方法已经放在下面了：
/**
* 添加图片水印
*
* @param $picPath
* @param $logoPath
*/
private function _addWaterMark($picPath, $logoPath)
{
//如果图片不存在或者logo不存在则不处理
if (!file_exists($picPath) || !file_exists($logoPath)) {
return;
}
//创建图片的实例
$im = imagecreatefromstring(file_get_contents($picPath));
//获取水印源
$watermark = imagecreatefromstring(file_get_contents($logoPath));
//获取图、水印 宽高类型
list($bgWidth, $bgHight, $bgType) = getimagesize($picPath);
list($logoWidth, $logoHight, $logoType) = getimagesize($logoPath);
//定义平铺数据
$xLength = $bgWidth - 10; //x轴总长度
$yLength = $bgHight - 10; //y轴总长度
//创建透明画布 伪白色
$opacity = 15;
$w = imagesx($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 < $xLength; $x++) {
for ($y = 0; $y < $yLength; $y++) {
imagecopymerge($im, $cut, $x, $y, 0, 0, $logoWidth, $logoHight, $opacity);
$y += $logoHight;
}
$x += $logoWidth;
}
imagejpeg($im, $picPath);
imagedestroy($im);
}
效果如下：
