README

Pure-object OpenType metadata, variable outlines, metrics and layout for PHP 8.3+.

OpenType belongs to PDFToolkit, while remaining independent of PDF: installing pdftoolkit/opentype installs no PDF package. Its names and structures follow the OpenType 1.9.1 specification.

Read individual TrueType/OTTO fonts, multilingual metadata and horizontal/vertical metrics; normalize user axes, evaluate variable metrics, assemble quadratic TrueType outlines and execute cubic CFF/CFF2 programs. GSUB substitutions and GPOS positioning use immutable script, language, feature, lookup, anchor and variation objects. Applications explicitly select instances and execution policies. There is no global registry or hidden file access.

composer require 'pdftoolkit/opentype:^0.3'

PHP 8.3 or newer and a 64-bit platform are required. There are no runtime package or extension dependencies. CI validates PHP 8.3, 8.4 and 8.5.

Follow the objects

use PDFToolkit\OpenType\Cmap\UnicodeCmapReader;
use PDFToolkit\OpenType\Sfnt\SfntReader;
use PDFToolkit\OpenType\Substitution\FeatureSelection;
use PDFToolkit\OpenType\Substitution\GlyphSequence;
use PDFToolkit\OpenType\Substitution\GsubReader;
use PDFToolkit\OpenType\Substitution\SubstitutionEngine;
use PDFToolkit\OpenType\Value\CodePoint;
use PDFToolkit\OpenType\Value\Tag;

// The application supplies bytes; the library does not open a file.
$font = (new SfntReader())->read($fontBytes);
$cmap = (new UnicodeCmapReader())->read($font->table(new Tag('cmap')), $font->glyphCount());
$input = new GlyphSequence([
    $cmap->glyphFor(new CodePoint(0x66)), // f
    $cmap->glyphFor(new CodePoint(0x66)), // f
    $cmap->glyphFor(new CodePoint(0x69)), // i
]);
$gsub = (new GsubReader())->read($font->table(new Tag('GSUB')), $font->glyphCount());
$selection = new FeatureSelection(new Tag('latn'), features: [new Tag('liga')]);
$result = (new SubstitutionEngine())->apply($gsub, $selection, $input);

The character map first maps Unicode scalars to this font's glyph IDs. The GSUB reader constructs its layout tables. The engine selects the language system and features, applies their lookups and returns a new glyph sequence. An ffi ligature is produced only if the font and selection define it. Source clusters remain available for subsequent text handling.

Guides follow each object contract:

The architecture, coverage, security policy and shared documentation describe the boundaries. API pages are generated from the exact published source.

Scope of 0.3

Mechanism	Implementation
Individual SFNT and cmap	TrueType/OTTO directories, checksums, Unicode 4/12/14 mappings
Metadata	Complete head/hhea/maxp/post, name 0/1, OS/2 0–5 and STAT 1.0–1.2 records
Axes and metrics	fvar/avar 1.0 normalization, horizontal/vertical metrics, native HVAR/VVAR/MVAR
TrueType geometry	Bounded loca/glyf decoding, composite assembly, quadratic paths, native gvar/cvar and explicit phantom metrics
CFF/CFF2 geometry	Bounded Type 2 programs and subroutines, cubic paths, explicit matrices, encodings and native blends
Layout	GSUB 1–8, GDEF, GPOS 1–9, all contextual formats, native variations and Device corrections
Device declarations	gasp recommendations, hdmx widths, LTSH thresholds and VDMX heights with explicit selection

The coverage inventory identifies 27 implemented table scopes, 4 partial tables and 19 pending tables. TrueType instruction execution, CFF hint application, color/bitmap/baseline/math/justification tables, legacy auxiliary tables, collections, WOFF/WOFF2, writing and subsetting remain absent. Executing an unhinted outline or metric instance does not write a static font. Preserved bytes do not establish semantic support.

The layout engines consume an already ordered glyph sequence. Complete Unicode shaping, bidirectional layout and rasterization need separate consumers. PDF embedding and HTML conversion retain their own explicit format contracts. The 0.x API may evolve between minor releases.

The supplied Adobe OTGuide.pdf is retained unchanged as a usage reference. Its original name, 13 pages and SHA-256 are recorded alongside it. Technical definitions use the official specification. The guide retains its original rights; MIT applies to the package code. The PDF and development fixtures are excluded from Composer distributions.

Development

composer install
composer check
php examples/substitution.php
php examples/manual-ligature.php
php examples/font-metrics.php
php examples/positioning.php
php examples/variable-layout.php
php examples/variable-outlines.php

The example uses a reproducible font authored for the tests and prints its glyph substitutions. Independent validators live in tools/. Release notes record each published version.

pdftoolkit / opentype

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README

Follow the objects

Scope of 0.3

Development