module Picture where

type Picture = [String]

-- vertikales, horizontales und diagonales Spiegeln 
flipV, flipH, flipD :: Picture -> Picture
flipV = map reverse
flipH = reverse
flipD []     = []
flipD ([]:_) = []
flipD pic    = (map head pic) : flipD (map mytail pic)
                where   mytail [] = []
                        mytail xs = tail xs

-- Farbinversion
invertColour :: Picture -> Picture 
invertColour = map (map changeColour) 
  where  changeColour '#' = '.'
         changeColour '.' = '#'

-- Bildschirmausgabe
printPic :: [String] -> IO ()
printPic pic = putStr (concat (map (++"\n") pic))

-- Positionierung zweier Bilder übereinander und nebeneinander
above, aside :: Picture -> Picture -> Picture
above = (++)
aside = zipWith (++)

-- Übereinanderlegen zweier Bilder (gleichen Ausmasses)
superimpose :: Picture -> Picture -> Picture
superimpose = zipWith (zipWith blackOverWhite)
  where blackOverWhite '#' _ = '#'
        blackOverWhite '.' c = c

-- Beispielbilder
lambda
      =["............",
        "..##........",
        "....#.......",
        "....###.....",
        "...##.##....",
        ".##.....###.",
        "............"
        ]

varwhite n = take n (repeat (take n (repeat '.')))
white = varwhite 2

blume= 
       [".....###....",
        "....#####...",
        ".....###....",
        "..#...#.....",
        "...##.#.#...",
        "....###.....",
        "...#........"]

smilie=["...######...",
        "..#......#..",
        ".#..#..#..#.",
        ".#........#.",
        ".#..#..#..#.",
        ".#...##...#.",
        "..#......#..",
        "...######..."]