Draws a rectangle given two coordinates and using the current stroke, stroke width, and fill settings.
function rectangle($strokeColor, $fillColor, $backgroundColor)
{
    $draw = new \ImagickDraw();
    $strokeColor = new \ImagickPixel($strokeColor);
    $fillColor = new \ImagickPixel($fillColor);

    $draw->setStrokeColor($strokeColor);
    $draw->setFillColor($fillColor);
    $draw->setStrokeOpacity(1);
    $draw->setStrokeWidth(2);

    $draw->rectangle(200, 200, 300, 300);
    $imagick = new \Imagick();
    $imagick->newImage(500, 500, $backgroundColor);
    $imagick->setImageFormat("png");

    $imagick->drawImage($draw);

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