OpenResty+lua+GraphicsMagick生成缩略图

1、安装GraphicsMagick

下载地址：http://www.graphicsmagick.org/

安装支持包：下载地址：ftp://ftp.graphicsmagick.org/pub/GraphicsMagick/delegates/
直接上传
libjpeg-6b.tar.gz
libpng-1.6.16.tar.gz
到/usr/local/software下。

tar zxvf libjpeg-6b.tar.gz
cd cd libjpeg-6b
./configure
make
make install

tar zxvf libpng-1.6.16.tar.gz
./configure
make
make install

tar zxvf GraphicsMagick-1.3.20.tar.gz
cd GraphicsMagick-1.3.20
./configure
make
make install
安装依赖包Ghostscript，不安装的话加水印会找不到字体

yum install -y ghostscript

为目标加权限
chmod 777 /usr/local/openresty/nginx/html/down/PersonImg -R

2、配置nginx.conf

        location /down/PersonImg
        {
            set $image_root /usr/local/openresty/nginx/html;
            set $file "$image_root$uri";
           #判断目标文件是不是存在？
           if (!-f $file)
           {
            rewrite_by_lua
            '
                ngx.header.content_type = "text/plain;charset=utf-8"
                local index = string.find(ngx.var.uri, "([0-9]+)w_([0-9]+)h_");
                if(index==nil) then return
                end;

                local originalUri = string.sub(ngx.var.uri, 0, index-2);

                local area = string.sub(ngx.var.uri, index);
                index = string.find(area, "([.])");
                area = string.sub(area, 0, index-1);

                index = string.find(area, "w_");
                local w=string.sub(area,0,index-1);
                local index_h = string.find(area, "h_");
                local h=string.sub(area,index+2,index_h-1);

                area=tostring(w).."x"..tostring(h);
                local image_sizes = {"140x140", "800x800", "90x90"};

                function table.contains(table, element)
                    for _, value in pairs(table) do
                        if value == element then
                            return true
                        end
                    end
                    return false
                end
                if table.contains(image_sizes, area) then
                    local command = "/usr/local/bin/gm convert " .. ngx.var.image_root .. originalUri .. " -thumbnail " .. area .. " -gravity center -extent " .. area .. " " .. ngx.var.file;
                   os.execute(command);

                else
                    ngx.exit(401)
                end
           ';
           }
                 alias /usr/local/openresty/nginx/html/down/PersonImg;
        }

3、
放文件：
/usr/local/openresty/nginx/html/down/PersonImg/3AFAE457-FDC8-27D3-E2B5-6C10A145A3A6.jpg

访问
http://10.10.3.178/down/PersonImg/3AFAE457-FDC8-27D3-E2B5-6C10A145A3A6.jpg@140w_140h_100q_1x.jpg

4、要加水印的话命令如下

/usr/local/GraphicsMagick/bin/gm convert /usr/local/openresty/nginx/html/down/PersonImg/3AFAE457-FDC8-27D3-E2B5-6C10A145A3A6.jpg -font ArialBold -pointsize 45 -fill red -draw "text 10,10 dsideal" /usr/local/openresty/nginx/html/down/PersonImg/3AFAE457-FDC8-27D3-E2B5-6C10A145A3A61111.jpg