一本のReadableStreamを、二本のReadableStreamにする

gistfile1.coffee

fs = require 'fs'
gm = require 'gm'

im = gm.subClass imageMagick: true

{PassThrough} = require 'stream'

stream = fs.createReadStream '/Users/hadashi/tmp/20.png'
stream2 = new PassThrough
stream3 = new PassThrough

stream.on 'data', (data) ->
  stream2.write data
  stream3.write data

stream.on 'end', ->
  stream2.end()
  stream3.end()

im(stream2)
.size (err, size) ->
  console.log arguments
  im(stream3)
  .size (err, size) ->
    console.log arguments