Adds matToVec and vecToMat

Safe versions of unsafeWithMatAsVec and unsafeWithVecAsMat. The safety
comes at the price of a data copy.

Author: roelvandijk

opencv/src/OpenCV/Core/Types/Mat.hs

@@ -21,6 +21,8 @@ module OpenCV.Core.Types.Mat
     , emptyMat
     , mkMat
     , eyeMat
+    , matToVec
+    , vecToMat
     , unsafeWithMatAsVec
     , unsafeWithVecAsMat
     , cloneMat

opencv/src/OpenCV/Internal/Core/Types/Mat.hs

@@ -32,6 +32,8 @@ module OpenCV.Internal.Core.Types.Mat
     , newEmptyMat
     , newMat
     , withMatData
+    , matToVec
+    , vecToMat
     , unsafeWithMatAsVec
     , unsafeWithVecAsMat
     , matElemAddress
@@ -436,8 +438,40 @@ withMatData mat f = withPtr mat $ \matPtr ->
       step    <- peekArray (fromIntegral dims) stepPtr
       f step dataPtr
 
+-- | Convert a Mat to a Storable Vector.
+matToVec
+    :: (Storable depth)
+    => Mat shape channels ('S depth)
+    -> VS.Vector depth
+matToVec mat =
+    unsafePerformIO $
+    unsafeWithMatAsVec mat $ \tmpVec ->
+      VS.thaw tmpVec >>= VS.unsafeFreeze
+
+-- | Convert a Storable Vector to a Mat.
+--
+-- The @shape@ and @channels@ of the Mat must exactly match the
+-- length of the vector.
+vecToMat
+    :: ( Storable depth
+       , ToShape shape
+       , ToChannels channels
+       , ToDepth (Proxy depth)
+       , MonadError CvException m
+       )
+    => shape
+    -> channels
+    -> VS.Vector depth
+    -> m (Mat (ShapeT shape) (ChannelsT channels) ('S depth))
+vecToMat shape channels vec =
+    unsafeCvExcept $
+    unsafeWithVecAsMat shape channels vec $ \tmpMat ->
+      liftIO $ cloneMatIO tmpMat
+
 -- | Access a Mat's data via a temporary Storable Vector.
 --
+-- Data is only copied when the Mat is not continuous.
+--
 -- The storable vector and its data may no longer be used after the
 -- supplied computation terminates.
 unsafeWithMatAsVec
@@ -464,6 +498,8 @@ unsafeWithMatAsVec mat f =
 -- The @shape@ and @channels@ of the Mat must exactly match the
 -- length of the vector.
 --
+-- No data is copied.
+--
 -- The Mat and its data may no longer be used after the supplied
 -- computation terminates.
 unsafeWithVecAsMat

opencv/test/test.hs

@@ -142,6 +142,16 @@ main = defaultMain $ testGroup "opencv"
               , HU.testCase "eye_m33 Double" $ testVecMatVec (eye_m33 :: M33 Double)
               , HU.testCase "1..9 Int16" $ testVecMatVec (V3 (V3 1 2 3) (V3 4 5 6) (V3 7 8 9) :: M33 Int16)
               ]
+            , testGroup "unsafe mat -> vec -> mat"
+              [ HU.testCase "eye_m33 Word8" $ testUnsafeMatVecMat (eye_m33 :: M33 Word8)
+              , HU.testCase "eye_m33 Double" $ testUnsafeMatVecMat (eye_m33 :: M33 Double)
+              , HU.testCase "1..9 Int16" $ testUnsafeMatVecMat (V3 (V3 1 2 3) (V3 4 5 6) (V3 7 8 9) :: M33 Int16)
+              ]
+            , testGroup "unsafe vec -> mat -> vec"
+              [ HU.testCase "eye_m33 Word8" $ testUnsafeVecMatVec (eye_m33 :: M33 Word8)
+              , HU.testCase "eye_m33 Double" $ testUnsafeVecMatVec (eye_m33 :: M33 Double)
+              , HU.testCase "1..9 Int16" $ testUnsafeVecMatVec (V3 (V3 1 2 3) (V3 4 5 6) (V3 7 8 9) :: M33 Int16)
+              ]
             ]
           ]
         ]
@@ -591,10 +601,34 @@ testUnsafeWithMatAsVec m33 = do
     assertEqual "" (concatMap toList $ toList m33) xs
 
 testMatVecMat
+    :: forall a
+     . (Eq a, Show a, ToDepth (Proxy a), Storable a, ToMat (M33 a))
+    => M33 a -> HU.Assertion
+testMatVecMat m33In = assertEqual "" m33In m33Out
+  where
+    m33Out :: M33 a
+    m33Out = fromMat $ exceptError $ vecToMat (Proxy @[3, 3]) (Proxy @1) $ matToVec $ toMat m33In
+
+testVecMatVec
+    :: forall a
+     . (Eq a, Show a, NFData a, ToDepth (Proxy a), Storable a)
+    => M33 a -> HU.Assertion
+testVecMatVec m33In = assertEqual "" elemsIn elemsOut
+  where
+    elemsOut :: [a]
+    elemsOut = VS.toList $ matToVec $ exceptError $ vecToMat (Proxy @[3, 3]) (Proxy @1) vecIn
+
+    vecIn :: VS.Vector a
+    vecIn = VS.fromList elemsIn
+
+    elemsIn :: [a]
+    elemsIn = concatMap toList $ toList m33In
+
+testUnsafeMatVecMat
     :: forall a
      . (Eq a, Show a, NFData a, ToDepth (Proxy a), Storable a, ToMat (M33 a))
     => M33 a -> HU.Assertion
-testMatVecMat m33In = do
+testUnsafeMatVecMat m33In = do
     m33Out <-
       unsafeWithMatAsVec matIn $ \(vec :: VS.Vector a) ->
         exceptErrorIO $
@@ -605,11 +639,11 @@ testMatVecMat m33In = do
     matIn :: Mat ('S '[ 'S 3, 'S 3 ]) ('S 1) ('S a)
     matIn = toMat m33In
 
-testVecMatVec
+testUnsafeVecMatVec
     :: forall a
      . (Eq a, Show a, NFData a, ToDepth (Proxy a), Storable a)
     => M33 a -> HU.Assertion
-testVecMatVec m33In = do
+testUnsafeVecMatVec m33In = do
     elemsOut <- exceptErrorIO $
       unsafeWithVecAsMat (Proxy @[3, 3]) (Proxy @1) vecIn $ \mat ->
         liftIO $ unsafeWithMatAsVec mat $ \vecOut ->