Zahlenstrahl (number line) & Brüche (fractions)

zahlenstrahl.php

<?php

require('fpdf.php'); // from fpdf.org

function BruchZahlenStrahl($pdf, $yOff) {
  $yBase = 2;
  $lnX1 = 20;
  $lnX2 = 200;
  $lineLength = $lnX2 - $lnX1;
  $lnY = $yOff * 14 + $yBase;
  $pdf->SetFont('Arial','',11);
  $pdf->Text($lnX1-10,$lnY, $yOff);
  $pdf->Line($lnX1, $lnY, $lnX2, $lnY);
  for ($part=0; $part<=$yOff; $part++) {
    $xPos = $lnX1 + ($part / $yOff) * $lineLength;
    $pdf->Line($xPos, $lnY-1, $xPos, $lnY+1);
    if ($part == 0 || $part == $yOff) {
      $pdf->SetFont('Arial','',10);
      $pdf->Text($xPos-1, $lnY-3, $part / $yOff);
      continue;
    }
    // Bruch
    $pdf->SetFont('Arial','',9);
    $pdf->Text($xPos-($part>9?2:1), $lnY-6, "$part");
    $pdf->Line($xPos-2, $lnY-5, $xPos+2, $lnY-5);
    $pdf->Text($xPos-($yOff>9?2:1), $lnY-2, "$yOff");
    // Dezimal
    $pdf->SetFont('Arial','',8);
    $pdf->Text($xPos-3.5, $lnY+4, sprintf("%.3f", $part / $yOff));
  }
}

$pdf = new FPDF('P','mm','A4');
$pdf->AddPage();
for ($i=1; $i<21; $i++) {
  BruchZahlenStrahl($pdf, $i);
}
$pdf->Output('F', 'zahlenstrahl.pdf');