createDummyGif.coffee

##
# create an insanely tiny placeholder gif
# output in base64
#
# i'm still working the bytes... so this is
# a working proto but it needs to be further
# edited...
#
# as much as possible in accordance to GIF spec.
class Dick
  createDummyGif: (width=10, height=10) ->
      gif   = ''
      chars = [
        71, 73, 70, 56, 57, 97      # 6 bytes (header: GIF89a)
        width, 0, height, 0         # 4 bytes (logical screen width, logical screen height)
        44                          # 1 byte (packed field of 8 bits)
                                    #
                                    # 1       = global color table flag (we want this on)
                                    # 0 1 1   = color resolution
                                    # null    = sort flag (withheld)
                                    # null    = size of global color table (withheld)
                                    #         =
                                    # 1011 00
                                    #
        0                           # 1 byte (bg color index)
        255                         # 1 byte (pixel aspect ratio)
        0, 0, 0                     # 3 bytes (global color table: black)
        59                          # 1 byte (trailer: ;)
      ]

      for char in chars
        gif += String.fromCharCode(char)
      btoa gif
a = new Dick
console.log a.createDummyGif(10,10)