Drawing in a PDF file

Question

I would like to draw in a PDF file.

Example: Open the PDF file and get such drawing tools like circle, square, text etc... Using these tools will draw shapes on the PDF

Answer 1

TCPDF (tcpdf.org) seems to handle PDF graphics methods.

Cf. examples/example_012.php:

// create new PDF document
$pdf = new TCPDF(PDF_PAGE_ORIENTATION, PDF_UNIT, PDF_PAGE_FORMAT, true, 'UTF-8', false);

// Line
$pdf->Text(5, 4, 'Line examples');
$pdf->Line(5, 10, 80, 30, $style);
$pdf->Line(5, 10, 5, 30, $style2);
$pdf->Line(5, 10, 80, 10, $style3);
// Rect
$pdf->Text(100, 4, 'Rectangle examples');
$pdf->Rect(100, 10, 40, 20, 'DF', $style4, array(220, 220, 200));
$pdf->Rect(145, 10, 40, 20, 'D', array('all' => $style3));

And its GitHub project tecnickcom/tcpdf indicated being 100% PHP.
However, this search shows it can create and modify a new PDF document. It might not be able to open and modify an existing one.