PHP生成透明背景

代码直接运行即可

<?php
$im = imagecreatetruecolor("500","500");
imagealphablending($im, false);
imagesavealpha($im, true);
$white = imagecolorallocatealpha($im,255,255,255,127);
imagefill($im,0,0,$white);
imagepng($im,time().".png");
imagedestroy($im);
?>