Pop\Pdf\Pdf::openLayer PHP Method

    public function openLayer()
    {
        $co_index = $this->getContentObject();
        $this->objects[$co_index]->setStream("\nq\n");
        return $this;
    }

<?php

require_once '../../bootstrap.php';
use Pop\Color\Space\Rgb;
use Pop\Pdf\Pdf;
try {
    $pdf = new Pdf('doc.pdf');
    $pdf->addPage('Letter');
    $pdf->openLayer();
    $pdf->setFillColor(new Rgb(255, 10, 25))->drawArc(300, 300, 120, 340, 200, 100)->setFillColor(new Rgb(25, 10, 255))->drawArc(310, 290, 35, 92, 200, 100)->setFillColor(new Rgb(25, 255, 10))->drawArc(310, 295, 5, 25, 200, 100);
    $pdf->closeLayer();
    $pdf->setFillColor(new Rgb(0, 0, 0));
    $pdf->addFont('Arial');
    $pdf->addText(200, 15, 18, 'Hello World!', 'Arial');
    $pdf->setFillColor(new Rgb(0, 128, 255));
    $pdf->drawRectangle(300, 600, 100, 50);
    $pdf->addText(50, 300, 36, 'Hello World 2!', 'Arial');
    $pdf->setFillColor(new Rgb(0, 128, 100));
    $pdf->drawRectangle(300, 375, 250, 75);
    $pdf->output();
} catch (\Exception $e) {
    echo $e->getMessage();
}