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    1 {-# LANGUAGE BangPatterns   #-}
    2 {-# LANGUAGE PackageImports #-}
    3 module Reanimate.Transform
    4   ( identity
    5   , transformPoint
    6   , mkMatrix
    7   , toTransformation
    8   ) where
    9 
   10 -- XXX: Use Linear.Matrix instead of Data.Matrix to drop the 'matrix' dependency.
   11 import           Data.List
   12 import           "matrix" Data.Matrix (Matrix)
   13 import qualified "matrix" Data.Matrix as M
   14 import           Data.Maybe
   15 import           Graphics.SvgTree
   16 import           Linear.V2
   17 
   18 type TMatrix = Matrix Coord
   19 
   20 identity :: TMatrix
   21 identity = M.identity 3
   22 
   23 fromList :: [Coord] -> TMatrix
   24 fromList [a,b,c,d,e,f] = M.fromList 3 3 [a,c,e,b,d,f,0,0,1]
   25 fromList _             = error "Reanimate.Transform.fromList: bad input"
   26 
   27 transformPoint :: TMatrix -> RPoint -> RPoint
   28 transformPoint m (V2 x y) = V2 (a*x +c*y + e) (b*x + d*y +f)
   29   where
   30     !a = M.unsafeGet 1 1 m
   31     !c = M.unsafeGet 1 2 m
   32     !e = M.unsafeGet 1 3 m
   33     !b = M.unsafeGet 2 1 m
   34     !d = M.unsafeGet 2 2 m
   35     !f = M.unsafeGet 2 3 m
   36     -- (a:c:e:b:d:f:_) = M.toList m
   37 
   38 mkMatrix :: Maybe [Transformation] -> TMatrix
   39 mkMatrix Nothing   = identity
   40 mkMatrix (Just ts) = foldl' (*) identity (map transformationMatrix ts)
   41 
   42 transformationMatrix :: Transformation -> TMatrix
   43 transformationMatrix transformation =
   44   case transformation of
   45     TransformMatrix a b c d e f -> fromList [a,b,c,d,e,f]
   46     Translate x y               -> translate x y
   47     Scale sx mbSy               -> fromList [sx,0,0,fromMaybe sx mbSy,0,0]
   48     Rotate a Nothing            -> rotate a
   49     Rotate a (Just (x,y))       -> translate x y * rotate a * translate (-x) (-y)
   50     SkewX a                     -> fromList [1,0,tan (a*pi/180),1,0,0]
   51     SkewY a                     -> fromList [1,tan (a*pi/180),0,1,0,0]
   52     TransformUnknown            -> identity
   53   where
   54     translate x y = fromList [1,0,0,1,x,y]
   55     rotate a = fromList [cos r,sin r,-sin r,cos r,0,0]
   56       where r = a * pi / 180
   57 
   58 toTransformation :: TMatrix -> Transformation
   59 toTransformation m = TransformMatrix a b c d e f
   60   where
   61     [a,c,e,b,d,f,_,_,_] = M.toList m