From d5253a67c07ac5f110471f7644c55b5ef40695ba Mon Sep 17 00:00:00 2001
From: Jaro <jaro@argonaut-constellation.org>
Date: Sun, 2 Jul 2023 08:44:57 +0200
Subject: [PATCH] Do not pass around text direction unnecessarily.

---
 .../Text/ParagraphLayout/Internal/Layout.hs   | 36 ++++++++++---------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/src/Data/Text/ParagraphLayout/Internal/Layout.hs b/src/Data/Text/ParagraphLayout/Internal/Layout.hs
index 829d35a..baa5708 100644
--- a/src/Data/Text/ParagraphLayout/Internal/Layout.hs
+++ b/src/Data/Text/ParagraphLayout/Internal/Layout.hs
@@ -172,9 +172,8 @@ verticalAlignment originY pl = (bottomY, PL.mapFragments setOrigin pl)
             boxVerticalAlignment (RB.boxOptions rb) == AlignLineBottom
         fragBoxes (WithSpan rs _) = RS.spanBoxes rs
         vors = sconcat $ fmap vor $ PL.protoFragments pl
-        vor (WithSpan rs pf) =
+        vor (WithSpan rs _) =
             verticalOffsetsRecursiveStruts
-                (PF.direction pf)
                 (RS.spanTextOptions rs)
                 (RS.spanBoxes rs)
 
@@ -429,12 +428,12 @@ layoutRunH (WithSpan rs run) = WithSpan rs pf
         glyphs = shapeRun (WithSpan rs run)
         dir = runDirection run
         lvl = runLevel run
-        vo = verticalOffsets dir (RS.spanTextOptions rs)
+        vo = verticalOffsets (RS.spanTextOptions rs)
         hard = runHardBreak run
 
 -- | Vertical offsets for the given fragment, with baseline set to 0.
-verticalOffsets :: Direction -> TextOptions -> VO.VerticalOffsets
-verticalOffsets dir opts = VO.VerticalOffsets
+verticalOffsets :: TextOptions -> VO.VerticalOffsets
+verticalOffsets opts = VO.VerticalOffsets
     { VO.layoutTop = ascent + topHalfLeading
     , VO.fontTop = ascent
     , VO.baseline = 0
@@ -453,6 +452,11 @@ verticalOffsets dir opts = VO.VerticalOffsets
         -- `descent` >= 0 for horizontal fonts
         descent = - (descender extents `fromMaybe` textDescender opts)
         extents = fontExtentsForDir (textFont opts) (Just dir)
+        -- Actual shaped text direction may differ from the direction set in
+        -- `TextOptions` (for example RTL characters in a LTR box), but
+        -- HarfBuzz only distinguished horizontal and vertical extents,
+        -- so this should make no difference.
+        dir = textDirection opts
         lineHeight = case textLineHeight opts of
             Normal -> normalLineHeight
             Absolute h -> h
@@ -464,9 +468,9 @@ verticalOffsets dir opts = VO.VerticalOffsets
 -- Note: The font extents are calculated using the same direction for the whole
 --       ancestry path regardless of the actual direction of these boxes, but
 --       this should not matter for text that is only horizontal.
-verticalOffsetsRecursive :: Direction -> TextOptions -> [RB.ResolvedBox d] ->
+verticalOffsetsRecursive :: TextOptions -> [RB.ResolvedBox d] ->
     (Maybe (RB.ResolvedBox d), VO.VerticalOffsets)
-verticalOffsetsRecursive dir opts boxes = case boxes of
+verticalOffsetsRecursive opts boxes = case boxes of
     [] -> -- Inline content directly in the root box.
         (Nothing, vo)
     (b : bs) -> case boxVerticalAlignment $ RB.boxOptions b of
@@ -474,20 +478,20 @@ verticalOffsetsRecursive dir opts boxes = case boxes of
         AlignLineBottom -> (Just b, vo)
         AlignBaseline offset ->
             let parentOpts = RB.boxParentTextOptions b
-                (anchor, parentVO) = verticalOffsetsRecursive dir parentOpts bs
+                (anchor, parentVO) = verticalOffsetsRecursive parentOpts bs
             in (anchor, VO.alignBaseline (VO.baseline parentVO + offset) vo)
     where
-        vo = verticalOffsets dir opts
+        vo = verticalOffsets opts
 
 -- | Like `verticalOffsetsRecursive`, but also generate struts for every
 -- ancestor box.
-verticalOffsetsRecursiveStruts :: Direction -> TextOptions -> [RB.ResolvedBox d]
-    -> NonEmpty (Maybe (RB.ResolvedBox d), VO.VerticalOffsets)
-verticalOffsetsRecursiveStruts dir opts [] =
-    verticalOffsetsRecursive dir opts [] :| []
-verticalOffsetsRecursiveStruts dir opts boxes@(b : bs) =
-    verticalOffsetsRecursive dir opts boxes <|
-    verticalOffsetsRecursiveStruts dir (RB.boxParentTextOptions b) bs
+verticalOffsetsRecursiveStruts :: TextOptions -> [RB.ResolvedBox d] ->
+    NonEmpty (Maybe (RB.ResolvedBox d), VO.VerticalOffsets)
+verticalOffsetsRecursiveStruts opts [] =
+    verticalOffsetsRecursive opts [] :| []
+verticalOffsetsRecursiveStruts opts boxes@(b : bs) =
+    verticalOffsetsRecursive opts boxes <|
+    verticalOffsetsRecursiveStruts (RB.boxParentTextOptions b) bs
 
 -- | Calculate layout for the given run independently of its position.
 shapeRun :: WithSpan d Run -> [(GlyphInfo, GlyphPos)]
-- 
2.30.2