1 files changed, 11 insertions(+), 1 deletions(-)

M src/Data/Text/ParagraphLayout/Internal/Plain.hs

@@ 198,13 198,23 @@ shapeRun :: WithSpan Run -> [(GlyphInfo, GlyphPos)]
 shapeRun (WithSpan rs run) = shape font buffer features
     where
         font = RS.spanFont rs
-        -- TODO: Set beginsText / endsText.
         buffer = defaultBuffer
             { text = Lazy.fromStrict $ runText run
             , contentType = Just ContentTypeUnicode
             , direction = runDirection run
             , script = runScript run
             , language = Just $ RS.spanLanguage rs
+            -- Perhaps counter-intuitively, the `beginsText` and `endsText`
+            -- flags refer to everything that "Data.Text.Glyphize" can see,
+            -- not just the current run.
+            --
+            -- Since all runs are cut from a single continuous `Text` that
+            -- represents the entire paragraph, and "Data.Text.Glyphize" peeks
+            -- at the whole underlying byte array, HarfBuzz will be able to see
+            -- both the beginning and the end of the paragraph at all times,
+            -- so these flags can always be set.
+            , beginsText = True
+            , endsText = True
             }
         features = []