# tc-lib-pdf-font > Font import, metrics, and stack management utilities for PDF generation. 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[Sponsor its maintenance →](https://github.com/sponsors/tecnickcom) --- ## Overview `tc-lib-pdf-font` provides font import and runtime font-stack services used by PDF composition engines. It handles font metrics, encodings, and font program references, turning static font assets into the definition files and PDF objects a document needs. | | | |---|---| | **Namespace** | `\Com\Tecnick\Pdf\Font` | | **Author** | Nicola Asuni | | **License** | [GNU LGPL v3](https://www.gnu.org/copyleft/lesser.html) - see [LICENSE](LICENSE) | | **API docs** | | | **Packagist** | | --- ## 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 - Glyph index encoding of composite fonts, with support for the supplementary planes --- ## Requirements - PHP 8.2 or later - Extensions: `json`, `zlib` - Composer --- ## Installation ```bash composer require tecnickcom/tc-lib-pdf-font ``` --- ## Quick Start ```php getFontMetrics(); var_dump($font->getFontName(), $metrics['type']); ``` For larger examples, refer to `test/OutputTest.php` and the conversion tooling in this repository. --- ## Character Encoding of Composite Fonts A `TrueTypeUnicode` font is emitted as a composite (Type0) font with the `Identity-H` encoding, so every character code in a content stream is 2 bytes wide. The character code is the glyph index of the font (`CID == GID`): the font dictionary declares `/CIDToGIDMap /Identity`, the `/W` array is keyed by glyph index, and a `/ToUnicode` CMap is generated for the glyphs used by the document so that the text stays searchable and extractable. ### Encoding a string The consumer of this library must encode composite text through the font stack, so that the glyphs used are recorded for the `/W` array and the `/ToUnicode` CMap: ```php $stack = new \Com\Tecnick\Pdf\Font\Stack(1.0); $stack->insert($objnum, 'dejavusans', '', 12); if ($stack->isCurrentGidEncoded()) { // 2-byte big-endian glyph indices, and the glyphs are recorded on the font $codes = $stack->ordArrToGidStr([0x41, 0x20, 0x1D703]); } else { // CID-0 fonts keep the UTF-16BE encoding expected by their predefined CMap $codes = $uniconv->toUTF16BE($str); } ``` The text object written to the page must also select the font the string was encoded with, otherwise the glyph indices are resolved against a different font. This does not apply to the fonts that are not GID encoded, whose character codes mean the same thing in every font. Relevant methods: - `Stack::isCurrentGidEncoded()`: true when the current font encodes text as glyph indices. - `Stack::ordArrToGidStr(array $uniarr)`: encodes codepoints as 2-byte glyph indices and records them. - `Stack::getGidForOrd(int $ord)`: glyph index of a codepoint, `0` when the font has no glyph for it. - `Buffer::addUsedGid(string $key, int $gid, int $ord)`: records a glyph and the codepoint it was encoded from. ### Font definition files The glyph index of a codepoint is read at runtime from the `.ctg.z` artifact of the font, which covers the whole Basic Multilingual Plane. The file must remain next to the `.json` definition file. Codepoints above U+FFFF do not fit that table and are stored in the definition file under the `ctgu` key: ```json "ctgu": {"120579": 1588, "119886": 941} ``` That key is only written when the font is converted with `--encoding_id=10`, which selects the format 12 cmap subtable. --- ## 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), every subset is recomputed. The library never evicts entries: the injected backend owns expiration and size limits. The cache key 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. A wrapper around any backend (PSR-16/PSR-6, Symfony Cache, Laravel, Redis, APCu) 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 {}()/\@:, so the raw key is hashed into a legal, fixed-length one. */ private function normalize(string $key): string { return 'tclpf_' . \sha1($key); } } ``` The raw key of the library is human-readable and works with permissive backends, while stricter PSR-16 implementations may reject or mangle it. 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=10 \ --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`). Use `--encoding_id=10` to read the format 12 subtable, which is required for the characters above U+FFFF. It is a safe default: a font without that subtable falls back to the BMP one. - `--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, run from a clone of this repository: ```bash php util/build_fonts.php ``` The script: 1. Installs the library dependencies with `composer install --no-dev` when no Composer autoloader is found. 2. Installs the `util` dependencies, which download the font sources from GitHub. 3. Clears `target/fonts/`. 4. Runs `bulk_convert.php`, which scans the mirror package and writes converted fonts under `target/fonts/`. It requires PHP, Composer and network access. It does not need make or a POSIX shell, so it also runs on Windows. In a repository clone the same step is available as `composer fonts` and `make fonts`. When the package is installed as a dependency, run the script from its location in the vendor directory, for example from the project root: ```bash php vendor/tecnickcom/tc-lib-pdf-font/util/build_fonts.php ``` The fonts are written to `vendor/tecnickcom/tc-lib-pdf-font/target/fonts/`. Composer replaces the package directory on update or reinstall, which removes them, so run the script again afterwards. Notes: - `build_fonts.php` takes no options. To write the fonts to another directory, run `php util/bulk_convert.php --outpath=/your/path/` after `build_fonts.php` has installed the `util` dependencies at least once. - `bulk_convert.php` also attempts OTF conversion via FontForge (`fontforge -script otf2ttf.ff ...`) before import. Without FontForge, OTF files are reported and skipped. The mirrored font set contains no OTF files. --- ## Upgrading from 3.x to 4.0 Version 4.0 changes the character codes emitted for `TrueTypeUnicode` fonts from Unicode codepoints to glyph indices, as described in [Character Encoding of Composite Fonts](#character-encoding-of-composite-fonts). A consumer of this library must be updated together with it: - Encode composite text with `Stack::ordArrToGidStr()` instead of writing UTF-16BE codepoints, and make the text object select the font the string was encoded with. A consumer that keeps writing codepoints produces PDFs whose text renders as unrelated glyphs, with no error raised. - A `TrueTypeUnicode` font emits one PDF object less, since the `CIDToGIDMap` stream is not embedded any more. Baselines that compare PDF output byte by byte, or that assert on object numbers, must be regenerated. - The `TFontData` shape gained the `ctgu`, `gidenc` and `usedgid` keys. Code that builds that array must add them. Unchanged: - No method was removed or changed signature. The new members are additions. - Font definition files and `.ctg.z` artifacts generated by 3.x keep working for the whole Basic Multilingual Plane. Regenerate a font only to gain the characters above U+FFFF, with `--encoding_id=10`. - The output of `Core`, `TrueType`, `Type1` and `cidfont0` fonts is unchanged. --- ## Development ```bash make deps make fonts make help make qa ``` `make fonts` runs the [Bulk Conversion](#bulk-conversion). The unit tests require the generated 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).