diff options
Diffstat (limited to 'lib/Graphics/Fountainhead/Metrics.hs')
| -rw-r--r-- | lib/Graphics/Fountainhead/Metrics.hs | 31 |
1 files changed, 27 insertions, 4 deletions
diff --git a/lib/Graphics/Fountainhead/Metrics.hs b/lib/Graphics/Fountainhead/Metrics.hs index e9b3c39..ca02c0d 100644 --- a/lib/Graphics/Fountainhead/Metrics.hs +++ b/lib/Graphics/Fountainhead/Metrics.hs @@ -5,6 +5,7 @@ {-# LANGUAGE DataKinds #-} {-# LANGUAGE OverloadedStrings #-} {-# LANGUAGE DuplicateRecordFields #-} +{-# LANGUAGE PatternSynonyms #-} module Graphics.Fountainhead.Metrics ( FontBBox(..) @@ -24,9 +25,14 @@ import Graphics.Fountainhead.TrueType , HheaTable(..) , NameRecord(..) , NameTable(..) + , Os2BaseFields(..) + , Os2Version4Fields(..) + , Os2Version5Fields(..) + , Os2Table(..) , PostHeader(..) , PostTable(..) , findTableByTag + , pattern Os2Version4CommonFields ) import Graphics.Fountainhead.Parser ( ParseErrorBundle @@ -35,14 +41,14 @@ import Graphics.Fountainhead.Parser , parseTable , headTableP , hheaTableP + , os2TableP , postTableP ) import qualified Text.Megaparsec as Megaparsec import Data.Bifunctor (Bifunctor(..)) -import Data.Int (Int16, Int32) +import Data.Int (Int16) import Data.Word (Word16) import GHC.Records (HasField(..)) -import Graphics.Fountainhead.Type (Fixed32(..)) type Number = Float @@ -99,6 +105,7 @@ data MetricsError = MetricsParseError ParseErrorBundle | MetricsRequiredTableMissingError String | MetricsNameRecordNotFound Word16 + | UnsupportedOs2VersionError deriving Eq instance Show MetricsError @@ -108,6 +115,8 @@ instance Show MetricsError "Required table " <> tableName <> " is missing." show (MetricsNameRecordNotFound nameId) = "Name record with ID " <> show nameId <> " was not found." + show UnsupportedOs2VersionError = + "OS/2 version 1 does not contain cap height." collectMetrics :: FilePath -> ByteString -> Either MetricsError FontDescriptor collectMetrics fontFile ttfContents = @@ -138,18 +147,32 @@ collectMetrics fontFile ttfContents = PostTable{ postHeader } <- first MetricsParseError $ parseTable postEntry postTableP processedState + (capHeight, weightClass) <- getCapHeight processedState initialResult + pure $ FontDescriptor { fontName = variableText nameRecord variable psNameIndex , flags = [] - , stemV = 1 + , stemV = calculateStemV $ fromIntegral weightClass , missingWidth = 0 , fontBBox = calculateBoundingBox scale headTable , italicAngle = realToFrac $ getField @"italicAngle" postHeader - , capHeight = 0 + , capHeight = fromIntegral $ scalePs scale capHeight , ascender = fromIntegral $ scalePs scale ascent , descender = fromIntegral $ scalePs scale descent } where + calculateStemV weightClass = 10 + 220 * (weightClass - 50) / 900 + getCapHeight processedState initialResult = do + os2Entry <- maybeMetricsError (MetricsRequiredTableMissingError "OS/2") + $ findTableByTag "OS/2" initialResult + os2Table <- first MetricsParseError + $ parseTable os2Entry os2TableP processedState + case os2Table of + Os2Version4CommonFields Os2BaseFields{ usWeightClass } Os2Version4Fields{ sCapHeight } -> + Right (sCapHeight, usWeightClass) + Os2Version5 Os2BaseFields{ usWeightClass } _ Os2Version5Fields{ sCapHeight } -> + Right (sCapHeight, usWeightClass) + _ -> Left UnsupportedOs2VersionError calculateBoundingBox scale HeadTable{ xMin, xMax, yMin, yMax } = let xMin' = fromIntegral $ scalePs scale xMin yMin' = fromIntegral $ scalePs scale yMin |