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fix(resize): use Int instead of Double to increase performance

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This commit is contained in:
Mahdi Dibaiee 2017-02-03 22:14:52 +03:30
parent 529d503204
commit 0a9712fe4a
1 changed files with 4 additions and 3 deletions
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7
src/Data/Picture.hs
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@ -178,13 +178,14 @@ module Data.Picture ( Picture
where where
initial = vector [0..fromIntegral sWidth * fromIntegral sHeight - 1] initial = vector [0..fromIntegral sWidth * fromIntegral sHeight - 1]
(width, height) = (rows r, cols r) (width, height) = (rows r, cols r)
(xRatio, yRatio) = (fromIntegral width / fromIntegral sWidth, fromIntegral height / fromIntegral sHeight) factor = 2 ^ 16
(xRatio, yRatio) = (width * factor `div` sWidth + 1, height * factor `div` sHeight + 1)
f m = tr $ reshape sWidth $ V.map replace initial f m = tr $ reshape sWidth $ V.map replace initial
where where
v = flatten (tr m) v = flatten (tr m)
replace index = replace index =
let (x, y) = (fromIntegral $ floor index `mod` sWidth, fromIntegral . floor $ index / fromIntegral sWidth) let (x, y) = (floor index `mod` sWidth, floor index `div` sWidth)
(px, py) = (floor $ x * xRatio, floor $ y * yRatio) (px, py) = (x * xRatio `div` factor, y * yRatio `div` factor)
in v ! (py * width + px) in v ! (py * width + px)
-- | Scale an image using the resize function -- | Scale an image using the resize function