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{-
Minmax.hs (adapted from minmax.c which is (c) Silicon Graphics, Inc.)
Copyright (c) Sven Panne 2002-2005 <sven.panne@aedion.de>
This file is part of HOpenGL and distributed under a BSD-style license
See the file libraries/GLUT/LICENSE
Determine the minimum and maximum values of a group of pixels. This
demonstrates use of the minmax function.
-}
import Foreign ( allocaArray, peekArray )
import System.Exit ( exitWith, ExitCode(ExitSuccess) )
import Graphics.UI.GLUT
import ReadImage
myInit :: IO ()
myInit = do
rowAlignment Unpack $= 1
clearColor $= Color4 0 0 0 0
minmax $= Just (RGB', PassThrough)
display :: Size -> PixelData a -> DisplayCallback
display size pixels = do
clear [ ColorBuffer ]
-- resolve overloading, not needed in "real" programs
let rasterPos2i = rasterPos :: Vertex2 GLint -> IO ()
rasterPos2i (Vertex2 1 1)
drawPixels size pixels
flush
[Color3 minR minG minB, Color3 maxR maxG maxB] <- allocaArray 2 $ \buf -> do
getMinmax Reset (PixelData RGB UnsignedByte buf)
peekArray 2 buf :: IO [Color3 GLubyte]
putStrLn (" Red : min = " ++ show minR ++ " max = " ++ show maxR)
putStrLn (" Green : min = " ++ show minG ++ " max = " ++ show maxG)
putStrLn (" Blue : min = " ++ show minB ++ " max = " ++ show maxB)
reshape :: ReshapeCallback
reshape size@(Size w h) = do
viewport $= (Position 0 0, size)
matrixMode $= Projection
loadIdentity
ortho 0 (fromIntegral w) 0 (fromIntegral h) (-1) 1
matrixMode $= Modelview 0
keyboard :: KeyboardMouseCallback
keyboard (Char '\27') Down _ _ = exitWith ExitSuccess
keyboard _ _ _ _ = return ()
-- Main Loop: Open window with initial window size, title bar, RGBA display
-- mode, and handle input events.
main :: IO ()
main = do
(progName, args) <- getArgsAndInitialize
(size, pixels) <- readImage (if null args then "Data/leeds.bin" else head args)
initialDisplayMode $= [ SingleBuffered, RGBMode ]
initialWindowSize $= size
initialWindowPosition $= Position 100 100
createWindow progName
myInit
reshapeCallback $= Just reshape
keyboardMouseCallback $= Just keyboard
displayCallback $= display size pixels
mainLoop
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