From 36244ed4d5d16aecf7c10f01c4fb1aa0323f909d Mon Sep 17 00:00:00 2001
From: Gregor Kleen <gkleen@yggdrasil.li>
Date: Thu, 11 Feb 2016 15:31:15 +0100
Subject: Size hints in embedded svgs

---
 src/Site.hs | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/Site.hs b/src/Site.hs
index bf501d8..9b08316 100644
--- a/src/Site.hs
+++ b/src/Site.hs
@@ -5,7 +5,7 @@ import Hakyll
 import Data.Monoid (Monoid(..), mconcat, (<>))
 import Control.Monad (liftM, forM_, (<=<))
 import Data.Char (toLower, isSpace, isAlphaNum)
-import Data.Maybe (mapMaybe, fromMaybe)
+import Data.Maybe (mapMaybe, fromMaybe, listToMaybe)
 import Data.Map (Map)
 import qualified Data.Map as Map
 import qualified Data.Set as Set
@@ -19,6 +19,7 @@ import Control.Applicative (Alternative(..), Applicative(..))
 import           Text.Blaze.Html                 (toHtml, toValue, (!))
 import qualified Text.Blaze.Html5                as H
 import qualified Text.Blaze.Html5.Attributes     as A
+import Text.Read (readMaybe)
 
 import System.FilePath (takeBaseName, (</>), (<.>))
 
@@ -30,6 +31,8 @@ import Data.Char (toLower)
 import Tex (compileTex)
 import Text.Printf (printf)
 
+import Text.Regex.TDFA ((=~))
+
 main :: IO ()
 main = hakyllWith config $ do
   match "templates/*" $ compile templateCompiler
@@ -225,8 +228,17 @@ texTransform = walkM texTransformInline <=< walkM texTransformBlock
       let
         texId = texTranslation' $ texT tex
       alignment <- loadSnapshotBody texId "alignment"
-      return $ printf "<object data=\"/%s\" type=\"image/svg+xml\" style=\"vertical-align:-%s\">%s</object>"
-               (toFilePath texId) (alignment :: String) tex
+      content <- loadBody texId
+      let
+        latexFontSize :: Double
+        latexFontSize = 12 / 1.25
+        match = (=~) :: String -> String -> (String, String, String, [String])
+        size = case match content "height='([-0-9\\.]+)pt' .* width='([-0-9\\.]+)pt'" of
+          (_, _, _, xs@[_, _]) -> (\[y, x] -> (x / latexFontSize, y / latexFontSize)) <$> mapM (readMaybe :: String -> Maybe Double) xs
+          _ -> Nothing
+        size' = maybe "" (\(a, b) -> printf " width:%.2fem; height:%.2fem;" a b) size
+      return $ printf "<object data=\"/%s\" type=\"image/svg+xml\" style=\"vertical-align:-%s;%s\">%s</object>"
+               (toFilePath texId) (alignment :: String) (size' :: String) tex
     classOf DisplayMath = "display-math"
     classOf InlineMath  = "inline-math"
 
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