3 files changed, 14 insertions(+), 14 deletions(-)

M src/Data/Text/ParagraphLayout/Internal/Layout.hs
M src/Data/Text/ParagraphLayout/Internal/ProtoFragment.hs
M src/Data/Text/ParagraphLayout/Internal/TextOptions.hs

@@ 295,9 295,10 @@ layoutRunsH runs = map layoutRunH runs
 layoutRunH :: WithSpan d Run -> ProtoFragmentWithSpan d
 layoutRunH (WithSpan rs run) = WithSpan rs pf
     where
-        pf = PF.protoFragmentH dir glyphs
+        pf = PF.protoFragmentH dir lvl glyphs
         glyphs = shapeRun (WithSpan rs run)
         dir = runDirection run
+        lvl = runLevel run
 
 -- | Calculate layout for the given run independently of its position.
 shapeRun :: WithSpan d Run -> [(GlyphInfo, GlyphPos)]

@@ 7,12 7,15 @@ where
 import Data.Int (Int32)
 import Data.Text.Glyphize (Direction (..), GlyphInfo, GlyphPos (x_advance))
 
-import Data.Text.ParagraphLayout.Internal.BiDiLevels
+import qualified Data.Text.ParagraphLayout.Internal.BiDiLevels as BiDi
 
 -- | A box fragment which has not been positioned yet.
 data ProtoFragment = ProtoFragment
     { direction :: Maybe Direction
     -- ^ Text direction, which is constant within a fragment.
+    , level :: BiDi.Level
+    -- ^ BiDi embedding level.
+    -- Should be even for LTR fragments and odd for RTL fragments.
     , advance :: Int32
     -- ^ Total advance of glyphs in this fragment,
     -- depending on the text direction.


@@ 21,17 24,11 @@ data ProtoFragment = ProtoFragment
 
 -- | Construct a `ProtoFragment`, automatically calculating the total advance
 -- for a horizontal text direction.
-protoFragmentH :: Maybe Direction -> [(GlyphInfo, GlyphPos)] -> ProtoFragment
-protoFragmentH dir gs = ProtoFragment dir adv gs
+protoFragmentH :: Maybe Direction -> BiDi.Level -> [(GlyphInfo, GlyphPos)] ->
+    ProtoFragment
+protoFragmentH dir lvl gs = ProtoFragment dir lvl adv gs
     where
         adv = sum $ map (x_advance . snd) gs
 
-instance WithLevel ProtoFragment where
-    level pf = case direction pf of
-        -- TODO: Allow externally set paragraph embedding level.
-        -- TODO: Properly calculate BiDi levels.
-        Just DirLTR -> 0
-        Just DirRTL -> 1
-        Just DirTTB -> 0
-        Just DirBTT -> 1
-        Nothing -> 0
+instance BiDi.WithLevel ProtoFragment where
+    level = level -- BiDi.level = ProtoFragment.level

@@ 33,10 33,12 @@ data TextOptions = TextOptions
 
     , textDirection :: Direction
     -- ^ Base text direction.
+    --
     -- Used to determine which box fragment gets the left spacing and which
     -- gets the right spacing when broken over multiple lines.
     --
-    -- TODO: Also use for the visual order of boxes.
+    -- When applied to the root box in a paragraph, this is also used to
+    -- determine the base direction of the paragraph.
 
     -- TODO: textVerticalAlign
     -- TODO: textLetterSpacing