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{-# LANGUAGE OverloadedStrings #-}
-- | Infrastructure for parsing & desugaring text related CSS properties.
module Graphics.Layout.Inline.CSS(CSSInline(..), ParagraphBuilder(..),
buildParagraph, concatParagraph, finalizeParagraph) where
import Data.CSS.Syntax.Tokens (Token(..))
import Stylist (PropertyParser(..))
import qualified Data.Text.Lazy as Lz
import qualified Data.Text as Txt
import Data.Text.Internal (Text(..))
import Data.Text.ParagraphLayout (Span(..), SpanOptions(..), LineHeight(..),
Paragraph(..), ParagraphOptions(..))
import Graphics.Layout.CSS.Font (Font'(..), hbScale)
import Data.Char (isSpace)
-- | Document text with Balkón styling options, CSS stylable.
data CSSInline = CSSInline Lz.Text SpanOptions
instance PropertyParser CSSInline where
temp = CSSInline "" SpanOptions {
spanLanguage = "Zxx"
}
inherit (CSSInline _ opts) = CSSInline "" opts
longhand _ (CSSInline _ opts) "content" toks
| all isString toks =
Just $ CSSInline (Lz.concat [Lz.fromStrict x | String x <- toks]) opts
where
isString (String _) = True
isString _ = False
longhand _ (CSSInline txt opts) "-argo-lang" [String x] =
Just $ CSSInline txt opts { spanLanguage = Txt.unpack x }
longhand _ _ _ _ = Nothing
-- | Helper datastructure for concatenating CSSInlines.
data ParagraphBuilder = ParagraphBuilder Lz.Text [Span]
-- | Convert a CSSInline to a paragraph builder, with a span covering the entire text.
buildParagraph :: CSSInline -> ParagraphBuilder
buildParagraph (CSSInline txt opts) =
ParagraphBuilder txt [flip Span opts $ fromEnum $ Lz.length txt]
-- | Concatenate two `ParagraphBuilder`s, adjusting the spans appropriately.
concatParagraph :: ParagraphBuilder -> ParagraphBuilder -> ParagraphBuilder
concatParagraph (ParagraphBuilder aTxt aOpts) (ParagraphBuilder bTxt bOps) =
ParagraphBuilder (aTxt `Lz.append` bTxt)
(aOpts ++ [Span (toEnum (fromEnum $ Lz.length aTxt) + off) opts
| Span off opts <- bOps])
-- | Convert a builder + font to a Balkón paragraph.
finalizeParagraph :: ParagraphBuilder -> Font' -> Maybe Paragraph
finalizeParagraph (ParagraphBuilder txt _) _ | Lz.all isSpace txt || Lz.null txt = Nothing
finalizeParagraph (ParagraphBuilder txt ops) font' = Just $ Paragraph txt' 0 ops pOps
where
Text txt' _ _ = Lz.toStrict txt
pOps = ParagraphOptions {
paragraphFont = hbFont font',
paragraphLineHeight = Absolute $ round (lineheight font' * hbScale font'),
-- This is what we're computing! Configure to give natural width.
paragraphMaxWidth = maxBound -- i.e. has all the space it needs...
}