72 lines
2.3 KiB
Haskell
72 lines
2.3 KiB
Haskell
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{-# LANGUAGE RecordWildCards #-}
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-- | Module for drawing primitives
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module Affection.Draw
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( drawRect
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) where
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import Affection.Types (DrawType(..), Affection, GeglRectangle(..), liftIO)
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import Foreign.C.Types
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import qualified BABL as B
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import qualified GEGL as G
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-- | Draw a rectangle on target buffer
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drawRect
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:: G.GeglBuffer -- ^ Target buffer
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-> G.Color -- ^ Color to draw in
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-> DrawType -- ^ Draw type
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-> GeglRectangle -- ^ Dimensions of Rectangle
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-> Affection a ()
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drawRect buf color dt rect@G.GeglRectangle{..} =
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liftIO $ G.iterateOver buf rect (B.PixelFormat B.RGBA B.CFdouble) G.GeglAccessReadWrite G.GeglAbyssNone $
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(\(G.Pixel px py pc) ->
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case dt of
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Fill ->
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let col = colorize pc color
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in
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G.Pixel px py col
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Line width ->
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if (px >= rectangleX && px <= (rectangleX + width) ||
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px <= (rectangleX + rectangleWidth) && px >= (rectangleX + rectangleWidth - width)) &&
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(py >= rectangleY && py <= (rectangleY + width) ||
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py <= (rectangleY + rectangleHeight) && py >= (rectangleY + rectangleHeight - width))
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then
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let col = colorize pc color
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in G.Pixel px py col
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else
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G.Pixel px py pc
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)
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-- | compute color for a single pixel
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colorize
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:: (G.ComponentValue, G.ComponentValue, G.ComponentValue, G.ComponentValue) -- ^ Pixel information in buffer
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-> G.Color -- ^ Color to draw over
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-> (G.ComponentValue, G.ComponentValue, G.ComponentValue, G.ComponentValue) -- ^ Resulting colour
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colorize (rr, rg, rb, ra) col =
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let (G.CVdouble (CDouble br)) = rr
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(G.CVdouble (CDouble bg)) = rg
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(G.CVdouble (CDouble bb)) = rb
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(G.CVdouble (CDouble ba)) = ra
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(cr, cg, cb) = case col of
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G.RGBA r g b _ -> (r, g, b)
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G.RGB r g b -> (r, g, b)
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ca = case col of
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G.RGBA _ _ _ a -> a
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G.RGB _ _ _ -> 1
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alpha = ca
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dst_a = ba
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da = alpha + dst_a * (1 - alpha)
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a_term = dst_a * (1 - alpha)
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red = cr * alpha + br * a_term
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gre = cg * alpha + bg * a_term
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blu = cb * alpha + bb * a_term
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in
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( G.CVdouble $ CDouble $ red / da
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, G.CVdouble $ CDouble $ gre / da
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, G.CVdouble $ CDouble $ blu / da
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, G.CVdouble $ CDouble $ ca
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)
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