title: imagecreatefrompng() Makes a black background instead of transparent?
body: <p>I make thumbnails using PHP and GD library but my code turn png transparency into a solid black color, Is there a solution to improve my code?</p>
  
  <p>this is my php thumbnail maker code:</p>
  
  <pre><code>function cropImage($nw, $nh, $source, $stype, $dest) {
       $size = getimagesize($source);
       $w = $size[0];
        $h = $size[1];
  
        switch($stype) {
            case 'gif':
            $simg = imagecreatefromgif($source);
            break;
            case 'jpg':
            $simg = imagecreatefromjpeg($source);
            break;
            case 'png':
            $simg = imagecreatefrompng($source);
            break;
        }
  
        $dimg = imagecreatetruecolor($nw, $nh);
        $wm = $w/$nw;
        $hm = $h/$nh;
        $h_height = $nh/2;
        $w_height = $nw/2;
  
        if($w&gt; $h) {
            $adjusted_width = $w / $hm;
            $half_width = $adjusted_width / 2;
            $int_width = $half_width - $w_height;
            imagecopyresampled($dimg,$simg,-$int_width,0,0,0,$adjusted_width,$nh,$w,$h);
        } elseif(($w &lt;$h) || ($w == $h)) {
            $adjusted_height = $h / $wm;
            $half_height = $adjusted_height / 2;
            $int_height = $half_height - $h_height;
  
            imagecopyresampled($dimg,$simg,0,-$int_height,0,0,$nw,$adjusted_height,$w,$h);
        } else {
            imagecopyresampled($dimg,$simg,0,0,0,0,$nw,$nh,$w,$h);
        }
  
        imagejpeg($dimg,$dest,100);
  }
  </code></pre>
  
  <p>Thank you</p>