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module Data.Text.ParagraphLayout.Internal.TextOptions
( TextOptions (..)
, defaultTextOptions
)
where
import Data.Int (Int32)
import Data.Text.Glyphize (Direction, Font, emptyFont)
import Data.Text.ParagraphLayout.Internal.LineHeight
-- | Style options to be applied to a text sequence.
--
-- This record type is likely to be extended in the future.
-- Use `defaultTextOptions` and update it with specific record selectors
-- instead of constructing `TextOptions` directly.
data TextOptions = TextOptions
{ textFont :: Font
-- ^ Font to be used for shaping and measurement.
-- Make sure to set its scale (see `Data.Text.Glyphize.optionScale`) using
-- the same units that you want in the output.
, textAscender :: Maybe Int32
-- ^ How much to add to the text's baseline coordinate to reach its
-- ascender line. This is usually a positive value.
--
-- If set to `Nothing`, the font's own `Data.Text.Glyphize.ascender`
-- metric will be used.
--
-- Setting an explicit value with @`Just` x@ is intended as an override
-- for situations where the text is intended to be replaced by an object
-- with differently calculated dimensions.
, textDescender :: Maybe Int32
-- ^ How much to add to the text's baseline coordinate to reach its
-- descender line. Note that this is usually a negative value because
-- the descender is usually below the baseline.
--
-- If set to `Nothing`, the font's own `Data.Text.Glyphize.descender`
-- metric will be used.
--
-- Setting an explicit value with @`Just` x@ is intended as an override
-- for situations where the text is intended to be replaced by an object
-- with differently calculated dimensions.
, textLineHeight :: LineHeight
-- ^ Preferred line height of the resulting fragments.
, textLanguage :: String
-- ^ IETF BCP 47 language tag, such as the value expected to be found in
-- the HTML @lang@ attribute, specifying the primary language for the
-- span's text content. An empty string explicitly means "language unknown".
--
-- 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.
--
-- When applied to the root box in a paragraph, this is also used to
-- determine the base direction of the paragraph.
-- TODO: textLetterSpacing
-- TODO: textWordSpacing
-- TODO: textFontFeatures
-- TODO: textSoftBreaks
}
deriving (Eq)
-- | `TextOptions` with default values.
defaultTextOptions
:: Direction
-- ^ Required value for `textDirection`.
-> TextOptions
defaultTextOptions dir = TextOptions
{ textFont = emptyFont
, textAscender = Nothing
, textDescender = Nothing
, textLineHeight = Normal
, textLanguage = ""
, textDirection = dir
}