@@ -2,148 +2,41 @@
22Module: Reflex.Vty.Widget
33Description: Basic set of widgets and building blocks for reflex-vty applications
44-}
5−{-# LANGUAGE FlexibleContexts #-}
6−{-# LANGUAGE FlexibleInstances #-}
7−{-# LANGUAGE FunctionalDependencies #-}
8−{-# LANGUAGE GeneralizedNewtypeDeriving #-}
9−{-# LANGUAGE LambdaCase #-}
10−{-# LANGUAGE MultiParamTypeClasses #-}
11−{-# LANGUAGE OverloadedStrings #-}
12−{-# LANGUAGE RankNTypes #-}
13−{-# LANGUAGE RecursiveDo #-}
14−{-# LANGUAGE ScopedTypeVariables #-}
15−{-# LANGUAGE StandaloneDeriving #-}
16−{-# LANGUAGE TypeFamilies #-}
17−{-# LANGUAGE UndecidableInstances #-}
18−module Reflex.Vty.Widget
19− ( VtyWidgetCtx(..)
20− , VtyWidget(..)
21− , VtyWidgetOut(..)
22− , runVtyWidget
23− , mainWidget
24− , mainWidgetWithHandle
25− , HasDisplaySize(..)
26− , displayWidth
27− , displayHeight
28− , HasFocus(..)
29− , HasVtyInput(..)
30− , Region(..)
31− , regionSize
32− , regionBlankImage
33− , Drag(..)
34− , drag
35− , MouseDown(..)
36− , MouseUp(..)
37− , mouseDown
38− , mouseUp
39− , pane
40− , modifyImages
41− , tellImages
42− , tellShutdown
43− , splitV
44− , splitVDrag
45− , box
46− , boxStatic
47− , text
48− , display
49− , hyphenBoxStyle
50− , singleBoxStyle
51− , roundedBoxStyle
52− , thickBoxStyle
53− , doubleBoxStyle
54− , fill
55− , hRule
56− ) where
5+{-# Language UndecidableInstances #-}
6+
7+module Reflex.Vty.Widget where
578
589import Control.Applicative (liftA2)
5910import Control.Monad.Fix (MonadFix)
60−import Control.Monad.Trans (lift)
61−import Control.Monad.Trans.Reader (ReaderT, runReaderT, asks, ask)
62−import Control.Monad.Trans.Writer (WriterT, runWriterT, censor, tell)
63−import Control.Monad.Writer.Adjustable ()
64−import Data.Default (Default(..))
65−import Data.Text (Text)
66−import qualified Data.Text as T
67−import qualified Data.Text.Zipper as TZ
11+import Control.Monad.IO.Class (MonadIO)
12+import Control.Monad.Morph
13+import Control.Monad.NodeId
14+import Control.Monad.Reader (ReaderT, ask, local, runReaderT)
15+import Control.Monad.Ref
16+import Control.Monad.Trans (MonadTrans, lift)
17+import Data.Set (Set)
18+import qualified Data.Set as Set
6819import Graphics.Vty (Image)
6920import qualified Graphics.Vty as V
7021import Reflex
71−import Reflex.Class.Switchable
72−import Reflex.NotReady.Class
73−import Reflex.NotReady.Class.Orphans ()
74−
22+import Reflex.Class ()
23+import Reflex.Host.Class (MonadReflexCreateTrigger)
7524import Reflex.Vty.Host
7625
77−-- | The context within which a 'VtyWidget' runs
78−data VtyWidgetCtx t = VtyWidgetCtx
79− { _vtyWidgetCtx_size :: Dynamic t (Int,Int)
80− -- ^ The width and height of the region allocated to the widget.
81− , _vtyWidgetCtx_focus :: Dynamic t Bool
82− -- ^ Whether the widget should behave as if it has focus for keyboard input.
83− , _vtyWidgetCtx_input :: Event t VtyEvent
84− -- ^ User input events that the widget's parent chooses to share. These will generally
85− -- be filtered for relevance:
86− -- * Keyboard inputs are restricted to focused widgets
87− -- * Mouse inputs are restricted to the region in which the widget resides and are
88− -- translated into its internal coordinates.
89− }
90−
91−-- | The output of a 'VtyWidget'
92−data VtyWidgetOut t = VtyWidgetOut
93− { _vtyWidgetOut_images :: Behavior t [Image]
94− -- ^ The visual output of the 'VtyWidget'
95− , _vtyWidgetOut_shutdown :: Event t ()
96− }
97−
98−instance Reflex t => Semigroup (VtyWidgetOut t) where
99− wo <> wo' = VtyWidgetOut
100− { _vtyWidgetOut_images = _vtyWidgetOut_images wo <> _vtyWidgetOut_images wo'
101− , _vtyWidgetOut_shutdown = _vtyWidgetOut_shutdown wo <> _vtyWidgetOut_shutdown wo'
102− }
103−
104−instance (Reflex t) => Monoid (VtyWidgetOut t) where
105− mempty = VtyWidgetOut mempty mempty
106− mappend wo wo' = wo <> wo'
107−
108−instance Reflex t => Switchable t (VtyWidgetOut t) where
109− switching e0 e = do
110− shutdown <- switching (_vtyWidgetOut_shutdown e0) $ fmap _vtyWidgetOut_shutdown e
111− images <- switching (_vtyWidgetOut_images e0) $ fmap _vtyWidgetOut_images e
112− return $ VtyWidgetOut
113− { _vtyWidgetOut_images = images
114− , _vtyWidgetOut_shutdown = shutdown
115− }
116−
117−-- | A widget that can read its context and produce image output
118−newtype VtyWidget t m a = VtyWidget
119− { unVtyWidget :: WriterT (VtyWidgetOut t) (ReaderT (VtyWidgetCtx t) m) a
120− }
121− deriving (Functor, Applicative, Monad, MonadSample t, MonadHold t, MonadFix, NotReady t)
122−
123−instance (PostBuild t m, Reflex t) => PostBuild t (VtyWidget t m) where
124− getPostBuild = VtyWidget $ lift getPostBuild
125−
126−instance (Adjustable t m, MonadHold t m, Reflex t) => Adjustable t (VtyWidget t m) where
127− runWithReplace a0 a' = VtyWidget $ runWithReplace (unVtyWidget a0) $ fmap unVtyWidget a'
128− traverseIntMapWithKeyWithAdjust f dm0 dm' = VtyWidget $
129− traverseIntMapWithKeyWithAdjust (\k v -> unVtyWidget (f k v)) dm0 dm'
130− traverseDMapWithKeyWithAdjust f dm0 dm' = VtyWidget $ do
131− traverseDMapWithKeyWithAdjust (\k v -> unVtyWidget (f k v)) dm0 dm'
132− traverseDMapWithKeyWithAdjustWithMove f dm0 dm' = VtyWidget $ do
133− traverseDMapWithKeyWithAdjustWithMove (\k v -> unVtyWidget (f k v)) dm0 dm'
134−
135−-- | Runs a 'VtyWidget' with a given context
136−runVtyWidget
137− :: Reflex t
138− => VtyWidgetCtx t
139− -> VtyWidget t m a
140− -> m (a, VtyWidgetOut t)
141−runVtyWidget ctx w = runReaderT (runWriterT (unVtyWidget w)) ctx
26+-- * Running a vty application
14227
143−-- | Sets up the top-level context for a 'VtyWidget' and runs it with that context
28+-- | Sets up the top-level context for a vty widget and runs it with that context
14429mainWidgetWithHandle
14530 :: V.Vty
146− -> (forall t m. MonadVtyApp t m => VtyWidget t m ())
31+ -> (forall t m.
32+ ( MonadVtyApp t m
33+ , HasImageWriter t m
34+ , MonadNodeId m
35+ , HasDisplayRegion t m
36+ , HasFocusReader t m
37+ , HasInput t m
38+ , HasTheme t m
39+ ) => m (Event t ()))
14740 -> IO ()
14841mainWidgetWithHandle vty child =
14942 runVtyAppWithHandle vty $ \dr0 inp -> do
@@ -153,71 +46,178 @@ mainWidgetWithHandle vty child =
15346 let inp' = fforMaybe inp $ \case
15447 V.EvResize {} -> Nothing
15548 x -> Just x
156− let ctx = VtyWidgetCtx
157− { _vtyWidgetCtx_size = size
158− , _vtyWidgetCtx_input = inp'
159− , _vtyWidgetCtx_focus = constDyn True
160− }
161− ((), wo) <- runVtyWidget ctx $ do
162− tellImages . ffor (current size) $ \(w, h) -> [V.charFill V.defAttr ' ' w h]
163− child
49+ (shutdown, images) <- runThemeReader (constant V.defAttr) $
50+ runFocusReader (pure True) $
51+ runDisplayRegion (fmap (\(w, h) -> Region 0 0 w h) size) $
52+ runImageWriter $
53+ runNodeIdT $
54+ runInput inp' $ do
55+ tellImages . ffor (current size) $ \(w, h) -> [V.charFill V.defAttr ' ' w h]
56+ child
16457 return $ VtyResult
165− { _vtyResult_picture = fmap (V.picForLayers . reverse) (_vtyWidgetOut_images wo)
166− , _vtyResult_shutdown = _vtyWidgetOut_shutdown wo
58+ { _vtyResult_picture = fmap (V.picForLayers . reverse) images
59+ , _vtyResult_shutdown = shutdown
16760 }
16861
62+-- | The output of a vty widget
63+data VtyWidgetOut t = VtyWidgetOut
64+ { _vtyWidgetOut_shutdown :: Event t ()
65+ }
66+
16967-- | Like 'mainWidgetWithHandle', but uses a default vty configuration
17068mainWidget
171− :: (forall t m. MonadVtyApp t m => VtyWidget t m ())
69+ :: (forall t m.
70+ ( MonadVtyApp t m
71+ , HasImageWriter t m
72+ , MonadNodeId m
73+ , HasDisplayRegion t m
74+ , HasFocusReader t m
75+ , HasTheme t m
76+ , HasInput t m
77+ ) => m (Event t ()))
17278 -> IO ()
17379mainWidget child = do
17480 vty <- getDefaultVty
17581 mainWidgetWithHandle vty child
17682
177−-- | A class for things that know their own display size dimensions
178−class (Reflex t, Monad m) => HasDisplaySize t m | m -> t where
179− displaySize :: m (Dynamic t (Int, Int))
180−
181−instance (Reflex t, Monad m) => HasDisplaySize t (VtyWidget t m) where
182− displaySize = VtyWidget . lift $ asks _vtyWidgetCtx_size
183−
184−-- | Retrieve the display width (columns)
185−displayWidth :: HasDisplaySize t m => m (Dynamic t Int)
186−displayWidth = fmap fst <$> displaySize
187−
188−-- | Retrieve the display height (rows)
189−displayHeight :: HasDisplaySize t m => m (Dynamic t Int)
190−displayHeight = fmap snd <$> displaySize
83+-- * Input Events
19184
19285-- | A class for things that can receive vty events as input
193−class HasVtyInput t m | m -> t where
86+class HasInput t m | m -> t where
19487 input :: m (Event t VtyEvent)
88+ default input :: (f m' ~ m, Monad m', MonadTrans f, HasInput t m') => m (Event t VtyEvent)
89+ input = lift input
90+ -- | User input events that the widget's parent chooses to share. These will generally
91+ -- be filtered for relevance.
92+ localInput :: (Event t VtyEvent -> Event t VtyEvent) -> m a -> m a
93+ default localInput :: (f m' ~ m, Monad m', MFunctor f, HasInput t m') => (Event t VtyEvent -> Event t VtyEvent) -> m a -> m a
94+ localInput f = hoist (localInput f)
95+
96+instance (Reflex t, Monad m) => HasInput t (Input t m) where
97+ input = Input ask
98+ localInput f (Input m) = Input $ local f m
99+
100+-- | A widget that can receive input events. See 'Graphics.Vty.Event'
101+newtype Input t m a = Input
102+ { unInput :: ReaderT (Event t VtyEvent) m a
103+ } deriving
104+ ( Functor
105+ , Applicative
106+ , Monad
107+ , MonadSample t
108+ , MonadHold t
109+ , MonadFix
110+ , MonadIO
111+ , MonadRef
112+ )
113+
114+instance (Adjustable t m, MonadHold t m, Reflex t) => Adjustable t (Input t m) where
115+ runWithReplace a0 a' = Input $ runWithReplace (unInput a0) $ fmap unInput a'
116+ traverseIntMapWithKeyWithAdjust f dm0 dm' = Input $
117+ traverseIntMapWithKeyWithAdjust (\k v -> unInput (f k v)) dm0 dm'
118+ traverseDMapWithKeyWithAdjust f dm0 dm' = Input $ do
119+ traverseDMapWithKeyWithAdjust (\k v -> unInput (f k v)) dm0 dm'
120+ traverseDMapWithKeyWithAdjustWithMove f dm0 dm' = Input $ do
121+ traverseDMapWithKeyWithAdjustWithMove (\k v -> unInput (f k v)) dm0 dm'
122+
123+deriving instance MonadReflexCreateTrigger t m => MonadReflexCreateTrigger t (Input t m)
124+deriving instance NotReady t m => NotReady t (Input t m)
125+deriving instance PerformEvent t m => PerformEvent t (Input t m)
126+deriving instance PostBuild t m => PostBuild t (Input t m)
127+deriving instance TriggerEvent t m => TriggerEvent t (Input t m)
128+instance HasImageWriter t m => HasImageWriter t (Input t m)
129+instance HasDisplayRegion t m => HasDisplayRegion t (Input t m)
130+instance HasFocusReader t m => HasFocusReader t (Input t m)
131+
132+instance MonadTrans (Input t) where
133+ lift f = Input $ lift f
134+
135+instance MFunctor (Input t) where
136+ hoist f = Input . hoist f . unInput
137+
138+instance MonadNodeId m => MonadNodeId (Input t m)
139+
140+-- | Runs an 'Input' with a given context
141+runInput
142+ :: Reflex t
143+ => Event t VtyEvent
144+ -> Input t m a
145+ -> m a
146+runInput e w = runReaderT (unInput w) e
147+
148+-- ** Filtering input
149+
150+-- | Type synonym for a key and modifier combination
151+type KeyCombo = (V.Key, [V.Modifier])
152+
153+-- | Emits an event that fires on a particular key press (without modifiers)
154+key :: (Monad m, Reflex t, HasInput t m) => V.Key -> m (Event t KeyCombo)
155+key = keyCombos . Set.singleton . (,[])
156+
157+-- | Emits an event that fires on particular key presses (without modifiers)
158+keys :: (Monad m, Reflex t, HasInput t m) => [V.Key] -> m (Event t KeyCombo)
159+keys = keyCombos . Set.fromList . fmap (,[])
160+
161+-- | Emit an event that fires whenever the provided key combination occurs
162+keyCombo
163+ :: (Reflex t, Monad m, HasInput t m)
164+ => KeyCombo
165+ -> m (Event t KeyCombo)
166+keyCombo = keyCombos . Set.singleton
167+
168+-- | Emit an event that fires whenever any of the provided key combinations occur
169+keyCombos
170+ :: (Reflex t, Monad m, HasInput t m)
171+ => Set KeyCombo
172+ -> m (Event t KeyCombo)
173+keyCombos ks = do
174+ i <- input
175+ return $ fforMaybe i $ \case
176+ V.EvKey k m -> if Set.member (k, m) ks
177+ then Just (k, m)
178+ else Nothing
179+ _ -> Nothing
195180
196−instance (Reflex t, Monad m) => HasVtyInput t (VtyWidget t m) where
197− input = VtyWidget . lift $ asks _vtyWidgetCtx_input
198−
199−-- | A class for things that can dynamically gain and lose focus
200−class HasFocus t m | m -> t where
201− focus :: m (Dynamic t Bool)
202−
203−instance (Reflex t, Monad m) => HasFocus t (VtyWidget t m) where
204− focus = VtyWidget . lift $ asks _vtyWidgetCtx_focus
205−
206−-- | A class for widgets that can produce images to draw to the display
207−class (Reflex t, Monad m) => ImageWriter t m | m -> t where
208− -- | Send images upstream for rendering
209− tellImages :: Behavior t [Image] -> m ()
210−
211−instance (Reflex t, Monad m) => ImageWriter t (VtyWidget t m) where
212− tellImages imgs = VtyWidget $ tell (mempty { _vtyWidgetOut_images = imgs })
213−
214−-- | A class for things that can shut down the vty application
215−class (Reflex t, Monad m) => Shutdown t m where
216− -- | Signals that the vty application should shut down
217− tellShutdown :: Event t () -> m ()
181+-- | Filter the keyboard input that a child widget may receive
182+filterKeys :: (Reflex t, HasInput t m) => (KeyCombo -> Bool) -> m a -> m a
183+filterKeys f x = localInput (ffilter (\case
184+ V.EvKey k mods -> f (k, mods)
185+ _ -> True)) x
186+
187+-- | Filter mouse input events based on whether they target a particular region
188+-- and translate them to the internal coordinate system of that region.
189+--
190+-- NB: Non-mouse events are passed through unfiltered and unchanged
191+mouseInRegion :: Region -> VtyEvent -> Maybe VtyEvent
192+mouseInRegion (Region l t w h) e = case e of
193+ V.EvMouseDown x y btn m -> mouse (\u v -> V.EvMouseDown u v btn m) x y
194+ V.EvMouseUp x y btn -> mouse (\u v -> V.EvMouseUp u v btn) x y
195+ _ -> Just e
196+ where
197+ mouse con x y
198+ | or [ x < l
199+ , y < t
200+ , x >= l + w
201+ , y >= t + h ] = Nothing
202+ | otherwise =
203+ Just (con (x - l) (y - t))
204+
205+-- | Filter mouse input outside the current display region and
206+-- all input if the region is not focused
207+inputInFocusedRegion
208+ :: (HasDisplayRegion t m, HasFocusReader t m, HasInput t m)
209+ => m (Event t VtyEvent)
210+inputInFocusedRegion = do
211+ inp <- input
212+ reg <- current <$> askRegion
213+ foc <- current <$> focus
214+ pure $ fmapMaybe id $ attachWith filterInput ((,) <$> reg <*> foc) inp
215+ where
216+ filterInput (r, f) = \case
217+ V.EvKey {} | not f -> Nothing
218+ x -> mouseInRegion r x
218219
219−instance (Reflex t, Monad m) => Shutdown t (VtyWidget t m) where
220− tellShutdown sd = VtyWidget $ tell (mempty { _vtyWidgetOut_shutdown = sd })
220+-- * Getting and setting the display region
221221
222222-- | A chunk of the display area
223223data Region = Region
@@ -228,14 +228,293 @@ data Region = Region
228228 }
229229 deriving (Show, Read, Eq, Ord)
230230
231+-- | A region that occupies no space.
232+nilRegion :: Region
233+nilRegion = Region 0 0 0 0
234+
231235-- | The width and height of a 'Region'
232236regionSize :: Region -> (Int, Int)
233237regionSize (Region _ _ w h) = (w, h)
234238
235239-- | Produces an 'Image' that fills a region with space characters
236−regionBlankImage :: Region -> Image
237−regionBlankImage r@(Region _ _ width height) =
238− withinImage r $ V.charFill V.defAttr ' ' width height
240+regionBlankImage :: V.Attr -> Region -> Image
241+regionBlankImage attr r@(Region _ _ width height) =
242+ withinImage r $ V.charFill attr ' ' width height
243+
244+-- | A class for things that know their own display size dimensions
245+class (Reflex t, Monad m) => HasDisplayRegion t m | m -> t where
246+ -- | Retrieve the display region
247+ askRegion :: m (Dynamic t Region)
248+ default askRegion :: (f m' ~ m, MonadTrans f, HasDisplayRegion t m') => m (Dynamic t Region)
249+ askRegion = lift askRegion
250+ -- | Run an action in a local region, by applying a transformation to the region
251+ localRegion :: (Dynamic t Region -> Dynamic t Region) -> m a -> m a
252+ default localRegion :: (f m' ~ m, Monad m', MFunctor f, HasDisplayRegion t m') => (Dynamic t Region -> Dynamic t Region) -> m a -> m a
253+ localRegion f = hoist (localRegion f)
254+
255+-- | Retrieve the display width
256+displayWidth :: HasDisplayRegion t m => m (Dynamic t Int)
257+displayWidth = fmap _region_width <$> askRegion
258+
259+-- | Retrieve the display height
260+displayHeight :: HasDisplayRegion t m => m (Dynamic t Int)
261+displayHeight = fmap _region_height <$> askRegion
262+
263+instance HasDisplayRegion t m => HasDisplayRegion t (ReaderT x m)
264+instance HasDisplayRegion t m => HasDisplayRegion t (BehaviorWriterT t x m)
265+instance HasDisplayRegion t m => HasDisplayRegion t (DynamicWriterT t x m)
266+instance HasDisplayRegion t m => HasDisplayRegion t (EventWriterT t x m)
267+instance HasDisplayRegion t m => HasDisplayRegion t (NodeIdT m)
268+
269+-- | A widget that has access to a particular region of the vty display
270+newtype DisplayRegion t m a = DisplayRegion
271+ { unDisplayRegion :: ReaderT (Dynamic t Region) m a }
272+ deriving
273+ ( Functor
274+ , Applicative
275+ , Monad
276+ , MonadFix
277+ , MonadHold t
278+ , MonadIO
279+ , MonadRef
280+ , MonadSample t
281+ )
282+
283+instance (Monad m, Reflex t) => HasDisplayRegion t (DisplayRegion t m) where
284+ askRegion = DisplayRegion ask
285+ localRegion f = DisplayRegion . local f . unDisplayRegion
286+
287+deriving instance MonadReflexCreateTrigger t m => MonadReflexCreateTrigger t (DisplayRegion t m)
288+deriving instance NotReady t m => NotReady t (DisplayRegion t m)
289+deriving instance PerformEvent t m => PerformEvent t (DisplayRegion t m)
290+deriving instance PostBuild t m => PostBuild t (DisplayRegion t m)
291+deriving instance TriggerEvent t m => TriggerEvent t (DisplayRegion t m)
292+instance HasImageWriter t m => HasImageWriter t (DisplayRegion t m)
293+instance HasFocusReader t m => HasFocusReader t (DisplayRegion t m)
294+
295+instance (Adjustable t m, MonadFix m, MonadHold t m) => Adjustable t (DisplayRegion t m) where
296+ runWithReplace (DisplayRegion a) e = DisplayRegion $ runWithReplace a $ fmap unDisplayRegion e
297+ traverseIntMapWithKeyWithAdjust f m e = DisplayRegion $ traverseIntMapWithKeyWithAdjust (\k v -> unDisplayRegion $ f k v) m e
298+ traverseDMapWithKeyWithAdjust f m e = DisplayRegion $ traverseDMapWithKeyWithAdjust (\k v -> unDisplayRegion $ f k v) m e
299+ traverseDMapWithKeyWithAdjustWithMove f m e = DisplayRegion $ traverseDMapWithKeyWithAdjustWithMove (\k v -> unDisplayRegion $ f k v) m e
300+
301+instance MonadTrans (DisplayRegion t) where
302+ lift = DisplayRegion . lift
303+
304+instance MFunctor (DisplayRegion t) where
305+ hoist f = DisplayRegion . hoist f . unDisplayRegion
306+
307+instance MonadNodeId m => MonadNodeId (DisplayRegion t m)
308+
309+-- | Run a 'DisplayRegion' action with a given 'Region'
310+runDisplayRegion
311+ :: (Reflex t, Monad m)
312+ => Dynamic t Region
313+ -> DisplayRegion t m a
314+ -> m a
315+runDisplayRegion r = flip runReaderT r . unDisplayRegion
316+
317+-- * Getting focus state
318+
319+-- | A class for things that can dynamically gain and lose focus
320+class (Reflex t, Monad m) => HasFocusReader t m | m -> t where
321+ focus :: m (Dynamic t Bool)
322+ default focus :: (f m' ~ m, Monad m', MonadTrans f, HasFocusReader t m') => m (Dynamic t Bool)
323+ focus = lift focus
324+ localFocus :: (Dynamic t Bool -> Dynamic t Bool) -> m a -> m a
325+ default localFocus :: (f m' ~ m, Monad m', MFunctor f, HasFocusReader t m') => (Dynamic t Bool -> Dynamic t Bool) -> m a -> m a
326+ localFocus f = hoist (localFocus f)
327+
328+instance HasFocusReader t m => HasFocusReader t (ReaderT x m)
329+instance HasFocusReader t m => HasFocusReader t (BehaviorWriterT t x m)
330+instance HasFocusReader t m => HasFocusReader t (DynamicWriterT t x m)
331+instance HasFocusReader t m => HasFocusReader t (EventWriterT t x m)
332+instance HasFocusReader t m => HasFocusReader t (NodeIdT m)
333+
334+-- | A widget that has access to information about whether it is focused
335+newtype FocusReader t m a = FocusReader
336+ { unFocusReader :: ReaderT (Dynamic t Bool) m a }
337+ deriving
338+ ( Functor
339+ , Applicative
340+ , Monad
341+ , MonadFix
342+ , MonadHold t
343+ , MonadIO
344+ , MonadRef
345+ , MonadSample t
346+ )
347+
348+instance (Monad m, Reflex t) => HasFocusReader t (FocusReader t m) where
349+ focus = FocusReader ask
350+ localFocus f = FocusReader . local f . unFocusReader
351+
352+deriving instance MonadReflexCreateTrigger t m => MonadReflexCreateTrigger t (FocusReader t m)
353+deriving instance NotReady t m => NotReady t (FocusReader t m)
354+deriving instance PerformEvent t m => PerformEvent t (FocusReader t m)
355+deriving instance PostBuild t m => PostBuild t (FocusReader t m)
356+deriving instance TriggerEvent t m => TriggerEvent t (FocusReader t m)
357+instance HasImageWriter t m => HasImageWriter t (FocusReader t m)
358+
359+instance (Adjustable t m, MonadFix m, MonadHold t m) => Adjustable t (FocusReader t m) where
360+ runWithReplace (FocusReader a) e = FocusReader $ runWithReplace a $ fmap unFocusReader e
361+ traverseIntMapWithKeyWithAdjust f m e = FocusReader $ traverseIntMapWithKeyWithAdjust (\k v -> unFocusReader $ f k v) m e
362+ traverseDMapWithKeyWithAdjust f m e = FocusReader $ traverseDMapWithKeyWithAdjust (\k v -> unFocusReader $ f k v) m e
363+ traverseDMapWithKeyWithAdjustWithMove f m e = FocusReader $ traverseDMapWithKeyWithAdjustWithMove (\k v -> unFocusReader $ f k v) m e
364+
365+instance MonadTrans (FocusReader t) where
366+ lift = FocusReader . lift
367+
368+instance MFunctor (FocusReader t) where
369+ hoist f = FocusReader . hoist f . unFocusReader
370+
371+instance MonadNodeId m => MonadNodeId (FocusReader t m)
372+
373+-- | Run a 'FocusReader' action with the given focus value
374+runFocusReader
375+ :: (Reflex t, Monad m)
376+ => Dynamic t Bool
377+ -> FocusReader t m a
378+ -> m a
379+runFocusReader b = flip runReaderT b . unFocusReader
380+
381+-- * "Image" output
382+
383+-- | A class for widgets that can produce images to draw to the display
384+class (Reflex t, Monad m) => HasImageWriter t m | m -> t where
385+ -- | Send images upstream for rendering
386+ tellImages :: Behavior t [Image] -> m ()
387+ default tellImages :: (f m' ~ m, Monad m', MonadTrans f, HasImageWriter t m') => Behavior t [Image] -> m ()
388+ tellImages = lift . tellImages
389+ -- | Apply a transformation to the images produced by the child actions
390+ mapImages :: (Behavior t [Image] -> Behavior t [Image]) -> m a -> m a
391+ default mapImages :: (f m' ~ m, Monad m', MFunctor f, HasImageWriter t m') => (Behavior t [Image] -> Behavior t [Image]) -> m a -> m a
392+ mapImages f = hoist (mapImages f)
393+
394+-- | A widget that can produce images to draw onto the display
395+newtype ImageWriter t m a = ImageWriter
396+ { unImageWriter :: BehaviorWriterT t [Image] m a }
397+ deriving
398+ ( Functor
399+ , Applicative
400+ , Monad
401+ , MonadFix
402+ , MonadHold t
403+ , MonadIO
404+ , MonadRef
405+ , MonadReflexCreateTrigger t
406+ , MonadSample t
407+ , NotReady t
408+ , PerformEvent t
409+ , PostBuild t
410+ , TriggerEvent t
411+ )
412+
413+instance MonadTrans (ImageWriter t) where
414+ lift = ImageWriter . lift
415+
416+instance MFunctor (ImageWriter t) where
417+ hoist f = ImageWriter . (hoist f) . unImageWriter
418+
419+instance (Adjustable t m, MonadFix m, MonadHold t m) => Adjustable t (ImageWriter t m) where
420+ runWithReplace (ImageWriter a) e = ImageWriter $ runWithReplace a $ fmap unImageWriter e
421+ traverseIntMapWithKeyWithAdjust f m e = ImageWriter $ traverseIntMapWithKeyWithAdjust (\k v -> unImageWriter $ f k v) m e
422+ traverseDMapWithKeyWithAdjust f m e = ImageWriter $ traverseDMapWithKeyWithAdjust (\k v -> unImageWriter $ f k v) m e
423+ traverseDMapWithKeyWithAdjustWithMove f m e = ImageWriter $ traverseDMapWithKeyWithAdjustWithMove (\k v -> unImageWriter $ f k v) m e
424+
425+instance HasImageWriter t m => HasImageWriter t (ReaderT x m)
426+instance HasImageWriter t m => HasImageWriter t (BehaviorWriterT t x m)
427+instance HasImageWriter t m => HasImageWriter t (DynamicWriterT t x m)
428+instance HasImageWriter t m => HasImageWriter t (EventWriterT t x m)
429+instance HasImageWriter t m => HasImageWriter t (NodeIdT m)
430+
431+instance (Monad m, Reflex t) => HasImageWriter t (ImageWriter t m) where
432+ tellImages = ImageWriter . tellBehavior
433+ mapImages f (ImageWriter x) = ImageWriter $ do
434+ (a, images) <- lift $ runBehaviorWriterT x
435+ tellBehavior $ f images
436+ pure a
437+
438+instance HasDisplayRegion t m => HasDisplayRegion t (ImageWriter t m)
439+instance HasFocusReader t m => HasFocusReader t (ImageWriter t m)
440+
441+-- | Run a widget that can produce images
442+runImageWriter
443+ :: (Reflex t, Monad m)
444+ => ImageWriter t m a
445+ -> m (a, Behavior t [Image])
446+runImageWriter = runBehaviorWriterT . unImageWriter
447+
448+-- * Theming
449+
450+-- | A class for things that can be visually styled
451+class (Reflex t, Monad m) => HasTheme t m | m -> t where
452+ theme :: m (Behavior t V.Attr)
453+ default theme :: (f m' ~ m, Monad m', MonadTrans f, HasTheme t m') => m (Behavior t V.Attr)
454+ theme = lift theme
455+ localTheme :: (Behavior t V.Attr -> Behavior t V.Attr) -> m a -> m a
456+ default localTheme :: (f m' ~ m, Monad m', MFunctor f, HasTheme t m') => (Behavior t V.Attr -> Behavior t V.Attr) -> m a -> m a
457+ localTheme f = hoist (localTheme f)
458+
459+instance HasTheme t m => HasTheme t (ReaderT x m)
460+instance HasTheme t m => HasTheme t (BehaviorWriterT t x m)
461+instance HasTheme t m => HasTheme t (DynamicWriterT t x m)
462+instance HasTheme t m => HasTheme t (EventWriterT t x m)
463+instance HasTheme t m => HasTheme t (NodeIdT m)
464+instance HasTheme t m => HasTheme t (Input t m)
465+instance HasTheme t m => HasTheme t (ImageWriter t m)
466+instance HasTheme t m => HasTheme t (DisplayRegion t m)
467+instance HasTheme t m => HasTheme t (FocusReader t m)
468+
469+-- | A widget that has access to theme information
470+newtype ThemeReader t m a = ThemeReader
471+ { unThemeReader :: ReaderT (Behavior t V.Attr) m a }
472+ deriving
473+ ( Functor
474+ , Applicative
475+ , Monad
476+ , MonadFix
477+ , MonadHold t
478+ , MonadIO
479+ , MonadRef
480+ , MonadSample t
481+ )
482+
483+instance (Monad m, Reflex t) => HasTheme t (ThemeReader t m) where
484+ theme = ThemeReader ask
485+ localTheme f = ThemeReader . local f . unThemeReader
486+
487+deriving instance MonadReflexCreateTrigger t m => MonadReflexCreateTrigger t (ThemeReader t m)
488+deriving instance NotReady t m => NotReady t (ThemeReader t m)
489+deriving instance PerformEvent t m => PerformEvent t (ThemeReader t m)
490+deriving instance PostBuild t m => PostBuild t (ThemeReader t m)
491+deriving instance TriggerEvent t m => TriggerEvent t (ThemeReader t m)
492+instance HasImageWriter t m => HasImageWriter t (ThemeReader t m)
493+
494+instance (Adjustable t m, MonadFix m, MonadHold t m) => Adjustable t (ThemeReader t m) where
495+ runWithReplace (ThemeReader a) e = ThemeReader $ runWithReplace a $ fmap unThemeReader e
496+ traverseIntMapWithKeyWithAdjust f m e = ThemeReader $ traverseIntMapWithKeyWithAdjust (\k v -> unThemeReader $ f k v) m e
497+ traverseDMapWithKeyWithAdjust f m e = ThemeReader $ traverseDMapWithKeyWithAdjust (\k v -> unThemeReader $ f k v) m e
498+ traverseDMapWithKeyWithAdjustWithMove f m e = ThemeReader $ traverseDMapWithKeyWithAdjustWithMove (\k v -> unThemeReader $ f k v) m e
499+
500+instance MonadTrans (ThemeReader t) where
501+ lift = ThemeReader . lift
502+
503+instance MFunctor (ThemeReader t) where
504+ hoist f = ThemeReader . hoist f . unThemeReader
505+
506+instance MonadNodeId m => MonadNodeId (ThemeReader t m)
507+
508+-- | Run a 'ThemeReader' action with the given focus value
509+runThemeReader
510+ :: (Reflex t, Monad m)
511+ => Behavior t V.Attr
512+ -> ThemeReader t m a
513+ -> m a
514+runThemeReader b = flip runReaderT b . unThemeReader
515+
516+
517+-- ** Manipulating images
239518
240519-- | Translates and crops an 'Image' so that it is contained by
241520-- the given 'Region'.
@@ -247,7 +526,17 @@ withinImage (Region left top width height)
247526 | width < 0 || height < 0 = withinImage (Region left top 0 0)
248527 | otherwise = V.translate left top . V.crop width height
249528
250−-- | Low-level widget combinator that runs a child 'VtyWidget' within
529+-- | Crop a behavior of images to a behavior of regions. See 'withinImage'.
530+imagesInRegion
531+ :: Reflex t
532+ => Behavior t Region
533+ -> Behavior t [Image]
534+ -> Behavior t [Image]
535+imagesInRegion reg = liftA2 (\r is -> map (withinImage r) is) reg
536+
537+-- * Running sub-widgets
538+
539+-- | Low-level widget combinator that runs a child widget within
251540-- a given region and context. This widget filters and modifies the input
252541-- that the child widget receives such that:
253542-- * unfocused widgets receive no key events
@@ -255,306 +544,18 @@ withinImage (Region left top width height)
255544-- * mouse inputs inside the region have their coordinates translated such
256545-- that (0,0) is the top-left corner of the region
257546pane
258− :: (Reflex t, Monad m)
259− => Dynamic t Region -- ^ Region into which we should draw the widget (in coordinates relative to our own)
547+ :: (Reflex t, Monad m, HasInput t m, HasImageWriter t m, HasDisplayRegion t m, HasFocusReader t m)
548+ => Dynamic t Region
260549 -> Dynamic t Bool -- ^ Whether the widget should be focused when the parent is.
261− -> VtyWidget t m a
262− -> VtyWidget t m a
263−pane reg foc child = VtyWidget $ do
264− ctx <- lift ask
265− let ctx' = VtyWidgetCtx
266− { _vtyWidgetCtx_input = leftmost -- TODO: think about this leftmost more.
267− [ fmapMaybe id $
268− attachWith (\(r,f) e -> filterInput r f e)
269− (liftA2 (,) (current reg) (current foc))
270− (_vtyWidgetCtx_input ctx)
271− ]
272− , _vtyWidgetCtx_focus = liftA2 (&&) (_vtyWidgetCtx_focus ctx) foc
273− , _vtyWidgetCtx_size = fmap regionSize reg }
274− (result, wo) <- lift . lift $ runVtyWidget ctx' child
275− let images = _vtyWidgetOut_images wo
276− images' = liftA2 (\r is -> map (withinImage r) is) (current reg) images
277− wo' = wo { _vtyWidgetOut_images = images' }
278− tell wo'
279− return result
280− where
281− filterInput :: Region -> Bool -> VtyEvent -> Maybe VtyEvent
282− filterInput (Region l t w h) focused e = case e of
283− V.EvKey _ _ | not focused -> Nothing
284− V.EvMouseDown x y btn m -> mouse (\u v -> V.EvMouseDown u v btn m) x y
285− V.EvMouseUp x y btn -> mouse (\u v -> V.EvMouseUp u v btn) x y
286− _ -> Just e
287− where
288− mouse con x y
289− | or [ x < l
290− , y < t
291− , x >= l + w
292− , y >= t + h ] = Nothing
293− | otherwise =
294− Just (con (x - l) (y - t))
295−
296−-- | Information about a drag operation
297−data Drag = Drag
298− { _drag_from :: (Int, Int) -- ^ Where the drag began
299− , _drag_to :: (Int, Int) -- ^ Where the mouse currently is
300− , _drag_button :: V.Button -- ^ Which mouse button is dragging
301− , _drag_modifiers :: [V.Modifier] -- ^ What modifiers are held
302− , _drag_end :: Bool -- ^ Whether the drag ended (the mouse button was released)
303− }
304− deriving (Eq, Ord, Show)
305−
306−-- | Converts raw vty mouse drag events into an event stream of 'Drag's
307−drag
308− :: (Reflex t, MonadFix m, MonadHold t m)
309− => V.Button
310− -> VtyWidget t m (Event t Drag)
311−drag btn = do
312− inp <- input
313− let f :: Maybe Drag -> V.Event -> Maybe Drag
314− f Nothing = \case
315− V.EvMouseDown x y btn' mods
316− | btn == btn' -> Just $ Drag (x,y) (x,y) btn' mods False
317− | otherwise -> Nothing
318− _ -> Nothing
319− f (Just (Drag from _ _ mods end)) = \case
320− V.EvMouseDown x y btn' mods'
321− | end -> Just $ Drag (x,y) (x,y) btn' mods' False
322− | btn == btn' -> Just $ Drag from (x,y) btn mods' False
323− | otherwise -> Nothing -- Ignore other buttons.
324− V.EvMouseUp x y (Just btn')
325− | end -> Nothing
326− | btn == btn' -> Just $ Drag from (x,y) btn mods True
327− | otherwise -> Nothing
328− V.EvMouseUp x y Nothing -- Terminal doesn't specify mouse up button,
329− -- assume it's the right one.
330− | end -> Nothing
331− | otherwise -> Just $ Drag from (x,y) btn mods True
332− _ -> Nothing
333− rec let newDrag = attachWithMaybe f (current dragD) inp
334− dragD <- holdDyn Nothing $ Just <$> newDrag
335− return (fmapMaybe id $ updated dragD)
336−
337−-- | Mouse down events for a particular mouse button
338−mouseDown
339− :: (Reflex t, Monad m)
340− => V.Button
341− -> VtyWidget t m (Event t MouseDown)
342−mouseDown btn = do
343− i <- input
344− return $ fforMaybe i $ \case
345− V.EvMouseDown x y btn' mods -> if btn == btn'
346− then Just $ MouseDown btn' (x, y) mods
347− else Nothing
348− _ -> Nothing
349−
350−-- | Mouse up events for a particular mouse button
351−mouseUp
352− :: (Reflex t, Monad m)
353− => VtyWidget t m (Event t MouseUp)
354−mouseUp = do
355− i <- input
356− return $ fforMaybe i $ \case
357− V.EvMouseUp x y btn' -> Just $ MouseUp btn' (x, y)
358− _ -> Nothing
359−
360−-- | Information about a mouse down event
361−data MouseDown = MouseDown
362− { _mouseDown_button :: V.Button
363− , _mouseDown_coordinates :: (Int, Int)
364− , _mouseDown_modifiers :: [V.Modifier]
365− }
366− deriving (Eq, Ord, Show)
367−
368−-- | Information about a mouse up event
369−data MouseUp = MouseUp
370− { _mouseUp_button :: Maybe V.Button
371− , _mouseUp_coordinates :: (Int, Int)
372− }
373− deriving (Eq, Ord, Show)
374−
375−-- | A plain split of the available space into vertically stacked panes.
376−-- No visual separator is built in here.
377−splitV :: (Reflex t, Monad m)
378− => Dynamic t (Int -> Int)
379− -- ^ Function used to determine size of first pane based on available size
380− -> Dynamic t (Bool, Bool)
381− -- ^ How to focus the two sub-panes, given that we are focused.
382− -> VtyWidget t m a
383− -- ^ Widget for first pane
384− -> VtyWidget t m b
385− -- ^ Widget for second pane
386− -> VtyWidget t m (a,b)
387−splitV sizeFunD focD wA wB = do
388− sz <- displaySize
389− let regA = (\f (w,h) -> Region 0 0 w (f h)) <$> sizeFunD <*> sz
390− regB = (\(w,h) (Region _ _ _ hA) -> Region 0 hA w (h - hA)) <$> sz <*> regA
391− ra <- pane regA (fst <$> focD) wA
392− rb <- pane regB (snd <$> focD) wB
393− return (ra,rb)
394−
395−-- | A split of the available space into two parts with a draggable separator.
396−-- Starts with half the space allocated to each, and the first pane has focus.
397−-- Clicking in a pane switches focus.
398−splitVDrag :: (Reflex t, MonadFix m, MonadHold t m)
399− => VtyWidget t m ()
400− -> VtyWidget t m a
401− -> VtyWidget t m b
402− -> VtyWidget t m (a,b)
403−splitVDrag wS wA wB = do
404− sz <- displaySize
405− (_, h0) <- sample $ current sz
406− dragE <- drag V.BLeft
407− let splitter0 = h0 `div` 2
408− rec splitterCheckpoint <- holdDyn splitter0 $ leftmost [fst <$> ffilter snd dragSplitter, resizeSplitter]
409− splitterPos <- holdDyn splitter0 $ leftmost [fst <$> dragSplitter, resizeSplitter]
410− splitterFrac <- holdDyn ((1::Double) / 2) $ ffor (attach (current sz) (fst <$> dragSplitter)) $ \((_,h),x) ->
411− fromIntegral x / fromIntegral h
412− let dragSplitter = fforMaybe (attach (current splitterCheckpoint) dragE) $
413− \(splitterY, Drag (_, fromY) (_, toY) _ _ end) ->
414− if splitterY == fromY then Just (toY, end) else Nothing
415− regA = (\(w,_) sp -> Region 0 0 w sp) <$> sz <*> splitterPos
416− regS = (\(w,_) sp -> Region 0 sp w 1) <$> sz <*> splitterPos
417− regB = (\(w,h) sp -> Region 0 (sp + 1) w (h - sp - 1)) <$> sz <*> splitterPos
418− resizeSplitter = ffor (attach (current splitterFrac) (updated sz)) $
419− \(frac, (_,h)) -> round (frac * fromIntegral h)
420− focA <- holdDyn True $ leftmost
421− [ True <$ mA
422− , False <$ mB
423− ]
424− (mA, rA) <- pane regA focA $ withMouseDown wA
425− pane regS (pure False) wS
426− (mB, rB) <- pane regB (not <$> focA) $ withMouseDown wB
427− return (rA, rB)
428− where
429− withMouseDown x = do
430− m <- mouseDown V.BLeft
431− x' <- x
432− return (m, x')
433−
434−-- | Fill the background with a particular character.
435−fill :: (Reflex t, Monad m) => Char -> VtyWidget t m ()
436−fill c = do
437− sz <- displaySize
438− let fillImg = ffor (current sz) $ \(w,h) -> [V.charFill V.defAttr c w h]
439− tellImages fillImg
440−
441−-- | Fill the background with the bottom
442−hRule :: (Reflex t, Monad m) => BoxStyle -> VtyWidget t m ()
443−hRule boxStyle = fill (_boxStyle_s boxStyle)
444−
445−-- | Transform the images produces by a widget
446−modifyImages
447− :: (Reflex t, MonadHold t m, MonadFix m)
448− => Behavior t ([Image] -> [Image])
449− -> VtyWidget t m a
450− -> VtyWidget t m a
451−modifyImages f (VtyWidget w) = VtyWidget $ flip censor w $ \wo ->
452− wo { _vtyWidgetOut_images = f <*> (_vtyWidgetOut_images wo) }
453−
454−-- | Defines a set of symbols to use to draw the outlines of boxes
455−-- C.f. https://en.wikipedia.org/wiki/Box-drawing_character
456−data BoxStyle = BoxStyle
457− { _boxStyle_nw :: Char
458− , _boxStyle_n :: Char
459− , _boxStyle_ne :: Char
460− , _boxStyle_e :: Char
461− , _boxStyle_se :: Char
462− , _boxStyle_s :: Char
463− , _boxStyle_sw :: Char
464− , _boxStyle_w :: Char
465− }
466−
467−instance Default BoxStyle where
468− def = singleBoxStyle
469−
470−-- | A box style that uses hyphens and pipe characters. Doesn't handle
471−-- corners very well.
472−hyphenBoxStyle :: BoxStyle
473−hyphenBoxStyle = BoxStyle '-' '-' '-' '|' '-' '-' '-' '|'
474−
475−-- | A single line box style
476−singleBoxStyle :: BoxStyle
477−singleBoxStyle = BoxStyle '┌' '─' '┐' '│' '┘' '─' '└' '│'
478−
479−-- | A thick single line box style
480−thickBoxStyle :: BoxStyle
481−thickBoxStyle = BoxStyle '┏' '━' '┓' '┃' '┛' '━' '┗' '┃'
482−
483−-- | A double line box style
484−doubleBoxStyle :: BoxStyle
485−doubleBoxStyle = BoxStyle '╔' '═' '╗' '║' '╝' '═' '╚' '║'
486−
487−-- | A single line box style with rounded corners
488−roundedBoxStyle :: BoxStyle
489−roundedBoxStyle = BoxStyle '╭' '─' '╮' '│' '╯' '─' '╰' '│'
490−
491−-- | Draws a box in the provided style and a child widget inside of that box
492−box :: (Monad m, Reflex t)
493− => Behavior t BoxStyle
494− -> VtyWidget t m a
495− -> VtyWidget t m a
496−box boxStyle child = do
497− sz <- displaySize
498− let boxReg = ffor (current sz) $ \(w,h) -> Region 0 0 w h
499− innerReg = ffor sz $ \(w,h) -> Region 1 1 (w - 2) (h - 2)
500− tellImages (boxImages <$> boxStyle <*> boxReg)
501− tellImages (fmap (\r -> [regionBlankImage r]) (current innerReg))
502− pane innerReg (pure True) child
503− where
504− boxImages :: BoxStyle -> Region -> [Image]
505− boxImages style (Region left top width height) =
506− let right = left + width - 1
507− bottom = top + height - 1
508− sides =
509− [ withinImage (Region (left + 1) top (width - 2) 1) $
510− V.charFill V.defAttr (_boxStyle_n style) (width - 2) 1
511− , withinImage (Region right (top + 1) 1 (height - 2)) $
512− V.charFill V.defAttr (_boxStyle_e style) 1 (height - 2)
513− , withinImage (Region (left + 1) bottom (width - 2) 1) $
514− V.charFill V.defAttr (_boxStyle_s style) (width - 2) 1
515− , withinImage (Region left (top + 1) 1 (height - 2)) $
516− V.charFill V.defAttr (_boxStyle_w style) 1 (height - 2)
517− ]
518− corners =
519− [ withinImage (Region left top 1 1) $
520− V.char V.defAttr (_boxStyle_nw style)
521− , withinImage (Region right top 1 1) $
522− V.char V.defAttr (_boxStyle_ne style)
523− , withinImage (Region right bottom 1 1) $
524− V.char V.defAttr (_boxStyle_se style)
525− , withinImage (Region left bottom 1 1) $
526− V.char V.defAttr (_boxStyle_sw style)
527− ]
528− in sides ++ if width > 1 && height > 1 then corners else []
529−
530−-- | A box whose style is static
531−boxStatic
532− :: (Reflex t, Monad m)
533− => BoxStyle
534− -> VtyWidget t m a
535− -> VtyWidget t m a
536−boxStatic = box . pure
537−
538−-- | Renders text, wrapped to the container width
539−text
540− :: (Reflex t, Monad m)
541− => Behavior t Text
542− -> VtyWidget t m ()
543−text msg = do
544− dw <- displayWidth
545− let img = (\w s -> [wrapText w V.defAttr s]) <$> current dw <*> msg
546− tellImages img
547− where
548− wrapText maxWidth attrs = V.vertCat
549− . concatMap (fmap (V.string attrs . T.unpack) . TZ.wrapWithOffset maxWidth 0)
550− . T.split (=='\n')
551−
552−-- | Renders any behavior whose value can be converted to
553−-- 'String' as text
554−display
555− :: (Reflex t, Monad m, Show a)
556− => Behavior t a
557− -> VtyWidget t m ()
558−display a = text $ T.pack . show <$> a
559−
560−
550+ -> m a
551+ -> m a
552+pane dr foc child = localRegion (const dr) $
553+ mapImages (imagesInRegion $ current dr) $
554+ localFocus (const foc) $
555+ inputInFocusedRegion >>= \e -> localInput (const e) child
556+
557+-- * Misc
558+
559+-- | A widget that draws nothing
560+blank :: Monad m => m ()
561+blank = return ()