Font

Glyphs

Use this section to check whether a font can display a character, to measure a glyph before placing text yourself, or to read its shape in order to draw it. A font maps Unicode codepoints to glyph identifiers through its cmap table; a glyph is the font-specific shape and set of measurements, and its identifier is valid only within that font, and only until a compact subset renumbers the glyphs.

  • Glyph metrics reads the advance width and side bearing, at the default or a selected weight.
  • Outlines reads and transforms the contour geometry.
  • Glyph names derives Unicode text from Adobe and Unicode-style glyph names.
  • Glyph counts explains slots, retained glyphs, and the counts a subset reports.

Resolve a character

Place a font at fonts/Inter-Regular.ttf and run this script beside vendor. The remaining examples continue with the same $font:

<?php

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

use Alto\Font\Font;

$font = Font::fromFile(__DIR__.'/fonts/Inter-Regular.ttf');
$glyphId = $font->glyphIdForCodepoint(0x00E9); // é

echo null === $glyphId ? "é is missing\n" : "é is available\n";

glyphIdForCodepoint() returns null when the font's character map has no entry. It does not perform font fallback.

When working with one character, glyphMetrics() resolves it and reports a clear failure if it is absent:

<?php

$metrics = $font->glyphMetrics('A');

printf("Glyph: %d\n", $metrics->glyphId->value);
printf("Advance: %d\n", $metrics->advanceWidth);
printf("Side bearing: %d\n", $metrics->leftSideBearing);

Passing invalid UTF-8, an empty string, or more than one Unicode code point raises InvalidTextException. A valid character absent from the font raises GlyphNotFoundException. Use the explicit code-point method when absence is expected.

Contracts

  • glyphIdForCodepoint(int $codepoint): ?GlyphId finds the face-specific identifier for one Unicode codepoint and returns null when the character map has no entry.
  • glyphMetrics(GlyphId|string $glyph): GlyphMetrics reads horizontal metrics from an identifier or one Unicode character. See Glyph metrics.
  • glyphOutline(GlyphId $glyphId): GlyphOutline reads neutral contour geometry using an identifier from this face. See Outlines.

GlyphId::$value is a non-negative integer. A glyph identifier is specific to its font; do not reuse it with another face or after compact subsetting. glyphMetrics() throws InvalidTextException for invalid UTF-8, empty text, or more than one codepoint, and GlyphNotFoundException for a missing character. Identifier-based reads can throw InvalidFontException for an out-of-range identifier or malformed glyph data, and UnsupportedFontException for unsupported outline structures.