Erlang/Elixir: 使用 OpenCV, Python 搭建图片缩略图服务器

时间  2021-01-02
标签 图片 服务器 python 栏目 Python 繁體版
原文   原文链接

这篇文章是在OSX上测试和运行的的, Ubuntu下的安装和配置请移步到这里

应用程序进程树, 默认 Poolboy 中初始化10个用于处理图片的 Python 工作进程(Worker)

首先安装OpenCV需要的工具包

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ruby - e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
brew install python
brew tap homebrew / science
brew install opencv
sudo pip install numpy
sudo pip install matplotlib

使用 Homebrew 的 Python 版本, 而不是 Mac OS X 系统自带的 Python

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alias python = '/usr/local/bin/python'

创建 Elixir 项目

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➜    mix new opencv_thumbnail_server -- sup
* creating README . md
* creating . gitignore
* creating mix . exs
* creating config
* creating config / config . exs
* creating lib
* creating lib / opencv_thumbnail_server . ex
* creating test
* creating test / test_helper . exs
* creating test / opencv_thumbnail_server_test . exs
 
Your Mix project was created successfully .
You can use "mix" to compile it , test it , and more :
 
     cd opencv_thumbnail_server
     mix test
 
Run "mix help" for more commands .

Elixir 模块

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require Logger
defmodule OpencvThumbnailServer do
   use Application
   def start ( _type , _args ) do
     Logger . info "Start opencv thumbnail server"
     OpencvThumbnailServer . Supervisor . start_link ( )
   end
end

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defmodule OpencvThumbnailServer . Supervisor do
   use Supervisor
 
   < a href = "http://www.jobbole.com/members/chkconfig" > @ config < / a > Application . get_env : opencv_thumbnail_server , : settings
 
   def start_link ( ) do
     Supervisor . start_link ( __MODULE__ , [ ] , name : { : global , __MODULE__ } )
   end
 
   def init ( [ ] ) do
     pool_options = @ config [ : poolboy ]
     { _ , name } = pool_options [ : name ]
     children = [
       : poolboy . child_spec ( name , pool_options , @ config [ : module_name ] )
     ]
     supervise ( children , strategy : : one_for_all , max_restarts : 1000 , max_seconds : 3600 )
   end
end

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defmodule OpencvThumbnailServer . Worker do
   use GenServer
   < a href = "http://www.jobbole.com/members/chkconfig" > @ config < / a > Application . get_env ( : opencv_thumbnail_server , : settings )
 
   def start_link ( python_module ) do
     GenServer . start_link ( __MODULE__ , python_module , [ ] )
   end
 
   def call_python ( worker , function , args ) do
     GenServer . call ( worker , { : call_python , function , args } , 10_000 )
   end
 
   def init ( python_module ) do
     IO . puts "Start worker"
     { : ok , pid } = : python . start_link ( [
       { : python_path , @ config [ : python_path ] } ,
       { : python , @ config [ : python ] }
     ] )
     state = { python_module , pid }
     { : ok , state }
   end
 
   def handle_call ( { : call_python , function , args } , _from , state ) do
     { module , pid } = state
     result = : python . call ( pid , module , function , args )
     reply = { : ok , result }
     { : reply , reply , state }
   end
 
   def handle_call ( _request , _from , state ) do
     { : stop , : error , : bad_call , state }
   end
 
   def handle_info ( _msg , { module , py_pid } ) do
     { : stop , : error , { module , py_pid } }
   end
 
   def terminate ( _reason , { _ , py_pid } ) do
     : python . stop ( py_pid )
     : ok
   end
end

图像处理

获取宽高

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# -*- coding: utf-8 -*-
 
import urllib2 as urllib
import numpy as np
import cv2
 
 
def load_image_url ( url ) :
     resp = urllib . urlopen ( url )
     buf = resp . read ( )
     return buf
 
 
def load_image_file ( filename ) :
     image = cv2 . imdecode ( filename , cv2 . IMREAD_COLOR )
     return image
 
def get_photo_sizes ( ) :
     return [
         [ 160 , 160 ] ,
         [ 320 , 320 ] ,
         [ 640 , 640 ] ,
         [ 1060 , 1060 ] ,
         [ 1280 , 1280 ]
     ]
def show ( buf ) :
     # print buf
     # x = cv2.imdecode(image, cv2.IMREAD_COLOR)
     # d = cv2.cvtColor(c, cv2.COLOR_RGB2BGR)
     np_ndarray = np . fromstring ( buf , dtype = np . uint8 )
     x = cv2 . imdecode ( np_ndarray , cv2 . IMREAD_UNCHANGED )
     return cv2 . imshow ( 'NBA Image' , x )
 
def write ( buf ) :
     nparray = np . fromstring ( buf , dtype = np . uint8 )
     img = cv2 . imdecode ( nparray , cv2 . IMREAD_UNCHANGED )
     return cv2 . imwrite ( '/tmp/imwrite.png' , img )
 
# def get_dimension():
#     url = 'http://img1.gtimg.com/16/1601/160106/16010642_1200x1000_0.jpg'
#     resp = urllib.urlopen(url)
#     buf = resp.read()
#     x = np.fromstring(buf, dtype=np.uint8)
#     img = cv2.imdecode(x, cv2.IMREAD_UNCHANGED)
#     # height = np.size(img, 0)
#     # width = np.size(img, 1)
#     height, width = image.shape[:2]
#     return (width, height)
 
def get_dimension ( buffer ) :
     # 把原始的二进制图片数据转换为NpArray
     nparray = np . fromstring ( buffer , dtype = np . uint8 )
     # 把 nparray 转换为 opencv 的图像格式
     image = cv2 . imdecode ( nparray , cv2 . IMREAD_UNCHANGED )
     height , width = image . shape [ : 2 ]
     return ( width , height )
 
def convert_color ( ) :
     url = 'http://ww3.sinaimg.cn/mw690/6941baebgw1epzcuv9vmxj20me0hy0u1.jpg'
     resp = urllib . urlopen ( url )
     buf = resp . read ( )
     x = np . fromstring ( buf , dtype = np . uint8 )
     img = cv2 . imdecode ( x , cv2 . IMREAD_UNCHANGED )
 
if __name__ == '__main__' :
     get_dimension ( )

在 Erlang 和 Python 之间传输二进制数据

Erlang 的binary()数据类型和 Python 之间的映射关系, 在Python 2.x 中二进制数据类型为 str() 表示, Python 3.x 中为 bytes()

buf = resp.read(), 其中变量 buf 的类型为

在 Elixir 我们看的如下的值

Python
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{ : ok , << 255 , 216 , 255 , 224 , 0 , 16 , 74 , 70 , : ok , << 255 , 216 , 255 , 224 , 0 , 16 , 74 , 70 , 73 , 70 , 0 , 1 , 216 , 255 , 224 , 0 , 16 , 74 , 70 , 73 , 70 , 0 , 1 , 1 , 224 ,
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