README

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.

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, zlib
• Composer

Installation

composer require tecnickcom/tc-lib-pdf-font

Quick Start

<?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:

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:

$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:

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:

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:

php util/convert.php --help

Bulk Conversion

For batch generation from the mirrored font set:

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

make deps
make help
make qa

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

Packaging

make rpm
make deb

For system packages, bootstrap with:

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

Contributing

Contributions are welcome. Please review CONTRIBUTING.md, CODE_OF_CONDUCT.md, and SECURITY.md.