Implement proper text formatting into PDF instructions using the new encode feature available in Fonts

src/PDF/Content/Text.hs

@@ -14,9 +14,9 @@ import Control.Monad (foldM)
 import Control.Monad.Fail (MonadFail(..))
 import Control.Monad.Reader (MonadReader(..), asks, runReaderT)
 import Control.Monad.State (MonadState(..), evalStateT)
-import Data.ByteString.Char8 (pack)
 import Data.Map ((!))
-import Data.Text (Text)
+import Data.Text (Text, breakOn)
+import qualified Data.Text as Text (drop)
 import PDF.Box (Box(..))
 import PDF.Content (
       Content, ContentUnit(..), Id(..), Indexed, GraphicContextUnit(..)
@@ -27,6 +27,7 @@ import PDF.Content.Operator (Instruction, Operator(..))
 import PDF.Content.Operator.Text (Operator(..))
 import PDF.Font (Font(..), FontSet, emptyFont)
 import PDF.Object (DirectObject(..), StringObject(..), toByteString)
+import PDF.Pages (Page(..))
 import Prelude hiding (fail)
 
 data ROContext = ROContext {
@@ -91,9 +92,13 @@ renderInstruction (Text DQuote, [StringObject outputString]) =
 
 renderInstruction _ = return []
 
-format :: String -> [Instruction]
-format s =
-  case break (== '\n') s of
-    ("", "") -> []
-    ("", left) -> (Text Tstar, []) : format (drop 1 left)
-    (line, left) -> (Text Tj, [StringObject . Literal $ pack line]) : format left
+format :: (MonadFail m, MonadReader Font m) => Text -> m [Instruction]
+format input =
+  case breakOn "\n" input of
+    ("", "") -> return []
+    ("", left) -> ((Text Tstar, []) :) <$> format (Text.drop 1 left)
+    (line, left) -> (:) <$> tj line <*> format left
+  where
+    tj t = do
+      literal <- either fail (return . Literal) =<< asks (($t) . encode)
+      return (Text Tj, [StringObject literal])