7 files changed, 38 insertions(+), 20 deletions(-)

M CHANGELOG.md
M lib/Data/Text/ParagraphLayout/Rich.hs
M src/Data/Text/ParagraphLayout/Internal/Plain.hs
M src/Data/Text/ParagraphLayout/Internal/TextOptions.hs
M test/Data/Text/ParagraphLayout/Internal/TreeSpec.hs
M test/Data/Text/ParagraphLayout/Rich/ParagraphData.hs
M test/Data/Text/ParagraphLayout/SpanData.hs

@@ 7,6 7,8 @@
     * Supports multiple fonts in the same paragraph. Where line height varies,
       text will be aligned by its top edge.
 
+    * Requires user to set base text direction (LTR or RTL).
+
 * Moved existing plain text interface into `Data.Text.ParagraphLayout.Plain`
   submodule and marked it as deprecated.
 

@@ 33,6 33,7 @@ module Data.Text.ParagraphLayout.Rich
     , textFont
     , textLineHeight
     , textLanguage
+    , textDirection
     -- ** Verification
     , paragraphSpanBounds
     , paragraphSpanTexts

@@ 2,6 2,8 @@
 module Data.Text.ParagraphLayout.Internal.Plain (layoutPlain)
 where
 
+import Data.Text.Glyphize (Direction (DirLTR))
+
 import Data.Text.ParagraphLayout.Internal.BoxOptions
 import Data.Text.ParagraphLayout.Internal.Fragment
 import Data.Text.ParagraphLayout.Internal.ParagraphOptions


@@ 36,7 38,7 @@ plainToRich (P.Paragraph arr off spans opts) = R.Paragraph arr off rootNode opts
             (boxFromPlain baseOpts i s)
             defaultBoxOptions
         indexedSpans = zip [0 ..] spans
-        baseOpts = defaultTextOptions
+        baseOpts = (defaultTextOptions DirLTR)
             { textFont = paragraphFont opts
             , textLineHeight = paragraphLineHeight opts
             }

@@ 4,7 4,7 @@ module Data.Text.ParagraphLayout.Internal.TextOptions
     )
 where
 
-import Data.Text.Glyphize (Font, emptyFont)
+import Data.Text.Glyphize (Direction, Font, emptyFont)
 
 import Data.Text.ParagraphLayout.Internal.LineHeight
 


@@ 31,10 31,16 @@ data TextOptions = TextOptions
     -- Used for selecting the appropriate glyphs and line breaking rules,
     -- primarily in East Asian languages.
 
+    , 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.
+
     -- TODO: textVerticalAlign
     -- TODO: textLetterSpacing
     -- TODO: textWordSpacing
-    -- TODO: textDirection
     -- TODO: textFontFeatures
     -- TODO: textSoftBreaks
 


@@ 42,9 48,13 @@ data TextOptions = TextOptions
     deriving (Eq)
 
 -- | `TextOptions` with default values.
-defaultTextOptions :: TextOptions
-defaultTextOptions = TextOptions
+defaultTextOptions
+    :: Direction
+    -- ^ Required value for `textDirection`.
+    -> TextOptions
+defaultTextOptions dir = TextOptions
     { textFont = emptyFont
     , textLineHeight = Normal
     , textLanguage = ""
+    , textDirection = dir
     }

@@ 6,6 6,9 @@ import Data.Text.ParagraphLayout.Internal.ResolvedBox
 import Data.Text.ParagraphLayout.Internal.TextOptions
 import Data.Text.ParagraphLayout.Internal.Tree
 
+t :: TextOptions
+t = defaultTextOptions undefined
+
 complexTree :: RootNode String
 complexTree = RootBox $ Box
     [ TextSequence "a" 1


@@ 20,7 23,7 @@ complexTree = RootBox $ Box
                     [ TextSequence "d" 1
                     , TextSequence "e" 1
                     ]
-                    defaultTextOptions
+                    t
                 )
                 defaultBoxOptions
             , TextSequence "f" 1


@@ 33,16 36,16 @@ complexTree = RootBox $ Box
                         (Box
                             [ TextSequence "h" 1
                             ]
-                            defaultTextOptions
+                            t
                         )
                         defaultBoxOptions
                     , TextSequence "i" 1
                     ]
-                    defaultTextOptions
+                    t
                 )
                 defaultBoxOptions
             ]
-            defaultTextOptions
+            t
         )
         defaultBoxOptions
     , InlineBox


@@ 54,7 57,7 @@ complexTree = RootBox $ Box
                     [ TextSequence "j" 1
                     , TextSequence "k" 1
                     ]
-                    defaultTextOptions
+                    t
                 )
                 defaultBoxOptions
             , InlineBox


@@ 65,20 68,20 @@ complexTree = RootBox $ Box
                         (Box
                             [ TextSequence "l" 1
                             ]
-                            defaultTextOptions
+                            t
                         )
                         defaultBoxOptions
                     ]
-                    defaultTextOptions
+                    t
                 )
                 defaultBoxOptions
             , TextSequence "m" 1
             ]
-            defaultTextOptions
+            t
         )
         defaultBoxOptions
     ]
-    defaultTextOptions
+    t
 
 leafData :: Leaf d -> d
 leafData (TextLeaf d _ _ _) = d

@@ 6,7 6,7 @@ module Data.Text.ParagraphLayout.Rich.ParagraphData
 where
 
 import Data.Text (pack)
-import Data.Text.Glyphize (Font)
+import Data.Text.Glyphize (Direction (DirLTR), Font)
 
 import Data.Text.ParagraphLayout.Internal.BoxOptions
 import Data.Text.ParagraphLayout.Internal.ParagraphOptions


@@ 15,7 15,7 @@ import Data.Text.ParagraphLayout.Internal.TextOptions
 import Data.Text.ParagraphLayout.Internal.TreeOfTexts
 
 t_ :: TextOptions
-t_ = defaultTextOptions
+t_ = defaultTextOptions DirLTR
 
 b_ :: BoxOptions
 b_ = defaultBoxOptions

@@ 6,7 6,7 @@ module Data.Text.ParagraphLayout.SpanData
 where
 
 import Data.Text (pack)
-import Data.Text.Glyphize (Font)
+import Data.Text.Glyphize (Direction (DirLTR), Font)
 
 import Data.Text.ParagraphLayout.Internal.BoxOptions
 import Data.Text.ParagraphLayout.Internal.LineHeight


@@ 23,7 23,7 @@ emptySpan font = ResolvedSpan
     , spanIndex = 0
     , spanOffsetInParagraph = 0
     , spanText = pack ""
-    , spanTextOptions = defaultTextOptions
+    , spanTextOptions = (defaultTextOptions DirLTR)
         { textFont = font
         , textLineHeight = Normal
         , textLanguage = "en"


@@ 39,7 39,7 @@ czechHello font = ResolvedSpan
     , spanIndex = 0
     , spanOffsetInParagraph = 0
     , spanText = pack "Ahoj, světe!"
-    , spanTextOptions = defaultTextOptions
+    , spanTextOptions = (defaultTextOptions DirLTR)
         { textFont = font
         , textLineHeight = Normal
         , textLanguage = "cs"


@@ 55,7 55,7 @@ serbianMixedScript font = ResolvedSpan
     , spanIndex = 0
     , spanOffsetInParagraph = 0
     , spanText = pack "Vikipedija (Википедија)"
-    , spanTextOptions = defaultTextOptions
+    , spanTextOptions = (defaultTextOptions DirLTR)
         { textFont = font
         , textLineHeight = Normal
         , textLanguage = "sr"