phpGD库-图片水印

用到的函数

//imagecopy
//1,2水印图和原图资源
//3,4 水印图的起始点坐标
//5,6 原图的起始点坐标
//7,8 宽高
//9 透明度 (0-100)
imagecopymerge($img , $water, $x, $y, 0, 0, $water_w, $water_h, 50);

案例

<?php 
header("content-type:text/html;chsrset=urf-8");
date_default_timezone_set("PRC");

function picMark ($src_img, $water_img, $postion=1)
{
//获取原图信息
$srcinfo = getimagesize($src_img);
//水印图信息
$waterinfo = getimagesize($water_img);
//判断
if (!$srcinfo || !$waterinfo) {
echo "非法图片";
return false;
}
//得到原图和水印图宽高
list($src_w, $src_h) = $srcinfo;
list($water_w, $water_h) = $waterinfo;
if (($water_w > $src_w) || ($water_h > $src_h)) {
echo "水印图过大";
return false;
}
list($src_type, $src_subtype) = explode('/', $srcinfo['mime']);
list($water_type, $water_subtype) = explode('/', $waterinfo['mime']);

//生成打开函数的名称
$open_src = 'imagecreatefrom'.$src_subtype;
$open_water = 'imagecreatefrom'.$water_subtype;
//保存图片的函数名
$save_img = 'image'.$src_subtype;

//水印位置
switch ($postion) {
    case 1:
        $x = 0;
        $y = 0;
        break;
    case 2:
        $x = $src_w /2 - $water_w/2;
        $y = 0;
        break;
    default:
    break;
}

//打开图片资源
$img = $open_src($src_img);
$water = $open_water($water_img);

imagecopymerge($img , $water, $x, $y, 0, 0, $water_w, $water_h, 50);

$ext = pathinfo($src_img, PATHINFO_EXTENSION);
//生成保存路径
$save_img_name = './cut/'.date('YmdHis').uniqid().'.'.$ext;
//保存图片
$save_img($img, $save_img_name);
//关闭
imagedestroy($img);
imagedestroy($water);

return $save_img_name;
}

echo picMark('./imgs/01.png', './imgs/qq.png',1);