diff --git a/LICENSE b/LICENSE new file mode 100644 --- /dev/null +++ b/LICENSE @@ -0,0 +1,30 @@ +Copyright (c) 2020 Oleg Grenrus, 2015 Liam O'Connor + +All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are met: + + * Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. + + * Redistributions in binary form must reproduce the above + copyright notice, this list of conditions and the following + disclaimer in the documentation and/or other materials provided + with the distribution. + + * Neither the name of Liam O'Connor nor the names of other + contributors may be used to endorse or promote products derived + from this software without specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,2 @@ +import Distribution.Simple +main = defaultMain diff --git a/latex-svg-image.cabal b/latex-svg-image.cabal new file mode 100644 --- /dev/null +++ b/latex-svg-image.cabal @@ -0,0 +1,55 @@ +cabal-version: 2.2 +name: latex-svg-image +version: 0.1 +synopsis: + A library for rendering LaTeX formulae as SVG using an actual LaTeX + +description: + This library provides the basic infrastructure necessary to convert LaTeX + formulae into SVG images, using a real LaTeX installation. This is useful in + particular for showing formulae on websites, where using alternatives like + MathJax is not an option (e.g, when you want to use various LaTeX packages that + MathJax doesn't support). + . + This library requires @latex@, @dvisvgm@ to be present in the system. + . + The companion library to this, @latex-svg-pandoc@, provides useful tools to + integrate this library with pandoc, when generating HTML documents. + . + This is a fork of https://github.com/liamoc/latex-formulae + +homepage: http://github.com/phadej/latex-svg#readme +license: BSD-3-Clause +license-file: LICENSE +author: Oleg Grenrus, Liam O'Connor +maintainer: Oleg Grenrus +copyright: 2020 Oleg Grenrus, 2015-2019 Liam O'Connor +category: Image +build-type: Simple +tested-with: GHC ==8.2.2 || ==8.4.4 || ==8.6.5 || ==8.8.3 + +source-repository head + type: git + location: https://github.com/phadej/latex-svg + subdir: latex-svg-image + +library + default-language: Haskell2010 + hs-source-dirs: src + ghc-options: -Wall + exposed-modules: Image.LaTeX.Render + build-depends: + , base >=4.10 && <4.14 + , deepseq ^>=1.4.3.0 + , directory ^>=1.3.0.1 + , filepath ^>=1.4.1.2 + , parsec ^>=3.1.13.0 + , process ^>=1.6.1.0 + , temporary ^>=1.3 + , transformers ^>=0.5.2.0 + + -- used for caching + build-depends: + , base64-bytestring ^>=1.0.0.3 + , bytestring ^>=0.10.8.2 + , cryptohash-sha256 ^>=0.11.101.0 diff --git a/src/Image/LaTeX/Render.hs b/src/Image/LaTeX/Render.hs new file mode 100644 --- /dev/null +++ b/src/Image/LaTeX/Render.hs @@ -0,0 +1,327 @@ +{-# LANGUAGE FlexibleContexts #-} +{-# LANGUAGE RecordWildCards #-} +module Image.LaTeX.Render ( + -- * Rendering Formulas + imageForFormula, + Formula, SVG, + -- * BaseLine + BaseLine, getBaseline, alterForHTML, + -- * Errors + RenderError (..), + -- * Options + -- ** Environment Options + EnvironmentOptions (..), + defaultEnv, + TempDirectoryHandling (..), + -- ** Formula Options + FormulaOptions (..), + displaymath, + math, + ) where + +import Control.Applicative (some, (<|>)) +import Control.DeepSeq (NFData (..), ($!!)) +import Control.Monad (when) +import Control.Monad.IO.Class (MonadIO (..)) +import Control.Monad.Trans.Except (ExceptT (..), runExceptT, throwE, withExceptT) +import Data.Char (isSpace) +import Data.List (foldl', isPrefixOf) +import Numeric (showFFloat) +import System.Exit (ExitCode (..)) +import System.FilePath ((<.>), ()) +import System.IO.Temp (withSystemTempDirectory, withTempDirectory) + +-- import System.IO + +import qualified Control.Exception as E +import qualified Crypto.Hash.SHA256 as SHA256 +import qualified Data.ByteString.Base64.URL as Base64 +import qualified Data.ByteString.Builder as B +import qualified Data.ByteString.Char8 as BS8 +import qualified System.Directory as Dir +import qualified System.Process as Proc +import qualified Text.Parsec as P +import qualified Text.Parsec.String as P + +------------------------------------------------------------------------------- +-- Types +------------------------------------------------------------------------------- + +-- | A LaTeX formula, e.g @x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}@ for the quadratic formula. Do not include any @$@s to denote the environment, just +-- specify the environment in the 'FormulaOptions' instead. +type Formula = String + +-- | Number of points (@pt@) from the bottom of the image to the typesetting baseline. Useful for setting your formulae inline with text +type BaseLine = Double + +-- | A source of 'SVG' image. +type SVG = String + +-- | This type contains all possible errors than can happen while rendering an equation. +-- It includes all IO errors that can happen as well as more specific errors. +data RenderError + = LaTeXFailure String -- ^ @latex@ returned a nonzero error code + | DVISVGMFailure String -- ^ @dvisvgm@ returned a nonzero error code + | IOException E.IOException -- ^ An 'IOException' occurred while managing the temporary files used to convert the equation + deriving (Show, Eq) + +data TempDirectoryHandling + = UseSystemTempDir String -- ^ A temporary directory with a name based on the given template will be created in the system temporary files location + | UseCurrentDir String -- ^ A temporary directory with a name based on the given template will be created in the current directory + deriving (Eq, Show, Read, Ord) + +data EnvironmentOptions = EnvironmentOptions + { latexCommand :: String -- ^ Command to use for @latex@, default is @latex@ + , dvisvgmCommand :: String -- ^ Command to use for @dvisvgm@, default is @dvisvgm@ + , latexArgs :: [String] -- ^ Any additional arguments for @latex@ + , dvisvgmArgs :: [String] -- ^ Any additional arguments for @dvisvgm@ + , tempDir :: TempDirectoryHandling -- ^ How to handle temporary files + , tempFileBaseName :: String -- ^ The base name to use for the temporary files. + , globalCache :: Bool -- ^ Cache outputs globally in @XDG_CACHE/latex-svg@ + } + deriving (Eq, Show, Read, Ord) + +data FormulaOptions = FormulaOptions + { preamble :: String -- ^ LaTeX preamble to use. Put your @\usepackage@ commands here.@ commands here. + , environment :: String -- ^ LaTeX environment in which the equation will be typeset, usually @math@ or @displaymath@ + } + deriving (Eq, Show, Read, Ord) + +------------------------------------------------------------------------------- +-- Defaults +------------------------------------------------------------------------------- + +-- | Use the @amsmath@ package, the @displaymath@ environment. +displaymath :: FormulaOptions +displaymath = FormulaOptions "\\usepackage{amsmath}\\usepackage{amsfonts}\\usepackage{stmaryrd}" "displaymath" + +-- | Use the @amsmath@ package, the @math@ environment. +math :: FormulaOptions +math = displaymath { environment = "math" } + +-- | Sensible defaults for system environments. Works if @dvisvgm@ and @latex@ are recent enough and in your @$PATH@. +defaultEnv :: EnvironmentOptions +defaultEnv = EnvironmentOptions + { latexCommand = "latex" + , dvisvgmCommand = "dvisvgm" + , latexArgs = [] + , dvisvgmArgs = ["--no-fonts=1", "--clipjoin"] -- "--exact-bbox" is good idea if you have recent dvisvgm + , tempDir = UseSystemTempDir "latex-eqn-temp" + , tempFileBaseName = "working" + , globalCache = False + } + +------------------------------------------------------------------------------- +-- Image for formula +------------------------------------------------------------------------------- + +-- | Convert a formula into a SVG image. +imageForFormula :: EnvironmentOptions -> FormulaOptions -> Formula -> IO (Either RenderError SVG) +imageForFormula EnvironmentOptions {..} FormulaOptions {..} eqn = + withTemp $ \temp -> runExceptT $ do + let doc :: String + doc = unlines $ + [ "% " ++ latexCommand ++ " " ++ show latexArgs + , "% " ++ dvisvgmCommand ++ " " ++ show dvisvgmArgs + , "\\nonstopmode" + , "\\documentclass[12pt]{article}" + , "\\pagestyle{empty}" + , "\\usepackage[active,tightpage]{preview}" + , "\\usepackage{amsmath}" + , "\\usepackage{xcolor}" + , preamble + , "\\begin{document}" + , "\\begin{preview}" + , "\\begin{" ++ environment ++ "}" + ] ++ filter (not . all isSpace) (lines eqn) ++ + [ "\\end{" ++ environment ++ "}" + , "\\end{preview}" + , "\\end{document}" + ] + + cached doc $ do + -- io $ hPutStrLn stderr doc + io $ writeFile (temp tempFileBaseName <.> "tex") doc + + (c,o,e) <- io $ readProcessWithCWD temp latexCommand $ latexArgs ++ [tempFileBaseName <.> "tex"] + when (c /= ExitSuccess) $ throwE $ LaTeXFailure (o ++ "\n" ++ e) + + (c',o',e') <- io $ readProcessWithCWD temp dvisvgmCommand $ dvisvgmArgs ++ ["-o", tempFileBaseName <.> "svg", tempFileBaseName <.> "dvi"] + when (c' /= ExitSuccess) $ throwE $ DVISVGMFailure (o' ++ "\n" ++ e') + + svg <- io $ readFile (temp tempFileBaseName <.> "svg") + + return $ addTitle eqn svg + where + io :: NFData a => IO a -> ExceptT RenderError IO a + io = withExceptT IOException . tryIO + + withTemp a = case tempDir of + UseSystemTempDir f -> withSystemTempDirectory f a + UseCurrentDir f -> withTempDirectory "." f a + + cached :: String -> ExceptT RenderError IO String -> ExceptT RenderError IO String + cached doc action + | not globalCache = action + | otherwise = do + let key :: String + key = filter (/= '=') + $ BS8.unpack + $ Base64.encode + $ SHA256.hashlazy + $ B.toLazyByteString + $ B.stringUtf8 doc + + -- cache directory + xdgCache <- io $ Dir.getXdgDirectory Dir.XdgCache "latex-svg" + io $ Dir.createDirectoryIfMissing True xdgCache + let path = xdgCache key <.> "svg" + + readFile path `orElse` do + result <- action + io $ writeFile path result + return result + + orElse :: IO a -> ExceptT e IO a -> ExceptT e IO a + orElse lft rgt = ExceptT $ fmap Right lft `E.catch` handler rgt + + handler :: ExceptT e IO a -> E.IOException -> IO (Either e a) + handler rgt _ = runExceptT rgt + +------------------------------------------------------------------------------- +-- Baseline and other postprocessing +------------------------------------------------------------------------------- + +addTitle :: Formula -> String -> String +addTitle eqn svg = + let (x0,x1) = spanL "' x1 + in x0 ++ y1 ++ "\n" ++ processAltString eqn ++ "" ++ y2 + +spanL :: Eq a => [a] -> [a] -> ([a], [a]) +spanL sep = go where + go str@[] = (str, str) + go str@(c:sfx) + | sep `isPrefixOf` str = ([], str) + | otherwise = (c:xs , ys) + where + ~(xs,ys) = go sfx + +spanR :: Eq a => a -> [a] -> ([a], [a]) +spanR sep = go where + go str@[] = (str, str) + go _str@(c:sfx) + | sep == c = ([c], sfx) + | otherwise = (c:xs , ys) + where + ~(xs,ys) = go sfx + +processAltString :: String -> String +processAltString = concatMap $ \c -> case c of + '<' -> "<" + '>' -> ">" + '&' -> "&" + '"' -> """ + '\'' -> "&39;" + '\n' -> " " + '\r' -> " " + '\t' -> " " + x -> [x] + +getBaseline :: SVG -> Double +getBaseline str = getBaseline' sfx + where + (_pfx, sfx) = spanL viewboxMarker str + +-- | Alter 'SVG' image to be embeddable in HTML page, i.e.align baseline. +-- +-- * Add @style="vertical-align: baseline-correction"@ +-- +alterForHTML :: SVG -> SVG +alterForHTML xml = + pfx ++ " style='vertical-align: " ++ showFFloat (Just 6) baseline "" ++ "pt'" ++ sfx + where + (_, svg) = spanL " Double +getBaseline' sfx = case P.parse parser "" sfx of + Left err -> error $ show (err, sfx) + Right x -> negate x + where + parser :: P.Parser Double + parser = do + _ <- P.string viewboxMarker + _ <- lexeme double + _ <- P.spaces + x <- lexeme double + _ <- lexeme double + y <- lexeme double + return (y + x) + + double :: P.Parser Double + double = sign <*> (float1 <|> float2) + + float1 :: P.Parser Double + float1 = do + d <- decimal + f <- P.option 0 (P.char '.' *> fraction) + return (d + f) + + float2 :: P.Parser Double + float2 = P.char '.' *> fraction + + decimal :: P.Parser Double + decimal = foldl' (\x d -> 10*x + digitToInt d) 0 + <$> digits1 + + fraction :: P.Parser Double + fraction = uncurry (/) . foldl' (\(x,n) d -> (10*x + digitToInt d,n*10)) (0,1) + <$> digits1 + + digits1 = some P.digit + + digitToInt '0' = 0 + digitToInt '1' = 1 + digitToInt '2' = 2 + digitToInt '3' = 3 + digitToInt '4' = 4 + digitToInt '5' = 5 + digitToInt '6' = 6 + digitToInt '7' = 7 + digitToInt '8' = 8 + digitToInt '9' = 9 + digitToInt _ = 0 + + sign :: P.Parser (Double -> Double) + sign = P.option id (negate <$ P.char '-') + + lexeme :: P.Parser a -> P.Parser a + lexeme p = p <* P.spaces + +------------------------------------------------------------------------------- +-- Utilities +------------------------------------------------------------------------------- + +readProcessWithCWD + :: FilePath -- ^ working directory + -> FilePath -- ^ Filename of the executable (see 'RawCommand' for details) + -> [String] -- ^ any arguments + -> IO (ExitCode,String,String) -- ^ exitcode, stdout, stderr +readProcessWithCWD cwd cmd args = Proc.readCreateProcessWithExitCode + ((Proc.proc cmd args) { Proc.cwd = Just cwd }) + "" + +-- | Catch 'IOException's and convert them to the 'ExceptT' monad +tryIO :: (MonadIO m, NFData a) => IO a -> ExceptT E.IOException m a +tryIO action = ExceptT $ liftIO $ E.try $ evaluateDeep action + +-- | Internal helper function +evaluateDeep :: NFData a => IO a -> IO a +evaluateDeep action = do + res <- action + E.evaluate $!! res