PHP barcode generation package class

<?php
// 引用class文件夹对应的类
require_once(&#39;class/BCGFontFile.php&#39;);
require_once(&#39;class/BCGColor.php&#39;);
require_once(&#39;class/BCGDrawing.php&#39;);
  
// 条形码的编码格式
require_once(&#39;class/BCGcode39.barcode.php&#39;);
  
// 加载字体大小
$font = new BCGFontFile(&#39;./class/font/Arial.ttf&#39;, 18);
  
//颜色条形码
$color_black = new BCGColor(0, 0, 0);
$color_white = new BCGColor(255, 255, 255);
  
$drawException = null;
try {
    $code = new BCGcode39();
    $code->setScale(2); 
    $code->setThickness(30); // 条形码的厚度
    $code->setForegroundColor($color_black); // 条形码颜色
    $code->setBackgroundColor($color_white); // 空白间隙颜色
    $code->setFont($font); // 
    $code->parse(&#39;HELLO&#39;); // 条形码需要的数据内容
} catch(Exception $exception) {
    $drawException = $exception;
}
  
//根据以上条件绘制条形码
$drawing = new BCGDrawing(&#39;&#39;, $color_white);
if($drawException) {
    $drawing->drawException($drawException);
} else {
    $drawing->setBarcode($code);
    $drawing->draw();
}
  
// 生成PNG格式的图片
header(&#39;Content-Type: image/png&#39;);
  
  
$drawing->finish(BCGDrawing::IMG_FORMAT_PNG);
?>