1 files changed, 73 insertions(+), 7 deletions(-)

M Data/Text/Glyphize/Buffer.hs

@@ 2,6 2,7 @@ module Data.Text.Glyphize.Buffer where
 
 import Data.Text.Lazy as Lazy
 import Data.ByteString.Lazy as Lazy
+import Data.ByteString.Lazy as LBS
 import Data.Text.Short
 
 import Foreign.ForeignPtr


@@ 19,21 20,80 @@ import Data.Char (ord)
 
 data Buffer = Buffer {
     text :: Either Lazy.Text Lazy.ByteString,
+    -- ^ The Unicode text, in visual order, for HarfBuzz to convert into glyphs.
     contentType :: Maybe ContentType,
+    -- ^ What the bytes of the ByteString contents represents,
+    -- namely unicode characters (before shaping) or glyphs (result of shaping).
+    -- Typically callers should leave this as `Just ContentTypeUnicode`.
     direction :: Maybe Direction,
+    -- ^ The text flow direction of the buffer.
+    -- No shaping can happen without setting buffer direction, and it controls
+    -- the visual direction for the output glyphs; for RTL direction the glyphs
+    -- will be reversed. Many layout features depend on the proper setting of
+    -- the direction, for example, reversing RTL text before shaping,
+    -- then shaping with LTR direction is not the same as keeping the text in
+    -- logical order and shaping with RTL direction.
     script :: Maybe ShortText,
+    -- ^ Script is crucial for choosing the proper shaping behaviour for scripts
+    -- that require it (e.g. Arabic) and the which OpenType features defined in
+    -- the font to be applied.
     language :: Maybe ShortText,
+    -- ^ Languages are crucial for selecting which OpenType feature to apply to
+    -- the buffer which can result in applying language-specific behaviour.
+    -- Languages are orthogonal to the scripts, and though they are related,
+    -- they are different concepts and should not be confused with each other.
     beginsText :: Bool,
+    -- ^ special handling of the beginning of text paragraph can be applied to
+    -- this buffer. Should usually be set, unless you are passing to the buffer
+    -- only part of the text without the full context.
     endsText :: Bool,
+    -- ^ special handling of the end of text paragraph can be applied to this buffer.
     preserveDefaultIgnorables :: Bool,
+    -- ^ character with Default_Ignorable Unicode property should use the
+    -- corresponding glyph from the font, instead of hiding them (done by
+    -- replacing them with the space glyph and zeroing the advance width.)
+    -- Takes precedance over `removeDefaultIgnorables`.
     removeDefaultIgnorables :: Bool,
+    -- ^ character with Default_Ignorable Unicode property should be removed
+    -- from glyph string instead of hiding them (done by replacing them with
+    -- the space glyph and zeroing the advance width.)
     don'tInsertDottedCircle :: Bool,
+    -- ^ a dotted circle should not be inserted in the rendering of incorrect
+    -- character sequences (such at <0905 093E>).
     clusterLevel :: ClusterLevel,
-    invisibleGlyph :: Char,
-    notFoundGlyph :: Char,
+    -- ^ dictates one aspect of how HarfBuzz will treat non-base characters
+    -- during shaping.
+    invisibleGlyph :: Int,
+    -- ^ The glyph number that replaces invisible characters in the
+    -- shaping result. If set to zero (default), the glyph for the U+0020
+    -- SPACE character is used. Otherwise, this value is used verbatim.
+    notFoundGlyph :: Int,
+    -- ^ the glyph number that replaces characters not found in the font during shaping.
+    -- The not-found glyph defaults to zero, sometimes knows as the ".notdef" glyph.
+    -- This API allows for differentiating the two.
     replacementCodepoint :: Char
+    -- ^ the hb_codepoint_t that replaces invalid entries for a given encoding
+    -- when adding text to buffer .
 }
 
+-- | An empty buffer with sensible default properties.
+defaultBuffer = Buffer {
+        text = Right LBS.empty,
+        contentType = Just ContentTypeUnicode,
+        direction = Nothing,
+        script = Nothing,
+        language = Nothing,
+        beginsText = True,
+        endsText = True,
+        preserveDefaultIgnorables = False,
+        removeDefaultIgnorables = False,
+        don'tInsertDottedCircle = False,
+        clusterLevel = ClusterMonotoneGraphemes,
+        invisibleGlyph = 0,
+        notFoundGlyph = 0,
+        replacementCodepoint = '\xFFFD'
+    }
+
 data ContentType = ContentTypeUnicode | ContentTypeGlyphs deriving (Eq, Show)
 data Direction = DirLTR | DirRTL | DirTTB | DirBTT deriving (Eq, Show)
 data ClusterLevel = ClusterMonotoneGraphemes | ClusterMonotoneChars | ClusterChars deriving (Eq, Show)


@@ 65,7 125,8 @@ dirVertical dir = dir `Prelude.elem` [DirTTB, DirBTT]
 type Buffer' = ForeignPtr Buffer''
 data Buffer''
 
-buffer2buffer' buf = unsafePerformIO $ do
+freeze = unsafePerformIO . freeze'
+freeze' buf = do
     buffer <- hb_buffer_create
     case text buf of
         Right bs -> hb_buffer_add_bytestring buffer bs


@@ 100,13 161,16 @@ buffer2buffer' buf = unsafePerformIO $ do
         ClusterMonotoneGraphemes -> 0
         ClusterMonotoneChars -> 1
         ClusterChars -> 2
-    hb_buffer_set_invisible_glyph buffer $ ord $ invisibleGlyph buf
-    hb_buffer_set_not_found_glyph buffer $ ord $ notFoundGlyph buf
+    hb_buffer_set_invisible_glyph buffer $ invisibleGlyph buf
+    hb_buffer_set_not_found_glyph buffer $ notFoundGlyph buf
     hb_buffer_set_replacement_codepoint buffer $ ord $ replacementCodepoint buf
+    case (contentType buf, direction buf, script buf, language buf) of
+        (Just ContentTypeUnicode, Nothing, _, _) -> hb_buffer_guess_segment_properties buffer
+        (Just ContentTypeUnicode, _, Nothing, _) -> hb_buffer_guess_segment_properties buffer
+        (Just ContentTypeUnicode, _, _, Nothing) -> hb_buffer_guess_segment_properties buffer
     newForeignPtr hb_buffer_destroy buffer
 
-buffer'2buffer buf' = unsafePerformIO $ do
-    return ()
+thaw buf' = ()
 
 foreign import ccall "hb_buffer_create" hb_buffer_create :: IO (Ptr Buffer'')
 foreign import ccall "&hb_buffer_destroy" hb_buffer_destroy :: FunPtr (Ptr Buffer'' -> IO ())


@@ 141,3 205,5 @@ foreign import ccall "hb_buffer_set_not_found_glyph" hb_buffer_set_not_found_gly
     :: Ptr Buffer'' -> Int -> IO ()
 foreign import ccall "hb_buffer_set_replacement_codepoint" hb_buffer_set_replacement_codepoint
     :: Ptr Buffer'' -> Int -> IO ()
+foreign import ccall "hb_buffer_guess_segment_properties" hb_buffer_guess_segment_properties
+    :: Ptr Buffer'' -> IO ()