php 图片的水印效果

这里我们实现一种水印的效果，微博，淘宝挺多这样的 于是就尝试写了一个方法

这里我们写代码：(postion是水印的位置，9个位置，不在之间随机存在)

<?php
/*
*@prame resource $bigImage
*@prame resource $smallImage
*@prame string $type;
*@prame string $path;
*@prame bool $isfileName
*@prame int $postion 
*@prame int $apahle
*
*
*/
function shuiyin($bigImage,$smallImage,$type ='png',$path = "path",$isfileName = true,$postion =5,$apahle=100){
    //打开两个图片
    $bigImageRes = open($bigImage);
    $smallImageRes = open($smallImage);
    //获取大图和小图的信息来为水印的位置做准备
    $bigImageInfo = getimagesize($bigImage);
    $smallImageInfo = getimagesize($smallImage);
    //位置
    switch($postion){
        case 1:
            $x = 0;
            $y = 0;
            break;
        case 2:
            $x = ($bigImageInfo[0]-$smallImageInfo[0])/2;
            $y = 0;
            break;
        case 3:
            $x = $bigImageInfo[0]-$smallImageInfo[0];
            $y = 0;
            break;
        case 4:
            $x = 0;
            $y = ($bigImageInfo[1]-$smallImageInfo[1])/2;
            break;
        case 5:
            $x = ($bigImageInfo[0]-$smallImageInfo[0])/2;
            $y = ($bigImageInfo[1]-$smallImageInfo[1])/2;
            break;
        case 6:
            $x = $bigImageInfo[0]-$smallImageInfo[0];
            $y = ($bigImageInfo[1]-$smallImageInfo[1])/2;
            break;
        case 7:
            $x = 0;
            $y= $bigImageInfo[1]-$smallImageInfo[1];
            break;
        case 8:
            $x = ($bigImageInfo[0]-$smallImageInfo[0])/2;
            $y = $bigImageInfo[1]-$smallImageInfo[1];
            break;
        case 9:
            $x = $bigImageInfo[0]-$smallImageInfo[0];
            $y = $bigImageInfo[1]-$smallImageInfo[1];
            break;
        default :
            $x = mt_rand(0,$bigImageInfo[0]-$smallImageInfo[0]);
            $y = mt_rand(0,$bigImageInfo[1]-$smallImageInfo[1]);
            break;
    }
    //合并图片
    imagecopymerge($bigImageRes,$smallImageRes,$x,$y,0,0,$smallImageInfo[0],$smallImageInfo[1],$apahle);
    //文件随机
    if($isfileName){
        $name = uniqid().'.'.$type;
    }else{
        $info = pathinfo($path);
        $name = $info['filename'].'.'.$type;
    }
    $path = rtrim($path,'/').'/'.$name;
    //输出图片
    $func = 'image'.$type;
    if(!function_exists($func)){
        return false;
    }
    $func($bigImageRes,$path);
    imagedestroy($bigImageRes);
    imagedestroy($smallImageRes);
    return $path;
}
function open($path){
    //判断文件是否存在
    if(!file_exists($path)){
        return '不存在';
    }
    $info = getimagesize($path);
    switch($info['mime']){
        case 'image/jpg':
        case 'image/jpeg':
        case 'image/jpe':
        case 'image/pjpeg':
            $res = imagecreatefromjpeg($path);
        break;

        case 'image/png':
            $res = imagecreatefrompng($path);
            break;
        case 'image/gif':
            $res = imagecreatefromgif($path);
            break;
    }
    return $res;
}
shuiyin('big.jpg','small.jpg');