tecnick\Pdf\Font\FontSubsetCacheInterface;
use Psr\SimpleCache\CacheInterface;

final class Psr16SubsetCache implements FontSubsetCacheInterface
{
    public function __construct(private CacheInterface $cache) {}

    public function get(string $key): ?string
    {
        $value = $this->cache->get($this->normalize($key));

        return \is_string($value) ? $value : null;
    }

    public function set(string $key, string $subsetFont): void
    {
        $this->cache->set($this->normalize($key), $subsetFont);
    }

    /**
     * PSR-16 only guarantees keys matching [A-Za-z0-9_.] up to 64 chars and
     * reserves {}()/\@: — the library's raw key uses ':' and '-' and is longer,
     * so hash it into a guaranteed-legal, fixed-length key.
     */
    private function normalize(string $key): string
    {
        return 'tclpf_' . \sha1($key);
    }
}
```

The `normalize()` step matters: the library's raw key is human-readable and
works with permissive backends, but stricter PSR-16 implementations may reject
or mangle it. Hashing it keeps the wrapper portable. Note that hashing discards
the readable namespace, so scope the underlying PSR-16 pool to this library if
you share it with other consumers.

---

## Converting Existing Fonts

Use the CLI utilities in `util/` to convert existing font files into the JSON/Z format consumed by this library.

### Convert One or More Fonts

Run `util/convert.php` and pass one or more input files with `--fonts`:

```bash
php util/convert.php \
	--outpath=./target/fonts/custom/ \
	--type=TrueTypeUnicode \
	--flags=32 \
	--encoding_id=1 \
	--fonts=/path/to/MyFont-Regular.ttf,/path/to/MyFont-Bold.ttf
```

The command writes generated font definition files to `--outpath`.

Common options:

- `--type`: Explicit font type (`TrueTypeUnicode`, `TrueType`, `Type1`, `CID0JP`, `CID0KR`, `CID0CS`, `CID0CT`). Leave empty for autodetect.
- `--encoding`: Encoding table (for example `cp1252` for many non-Unicode Type1/Core cases). Omit for Unicode and symbolic fonts.
- `--flags`: PDF descriptor flags. Default is `32` (non-symbolic).
- `--platform_id` and `--encoding_id`: CMAP selection for TrueType Unicode imports (defaults: `3` and `1`).
- `--linked`: Link to system font file instead of embedding/copying it (not transportable).

To see full usage help:

```bash
php util/convert.php --help
```

### Bulk Conversion

For batch generation from the mirrored font set:

```bash
cd util
make build
```

This installs `util` dependencies and runs `bulk_convert.php`, which scans the mirror package and writes converted fonts under `target/fonts/`.

Notes:

- `bulk_convert.php` also attempts OTF conversion via FontForge (`fontforge -script otf2ttf.ff ...`) before import.
- If you run bulk conversion directly, customize destination with `php util/bulk_convert.php --outpath=/your/path/`.

---

## Development

```bash
make deps
make help
make qa
```

Font generation helpers are also available through Make targets such as `fonts`.

---

## Packaging

```bash
make rpm
make deb
```

For system packages, bootstrap with:

```php
require_once '/usr/share/php/Com/Tecnick/Pdf/Font/autoload.php';
```

---

## Contributing

Contributions are welcome. Please review [CONTRIBUTING.md](CONTRIBUTING.md), [CODE_OF_CONDUCT.md](CODE_OF_CONDUCT.md), and [SECURITY.md](SECURITY.md).

