DompdfAdapter¶

The DompdfAdapter class converts EPUB content into PDF using the Dompdf library (composer require dompdf/dompdf).

Dompdf needs the gd extension to embed PNG, GIF and WebP images; without it, converting a book that has such images throws a ConversionException ("The PHP GD extension is required"). TCPDF needs gd as well for PNG images with an alpha channel.

Key Methods¶

• __construct(array $styles = [], EpubDocumentLoader $loader = new EpubDocumentLoader(), ?PdfConversionOptions $options = null): Optional styling parameters (the options, such as limits, a contents page and a custom page size, are described in Converter; without options the adapter behaves as before, and with options fixed-layout books are refused unless allowFixedLayout is set):

  Style	Type	Default
  font	string	DejaVu Sans	A font family Dompdf knows.
  font_size	int or float	12	In points; greater than zero.
  paper_size	string	A4	A size Dompdf knows (any case), as in TCPDFAdapter.
  orientation	string	portrait	portrait or landscape.
  margin_top, margin_right, margin_bottom, margin_left	int or float	none	In mm (12.5 is fine; not negative), as in TCPDFAdapter. Without any margin option Dompdf keeps its own default margins; once one is given, sides that are not given are 0.

  The constructor throws an Exception for a style it does not know (the message lists the valid ones), a value of the wrong type (a numeric string is not a number), an unusable value (a negative margin, an unknown orientation) and a paper size Dompdf does not know (Dompdf itself would fall back to letter without a word).

  Fonts and languages: the default font is DejaVu Sans, which Dompdf ships and which covers Latin, Greek, Cyrillic, Hebrew and Arabic, not only Latin-1 like the PDF core fonts (Arial is mapped to Helvetica). Chinese, Japanese and Korean need a font installed in Dompdf: pass its family as font, which always wins. Books with page-progression-direction="rtl" in the spine, or (when the spine says nothing) with a primary language of ar, he, fa, ur, yi, ps, sd, ug or dv, get dir="rtl" on the generated <html> and <body>; the book's language is set as lang. Dompdf does not shape Arabic script, so Arabic letters are not joined.

  Embedded fonts: the fonts a book loads with @font-face are used. Obfuscated fonts (IDPF or Adobe, listed in META-INF/encryption.xml) are de-obfuscated in memory and handed to Dompdf as data: URIs, so nothing is written into the book; a font that cannot be de-obfuscated (an Adobe font in a book without a urn:uuid: identifier) is dropped. Dompdf loads only TrueType fonts (a src without format(), or format("truetype")). Dompdf keeps the fonts it loads in a font directory; each conversion gets a private temporary one, deleted afterwards, so books leave nothing in Dompdf's own lib/fonts and cannot change the fonts of later conversions.

  A DRM-protected book is refused with a ConversionException.

  Dompdf has no API to write a PDF outline (bookmarks), so use TCPDFAdapter when you need them; it follows the book's nested table of contents.

• convert(string $epubDirectory, string $outputPath): void: Renders every spine document in reading order, each on a new page, sets the PDF title and author from the EPUB metadata, and writes the PDF. Throws a ConversionException if the book cannot be read, Dompdf fails (its exception is kept as the previous exception) or the PDF cannot be written.

• buildHtml(string $epubDirectory): string: Returns the HTML document that convert() renders, e.g. for previews or debugging.

Dompdf runs with remote resources, PHP and JavaScript disabled and its file access limited to the book directory; see Converter.

Usage Example¶

use PhpEpub\ConversionException;
use PhpEpub\Converters\DompdfAdapter;

$dompdfAdapter = new DompdfAdapter([
    'font' => 'Times New Roman',
    'font_size' => 14,
    'paper_size' => 'A4',
    'orientation' => 'landscape',
]);

try {
    $dompdfAdapter->convert('/path/to/extracted/epub', '/path/to/output.pdf');
    echo "EPUB successfully converted to PDF.";
} catch (ConversionException $e) {
    echo "Conversion failed: " . $e->getMessage();
}