ASCII Art Server in Julia.ipynb

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  "language": "Julia",
  "name": ""
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   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "#### Rendering images in the terminal over the network\n",
      "\n",
      "This is a simple server written in Julia that, given an image url, displays images, including animated gifs, in the terminal:\n",
      "\n",
      "* Waits for incoming connections\n",
      "* Asks for url\n",
      "* Converts image into RGB byte array with ImageMagick\n",
      "* Groups and maps RGB values to terminal color space\n",
      "* Divide into frames for animation\n",
      "* Renders color-escaped text representation of each frame\n",
      "* Pushes frames out to client for ~10 seconds\n",
      "* Asks for another url\n",
      "\n",
      "When the server is running, connect with `telnet` or `nc`:\n",
      "\n",
      "`nc localhost 8888`\n",
      "\n",
      "It will play the gif for about 10 seconds, then ask for more urls until you quit the session"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "function getframes(image::String, width=40)\n",
      "    # get number of frames \n",
      "    num_frames = int(strip(readall(`identify $image` |> `wc -l`)))\n",
      "    \n",
      "    # get pixel data as raw rgb bytes from ImageMagick's convert tool\n",
      "    RGB = int(readbytes(`convert $image -resize $width -coalesce RGB:-`))\n",
      "\n",
      "    # group raw rgb bytes into lists for each pixel: [a,b,c,a,b,c...] -> [[a,b,c][a,b,c]...]\n",
      "    rgb_pixels = [[RGB[i], RGB[i+1], RGB[i+2]] for i=1:3:length(RGB)]\n",
      "    \n",
      "    # map rgb pixels into terminal colorspace:\n",
      "    map!(p -> [sum(int(p/50).*[36,6,1])+16], rgb_pixels)\n",
      "    \n",
      "    # calculate height and group by frame\n",
      "    height = int(length(rgb_pixels)/width/num_frames)\n",
      "    frame_pixels = [rgb_pixels[int((f-1)*width*height)+1:int(f*width*height)] for f=1:num_frames]\n",
      "    \n",
      "    # construct array of rendered images using escape codes\n",
      "    function render(frame)\n",
      "        join([\"\\e[48;5;$(p[1])m  $(if (i%width==0) \"\\e[0m\\n\";else \"\";end)\" for (i,p) in enumerate(frame)])\n",
      "    end\n",
      "\n",
      "    return [render(frame) for frame in frame_pixels]\n",
      "end"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 3,
       "text": [
        "# methods for generic function getframes\n",
        "getframes(image::String)\n",
        "getframes(image::String,width) at In[3]:3"
       ]
      }
     ],
     "prompt_number": 3
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# read url from client\n",
      "function handle_connection(conn)\n",
      "    # read image url\n",
      "    write(conn, \"\\nEnter image url: \")\n",
      "    url = strip(readline(conn))\n",
      "    frames = getframes(url)\n",
      "    frame_count = length(frames)\n",
      "    \n",
      "    # plays ~10 secs of gif based on number of frames\n",
      "    loops = (frame_count==1 || frame_count>100) ? 1 : int(100/frame_count)\n",
      "    \n",
      "    # write frames to client\n",
      "    for f in 1:loops\n",
      "        for frame in frames\n",
      "            write(conn, \"\\n\"^80)\n",
      "            write(conn, frame)\n",
      "            sleep(.1)\n",
      "        end\n",
      "    end\n",
      "end"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 4,
       "text": [
        "# methods for generic function handle_connection\n",
        "handle_connection(conn) at In[4]:4"
       ]
      }
     ],
     "prompt_number": 4
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "# start server and handle connections\n",
      "@async begin\n",
      "    server = listen(8888)\n",
      "    while true\n",
      "        sock = accept(server)\n",
      "        @async while true\n",
      "            handle_connection(sock)\n",
      "        end\n",
      "    end\n",
      "end"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 5,
       "text": [
        "Task"
       ]
      }
     ],
     "prompt_number": 5
    }
   ],
   "metadata": {}
  }
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}