使用在OTF字体中设置的stylistc将PHP文本转换为图像

Question

我尝试使用包含7个样式集的字体将文本输出到图像。我使用下面的代码，但无法找到如何在输出中使用样式。任何建议都将不胜感激。

<?php

header('Content-type: image/png');

// Create the image
$im = imagecreatetruecolor(400, 30);

// Create some colors
$white = imagecolorallocate($im, 255, 255, 255);
$grey = imagecolorallocate($im, 128, 128, 128);
$black = imagecolorallocate($im, 0, 0, 0);
imagefilledrectangle($im, 0, 0, 399, 29, $white);

// The text to draw
$text = 'This is a test!';

// Replace path by your own font path
$font = 'joined.otf';


// Add the text
imagettftext($im, 20, 0, 10, 20, $black, $font, $text);

// Using imagepng() results in clearer text compared with imagejpeg()
imagepng($im);
imagedestroy($im);

?>