在PHP中给图片添加图片水印

<?php
//判断GD库是否存在
if (function_exists('imagepng')) {
    dir('GD库不存在');
}

//图片路径
$imagePath = './img/a.jpg';
//图片信息
$imageInfo = getimagesize($imagePath);
//图片扩展名
$imageExtension = image_type_to_extension($imageInfo[2], false);
//获取图片
$func = 'imagecreatefrom' . $imageExtension;
$image = $func($imagePath);
//获取水印图片
$watermarkPath = './img/logo.png';
$watermarkInfo = getimagesize($watermarkPath);
$watermarkExtension = image_type_to_extension(getimagesize($watermarkPath)[2], false);
$func = 'imagecreatefrom' . $watermarkExtension;
$watermark = $func($watermarkPath);
//添加图片水印
imagecopymerge($image, $watermark, 10, 10, 0, 0, $watermarkInfo[0], $watermarkInfo[1], 100);
//销毁水印图片
imagedestroy($watermark);
//输出图片
header('Content-Type:' . $imageInfo['mime']);
$func = 'image' . $imageExtension;
$func($image);
//销毁图片
imagedestroy($image);