-----------------------------------------------------------------------------
-- |
-- Module : Text.BlogLiterately.Diagrams
-- Copyright : (c) Brent Yorgey 2012-2013
-- License : BSD-style (see LICENSE)
-- Maintainer : Brent Yorgey <byorgey@gmail.com>
--
-- Custom transformation passes for the @BlogLiterately@ blog-writing
-- tool (<http://hackage.haskell.org/package/BlogLiterately>),
-- allowing inclusion of inline code using the @diagrams@ framework
-- (<http://projects.haskell.org/diagrams>) which are compiled into
-- images. See "Text.BlogLiterately.Run" for more information.
--
-- Note that this package provides an executable, @BlogLiteratelyD@,
-- which compiles embedded diagrams code as well as all the standard
-- transforms provided by BlogLiterately.
-----------------------------------------------------------------------------
module Text.BlogLiterately.Diagrams
( diagramsXF, diagramsInlineXF
) where
import Safe (readMay)
import System.Directory (createDirectoryIfMissing)
import System.FilePath
import System.IO (hPutStrLn, stderr)
import qualified Codec.Picture as J
import Diagrams.Backend.Rasterific
import qualified Diagrams.Builder as DB
import Diagrams.Prelude (SizeSpec, V2, centerXY, pad, zero,
(&), (.~))
import Diagrams.TwoD.Size (mkSizeSpec2D)
import Text.BlogLiterately
import Text.Pandoc
-- | Transform a blog post by looking for code blocks with class
-- @dia@, and replacing them with images generated by evaluating the
-- identifier @dia@ and rendering the resulting diagram. In
-- addition, blocks with class @dia-def@ are collected (and deleted
-- from the output) and provided as additional definitions that will
-- be in scope during evaluation of all @dia@ blocks.
--
-- Be sure to use this transform /before/ the standard
-- 'Text.BlogLiterately.Transform.highlightXF' transform, /i.e./
-- with the 'Text.BlogLiterately.Run.blogLiteratelyCustom' function.
-- For example,
--
-- > main = blogLiteratelyCustom (diagramsXF : standardTransforms)
--
-- It also works well in conjunction with
-- 'Text.BlogLiterately.Transform.centerImagesXF' (which, of course,
-- should be placed after @diagramsXF@ in the pipeline). This
-- package provides an executable @BlogLiteratelyD@ which
-- includes @diagramsInlineXF@, @diagramsXF@, and @centerImagesXF@.
diagramsXF :: Transform
diagramsXF = ioTransform renderBlockDiagrams (const True)
renderBlockDiagrams :: BlogLiterately -> Pandoc -> IO Pandoc
renderBlockDiagrams _ p = bottomUpM (renderBlockDiagram defs) p
where
defs = queryWith extractDiaDef p
-- | Transform a blog post by looking for /inline/ code snippets with
-- class @dia@, and replacing them with images generated by
-- evaluating the contents of each code snippet as a Haskell
-- expression representing a diagram. Any code blocks with class
-- @dia-def@ will be in scope for the evaluation of these
-- expressions (such code blocks are unaffected).
--
-- Because @diagramsXF@ and @diagramsInlineXF@ both use blocks with
-- class @dia-def@, but @diagramsInlineXF@ leaves them alone whereas
-- @diagramsXF@ deletes them, @diagramsInlineXF@ must be placed
-- before @diagramsXF@ in the pipeline.
diagramsInlineXF :: Transform
diagramsInlineXF = ioTransform renderInlineDiagrams (const True)
renderInlineDiagrams :: BlogLiterately -> Pandoc -> IO Pandoc
renderInlineDiagrams _ p = bottomUpM (renderInlineDiagram defs) p
where
defs = queryWith extractDiaDef p
extractDiaDef :: Block -> [String]
extractDiaDef (CodeBlock (_, as, _) s)
= [src | "dia-def" `elem` (maybe id (:) tag) as]
where
(tag, src) = unTag s
extractDiaDef _ = []
diaDir :: FilePath
diaDir = "diagrams" -- XXX make this configurable
-- | Given some code with declarations, some attributes, and an
-- expression to render, render it and return the filename of the
-- generated image (or an error message).
renderDiagram :: Bool -- ^ Apply padding automatically?
-> [String] -- ^ Declarations
-> String -- ^ Expression to render
-> Attr -- ^ Code attributes
-> IO (Either String FilePath)
renderDiagram shouldPad decls expr (_ident, _cls, fields) = do
createDirectoryIfMissing True diaDir
let bopts = DB.mkBuildOpts Rasterific zero (RasterificOptions sz)
& DB.snippets .~ decls
& DB.imports .~ ["Diagrams.Backend.Rasterific"]
& DB.diaExpr .~ expr
& DB.postProcess .~ (if shouldPad then pad 1.1 . centerXY else id)
& DB.decideRegen .~
(DB.hashedRegenerate
(\_ opts -> opts)
diaDir
)
res <- DB.buildDiagram bopts
case res of
DB.ParseErr err -> do
let errStr = "\nParse error:\n" ++ err
putErrLn errStr
return (Left errStr)
DB.InterpErr ierr -> do
let errStr = "\nInterpreter error:\n" ++ DB.ppInterpError ierr
putErrLn errStr
return (Left errStr)
DB.Skipped hash -> return (Right $ mkFile (DB.hashToHexStr hash))
DB.OK hash img -> do
let imgFile = mkFile (DB.hashToHexStr hash)
J.savePngImage imgFile (J.ImageRGBA8 img)
return (Right imgFile)
where
sz :: SizeSpec V2 Double
sz = mkSizeSpec2D
(lookup "width" fields >>= readMay)
(lookup "height" fields >>= readMay)
mkFile base = diaDir </> base <.> "png"
renderBlockDiagram :: [String] -> Block -> IO Block
renderBlockDiagram defs c@(CodeBlock attr@(_, cls, _) s)
| "dia-def" `elem` classTags = return Null
| "dia" `elem` classTags = do
res <- renderDiagram True (src : defs) "dia" attr
case res of
Left err -> return (CodeBlock attr (s ++ err))
Right fileName -> return $ Para [Image [] (fileName, "")]
| otherwise = return c
where
(tag, src) = unTag s
classTags = (maybe id (:) tag) cls
renderBlockDiagram _ b = return b
renderInlineDiagram :: [String] -> Inline -> IO Inline
renderInlineDiagram defs c@(Code attr@(_, cls, _) expr)
| "dia" `elem` cls = do
res <- renderDiagram False defs expr attr
case res of
Left err -> return (Code attr (expr ++ err))
Right fileName -> return $ Image [] (fileName, "")
| otherwise = return c
renderInlineDiagram _ i = return i
putErrLn :: String -> IO ()
putErrLn = hPutStrLn stderr