Example

function polyline($strokeColor, $fillColor, $backgroundColor)
{
    $draw = new \ImagickDraw();

    $draw->setStrokeOpacity(1);
    $draw->setStrokeColor($strokeColor);
    $draw->setFillColor($fillColor);

    $draw->setStrokeWidth(5);

    $points = [
        ['x' => 40 * 5, 'y' => 10 * 5],
        ['x' => 20 * 5, 'y' => 20 * 5],
        ['x' => 70 * 5, 'y' => 50 * 5],
        ['x' => 60 * 5, 'y' => 15 * 5]
    ];

    $draw->polyline($points);

    $image = new \Imagick();
    $image->newImage(500, 300, $backgroundColor);
    $image->setImageFormat("png");
    $image->drawImage($draw);

    header("Content-Type: image/png");
    echo $image->getImageBlob();
}