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module Data.Text.ParagraphLayout.Internal.ProtoFragment
( ProtoFragment (direction, verticalOffsets, advance, glyphs, hardBreak)
, protoFragmentH
, mapVerticalOffsets
)
where
import Data.Int (Int32)
import Data.Text.Glyphize (Direction (..), GlyphInfo, GlyphPos (x_advance))
import qualified Data.Text.ParagraphLayout.Internal.BiDiLevels as BiDi
import qualified Data.Text.ParagraphLayout.Internal.VerticalOffsets as VO
-- | A box fragment which has not been positioned yet.
data ProtoFragment = ProtoFragment
{ direction :: Direction
-- ^ Text direction, which is constant within a fragment.
, level :: BiDi.Level
-- ^ BiDi embedding level.
-- Should be even for LTR fragments and odd for RTL fragments.
, verticalOffsets :: VO.VerticalOffsets
-- ^ Vertical offsets used for aligning the fragment within its line.
, advance :: Int32
-- ^ Total advance of glyphs in this fragment,
-- depending on the text direction.
, glyphs :: [(GlyphInfo, GlyphPos)]
, hardBreak :: Bool
-- ^ Marks fragment that ends with a forced line break.
}
-- | Construct a `ProtoFragment`, automatically calculating the total advance
-- for a horizontal text direction.
protoFragmentH
:: Direction
-> BiDi.Level
-> VO.VerticalOffsets
-> [(GlyphInfo, GlyphPos)]
-> Bool
-> ProtoFragment
protoFragmentH dir lvl vo gs hard = ProtoFragment dir lvl vo adv gs hard
where
adv = sum $ map (x_advance . snd) gs
-- | Apply the given function to the `verticalOffsets` in the given fragment.
mapVerticalOffsets
:: (VO.VerticalOffsets -> VO.VerticalOffsets)
-> ProtoFragment
-> ProtoFragment
mapVerticalOffsets mapFunc pf =
pf { verticalOffsets = mapFunc $ verticalOffsets pf }
instance BiDi.WithLevel ProtoFragment where
level = level -- BiDi.level = ProtoFragment.level