doc/handle-images.hs

   1 -- handle-images.hs
   2 --
   3 -- Copyright (C) 2012 by Werner Lemberg.
   4 --
   5 -- This file is part of the ttfautohint library, and may only be used,
   6 -- modified, and distributed under the terms given in `COPYING'.  By
   7 -- continuing to use, modify, or distribute this file you indicate
   8 -- that you have read `COPYING' and understand and accept it fully.
   9 --
  10 -- The file `COPYING' mentioned in the previous paragraph is
  11 -- distributed with the ttfautohint library.
  12 --
  13 --
  14 -- This is a simple pandoc filter to support different image formats
  15 -- for different backends.  It simply appends the suffix given as a
  16 -- command line option to all pandoc images and checks whether the
  17 -- image files actually exist.  For non-existent files the file name
  18 -- doesn't get altered.
  19 --
  20 -- Command line examples:
  21 --
  22 --   % pandoc -t json foo \
  23 --     | ./handle-images ".svg" \
  24 --     | pandoc -f json -t html \
  25 --     > foo.html
  26 --
  27 --   % pandoc -t json foo \
  28 --     | ./handle-images ".pdf" \
  29 --     | pandoc --latex-engine=pdflatex -f json -t latex \
  30 --     > foo.tex
  31
  32
  33 import Text.Pandoc
  34 import System.Environment(getArgs)
  35 import System.Directory(doesFileExist)
  36
  37
  38 handleImage :: String
  39                -> Inline
  40                -> IO Inline
  41 handleImage format
  42             (Image description (basename, title)) = do
  43   let
  44     filename = basename ++ format
  45
  46   fileExists <- doesFileExist filename
  47   if fileExists
  48     then
  49       return $ Image description (filename, title)
  50     else
  51       return $ Image description (basename, title)
  52 handleImage _ x = return x
  53
  54
  55 main :: IO ()
  56 main = do
  57   args <- getArgs
  58   toJsonFilter
  59     $ handleImage
  60     $ case args of
  61         [f] -> f
  62         _   -> "" -- default
  63
  64
  65 -- end of handle-images.hs