Erlang/Elixir: 使用 OpenCV, Python 搭建圖片縮略圖服務器

這篇文章是在OSX上測試和運行的的, Ubuntu下的安裝和配置請移步到這裏

應用程序進程樹, 默認 Poolboy 中初始化10個用於處理圖片的 Python 工作進程(Worker)

首先安裝OpenCV需要的工具包

1 2 3 4 5 6

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 系統自帶的 Python

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

創建 Elixir 項目

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

➜    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 模塊

1 2 3 4 5 6 7 8

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

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

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

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

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

圖像處理

獲取寬高

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66

# -*- 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 ) :      # 把原始的二進制圖片數據轉換爲NpArray      nparray = np . fromstring ( buffer , dtype = np . uint8 )      # 把 nparray 轉換爲 opencv 的圖像格式      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 之間傳輸二進制數據

Erlang 的binary()數據類型和 Python 之間的映射關係, 在Python 2.x 中二進制數據類型爲 str() 表示, Python 3.x 中爲 bytes()

buf = resp.read(), 其中變量 buf 的類型爲

在 Elixir 我們看的如下的值

Python

1 2 3

{ : 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 ,