Create a Metrics module

lib/Graphics/Fountainhead/Metrics.hs

@@ -0,0 +1,29 @@
+{- This Source Code Form is subject to the terms of the Mozilla Public License,
+   v. 2.0. If a copy of the MPL was not distributed with this file, You can
+   obtain one at https://mozilla.org/MPL/2.0/. -}
+
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
+
+module Graphics.Fountainhead.Metrics
+    ( FontMetrics(..)
+    , afmFontMetrics
+    ) where
+
+import qualified Data.Text.Lazy.Builder as Text.Builder
+import Data.Version (Version(..), showVersion)
+import Graphics.Fountainhead.Type (newlineBuilder)
+
+newtype FontMetrics = FontMetrics
+    { version :: Version
+    } deriving (Eq, Show)
+
+afmKeyString :: Text.Builder.Builder -> String -> Text.Builder.Builder
+afmKeyString key value = key <> Text.Builder.singleton '\t'
+    <> Text.Builder.fromString value <> newlineBuilder
+
+afmFontMetrics :: FontMetrics -> Text.Builder.Builder
+afmFontMetrics FontMetrics{..}
+    = afmKeyString "StartFontMetrics" (showVersion version)
+    <> afmKeyString "Comment" "Generated by Fountainhead"
+    <> "EndFontMetrics" <> newlineBuilder