4 files changed, 50 insertions(+), 25 deletions(-)

M .golden/paragraphLayout/arabicHelloParagraphUltraNarrow.golden
M CHANGELOG.md
M src/Data/Text/ParagraphLayout/Internal/Layout.hs
M src/Data/Text/ParagraphLayout/Internal/Rich.hs

@@ 1,5 1,5 @@
 ParagraphLayout
-    { paragraphRect = Rect {x_origin = 0, y_origin = 0, x_size = 827, y_size = -19500}
+    { paragraphRect = Rect {x_origin = -727, y_origin = 0, x_size = 827, y_size = -19500}
     , spanLayouts = [
         SpanLayout
         [ Fragment


@@ 8,7 8,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = NoEdge, boxRightEdge = SpacedEdge 0, boxStartEdge = SpacedEdge 0, boxEndEdge = NoEdge}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = 0, x_size = 224, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -124, y_origin = 0, x_size = 224, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 302, cluster = 5, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 224, y_advance = 0, x_offset = 0, y_offset = 0})


@@ 20,7 20,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = NoEdge, boxRightEdge = NoEdge, boxStartEdge = NoEdge, boxEndEdge = NoEdge}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = -1500, x_size = 269, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -169, y_origin = -1500, x_size = 269, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 477, cluster = 7, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 269, y_advance = 0, x_offset = 0, y_offset = 0})


@@ 32,7 32,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = NoEdge, boxRightEdge = NoEdge, boxStartEdge = NoEdge, boxEndEdge = NoEdge}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = -3000, x_size = 827, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -727, y_origin = -3000, x_size = 827, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 1665, cluster = 9, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 0, y_advance = 0, x_offset = 303, y_offset = -40})


@@ 45,7 45,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = NoEdge, boxRightEdge = NoEdge, boxStartEdge = NoEdge, boxEndEdge = NoEdge}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = -4500, x_size = 314, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -214, y_origin = -4500, x_size = 314, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 1588, cluster = 15, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 0, y_advance = 0, x_offset = 26, y_offset = 451})


@@ 58,7 58,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = NoEdge, boxRightEdge = NoEdge, boxStartEdge = NoEdge, boxEndEdge = NoEdge}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = -6000, x_size = 270, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -170, y_origin = -6000, x_size = 270, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 293, cluster = 19, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 270, y_advance = 0, x_offset = 0, y_offset = 0})


@@ 70,7 70,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = NoEdge, boxRightEdge = NoEdge, boxStartEdge = NoEdge, boxEndEdge = NoEdge}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = -7500, x_size = 555, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -455, y_origin = -7500, x_size = 555, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 1641, cluster = 21, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 0, y_advance = 0, x_offset = 185, y_offset = 120})


@@ 83,7 83,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = NoEdge, boxRightEdge = NoEdge, boxStartEdge = NoEdge, boxEndEdge = NoEdge}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = -9000, x_size = 479, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -379, y_origin = -9000, x_size = 479, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 1588, cluster = 26, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 0, y_advance = 0, x_offset = 99, y_offset = 170})


@@ 96,7 96,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = NoEdge, boxRightEdge = NoEdge, boxStartEdge = NoEdge, boxEndEdge = NoEdge}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = -10500, x_size = 314, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -214, y_origin = -10500, x_size = 314, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 1588, cluster = 30, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 0, y_advance = 0, x_offset = 26, y_offset = 451})


@@ 109,7 109,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = NoEdge, boxRightEdge = NoEdge, boxStartEdge = NoEdge, boxEndEdge = NoEdge}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = -12000, x_size = 310, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -210, y_origin = -12000, x_size = 310, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 1563, cluster = 34, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 0, y_advance = 0, x_offset = 42, y_offset = 40})


@@ 122,7 122,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = NoEdge, boxRightEdge = NoEdge, boxStartEdge = NoEdge, boxEndEdge = NoEdge}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = -13500, x_size = 452, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -352, y_origin = -13500, x_size = 452, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 1641, cluster = 38, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 0, y_advance = 0, x_offset = 4, y_offset = 379})


@@ 135,7 135,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = NoEdge, boxRightEdge = NoEdge, boxStartEdge = NoEdge, boxEndEdge = NoEdge}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = -15000, x_size = 524, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -424, y_origin = -15000, x_size = 524, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 1588, cluster = 42, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 0, y_advance = 0, x_offset = 131, y_offset = 80})


@@ 148,7 148,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = NoEdge, boxRightEdge = NoEdge, boxStartEdge = NoEdge, boxEndEdge = NoEdge}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = -16500, x_size = 270, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -170, y_origin = -16500, x_size = 270, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 293, cluster = 46, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 270, y_advance = 0, x_offset = 0, y_offset = 0})


@@ 160,7 160,7 @@ ParagraphLayout
             , fragmentAncestorBoxes =
                 [ AncestorBox {boxUserData = (), boxLeftEdge = SpacedEdge 0, boxRightEdge = NoEdge, boxStartEdge = NoEdge, boxEndEdge = SpacedEdge 0}
                 ]
-            , fragmentRect = Rect {x_origin = 0, y_origin = -18000, x_size = 284, y_size = -1500}
+            , fragmentRect = Rect {x_origin = -184, y_origin = -18000, x_size = 284, y_size = -1500}
             , fragmentPen = (0, -1085)
             , fragmentGlyphs =
                 [ (GlyphInfo {codepoint = 108, cluster = 48, unsafeToBreak = False, unsafeToConcat = False, safeToInsertTatweel = False}, GlyphPos {x_advance = 284, y_advance = 0, x_offset = 0, y_offset = 0})

@@ 2,6 2,9 @@
 
 ## 1.2.0.0 -- TBD
 
+* Text will now overflow the end edge of the paragraph according to the
+  text direction of the root box, instead of always overflowing the right edge.
+
 * Fixed a bug where only the height of the shortest fragment on a line
   would be considered when positioning the following line.
 

@@ 15,7 15,7 @@ import Data.Text.Foreign (lengthWord8)
 import Data.Text.Glyphize
     ( Buffer (..)
     , ContentType (ContentTypeUnicode)
-    , Direction (DirLTR, DirRTL)
+    , Direction (DirLTR, DirRTL, DirTTB, DirBTT)
     , FontExtents (..)
     , GlyphInfo
     , GlyphPos


@@ 54,12 54,16 @@ type ProtoFragmentWithBoxes d = WithBoxes d (ProtoFragmentWithSpan d)
 -- necessary to fit within the requested line width.
 --
 -- The output is a flat list of fragments positioned in both dimensions.
-layoutAndAlignLines :: Int32 -> NonEmpty (WithSpan d Run) ->
-    [FragmentWithSpan d]
-layoutAndAlignLines maxWidth runs = frags
+layoutAndAlignLines
+    :: Direction
+    -> Int32
+    -> NonEmpty (WithSpan d Run)
+    -> [FragmentWithSpan d]
+layoutAndAlignLines dir maxWidth runs = frags
     where
         frags = concatMap NonEmpty.toList fragsInLines
-        (_, fragsInLines) = mapAccumL positionLineH originY numberedLines
+        (_, fragsInLines) = mapAccumL positionLine originY numberedLines
+        positionLine = positionLineH dir maxWidth
         numberedLines = zip [1 ..] canonicalLines
         canonicalLines = fmap reorderProtoFragments logicalLines
         logicalLines = nonEmptyItems $ layoutLines maxWidth [] runs


@@ 99,15 103,30 @@ layoutLines maxWidth openBoxes runs = case nonEmpty rest of
 -- @vertical-align: top@ in CSS.
 --
 -- TODO: For rich text, allow other types of vertical alignment.
-positionLineH :: Int32 -> (Int, PL.ProtoLine NonEmpty d) ->
-    (Int32, NonEmpty (FragmentWithSpan d))
-positionLineH originY (num, pl) = (nextY, frags)
+positionLineH
+    :: Direction
+    -> Int32
+    -> Int32
+    -> (Int, PL.ProtoLine NonEmpty d)
+    -> (Int32, NonEmpty (FragmentWithSpan d))
+positionLineH dir maxWidth originY (num, pl) = (nextY, frags)
     where
         nextY = minimum $ fmap y_min rects
         rects = fmap (\ (WithSpan _ r) -> fragmentRect r) frags
         (_, frags) = mapAccumL (positionFragmentH num originY) originX wpfs
         wpfs = PL.applyBoxes pl
-        originX = paragraphOriginX
+        originX = paragraphOriginX + if lineWidth > maxWidth
+            then overflowingLineOffset dir (lineWidth - maxWidth)
+            else 0
+        lineWidth = PL.width pl
+
+-- | Inline offset of the first fragment on a line that overflows.
+overflowingLineOffset :: Direction -> Int32 -> Int32
+overflowingLineOffset DirLTR _ = 0
+overflowingLineOffset DirTTB _ = 0
+overflowingLineOffset DirRTL excess = -excess
+-- TODO: Check if the sign needs to be flipped for vertical text.
+overflowingLineOffset DirBTT excess = -excess
 
 -- | Position the given horizontal fragment on a line,
 -- using @originY@ as its top edge and @originX@ as its left edge,

@@ 23,14 23,17 @@ import Data.Text.ParagraphLayout.Internal.WithSpan
 
 -- | Lay out a rich text paragraph.
 layoutRich :: Paragraph d -> ParagraphLayout d
-layoutRich p@(Paragraph _ _ _ opts) = paragraphLayout $ map unwrap frags
+layoutRich p = paragraphLayout $ map unwrap frags
     where
+        Paragraph _ _ root opts = p
+        RootBox (Box _ rootTextOpts) = root
         unwrap (WithSpan rs frag) =
             frag { fragmentUserData = RS.spanUserData rs }
         frags = case nonEmpty wrappedRuns of
-            Just xs -> layoutAndAlignLines maxWidth xs
+            Just xs -> layoutAndAlignLines dir maxWidth xs
             Nothing -> []
         wrappedRuns = spansToRunsWrapped spans
+        dir = textDirection rootTextOpts
         maxWidth = paragraphMaxWidth opts
         spans = resolveSpans p