PHP平铺水印

$bigImgPath = "logo.png"; //原图
$logo = "logo2.png"; //水印
$im = imagecreatefromstring(file_get_contents($bigImgPath));
//获取水印源
$watermark = imagecreatefromstring(file_get_contents($logo));
//获取图、水印 宽高类型
list($bgWidth, $bgHight, $bgType) = getimagesize($bigImgPath);
list($logoWidth, $logoHight, $logoType) = getimagesize($logo);
//定义平铺数据
$x_length = $bgWidth - 10; //x轴总长度
$y_length = $bgHight - 10; //y轴总长度
//创建透明画布 伪白色
$opacity=20;
$w = imagesx($watermark);
$h = imagesy($watermark);
$cut = imagecreatetruecolor($w,$h);
$white = imagecolorallocatealpha($cut, 255,255,255,0);
imagefill( $cut, 0, 0, $white );
//整合水印
imagecopy($cut, $watermark, 0, 0, 0, 0, $w, $h);
//循环平铺水印
for ($x = 0; $x < $x_length; $x) {
for ($y = 0; $y < $y_length; $y) {
imagecopymerge($im, $cut, $x, $y, 0, 0, $logoWidth, $logoHight, $opacity);
$y += $logoHight;
}
$x += $logoWidth;
}
header("Content-type:image/png");
imagejpeg($im);
die;