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If not, see . + +Also add information on how to contact you by electronic and paper mail. + + If the program does terminal interaction, make it output a short +notice like this when it starts in an interactive mode: + + Copyright (C) + This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. + This is free software, and you are welcome to redistribute it + under certain conditions; type `show c' for details. + +The hypothetical commands `show w' and `show c' should show the appropriate +parts of the General Public License. Of course, your program's commands +might be different; for a GUI interface, you would use an "about box". + + You should also get your employer (if you work as a programmer) or school, +if any, to sign a "copyright disclaimer" for the program, if necessary. +For more information on this, and how to apply and follow the GNU GPL, see +. + + The GNU General Public License does not permit incorporating your program +into proprietary programs. If your program is a subroutine library, you +may consider it more useful to permit linking proprietary applications with +the library. If this is what you want to do, use the GNU Lesser General +Public License instead of this License. But first, please read +. diff --git a/README.md b/README.md new file mode 100644 --- /dev/null +++ b/README.md @@ -0,0 +1,30 @@ +## potrace + +Mid-level bindings to the [potrace] library tracing a bitmap image to +vector paths. Contains helpers for converting [JuicyPixel] images to +bitmaps. + +Uses [bindings-potrace] which is not yet on Hackage. + +See [potrace-diagrams] for creating diagrams from bitmap images. + +## potrace-bindings installation + +### mac + +With [homebrew]: + +``` +brew install potrace +``` + +`cabal` may complain about not finding the potrace library. In which can +you can add the `--extra-lib-dirs=/usr/local/lib +--extra-include-dirs=/usr/local/include` flags when `cabal install`ing. + + +[potrace]: http://potrace.sourceforge.net +[JuicyPixel]: https://github.com/Twinside/Juicy.Pixels +[bindings-potrace]: https://github.com/rwbarton/bindings-potrace +[potrace-diagrams]: https://github.com/diagrams/potrace-diagrams +[homebrew]: http://brew.sh diff --git a/Setup.hs b/Setup.hs new file mode 100644 --- /dev/null +++ b/Setup.hs @@ -0,0 +1,2 @@ +import Distribution.Simple +main = defaultMain diff --git a/diagrams/alphaMax.svg b/diagrams/alphaMax.svg new file mode 100644 --- /dev/null +++ b/diagrams/alphaMax.svg @@ -0,0 +1,186 @@ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + diff --git a/potrace.cabal b/potrace.cabal new file mode 100644 --- /dev/null +++ b/potrace.cabal @@ -0,0 +1,34 @@ +name: potrace +version: 0.1.0.0 +synopsis: Trace bitmap images to paths using potrace +description: + Trace bitmap images to paths using the potrace library. Helpers for + generating bitmap images from functions or JuicyPixel images. + . + See + for an implimentation for the diagrams library. +license: GPL-2 +license-file: LICENSE +author: Christopher Chalmers +maintainer: c.chalmers@me.com +copyright: Copyright (C) 2015 Christopher Chalmers +category: Graphics +build-type: Simple +extra-source-files: README.md, diagrams/*.svg +extra-doc-files: diagrams/*.svg +cabal-version: >=1.10 + +library + exposed-modules: + Graphics.Potrace + Graphics.Potrace.Base + build-depends: + base >=4.6 && <5, + bindings-potrace >=0.1 && <0.2, + vector, + JuicyPixels, + bytestring, + containers, + data-default + hs-source-dirs: src + default-language: Haskell2010 diff --git a/src/Graphics/Potrace.hs b/src/Graphics/Potrace.hs new file mode 100644 --- /dev/null +++ b/src/Graphics/Potrace.hs @@ -0,0 +1,189 @@ +{-# LANGUAGE RankNTypes #-} +{-# LANGUAGE TypeFamilies #-} + +----------------------------------------------------------------------------- +-- | +-- Module : Graphics.Potrace +-- Copyright : (c) 2015 Christopher Chalmers +-- License : BSD-style (see LICENSE) +-- Maintainer : c.chalmers@me.com +-- +-- Trace bitmap images into vector paths using the potrace library. This +-- module also provides helpers for turning any "JuicyPixel"s image to a +-- bitmap. +-- +module Graphics.Potrace + ( + -- * Tracing + trace + , trace' + , traceForest + , traceForest' + + -- * Path type + , Curve (..) + , Segment (..) + , P2 (..) + + -- * Bitmaps + , Bitmap + , generate + , fromImage + , toImage + , lumaThreshold + + -- * Parameters + , Parameters (..) + , TurnPolicy (..) + + -- ** Lenses + , Lens' + , turdSize + , turnPolicy + , alphaMax + , optTolerance + ) + where + +import Data.Bool +import Codec.Picture.Types + +import Graphics.Potrace.Base + +------------------------------------------------------------------------ +-- Images +------------------------------------------------------------------------ + +-- | Generate a bitmap by apply the predicate function to each pixel of +-- "JuicyPixels" image. 'True' corresponds to a black pixel, 'False' +-- corresponds to white. +fromImage :: Pixel a => Image a -> (a -> Bool) -> Bitmap +fromImage img@(Image w h _) f = + generate w h $ \i j -> f $ pixelAt img i (h - j - 1) + -- potrace starts at bottom left, juicy starts at top left + +-- | Convert a 'Bitmap' to an 'image' by using the given pixels for +-- 'True' and 'False'. This is mainly here for debugging purposes. +toImage :: Pixel a => Bitmap -> a -> a -> Image a +toImage bm@(Bitmap w h _ _) on off = generateImage f w h + where f i j = bool off on $ index bm i (h - j - 1) + +-- | Generate a bitmap choosing pixels according to their luma plane for +-- a threshold given between 0 and 1. Anything below the threshold is +-- white. Anything above the threshold is black. Throws an error for +-- CMYK images. +lumaThreshold :: DynamicImage -> Double -> Bitmap +lumaThreshold dimg t = case dimg of + ImageY8 i -> word8 i + ImageY16 i -> word16 i + ImageYF i -> float i + ImageYA8 i -> word8 i + ImageYA16 i -> word16 (dropAlphaLayer i) + ImageRGB8 i -> word8 i + ImageRGB16 i -> word16 i + ImageRGBF i -> float i + ImageRGBA8 i -> word8 i + ImageRGBA16 i -> word16 (dropAlphaLayer i) + ImageYCbCr8 i -> word8 i + _ -> error "unable to compute lumaTheshold for CMYK images" + -- ImageCMYK8 i -> word8 (promoteImage i :: Image PixelRGB8) + -- ImageCMYK16 i -> word16 (promoteImage i :: Image PixelRGB16) + where + word8 :: (PixelBaseComponent a ~ Pixel8, LumaPlaneExtractable a) + => Image a -> Bitmap + word8 img = fromImage img (( Image a -> Bitmap + word16 img = fromImage img (( Image a -> Bitmap + float img = fromImage img (( (a -> f a) -> s -> f s + +(<&>) :: Functor f => f a -> (a -> b) -> f b +(<&>) = flip fmap + +-- | The 'turdSize' parameter can be used to “despeckle” the bitmap to +-- be traced, by removing all curves whose enclosed area is below the +-- given threshold. +-- +-- Default is @2@. +turdSize :: Lens' Parameters Int +turdSize f ps = f (_turdSize ps) <&> \p' -> ps { _turdSize = p' } + +-- | The 'TurnPolicy' parameter determines how to resolve ambiguities +-- during decomposition of bitmaps into paths. +-- +-- Default is 'MinorityTP'. +turnPolicy :: Lens' Parameters TurnPolicy +turnPolicy f ps = f (_turnPolicy ps) <&> \p' -> ps { _turnPolicy = p' } + +-- | The `alphamax` parameter is a threshold for the detection of +-- corners. It controls the smoothness of the traced curve.The useful +-- range of this parameter is from 0.0 (polygon) to 1.3334 (no +-- corners). +-- +-- Default is @1.0@. +-- +-- <> +alphaMax :: Lens' Parameters Double +alphaMax f ps = f (_alphaMax ps) <&> \p' -> ps { _alphaMax = p' } + +-- | The `optTolerance` parameter defines the amount of error allowed in +-- this simplification. Larger values tend to decrease the number of +-- segments, at the expense of less accuracy. The useful range is from +-- 0 to infinity, although in practice one would hardly choose values +-- greater than 1 or so. For most purposes, the default value is a +-- good trade off between space and accuracy. 'Nothing' turns +-- simplification off. +-- +-- Default is @'Just' 1.0@. +optTolerance :: Lens' Parameters (Maybe Double) +optTolerance f ps = f (_optTolerance ps) <&> \p' -> ps { _optTolerance = p' } + +------------------------------------------------------------------------ +-- SVG +------------------------------------------------------------------------ + +-- | Very basic svg conversion. If you want more control over the output +-- consider "diagrams-potrace". + +-- path :: [P.Loop] -> [Builder] -> Builder +-- path ls attr = " attrs <> d_ (loops ls) + +-- d_ :: Builder -> Builder +-- d_ attrs = "d=\"" <> d <> "\"" + +-- -- | Multiple loops together in order, suitable to put inside a \"d\" attribute. +-- loops :: [P.Loop] -> Builder +-- loops = foldMap loop + +-- -- | A single loop in an svg suitable to put inside a \"d\" attribute. +-- loop :: P.Loop -> Builder +-- loop (Loop p0 segs) = "M" <> pt p0 <> foldMap seg path <> " Z" +-- where +-- seg (Cubic p1 p2 p3) = "C" <> pt p1 <> " " <> pt p2 <> " " <> pt p3 +-- seg (Corner p1 p2) = "L" <> pt p1 <> "L" <> pt p2 + +-- mv :: Point -> Builder +-- mv p = "M " <> pt p +-- {-# INLINE mv #-} + +-- pt :: Point -> Builder +-- pt (P2 x y) = n x <> " " <> n (-y) +-- {-# INLINE pt #-} + +-- -- Not the fastest way but it'll do. 4 d.p. should be enough. +-- n :: Double -> Builder +-- n = string7 . showFFloat (Just 4) +-- {-# INLINE n #-} + diff --git a/src/Graphics/Potrace/Base.hs b/src/Graphics/Potrace/Base.hs new file mode 100644 --- /dev/null +++ b/src/Graphics/Potrace/Base.hs @@ -0,0 +1,309 @@ +{-# LANGUAGE BangPatterns #-} +{-# LANGUAGE LambdaCase #-} + +----------------------------------------------------------------------------- +-- | +-- Module : Graphics.Potrace.Base +-- Copyright : (c) 2015 Christopher Chalmers +-- License : BSD-style (see LICENSE) +-- Maintainer : c.chalmers@me.com +-- +-- A mid-level interface to potrace. Includes helpers for making +-- bitmap images. This is useful for other libraries that want to +-- implement their own tools on top of potrace (see +-- "potrace-diagrams"). +-- +-- In principle this could be in a separate module but there's already +-- three separate potrace modules and the dependencies aren't huge. + + +module Graphics.Potrace.Base + ( + -- * Tracing + Curve (..) + , Segment (..) + , P2 (..) + , trace + , trace' + , traceForest + , traceForest' + + -- * Bitmaps + , Bitmap (..) + , generate + , index + + -- * Parameters + , Parameters (..) + , TurnPolicy (..) + ) where + +import Control.Applicative +import Data.Bits +import Data.Default +import Data.Monoid +import Data.Tree +import qualified Data.Vector.Storable as V +import Foreign.C.Types +import Foreign.Marshal.Alloc +import Foreign.Ptr +import Foreign.Storable +import System.IO.Unsafe (unsafePerformIO) + +import Bindings.Potrace + +------------------------------------------------------------------------ +-- Bitmap +------------------------------------------------------------------------ + +-- | Data type to represent a bit packed image. This can be passed to +-- potrace via 'trace'. The constructor is exported by +-- 'Graphics.Potrace.Base' but be aware the underlying vector has a +-- host dependant form. You are advised to use 'generate' to create a +-- 'Bitmap'. +data Bitmap = Bitmap + { bitmapWidth :: Int + , bitmapHeight :: Int + , bitmapDy :: Int + , bitmapData :: V.Vector CULong + } + +-- | Given an image and a predicate for whether a pixel is on or off, +-- create a bit-packed image suitable for passing to potrace. +generate :: Int -> Int -> (Int -> Int -> Bool) -> Bitmap +generate w h f = Bitmap w h dy v + where + -- The format of the vector potrace needs depends on the size and + -- endianness of the machine. + m = sizeOf (0 :: CULong) * 8 + + -- Potrace works in blocks of the Word size m. We make each x + -- (horizontal) line n words wide, the last word only uses r of its + -- bits. + (n,r) = w `divMod` m + dy = if r == 0 then n else n + 1 + + -- Number of potential pixels (bits) in each x line (we only use w of them). + l = dy * m + + -- Each x line is made up of dy words, so we need dy*h words for + -- the whole picture. + v = V.generate (dy*h) $ \i -> + -- The starting point in the image for current block of pixels. + let (y,x) = (i*m) `divMod` l + -- Number of pixels we need to fill. + c | x + m > w = r + | otherwise = m + + -- Loop to fill word with bits. XXX Deal with endianness + go !k !b + | k < 0 = b + | f (x + k) y = go (k - 1) $ setBit b (m - 1 - k) + | otherwise = go (k - 1) b + + in go (c - 1) 0 +{-# INLINE generate #-} + +-- | Index a pixel in a 'Bitmap'. This is mainly here for debugging +-- purposes. +index :: Bitmap -> Int -> Int -> Bool +index (Bitmap w h dy v) i j = testBit w (m - 1 - r) + where + m = sizeOf (0 :: CULong) * 8 + w = v V.! (j * dy + (i `div` m)) + (n,r) = i `divMod` m +{-# INLINE index #-} + +------------------------------------------------------------------------ +-- Parameters +------------------------------------------------------------------------ + +-- | Parameters to control the tracing operation of potrace. The default +-- parameters are +-- +-- @ +-- Parameters +-- { 'turdSize' = 2 +-- , 'turnPolicy' = 'MinorityTP' +-- , 'alphaMax' = 1.0 +-- , 'optTolerance' = 'Just' 0.2 +-- } +-- @ +data Parameters = Parameters + { _turdSize :: Int -- ^ See 'Graphics.Potrace.turdSize'. + , _turnPolicy :: TurnPolicy -- ^ See 'Graphics.Potrace.turnPolicy'. + , _alphaMax :: Double -- ^ See 'Graphics.Potrace.alphaMax'. + , _optTolerance :: (Maybe Double) -- ^ See 'Graphics.Potrace.optTolerance'. + } + +instance Default Parameters where + def = Parameters + { _turdSize = 2 + , _turnPolicy = MinorityTP + , _alphaMax = 1.0 + , _optTolerance = Just 0.2 + } + +-- | How to resolve ambiguities during decomposition of bitmaps into +-- paths. +data TurnPolicy + = BlackTP -- ^ Prefers to connect black (foreground) components + | WhiteTP -- ^ Prefers to connect white (background) components. + | LeftTP -- ^ Always take a left turn. + | RightTP -- ^ Always take a right turn. + | MinorityTP -- ^ Prefers to connect the color (black or white) that + -- occurs least frequently in a local neighborhood of the + -- current position. + | MajorityTP -- ^ Prefers to connect the color (black or white) that + -- occurs most frequently in a local neighborhood of + -- the current position. (default) + | RandomTP -- ^ Choose pseudo-randomly + +-- Parameter internals ------------------------------------------------- + +-- | Allocate new parameters from potrace's default parameters. This +-- should protect against future changes to the options. When no +-- longer needed, these should be deallocated with +-- 'p'potrace_param_free' +params :: Parameters -> IO (Ptr C'potrace_param_s) +params (Parameters ts tp am ot) = do + c_param <- c'potrace_param_default + poke (p'potrace_param_s'turdsize c_param) $ fromIntegral ts + poke (p'potrace_param_s'turnpolicy c_param) $ turn tp + poke (p'potrace_param_s'alphamax c_param) $ CDouble am + poke (p'potrace_param_s'opticurve c_param) $ optiOn + poke (p'potrace_param_s'opttolerance c_param) $ optiVal + return c_param + where (optiOn, optiVal) = case ot of + Just t -> (1, CDouble t) + Nothing -> (0, 0) + +turn :: TurnPolicy -> CInt +turn = \case + BlackTP -> c'POTRACE_TURNPOLICY_BLACK + WhiteTP -> c'POTRACE_TURNPOLICY_WHITE + LeftTP -> c'POTRACE_TURNPOLICY_LEFT + RightTP -> c'POTRACE_TURNPOLICY_RIGHT + MinorityTP -> c'POTRACE_TURNPOLICY_MINORITY + MajorityTP -> c'POTRACE_TURNPOLICY_MAJORITY + RandomTP -> c'POTRACE_TURNPOLICY_RANDOM + +------------------------------------------------------------------------ +-- Tracing +------------------------------------------------------------------------ + +-- | Data type representing a 2D point were the origin is at the bottom +-- left. +data P2 = P2 {-# UNPACK #-} !Double {-# UNPACK #-} !Double + deriving (Show, Read) + +-- | potrace defines a segment as either 'Bezier' or a 'Corner' (in most +-- systems this is equivalent to linear segments). +data Segment + = Bezier {-# UNPACK #-} !P2 {-# UNPACK #-} !P2 {-# UNPACK #-} !P2 + | Corner {-# UNPACK #-} !P2 {-# UNPACK #-} !P2 + deriving (Show, Read) + +-- | A curve is a list of segments. The starting point is provided for +-- convenience but this is just the final point of the last segment. +data Curve = Curve {-# UNPACK #-} !P2 [Segment] + +-- | Trace the bitmap image to a list of curves using potrace with 'def' +-- parameters. +trace :: Bitmap -> [Curve] +trace = trace' def + +-- | Trace the bitmap image to a list of curves using potrace with given +-- parameters. +trace' :: Parameters -> Bitmap -> [Curve] +trace' p bm = unsafePerformIO $ unsafeWithImage pathList p bm + +-- | Trace the bitmap image as a forest of curves using potrace with 'def' +-- parameters. Each child curve is completely contained in it's +-- parent. +traceForest :: Bitmap -> Forest Curve +traceForest = traceForest' def + +-- | Trace the bitmap image as a forest of curves using potrace with +-- given parameters parameters. Each child curve is completely +-- contained in it's parent. +traceForest' :: Parameters -> Bitmap -> Forest Curve +traceForest' p bm = unsafePerformIO $ unsafeWithImage pathForest p bm + +-- Internals ----------------------------------------------------------- + +-- | Go though the curve and turn in into a list of segments. +curve :: C'potrace_curve_s -> IO Curve +curve (C'potrace_curve_s n ts ps_) = Curve <$> p0 <*> go 0 where + ps = castPtr ps_ + -- The last point in the vector is also the starting point + p0 = peekElemOff ps (3*fromIntegral n - 1) + go i | i >= fromIntegral n = pure [] + go i = do + let o = 3*i + t <- peekElemOff ts i + s <- if t == c'POTRACE_CORNER + then Corner <$> peekElemOff ps (o + 1) + <*> peekElemOff ps (o + 2) + else Bezier <$> peekElemOff ps (o + 0) + <*> peekElemOff ps (o + 1) + <*> peekElemOff ps (o + 2) + ss <- go (i+1) + return (s:ss) + +-- | Helper for constructing lists from linked lists of pointers. If the +-- ptr is 'nullPtr' return mempty, otherwise pass the pointer value to +-- the function. +onPtr :: (Storable a, Monoid b) => (a -> IO b) -> Ptr a -> IO b +onPtr f ptr + | ptr == nullPtr = pure mempty + | otherwise = peek ptr >>= f +{-# INLINE onPtr #-} + +type State = C'potrace_state_s + +-- | List of curves in order, suitable for passing to a renderer. +pathList :: State -> IO [Curve] +pathList (C'potrace_state_s _i ptr0 _) = go ptr0 where + go = onPtr $ \p -> do + s <- curve $ c'potrace_path_s'curve p + ss <- go (c'potrace_path_s'next p) + pure (s:ss) + +-- | Tree structure of paths where each child is enclosed within it's +-- parent. +pathForest :: State -> IO (Forest Curve) +pathForest (C'potrace_state_s _i ptr0 _) = go ptr0 where + go = onPtr $ \p -> do + s <- curve $ c'potrace_path_s'curve p + ch <- go $ c'potrace_path_s'childlist p + sb <- go $ c'potrace_path_s'sibling p + pure (Node s ch : sb) + +unsafeWithImage :: (State -> IO r) -> Parameters -> Bitmap -> IO r +unsafeWithImage f ps (Bitmap w h dy v) = V.unsafeWith v $ \p -> do + c_param <- params ps + alloca $ \c_bitmap -> do + poke c_bitmap $ C'potrace_bitmap_s (fromIntegral w) (fromIntegral h) (fromIntegral dy) p + c_status <- c'potrace_trace c_param c_bitmap + r <- peek c_status >>= f + + c'potrace_state_free c_status + c'potrace_param_free c_param + return r +------------------------------------------------------------------------ +-- Instances +------------------------------------------------------------------------ + +instance Storable P2 where + sizeOf _ = 2 * sizeOf (undefined::Double) + {-# INLINE sizeOf #-} + alignment _ = alignment (undefined::Double) + {-# INLINE alignment #-} + poke ptr (P2 x y) = poke ptr' x >> pokeElemOff ptr' 1 y + where ptr' = castPtr ptr + {-# INLINE poke #-} + peek ptr = P2 <$> peek ptr' <*> peekElemOff ptr' 1 + where ptr' = castPtr ptr + {-# INLINE peek #-} +