-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | Functional Combinators for Computer Vision
--   
--   Initial version; using the <a>HOpenCV</a> package as a backend.
--   
--   Provides a functional combinator library, naturally expressed as Arrow
--   instances (but also Category, Functor and Applicative).
--   
--   Online documentation, if not built below, can be found at
--   <a>http://www.ee.bgu.ac.il/~noamle/</a>.
--   
--   Read the module docs for more information. See the test program
--   (<tt>src/Test.hs</tt>) for example usage.
@package cv-combinators
@version 0.1.2.1


-- | Framework for expressing IO actions that require initialization and
--   finalizers. This module provides a *functional* interface for defining
--   and chaining a series of processors.
--   
--   Motivating example: bindings to C libraries that use functions such
--   as: f(foo *src, foo *dst), where the pointer <tt>dst</tt> must be
--   pre-allocated. In this case we normally do:
--   
--   <pre>
--   foo *dst = allocateFoo();
--   ... 
--   while (something) {
--      f(src, dst);
--      ...
--   }
--   releaseFoo(dst);
--   </pre>
--   
--   You can use the <a>runUntil</a> function below to emulate that loop.
--   
--   Processor is an instance of Category, Functor, Applicative and Arrow.
--   
--   In addition to the general type <tt><a>Processor</a> m a b</tt>, this
--   module also defines the semantic model for <tt><a>Processor</a> IO a
--   b</tt>, which has synonym <tt><a>IOProcessor</a> a b</tt>.
module AI.CV.Processor

-- | The type of Processors
--   
--   <ul>
--   <li>a, b = the input and output types of the processor (think a -&gt;
--   b)</li>
--   <li>x = type of internal state (existentially quantified)</li>
--   </ul>
--   
--   The arguments to the constructor are:
--   
--   <ol>
--   <li>Processing function: Takes input and internal state, and returns
--   new internal state.</li>
--   <li>Allocator for internal state (this is run only once): Takes
--   (usually the first) input, and returns initial internal state.</li>
--   <li>Convertor from state x to output b: Takes internal state and
--   returns the output.</li>
--   <li>Releaser for internal state (finalizer, run once): Run after
--   processor is done being used, to release the internal state.</li>
--   </ol>
data Processor m a b
Processor :: (a -> x -> m x) -> (a -> m x) -> (x -> m b) -> (x -> m ()) -> Processor m a b

-- | The semantic model for <a>IOProcessor</a> is a function:
--   
--   <pre>
--   [[ 'IOProcessor' a b ]] = a -&gt; b
--   </pre>
--   
--   And the following laws:
--   
--   <ol>
--   <li>The processing function (<tt>a -&gt; x -&gt; m x</tt>) must act as
--   if purely, so that indeed for a given input the output is always the
--   same. One particular thing to be careful with is that the output does
--   not depend on time (for example, you shouldn't use IOProcessor to
--   implement an input device). The <tt>IOSource</tt> type is defined
--   exactly for time-dependent processors. For pointer typed inputs and
--   outputs, see next law.</li>
--   <li>For processors that work on pointers, <tt>[[ Ptr t ]] = t</tt>.
--   This is guaranteed by the following implementation constraints for
--   <tt>IOProcessor a b</tt>:</li>
--   <li>If <tt>a</tt> is a pointer type (<tt>a = Ptr p</tt>), then the
--   processor must NOT write (modify) the referenced data.</li>
--   <li>If <tt>b</tt> is a pointer, the memory it points to (and its
--   allocation status) is only allowed to change by the processor that
--   created it (in the processing and releasing functions). In a way this
--   generalizes the first constraint.</li>
--   </ol>
--   
--   Note, that unlike <a>Yampa</a>, this model does not allow
--   transformations of the type <tt>(Time -&gt; a) -&gt; (Time -&gt;
--   b)</tt>. The reason is that I want to prevent arbitrary time access
--   (whether causal or not). This limitation means that everything is
--   essentially <a>point-wise</a> in time. To allow memory-full operations
--   under this model, <a>scanlT</a> is defined. See
--   <a>http://www.ee.bgu.ac.il/~noamle/_downloads/gaccum.pdf</a> for more
--   about arbitrary time access.
type IOProcessor a b = Processor IO a b

-- | <tt><a>IOSource</a> a b</tt> is the type of time-dependent processors,
--   such that:
--   
--   <pre>
--   [[ 'IOSource' a b ]] = (a, Time) -&gt; b
--   </pre>
--   
--   Thus, it is ok to implement a processing action that outputs arbitrary
--   time-dependent values during runtime regardless of input. (Although
--   the more useful case is to calculate something from the input
--   <tt>a</tt> that is also time-dependent. The <tt>a</tt> input is often
--   not required and in those cases <tt>a = ()</tt> is used.
--   
--   Notice that this means that IOSource doesn't qualify as an
--   <a>IOProcessor</a>. However, currently the implementation <i>does
--   NOT</i> enforce this, i.e. IOSource is not a newtype; I don't know how
--   to implement it correctly. Also, one question is whether primitives
--   like <a>chain</a> will have to disallow placing <a>IOSource</a> as the
--   second element in a chain. Maybe they should, maybe they shouldn't.
type IOSource a b = Processor IO a b

-- | TODO: What's the semantic model for <tt><a>IOSink</a> a</tt>?
type IOSink a = IOProcessor a ()

-- | TODO: do we need this? we're exporting the data constructor anyway for
--   now, so maybe we don't.
processor :: (Monad m) => (a -> x -> m x) -> (a -> m x) -> (x -> m b) -> (x -> m ()) -> Processor m a b

-- | Chains two processors serially, so one feeds the next.
chain :: Processor m a b' -> Processor m b' b -> Processor m a b

-- | A processor that represents two sub-processors in parallel (although
--   the current implementation runs them sequentially, but that may change
--   in the future)
parallel :: Processor m a b -> Processor m c d -> Processor m (a, c) (b, d)

-- | Constructs a processor that: given two processors, gives source as
--   input to both processors and runs them independently, and after both
--   have have finished, outputs their combined outputs.
--   
--   Semantic meaning, using Arrow's (&amp;&amp;&amp;) operator: [[
--   forkJoin ]] = &amp;&amp;&amp; Or, considering the Applicative instance
--   of functions (which are the semantic meanings of a processor): [[
--   forkJoin ]] = liftA2 (,) Alternative implementation to consider: f
--   &amp;&amp;&amp; g = (,) <a>&amp;</a> f <a>*</a> g
forkJoin :: Processor m a b -> Processor m a b' -> Processor m a (b, b')

-- | The identity processor: output = input. Semantically, [[ empty ]] = id
empty :: (Monad m) => Processor m a a

-- | Splits (duplicates) the output of a functor, or on this case a
--   processor.
split :: (Functor f) => f a -> f (a, a)

-- | 'f --&lt; g' means: split f and feed it into g. Useful for feeding
--   parallelized (***'d) processors. For example, a --<a> (b *** c) = a
--   </a>&gt;&gt; (b &amp;&amp;&amp; c)
(--<) :: (Functor (cat a), Category cat) => cat a a1 -> cat (a1, a1) c -> cat a c

-- | Runs the processor once: allocates, processes, converts to output, and
--   deallocates.
run :: (Monad m) => Processor m a b -> a -> m b

-- | Keeps running the processing function in a loop until a predicate on
--   the output is true. Useful for processors whose main function is after
--   the allocation and before deallocation.
runUntil :: (Monad m) => Processor m a b -> a -> (b -> m Bool) -> m b

-- | Runs the processor once, but passes the processing + conversion action
--   to the given function.
runWith :: (Monad m) => (m b -> m b') -> Processor m a b -> a -> m b'
type DTime = Double
type Clock m = m Double

-- | scanlT provides the primitive for performing memory-full operations on
--   time-dependent processors, as described in
--   <a>http://www.ee.bgu.ac.il/~noamle/_downloads/gaccum.pdf</a>.
--   
--   <i>Untested</i>.
scanlT :: Clock IO -> (b -> b -> DTime -> c -> c) -> c -> IOSource a b -> IOSource a c

-- | Differentiate using scanlT. TODO: test, and also generalize for any
--   monad (trivial change of types).
differentiate :: (Real b) => Clock IO -> IOSource a b -> IOSource a Double
integrate :: (Real b) => Clock IO -> IOSource a b -> IOSource a Double
max_ :: (Ord b) => Clock IO -> b -> IOSource a b -> IOSource a b
min_ :: (Ord b) => Clock IO -> b -> IOSource a b -> IOSource a b
instance (Monad m) => Arrow (Processor m)
instance (Monad m) => Applicative (Processor m a)
instance (Monad m) => Functor (Processor m a)
instance (Monad m) => Category (Processor m)


-- | ImageProcessors is a functional (Processor-based) interface to
--   computer vision using OpenCV.
--   
--   The Processor interface allows the primitives in this library to take
--   care of all the allocation / deallocation of resources and other
--   setup/teardown requirements, and to appropriately nest them when
--   combining primitives.
--   
--   Simple example:
--   
--   <pre>
--   win = window 0        -- The number is essentially a label for the window
--   cam = camera 0        -- Autodetect camera
--   edge = canny 30 190 3 -- Edge detecting processor using canny operator
--   
--   test = cam &gt;&gt;&gt; edge &gt;&gt;&gt; win   
--   </pre>
--   
--   The last expression is a processor that captures frames from camera
--   and displays edge-detected version in the window.
module AI.CV.ImageProcessors
type ImageSink = IOSink Image
type ImageSource = IOSource () Image
type ImageProcessor = IOProcessor Image Image
type Image = PImage

-- | A capture device, using OpenCV's HighGui lib's cvCreateCameraCapture
--   should work with most webcames. See OpenCV's docs for information.
--   This processor outputs the latest image from the camera at each
--   invocation.
camera :: Int -> ImageSource
videoFile :: String -> ImageSource

-- | A window that displays images. Note: windows with the same index will
--   be the same window....is this ok?
window :: Int -> ImageSink

-- | OpenCV's cvResize
resize :: Int -> Int -> InterpolationMethod -> ImageProcessor

-- | OpenCV's cvDilate
dilate :: Int -> ImageProcessor

-- | OpenCV's cvCanny
canny :: Int -> Int -> Int -> ImageProcessor

-- | Wrapper for OpenCV's cvHaarDetectObjects and the surrounding required
--   things (mem storage, cascade loading, etc).
haarDetect :: String -> Double -> Int -> HaarDetectFlag -> CvSize -> IOProcessor Image [CvRect]

-- | OpenCV's cvRectangle, currently without width, color or line type
--   control
drawRects :: IOProcessor (Image, [CvRect]) Image

-- | Runs the processor until a predicate is true, for predicates, and
--   processors that take () as input (such as chains that start with a
--   camera).
runTill :: IOProcessor () b -> (b -> IO Bool) -> IO b

-- | Name (and type) says it all.
runTillKeyPressed :: (Show a) => IOProcessor () a -> IO ()

-- | Some general utility functions for use with Processors and OpenCV
--   
--   Predicate for pressed keys
keyPressed :: (Show a) => a -> IO Bool