Draw a COLR version 0 font in colour, and a colour font's plain glyphs from its outlines (#76)

src/Fonts/BlobReader.php

@@ -26,6 +26,14 @@ public function __construct($bytes)
 		$this->bytes = $bytes;
 	}
 
+	/**
+	 * @return int How many bytes there are to read
+	 */
+	public function length()
+	{
+		return strlen($this->bytes);
+	}
+
 	public function read($length)
 	{
 		$data = substr($this->bytes, $this->pos, $length);

src/Fonts/Color/BitmapSource.php

@@ -31,13 +31,12 @@ abstract class BitmapSource implements ColorGlyphSource
 	protected $scale;
 
 	/**
-	 * @param FileReader      $reader The font file
-	 * @param LoggerInterface $logger Told of a glyph the format has a bitmap for that cannot be drawn
+	 * @param ColorFontFile $file The font
 	 */
-	public function __construct(FileReader $reader, LoggerInterface $logger)
+	public function __construct(ColorFontFile $file)
 	{
-		$this->reader = $reader;
-		$this->logger = $logger;
+		$this->reader = $file->reader;
+		$this->logger = $file->logger;
 	}
 
 	/**

src/Fonts/Color/CbdtSource.php

@@ -2,10 +2,7 @@
 
 namespace Mpdf\Fonts\Color;
 
-use Mpdf\Fonts\FileReader;
 use Mpdf\Log\Context as LogContext;
-use Mpdf\TTFontFile;
-use Psr\Log\LoggerInterface;
 
 /**
  * Colour glyphs as PNG bitmaps, in CBDT with CBLC to index them: Noto Color Emoji's format.
@@ -39,16 +36,14 @@ class CbdtSource extends BitmapSource
 	private $subtables = [];
 
 	/**
-	 * @param TTFontFile      $font       The font, its table directory read
-	 * @param FileReader      $reader     The font file
-	 * @param int             $unitsPerEm
-	 * @param LoggerInterface $logger     Told of a bitmap in an image format mPDF does not draw
+	 * @param ColorFontFile $file The font, whose logger is told of a bitmap in an image format mPDF does
+	 *                            not draw
 	 */
-	public function __construct(TTFontFile $font, FileReader $reader, $unitsPerEm, LoggerInterface $logger)
+	public function __construct(ColorFontFile $file)
 	{
-		parent::__construct($reader, $logger);
-		$cblc = $font->getTablePosition('CBLC')[0];
-		list($cbdt, $cbdtLength) = $font->getTablePosition('CBDT');
+		parent::__construct($file);
+		$cblc = $file->table('CBLC')[0];
+		list($cbdt, $cbdtLength) = $file->table('CBDT');
 		$this->cbdtEnd = $cbdt + $cbdtLength;
 
 		$header = $this->reader->fieldsAt($cblc + 4, 4, 'N');
@@ -74,7 +69,7 @@ public function __construct(TTFontFile $font, FileReader $reader, $unitsPerEm, L
 		}
 
 		list($ppem, $array, $subtableCount) = $strike;
-		$this->scale = $unitsPerEm / $ppem;
+		$this->scale = $file->unitsPerEm / $ppem;
 
 		for ($i = 0; $i < $subtableCount; $i++) {
 			// The array ends with the file, if not before

src/Fonts/Color/ColorFontFile.php

@@ -0,0 +1,78 @@
+<?php
+
+namespace Mpdf\Fonts\Color;
+
+use Mpdf\Fonts\FileReader;
+use Mpdf\Fonts\GlyphOutline;
+use Mpdf\TTFontFile;
+use Psr\Log\LoggerInterface;
+
+/**
+ * An open font, as each ColorGlyphSource drawing it reads it: its tables, its file, the log a glyph
+ * that cannot be drawn is reported to, and its outlines, decoded once for every source that draws
+ * with them.
+ */
+class ColorFontFile
+{
+
+	/**
+	 * @var FileReader
+	 */
+	public $reader;
+
+	/**
+	 * @var LoggerInterface Told of a glyph the font has that cannot be drawn
+	 */
+	public $logger;
+
+	/**
+	 * @var int
+	 */
+	public $unitsPerEm;
+
+	/**
+	 * @var TTFontFile
+	 */
+	private $font;
+
+	/**
+	 * @var GlyphOutline|null
+	 */
+	private $outline;
+
+	/**
+	 * @param TTFontFile      $font       The font, its table directory read
+	 * @param FileReader      $reader     The font file
+	 * @param int             $unitsPerEm
+	 * @param LoggerInterface $logger     Told of a glyph the font has that cannot be drawn
+	 */
+	public function __construct(TTFontFile $font, FileReader $reader, $unitsPerEm, LoggerInterface $logger)
+	{
+		$this->font = $font;
+		$this->reader = $reader;
+		$this->unitsPerEm = $unitsPerEm;
+		$this->logger = $logger;
+	}
+
+	/**
+	 * @param string $tag
+	 *
+	 * @return int[] [where the table starts, its length], each 0 where the font has none
+	 */
+	public function table($tag)
+	{
+		return $this->font->getTablePosition($tag);
+	}
+
+	/**
+	 * @return GlyphOutline
+	 */
+	public function outline()
+	{
+		if ($this->outline === null) {
+			$this->outline = new GlyphOutline($this->font, $this->reader, $this->logger);
+		}
+
+		return $this->outline;
+	}
+}

src/Fonts/Color/ColorFormats.php

@@ -2,10 +2,7 @@
 
 namespace Mpdf\Fonts\Color;
 
-use Mpdf\Fonts\FileReader;
 use Mpdf\Mpdf;
-use Mpdf\TTFontFile;
-use Psr\Log\LoggerInterface;
 
 /**
  * The colour formats mPDF draws, and which of a font's it draws the font in.
@@ -18,6 +15,7 @@ class ColorFormats
 	 * carries several is drawn in
 	 */
 	const SOURCES = [
+		'COLRv0' => 'Mpdf\Fonts\Color\ColrV0Source',
 		'CBDT' => 'Mpdf\Fonts\Color\CbdtSource',
 		'sbix' => 'Mpdf\Fonts\Color\SbixSource',
 	];
@@ -66,8 +64,28 @@ public static function drawn(array $font, Mpdf $mpdf)
 	}
 
 	/**
-	 * Whether a font draws nothing in a document: its glyphs exist only in a colour format, and the
-	 * document may not draw colour. Its characters are left blank, unless a backup font has them.
+	 * What draws a font's glyphs in a document, each glyph by the first that has it: the format it is
+	 * drawn in, where the document may draw colour, then its outlines, where it has any
+	 *
+	 * @param array $font The font, as Mpdf::$fonts holds it
+	 * @param Mpdf  $mpdf The document
+	 *
+	 * @return string[] The ColorGlyphSource classes
+	 */
+	public static function sources(array $font, Mpdf $mpdf)
+	{
+		$format = self::drawn($font, $mpdf);
+		$sources = $format === '' ? [] : [self::SOURCES[$format]];
+		if (!empty($font['hasOutlines'])) {
+			$sources[] = 'Mpdf\Fonts\Color\OutlineSource';
+		}
+
+		return $sources;
+	}
+
+	/**
+	 * Whether a font written as Type3 draws nothing in a document: nothing draws its glyphs - see
+	 * sources() - so its characters are left blank, unless a backup font has them.
 	 *
 	 * @param array $font The font, as Mpdf::$fonts holds it
 	 * @param Mpdf  $mpdf The document
@@ -76,7 +94,7 @@ public static function drawn(array $font, Mpdf $mpdf)
 	 */
 	public static function blank(array $font, Mpdf $mpdf)
 	{
-		return !empty($font['colorFormats']) && self::drawable($font['colorFormats']) && !self::inColor($mpdf);
+		return !empty($font['colorFormats']) && self::drawable($font['colorFormats']) && !self::sources($font, $mpdf);
 	}
 
 	/**
@@ -93,20 +111,4 @@ public static function choose(array $fontFormats, $color)
 
 		return $formats ? reset($formats) : '';
 	}
-
-	/**
-	 * @param string          $format One of the keys of SOURCES
-	 * @param TTFontFile      $font   The font, its table directory read
-	 * @param FileReader      $reader The font file
-	 * @param int             $unitsPerEm
-	 * @param LoggerInterface $logger Told of a glyph the format has but mPDF cannot draw
-	 *
-	 * @return ColorGlyphSource
-	 */
-	public static function source($format, TTFontFile $font, FileReader $reader, $unitsPerEm, LoggerInterface $logger)
-	{
-		$class = self::SOURCES[$format];
-
-		return new $class($font, $reader, $unitsPerEm, $logger);
-	}
 }

src/Fonts/Color/ColrV0Source.php

@@ -0,0 +1,144 @@
+<?php
+
+namespace Mpdf\Fonts\Color;
+
+use Mpdf\Fonts\GlyphOutline;
+
+/**
+ * Colour glyphs as layers of outlines, in COLR version 0 with CPAL for their colours: Twemoji's
+ * format, and what a version 1 font carries for renderers that know only this.
+ *
+ * A colour glyph is a list of layers, each another glyph's outline filled in one colour of a
+ * palette, drawn bottom to top. A layer whose palette index is 0xFFFF is filled in the colour of the
+ * text, which is what a layer that sets no colour inside a Type3 glyph is drawn in, as is a layer
+ * naming a colour the palette does not have. The first palette is drawn.
+ *
+ * Every read is checked for coming up short - see FontReader::fieldsAt() - and a glyph whose layers
+ * run past the ones COLR counts draws nothing.
+ *
+ * @see https://learn.microsoft.com/en-us/typography/opentype/spec/colr
+ * @see https://learn.microsoft.com/en-us/typography/opentype/spec/cpal
+ */
+class ColrV0Source implements ColorGlyphSource
+{
+
+	const FOREGROUND = 0xFFFF;
+
+	/**
+	 * @var \Mpdf\Fonts\FileReader
+	 */
+	private $reader;
+
+	/**
+	 * @var GlyphOutline
+	 */
+	private $outline;
+
+	/**
+	 * @var int[][] Base glyph id => [its first layer record, how many layers]
+	 */
+	private $baseGlyphs = [];
+
+	/**
+	 * @var int Where the layer records start
+	 */
+	private $layers = 0;
+
+	/**
+	 * @var int How many layer records there are
+	 */
+	private $layerCount = 0;
+
+	/**
+	 * @var int[][] The first palette, each colour as [red, green, blue, alpha] from 0 to 255
+	 */
+	private $palette = [];
+
+	/**
+	 * @param ColorFontFile $file The font
+	 */
+	public function __construct(ColorFontFile $file)
+	{
+		$this->reader = $file->reader;
+		$this->outline = $file->outline();
+
+		// numBaseGlyphRecords, baseGlyphRecordsOffset, layerRecordsOffset, numLayerRecords
+		$colr = $file->table('COLR')[0];
+		$header = $this->reader->fieldsAt($colr + 2, 12, 'nbase/Nrecords/Nlayers/ncount');
+		if ($header === null) {
+			return;
+		}
+
+		list($baseCount, $records, $layers, $this->layerCount) = $header;
+		$this->layers = $colr + $layers;
+
+		// Each glyph id, its first layer and how many
+		$values = $this->reader->fieldsAt($colr + $records, $baseCount * 6, 'n*');
+		for ($i = 0; $values !== null && $i < 3 * $baseCount; $i += 3) {
+			$this->baseGlyphs[$values[$i]] = [$values[$i + 1], $values[$i + 2]];
+		}
+
+		$this->palette = $this->firstPalette($file->table('CPAL')[0]);
+	}
+
+	/**
+	 * @inheritdoc
+	 */
+	public function draw($glyph, GlyphResources $resources)
+	{
+		if (!isset($this->baseGlyphs[$glyph])) {
+			return null;
+		}
+
+		list($first, $count) = $this->baseGlyphs[$glyph];
+		$records = $first + $count > $this->layerCount ? null : $this->reader->fieldsAt($this->layers + $first * 4, $count * 4, 'n*');
+		if ($records === null) {
+			return null;
+		}
+
+		$content = '';
+		foreach (array_chunk($records, 2) as $layer) {
+			list($layerGlyph, $index) = $layer;
+			$path = $this->outline->path($layerGlyph);
+			if ($path === '') {
+				continue;
+			}
+
+			if ($index === self::FOREGROUND || !isset($this->palette[$index])) {
+				$content .= $path . "f\n";
+				continue;
+			}
+
+			list($red, $green, $blue, $alpha) = $this->palette[$index];
+			$content .= sprintf("q %s%.3F %.3F %.3F rg\n%sf\nQ\n", $alpha < 255 ? $resources->alpha($alpha / 255) . ' ' : '', $red / 255, $green / 255, $blue / 255, $path);
+		}
+
+		return $content === '' ? null : $content;
+	}
+
+	/**
+	 * @param int $cpal Where CPAL starts
+	 *
+	 * @return int[][] The first palette's colours, or none where CPAL has no palette or its first runs
+	 *                 past the colour records
+	 */
+	private function firstPalette($cpal)
+	{
+		// numPaletteEntries, numPalettes, numColorRecords, colorRecordsArrayOffset, colorRecordIndices[0]
+		$header = $this->reader->fieldsAt($cpal + 2, 12, 'nentries/npalettes/nrecords/Ncolors/nfirst');
+		if ($header === null || $header[1] === 0 || $header[4] + $header[0] > $header[2]) {
+			return [];
+		}
+
+		list($entries, , , $colors, $first) = $header;
+
+		// Each colour is stored blue, green, red, alpha
+		$bgra = $this->reader->fieldsAt($cpal + $colors + $first * 4, $entries * 4, 'C*');
+		$palette = [];
+		for ($i = 0; $bgra !== null && $i < 4 * $entries; $i += 4) {
+			$palette[] = [$bgra[$i + 2], $bgra[$i + 1], $bgra[$i], $bgra[$i + 3]];
+		}
+
+		return $palette;
+	}
+}