line-drawing 0.3.0.0 → 0.4.0.0

raw patch · 4 files changed

+36/−13 lines, 4 filesdep +QuickCheckPVP ok

version bump matches the API change (PVP)

Dependencies added: QuickCheck

API changes (from Hackage documentation)

Files

• changes.txt +6/−0
• line-drawing.cabal +2/−1
• src/Line/Draw.hs +17/−11
• test/Line/DrawSpec.hs +11/−1

@@ -1,3 +1,9 @@+0.4.0.0+-------++- fixes "third quadrant" bug.+- Released Sun 10 Nov 2019 19:14:01 CET.+ 0.3.0.0 ------- 

@@ -1,6 +1,6 @@ cabal-version:       >=1.10 name:                line-drawing-version:             0.3.0.0+version:             0.4.0.0 synopsis:            raster line drawing description:         Line drawing algorithms to approximate a                      line segment on discrete graphical media (raster).@@ -30,6 +30,7 @@   main-is:             Test.hs   build-depends:       base == 4.*                        , hspec == 2.7.*+                       , QuickCheck == 2.13.*   other-modules:       Line.Draw                        Line.DrawSpec   type:                exitcode-stdio-1.0

@@ -37,21 +37,23 @@             | m1Check   = bresenhamBase x y             | otherwise = let x' = T.swap x                               y' = T.swap y-                          in map (T.swap) (bresenhamBase x' y')+                          in map T.swap (bresenhamBase x' y')     where           m1Check :: Bool-          m1Check = abs (x2 - x1) >= abs (y2 - y1)+          m1Check = abs (x2 - x1) > abs (y2 - y1)   ----------------- -- ANCILLARIES -- ----------------- +-- bresenhamBase is only valid when y-distance is greater than x-one bresenhamBase :: forall a . Integral a => (a, a) -> (a, a) -> [(a, a)] bresenhamBase (x1, y1) (x2, y2) =         let -- first treshold             ti = 2 * ady - adx         in L.unfoldr f (x1, y1, ti)+           -- unfoldr :: (b -> Maybe (a, b)) -> b -> [a]     where           -- slope           dx, dy, adx, ady :: a@@ -63,23 +65,27 @@           -- sign of increment           ix, iy :: a -> a           ix | dx > 0    = (+1)-             | otherwise = (subtract 1)+             | otherwise = subtract 1           iy | dy > 0    = (+1)-             | otherwise = (subtract 1)+             | otherwise = subtract 1            -- step function, takes (x, y, treshold)-                -- type State  = (Int, Int, Int)                 -- curr x, curr y, treshold           f :: (a, a, a) -> Maybe ((a, a), (a, a, a))-          f (cx, cy, t)-              | abs cx > abs x2 = Nothing+          f (wx, wy, t)+                    -- pos dx and neg dx have different reach conditions+                    -- can't use abs wx > abs x2+              | dx >= 0 &&+                wx > x2         = Nothing+              | dx <  0 &&+                wx < x2         = Nothing               | otherwise       =-                    let cx' = ix cx+                    let wx' = ix wx -                        cy' | t > 0     = iy cy-                            | otherwise = cy+                        wy' | t > 0     = iy wy+                            | otherwise = wy                          t' | t > 0     = t - 2 * adx + 2 * ady                            | otherwise = t + 2 * ady-                    in Just ((cx, cy), (cx', cy', t'))+                    in Just ((wx, wy), (wx', wy', t')) 

@@ -3,6 +3,7 @@ import Line.Draw  import Test.Hspec+import Test.QuickCheck   main :: IO ()@@ -11,7 +12,7 @@ spec :: Spec spec = do -  describe "bresenham" $ do+  describe "bresenham (hspec)" $ do     it "rasterises a simple line" $       bresenham (0 :: Int, 0) (4, 4) `shouldBe`         [(0,0), (1,1), (2,2), (3,3), (4,4)]@@ -36,4 +37,13 @@     it "returns a singleton list if start and end are the same" $       bresenham (2 :: Int, 2) (2, 2) `shouldBe`         [(2,2)]+    it "does not get confused with points on second quadrant" $+      bresenham (13 :: Int, 17) (12, 18) `shouldBe`+        [(13,17), (12,18)] +  describe "bresenham (quickcheck)" $ do+    it "does never return an empty list" $ property $+      \(p1, p2) -> length (bresenham (p1 :: (Int, Int)) p2) /= 0+    it "is the same length with args flipped" $ property $+      \(p1, p2) -> length (bresenham (p1 :: (Int, Int)) p2) ==+                   length (bresenham p2                 p1)