diagrams-cairo-0.5: src/Diagrams/Backend/Cairo/Internal.hs
{-# LANGUAGE TypeFamilies
, MultiParamTypeClasses
, FlexibleInstances
, FlexibleContexts
, ExistentialQuantification
, TypeSynonymInstances
, DeriveDataTypeable
, ViewPatterns
#-}
-----------------------------------------------------------------------------
-- |
-- Module : Diagrams.Backend.Cairo.Internal
-- Copyright : (c) 2011 Diagrams-cairo team (see LICENSE)
-- License : BSD-style (see LICENSE)
-- Maintainer : diagrams-discuss@googlegroups.com
--
-- Implementation of the diagrams Cairo backend. This module exports the
-- internal helper functions, for usage elsewhere.
--
-----------------------------------------------------------------------------
module Diagrams.Backend.Cairo.Internal where
import Graphics.Rendering.Diagrams.Transform
import Diagrams.Prelude
import Diagrams.TwoD.Path (Clip(..), getFillRule)
import Diagrams.TwoD.Text
import Diagrams.TwoD.Image
import Diagrams.TwoD.Adjust (adjustDia2D, adjustSize)
import Graphics.UI.Gtk (DrawableClass)
import qualified Graphics.UI.Gtk.Cairo as CG
import qualified Graphics.Rendering.Cairo as C
import qualified Graphics.Rendering.Cairo.Matrix as CM
import Control.Monad.State
import Data.Maybe (catMaybes, fromMaybe)
import Data.List (isSuffixOf)
import Control.Exception (try)
import qualified Data.Foldable as F
import Data.Typeable
-- | This data declaration is simply used as a token to distinguish
-- this rendering engine.
data Cairo = Cairo
deriving (Eq,Ord,Read,Show,Typeable)
-- | Output types supported by cairo, including four different file
-- types (PNG, PS, PDF, SVG) as well as Gtk windows.
data OutputType =
-- | Output directly to a Gtk window. See "Diagrams.Backends.Cairo.Gtk".
forall dw. (DrawableClass dw) =>
GTK { gtkWindow :: dw
-- ^ The window on which to draw.
, gtkBypass :: Bool
-- ^ Should the 'adjustDia' step be bypassed during rendering?
}
| PNG -- ^ Portable Network Graphics output.
| PS -- ^ PostScript output
| PDF -- ^ Portable Document Format output.
| SVG -- ^ Scalable Vector Graphics output.
instance Monoid (Render Cairo R2) where
mempty = C $ return ()
(C rd1) `mappend` (C rd2) = C (rd1 >> rd2)
type RenderM a = StateT () C.Render a -- no state for now
-- simple, stupid implementations of save and restore for now, since
-- it suffices to just reset the text alignment to "centered" on
-- restore. But if need be we can switch to a more sophisticated
-- implementation using an "undoable state" monad which lets you save
-- (push state onto a stack) and restore (pop from the stack).
save :: RenderM ()
save = lift C.save
restore :: RenderM ()
restore = lift C.restore
instance Backend Cairo R2 where
data Render Cairo R2 = C (RenderM ())
type Result Cairo R2 = (IO (), C.Render ())
data Options Cairo R2 = CairoOptions
{ cairoFileName :: String -- ^ The name of the file you want generated
, cairoSizeSpec :: SizeSpec2D -- ^ The requested size of the output
, cairoOutputType :: OutputType -- ^ the output format and associated options
}
withStyle _ s t (C r) = C $ do
save
cairoMiscStyle s
r
lift $ do
cairoTransf t
cairoStrokeStyle s
C.stroke
restore
doRender _ (CairoOptions file size out) (C r) = (renderIO, r')
where r' = evalStateT r ()
renderIO = do
let surfaceF s = C.renderWith s r'
-- Everything except Dims is arbitrary. The backend
-- should have first run 'adjustDia' to update the
-- final size of the diagram with explicit dimensions,
-- so normally we would only expect to get Dims anyway.
(w,h) = case size of
Width w' -> (w',w')
Height h' -> (h',h')
Dims w' h' -> (w',h')
Absolute -> (100,100)
case out of
GTK win _ -> CG.renderWithDrawable win r'
PNG ->
C.withImageSurface C.FormatARGB32 (round w) (round h) $ \surface -> do
surfaceF surface
C.surfaceWriteToPNG surface file
PS -> C.withPSSurface file w h surfaceF
PDF -> C.withPDFSurface file w h surfaceF
SVG -> C.withSVGSurface file w h surfaceF
adjustDia c opts d = if bypass (cairoOutputType opts)
then (opts,d)
else adjustDia2D cairoSizeSpec
setCairoSizeSpec
c opts (d # reflectY)
where setCairoSizeSpec sz o = o { cairoSizeSpec = sz }
bypass (GTK _ x) = x
bypass _ = False
renderC :: (Renderable a Cairo, V a ~ R2) => a -> RenderM ()
renderC a = case (render Cairo a) of C r -> r
cairoMiscStyle :: Style v -> RenderM ()
cairoMiscStyle s =
sequence_
. catMaybes $ [ handle clip
, handle fSize
, handleFontFace
, handle fColor
, handle lFillRule
]
where handle :: AttributeClass a => (a -> RenderM ()) -> Maybe (RenderM ())
handle f = f `fmap` getAttr s
clip = mapM_ (\p -> renderC p >> lift C.clip) . getClip
fSize = lift . C.setFontSize . getFontSize
fFace = fromMaybe "" $ getFont <$> getAttr s
fSlant = fromFontSlant . fromMaybe FontSlantNormal
$ getFontSlant <$> getAttr s
fWeight = fromFontWeight . fromMaybe FontWeightNormal
$ getFontWeight <$> getAttr s
handleFontFace = Just . lift $ C.selectFontFace fFace fSlant fWeight
fColor c = lift $ setSource (getFillColor c) s
lFillRule = lift . C.setFillRule . fromFillRule . getFillRule
fromFontSlant :: FontSlant -> C.FontSlant
fromFontSlant FontSlantNormal = C.FontSlantNormal
fromFontSlant FontSlantItalic = C.FontSlantItalic
fromFontSlant FontSlantOblique = C.FontSlantOblique
fromFontWeight :: FontWeight -> C.FontWeight
fromFontWeight FontWeightNormal = C.FontWeightNormal
fromFontWeight FontWeightBold = C.FontWeightBold
cairoStrokeStyle :: Style v -> C.Render ()
cairoStrokeStyle s =
sequence_
. catMaybes $ [ handle fColor
, handle lColor -- see Note [color order]
, handle lWidth
, handle lCap
, handle lJoin
, handle lDashing
]
where handle :: (AttributeClass a) => (a -> C.Render ()) -> Maybe (C.Render ())
handle f = f `fmap` getAttr s
fColor c = setSource (getFillColor c) s >> C.fillPreserve
lColor c = setSource (getLineColor c) s
lWidth = C.setLineWidth . getLineWidth
lCap = C.setLineCap . fromLineCap . getLineCap
lJoin = C.setLineJoin . fromLineJoin . getLineJoin
lDashing (getDashing -> Dashing ds offs) =
C.setDash ds offs
setSource :: Color c => c -> Style v -> C.Render ()
setSource c s = C.setSourceRGBA r g b a'
where (r,g,b,a) = colorToRGBA c
a' = case getOpacity <$> getAttr s of
Nothing -> a
Just d -> a * d
cairoTransf :: T2 -> C.Render ()
cairoTransf t = C.transform m
where m = CM.Matrix a1 a2 b1 b2 c1 c2
(unr2 -> (a1,a2)) = apply t unitX
(unr2 -> (b1,b2)) = apply t unitY
(unr2 -> (c1,c2)) = transl t
{- ~~~~ Note [color order]
It's important for the line and fill colors to be handled in the
given order (fill color first, then line color) because of the way
Cairo handles them (both are taken from the sourceRGBA).
-}
fromLineCap :: LineCap -> C.LineCap
fromLineCap LineCapButt = C.LineCapButt
fromLineCap LineCapRound = C.LineCapRound
fromLineCap LineCapSquare = C.LineCapSquare
fromLineJoin :: LineJoin -> C.LineJoin
fromLineJoin LineJoinMiter = C.LineJoinMiter
fromLineJoin LineJoinRound = C.LineJoinRound
fromLineJoin LineJoinBevel = C.LineJoinBevel
fromFillRule :: FillRule -> C.FillRule
fromFillRule Winding = C.FillRuleWinding
fromFillRule EvenOdd = C.FillRuleEvenOdd
instance Renderable (Segment R2) Cairo where
render _ (Linear v) = C . lift $ uncurry C.relLineTo (unr2 v)
render _ (Cubic (unr2 -> (x1,y1))
(unr2 -> (x2,y2))
(unr2 -> (x3,y3)))
= C . lift $ C.relCurveTo x1 y1 x2 y2 x3 y3
instance Renderable (Trail R2) Cairo where
render _ (Trail segs c) = C $ do
mapM_ renderC segs
lift $ when c C.closePath
instance Renderable (Path R2) Cairo where
render _ (Path trs) = C $ lift C.newPath >> F.mapM_ renderTrail trs
where renderTrail (unp2 -> p, tr) = do
lift $ uncurry C.moveTo p
renderC tr
-- Can only do PNG files at the moment...
instance Renderable Image Cairo where
render _ (Image file sz tr) = C . lift $ do
if ".png" `isSuffixOf` file
then do
C.save
cairoTransf (tr <> reflectionY)
pngSurfChk <- liftIO (try $ C.imageSurfaceCreateFromPNG file
:: IO (Either IOError C.Surface))
case pngSurfChk of
Right pngSurf -> do
w <- C.imageSurfaceGetWidth pngSurf
h <- C.imageSurfaceGetHeight pngSurf
cairoTransf $ adjustSize sz (fromIntegral w, fromIntegral h)
C.setSourceSurface pngSurf (-fromIntegral w / 2)
(-fromIntegral h / 2)
Left _ ->
liftIO . putStrLn $
"Warning: can't read image file <" ++ file ++ ">"
C.paint
C.restore
else
liftIO . putStr . unlines $
[ "Warning: Cairo backend can currently only render embedded"
, " images in .png format. Ignoring <" ++ file ++ ">."
]
-- see http://www.cairographics.org/tutorial/#L1understandingtext
instance Renderable Text Cairo where
render _ (Text tr al str) = C $ do
lift $ do
C.save
-- XXX should use reflection font matrix here instead?
cairoTransf (tr <> reflectionY)
(refX, refY) <- case al of
BoxAlignedText xt yt -> do
tExt <- C.textExtents str
fExt <- C.fontExtents
let l = C.textExtentsXbearing tExt
r = C.textExtentsXadvance tExt
b = C.fontExtentsDescent fExt
t = C.fontExtentsAscent fExt
return (lerp l r xt, lerp (-b) t yt)
BaselineText -> return (0, 0)
cairoTransf (moveOriginBy (r2 (refX, -refY)) mempty)
C.showText str
C.restore