功能：
环境 Linux + Nginx + Php 在不修改现有的源代码与图片路径位置的情况下，达到通过传参宽高来动态输出对应大小的图片并缓存。图片的处理要求是通过传参宽高的算出可用最大宽高，得到原图宽高。尽可能不毁图，不填白，不失真。
实例：
100*100：https://www.caojiefeng.com/content/uploadfile/201711/ba911509726344.png?param=100y100
200*200：https://www.caojiefeng.com/content/uploadfile/201711/ba911509726344.png?param=200y200
400*400：https://www.caojiefeng.com/content/uploadfile/201711/ba911509726344.png?param=400y400
600*400：https://www.caojiefeng.com/content/uploadfile/201711/ba911509726344.png?param=600y400
代码：
//nginx伪静态规则如下：
//只要是带参数的图片均处理，不带参数显示原图
if ($args !~ "^$"){
set $rule_0 1$rule_0;
}
if ($rule_0 = "1"){
rewrite ^/([\s\S]*?)\.png(.*)$ /image.php?type=png&url=$1&m=$args last;
}
if ($args !~ "^$"){
set $rule_1 1$rule_1;
}
if ($rule_1 = "1"){
rewrite ^/([\s\S]*?)\.jpg(.*)$ /image.php?type=jpg&url=$1&m=$args last;
}
location ~* \.(gif|jpg|jpeg|png|css|js|ico)$ {
expires 30d;
error_page 404 =200 /default.png;
}
//image.php代码
<?php
header("Cache-Control: max-age=2592000");
header("Pragma: cache");
$offset = 30*60*60*24; // cache 1 month
$ExpStr = "Expires: ".gmdate("D, d M Y H:i:s", time() + $offset)." GMT";
header($ExpStr);
define('EMLOG_ROOT', dirname(__FILE__));
$imgurl = $_GET['url'].'.'.$_GET['type'];
$imgurl1 = EMLOG_ROOT.$imgurl;
$param = explode("y",$_GET['param']);
$width = $param[0];
$height = $param[1];
if(file_exists($imgurl1) || $width =='' || $height ==''){
exit('PARAM ERROR');
}
imagecropper($imgurl,$width,$height);
function imagecropper($source_path, $target_width, $target_height){
$source_info = getimagesize($source_path);
$source_width = $source_info[0];
$source_height = $source_info[1];
$source_mime = $source_info['mime'];
$source_ratio = $source_height / $source_width;
$target_ratio = $target_height / $target_width;
// 源图过高
if ($source_ratio > $target_ratio){
$cropped_width = $source_width;
$cropped_height = $source_width * $target_ratio;
$source_x = 0;
$source_y = ($source_height - $cropped_height) / 2;
}
// 源图过宽
elseif ($source_ratio < $target_ratio)
{
$cropped_width = $source_height / $target_ratio;
$cropped_height = $source_height;
$source_x = ($source_width - $cropped_width) / 2;
$source_y = 0;
}// 源图适中
else{
$cropped_width = $source_width;
$cropped_height = $source_height;
$source_x = 0;
$source_y = 0;
}
switch ($source_mime){
case 'image/gif':
$source_image = imagecreatefromgif($source_path);
break;
case 'image/jpeg':
$source_image = imagecreatefromjpeg($source_path);
break;
case 'image/png':
$source_image = imagecreatefrompng($source_path);
break;
default:
return false;
break;
}
$target_image = imagecreatetruecolor($target_width, $target_height);
$cropped_image = imagecreatetruecolor($cropped_width, $cropped_height);
// 裁剪
imagecopy($cropped_image, $source_image, 0, 0, $source_x, $source_y, $cropped_width, $cropped_height);
// 缩放
imagecopyresampled($target_image, $cropped_image, 0, 0, 0, 0, $target_width, $target_height, $cropped_width, $cropped_height);
//保存图片到本地(两者选一)
//$randNumber = mt_rand(00000, 99999). mt_rand(000, 999);
//$fileName = substr(md5($randNumber), 8, 16) .".png";
//imagepng($target_image,'./'.$fileName);
//imagedestroy($target_image);
//直接在浏览器输出图片(两者选一)
header('Content-Type: image/jpeg');
imagepng($target_image);
imagedestroy($target_image);
imagejpeg($target_image);
imagedestroy($source_image);
imagedestroy($target_image);
imagedestroy($cropped_image);
}
?>
评论
2条评论欧文斯 Lv.1
Chrome 74.0.3729.131 
Windows 回复
其实从未来迁移或者配置多域名的角度来看，使用相对路径好处远大于绝对路径。像我现在同时启用了 vircloud.net 和 blog.vircloud.net，如果使用据对路径，配置两个域名意义就不大了。
福建省福州市 联通
曹杰峰
Chrome 63.0.3239.132 
Windows 回复
回复了欧文斯：是的，当初我网站换域名的时候出现这个情况，改了好久的数据库后面看见这个，现在方便多了
浙江省杭州市 电信