From ce4f4845a30de2bbcbce4c8c9eb2a0607b57588d Mon Sep 17 00:00:00 2001
From: Jaro <jaro@argonaut-constellation.org>
Date: Tue, 20 Jun 2023 15:53:24 +0200
Subject: [PATCH] Generalise shiftFragment function.

Intended for testing paragraphSafeWidth.
---
 .../Text/ParagraphLayout/Internal/Fragment.hs | 10 ++++++++++
 .../ParagraphLayout/Internal/ParagraphLine.hs | 20 +++++++------------
 2 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/src/Data/Text/ParagraphLayout/Internal/Fragment.hs b/src/Data/Text/ParagraphLayout/Internal/Fragment.hs
index 1b6a50e..ba3a78e 100644
--- a/src/Data/Text/ParagraphLayout/Internal/Fragment.hs
+++ b/src/Data/Text/ParagraphLayout/Internal/Fragment.hs
@@ -3,6 +3,7 @@ module Data.Text.ParagraphLayout.Internal.Fragment
     , ShapedRun
     , fragmentSpacedRect
     , shapedRun
+    , shiftFragment
     )
 where
 
@@ -101,3 +102,12 @@ shapedRun f = (x, y, g)
         g = fragmentGlyphs f
         (px, py) = fragmentPen f
         r = fragmentRect f
+
+-- | Add @dx@ and @dy@ to the fragment's `x_origin` and `y_origin`,
+-- respectively.
+shiftFragment :: Int32 -> Int32 -> Fragment d -> Fragment d
+shiftFragment dx dy f = f'
+    where
+        f' = f { fragmentRect = r' }
+        r' = r { x_origin = x_origin r + dx, y_origin = y_origin r + dy }
+        r = fragmentRect f
diff --git a/src/Data/Text/ParagraphLayout/Internal/ParagraphLine.hs b/src/Data/Text/ParagraphLayout/Internal/ParagraphLine.hs
index 4966eae..0debcf6 100644
--- a/src/Data/Text/ParagraphLayout/Internal/ParagraphLine.hs
+++ b/src/Data/Text/ParagraphLayout/Internal/ParagraphLine.hs
@@ -28,8 +28,9 @@ class GenericLayout pl where
     -- | Keep only fragments with the given line number.
     limitFragments :: Int -> pl -> pl
 
-    -- | Add @dy@ to each fragment's `y_origin`.
-    shiftFragments :: Int32 -> pl -> pl
+    -- | Add @dx@ and @dy@ to each fragment's `x_origin` and `y_origin`,
+    -- respectively.
+    shiftFragments :: Int32 -> Int32 -> pl -> pl
 
     -- | Combine fragments from two layouts into one,
     -- without any adjustment of coordinates.
@@ -40,7 +41,7 @@ instance GenericLayout (P.ParagraphLayout d) where
     rect = P.paragraphRect
     topDistance pl = topFragmentOrigin $ P.paragraphFragments pl
     limitFragments n = P.filterFragments (fragmentIsOnLine n)
-    shiftFragments dy = P.mapFragments (shiftFragment dy)
+    shiftFragments dx dy = P.mapFragments (shiftFragment dx dy)
     appendFragments = P.appendFragments
 
 instance GenericLayout (R.ParagraphLayout d) where
@@ -48,7 +49,7 @@ instance GenericLayout (R.ParagraphLayout d) where
     rect = R.paragraphRect
     topDistance pl = topFragmentOrigin $ R.paragraphFragments pl
     limitFragments n = R.filterFragments (fragmentIsOnLine n)
-    shiftFragments dy = R.mapFragments (shiftFragment dy)
+    shiftFragments dx dy = R.mapFragments (shiftFragment dx dy)
     appendFragments = R.appendFragments
 
 -- | Split the given paragraph layout into single-line layouts.
@@ -61,7 +62,7 @@ cutLine n pl = trimTop $ limitFragments n pl
 
 -- | Add a constant to each fragment's `y_origin` so that their maximum is zero.
 trimTop :: GenericLayout pl => pl -> pl
-trimTop pl = shiftFragments (-topDistance pl) pl
+trimTop pl = shiftFragments 0 (-topDistance pl) pl
 
 topFragmentOrigin :: [Fragment d] -> Int32
 topFragmentOrigin frags = maximum $ map (y_origin . fragmentRect) frags
@@ -75,15 +76,8 @@ mergeLine :: GenericLayout pl => pl -> pl -> pl
 mergeLine pl nextLine = pl'
     where
         -- Quadratic time complexity. TODO: Consider optimising.
-        pl' = appendFragments pl $ shiftFragments y nextLine
+        pl' = appendFragments pl $ shiftFragments 0 y nextLine
         y = y_terminus $ rect pl
 
-shiftFragment :: Int32 -> Fragment d -> Fragment d
-shiftFragment dy f = f'
-    where
-        f' = f { fragmentRect = r' }
-        r' = r { y_origin = y_origin r + dy }
-        r = fragmentRect f
-
 fragmentIsOnLine :: Int -> Fragment d -> Bool
 fragmentIsOnLine n frag = n == fragmentLine frag
-- 
2.30.2