From 5fa1efb1b56816aa7c3034856fac9ef709889e99 Mon Sep 17 00:00:00 2001
From: Jaro <jaro@argonaut-constellation.org>
Date: Fri, 10 Mar 2023 07:45:14 +0100
Subject: [PATCH] Decompose ProtoFragment construction.

---
 src/Data/Text/ParagraphLayout/Internal/Plain.hs    |  6 ++----
 .../Text/ParagraphLayout/Internal/ProtoFragment.hs | 14 ++++++++++++--
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/src/Data/Text/ParagraphLayout/Internal/Plain.hs b/src/Data/Text/ParagraphLayout/Internal/Plain.hs
index 4fa5119..9392d2c 100644
--- a/src/Data/Text/ParagraphLayout/Internal/Plain.hs
+++ b/src/Data/Text/ParagraphLayout/Internal/Plain.hs
@@ -20,7 +20,7 @@ import Data.Text.Glyphize
     ,Direction(..)
     ,FontExtents(..)
     ,GlyphInfo
-    ,GlyphPos(x_advance)
+    ,GlyphPos
     ,defaultBuffer
     ,fontExtentsForDir
     ,shape
@@ -207,10 +207,8 @@ breakSplits closed (x:xs) = splits ++ breakSplits (x:closed) xs
 layoutRunH :: WithSpan Run -> WithSpan PF.ProtoFragment
 layoutRunH (WithSpan rs run) = WithSpan rs pf
     where
-        pf = PF.ProtoFragment dir totalX glyphs
+        pf = PF.protoFragmentH dir glyphs
         glyphs = shapeRun (WithSpan rs run)
-        positions = map snd glyphs
-        totalX = sum $ map x_advance positions
         dir = runDirection run
 
 -- | Calculate layout for the given run independently of its position.
diff --git a/src/Data/Text/ParagraphLayout/Internal/ProtoFragment.hs b/src/Data/Text/ParagraphLayout/Internal/ProtoFragment.hs
index c5ae878..1a7b8cc 100644
--- a/src/Data/Text/ParagraphLayout/Internal/ProtoFragment.hs
+++ b/src/Data/Text/ParagraphLayout/Internal/ProtoFragment.hs
@@ -1,8 +1,11 @@
-module Data.Text.ParagraphLayout.Internal.ProtoFragment (ProtoFragment(..))
+module Data.Text.ParagraphLayout.Internal.ProtoFragment
+    (ProtoFragment(direction, advance, glyphs)
+    ,protoFragmentH
+    )
 where
 
 import Data.Int (Int32)
-import Data.Text.Glyphize (Direction, GlyphInfo, GlyphPos)
+import Data.Text.Glyphize (Direction, GlyphInfo, GlyphPos(x_advance))
 
 -- | A box fragment which has not been positioned yet.
 data ProtoFragment = ProtoFragment
@@ -13,3 +16,10 @@ data ProtoFragment = ProtoFragment
     -- depending on the text direction.
     , glyphs :: [(GlyphInfo, GlyphPos)]
     }
+
+-- | 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
+    where
+        adv = sum $ map (x_advance . snd) gs
-- 
2.30.2