Created
June 10, 2012 14:14
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reactive-banana throttling events
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{----------------------------------------------------------------------------- | |
------------------------------------------------------------------------------} | |
{-# LANGUAGE ScopedTypeVariables #-} -- allows "forall t. NetworkDescription t" | |
import Graphics.UI.WX hiding (Event) | |
import Reactive.Banana | |
import Reactive.Banana.WX | |
{----------------------------------------------------------------------------- | |
Main | |
------------------------------------------------------------------------------} | |
data ThrottledValue a = FireStoredValue a | FireNowAndStartTimer a| HoldIt a | Stopped deriving Show | |
data ThrottledEvent a = TimerEvent | RealEvent a deriving Show | |
main :: IO () | |
main = start $ do | |
f <- frame [text := "Countercesss"] | |
sl1 <- hslider f False 0 100 [] | |
sl2 <- hslider f False 0 100 [] | |
set f [ layout := column 0 [widget sl1, widget sl2] ] | |
t <- timer f [] | |
set t [ enabled := False ] | |
let networkDescription :: forall t. NetworkDescription t () | |
networkDescription = do | |
slEv <- event0 sl1 command | |
tick <- event0 t command | |
slB <- behavior sl1 selection | |
throttledEv <- throttle (slB <@ slEv) tick t 100 | |
reactimate $ fmap (\x -> set sl2 [selection := x]) throttledEv | |
net <- compile networkDescription | |
actuate net | |
throttle::Event t a -> Event t () -> Timer -> Int -> NetworkDescription t (Event t a) | |
throttle ev tick timer dt = do | |
reactimate $ filterJust $ fmap stop result | |
reactimate $ filterJust $ fmap start result | |
return throttledEv | |
where | |
all = fmap RealEvent ev `union` fmap (const TimerEvent) tick | |
result = accumE Stopped $ fmap h all | |
where | |
h (RealEvent x) Stopped = FireNowAndStartTimer x | |
h TimerEvent Stopped = Stopped | |
h (RealEvent x) (FireNowAndStartTimer _) = HoldIt x | |
h TimerEvent (FireNowAndStartTimer _) = Stopped | |
h (RealEvent x) (HoldIt _) = HoldIt x | |
h (TimerEvent) (HoldIt y) = FireStoredValue y | |
h (RealEvent x) (FireStoredValue _) = HoldIt x | |
h (TimerEvent) (FireStoredValue _) = Stopped | |
start (FireStoredValue _) = Just $ resetTimer timer dt | |
start (FireNowAndStartTimer _) = Just $ resetTimer timer dt | |
start _ = Nothing | |
stop Stopped = Just $ stopTimer timer | |
stop _ = Nothing | |
filterFired (FireStoredValue a) = Just a | |
filterFired (FireNowAndStartTimer a) = Just a | |
filterFired _ = Nothing | |
throttledEv = filterJust $ fmap filterFired result | |
startTimer :: Timer -> Int -> IO () | |
startTimer t dt = set t [ enabled := True, interval := dt ] | |
stopTimer :: Timer -> IO () | |
stopTimer t = set t [ enabled := False ] | |
resetTimer t dt = stopTimer t >> startTimer t dt |
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