buildMultiPagePdf function

Uint8List buildMultiPagePdf(int pageCount)

Builds a pageCount-page PDF; page N shows the text "Page N".

Implementation

Uint8List buildMultiPagePdf(int pageCount) {
  final objects = <String>[];
  final kids = [
    for (var i = 0; i < pageCount; i++) '${3 + i * 2} 0 R',
  ].join(' ');
  final fontNumber = 3 + pageCount * 2;
  objects.add('<< /Type /Catalog /Pages 2 0 R >>');
  objects.add('<< /Type /Pages /Kids [$kids] /Count $pageCount >>');
  for (var i = 0; i < pageCount; i++) {
    final content = 'BT /F1 24 Tf 72 720 Td (Page ${i + 1}) Tj ET';
    objects.add('<< /Type /Page /Parent 2 0 R /MediaBox [0 0 612 792] '
        '/Contents ${4 + i * 2} 0 R '
        '/Resources << /Font << /F1 $fontNumber 0 R >> >> >>');
    objects.add('<< /Length ${content.length} >>\nstream\n$content\nendstream');
  }
  objects.add('<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>');

  final buffer = StringBuffer('%PDF-1.4\n');
  final offsets = <int>[];
  for (var i = 0; i < objects.length; i++) {
    offsets.add(buffer.length);
    buffer.write('${i + 1} 0 obj\n${objects[i]}\nendobj\n');
  }
  final xrefOffset = buffer.length;
  buffer
    ..write('xref\n0 ${objects.length + 1}\n')
    ..write('0000000000 65535 f \n');
  for (final offset in offsets) {
    buffer.write('${offset.toString().padLeft(10, '0')} 00000 n \n');
  }
  buffer
    ..write('trailer\n<< /Size ${objects.length + 1} /Root 1 0 R >>\n')
    ..write('startxref\n$xrefOffset\n%%EOF\n');
  return ascii(buffer.toString());
}