@@ -2,147 +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− , text
47− , display
48− , hyphenBoxStyle
49− , singleBoxStyle
50− , roundedBoxStyle
51− , thickBoxStyle
52− , doubleBoxStyle
53− , fill
54− , hRule
55− ) where
5+{-# Language UndecidableInstances #-}
6+
7+module Reflex.Vty.Widget where
568
579import Control.Applicative (liftA2)
5810import Control.Monad.Fix (MonadFix)
59−import Control.Monad.Trans (lift)
60−import Control.Monad.Trans.Reader (ReaderT, runReaderT, asks, ask)
61−import Control.Monad.Trans.Writer (WriterT, runWriterT, censor, tell)
62−import Control.Monad.Writer.Adjustable ()
63−import Data.Default (Default(..))
64−import Data.Text (Text)
65−import qualified Data.Text as T
66−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
6719import Graphics.Vty (Image)
6820import qualified Graphics.Vty as V
6921import Reflex
70−import Reflex.Class.Switchable
71−import Reflex.NotReady.Class
72−import Reflex.NotReady.Class.Orphans ()
73−
22+import Reflex.Class ()
23+import Reflex.Host.Class (MonadReflexCreateTrigger)
7424import Reflex.Vty.Host
7525
76−-- | The context within which a 'VtyWidget' runs
77−data VtyWidgetCtx t = VtyWidgetCtx
78− { _vtyWidgetCtx_size :: Dynamic t (Int,Int)
79− -- ^ The width and height of the region allocated to the widget.
80− , _vtyWidgetCtx_focus :: Dynamic t Bool
81− -- ^ Whether the widget should behave as if it has focus for keyboard input.
82− , _vtyWidgetCtx_input :: Event t VtyEvent
83− -- ^ User input events that the widget's parent chooses to share. These will generally
84− -- be filtered for relevance:
85− -- * Keyboard inputs are restricted to focused widgets
86− -- * Mouse inputs are restricted to the region in which the widget resides and are
87− -- translated into its internal coordinates.
88− }
89−
90−-- | The output of a 'VtyWidget'
91−data VtyWidgetOut t = VtyWidgetOut
92− { _vtyWidgetOut_images :: Behavior t [Image]
93− -- ^ The visual output of the 'VtyWidget'
94− , _vtyWidgetOut_shutdown :: Event t ()
95− }
96−
97−instance Reflex t => Semigroup (VtyWidgetOut t) where
98− wo <> wo' = VtyWidgetOut
99− { _vtyWidgetOut_images = _vtyWidgetOut_images wo <> _vtyWidgetOut_images wo'
100− , _vtyWidgetOut_shutdown = _vtyWidgetOut_shutdown wo <> _vtyWidgetOut_shutdown wo'
101− }
102−
103−instance (Reflex t) => Monoid (VtyWidgetOut t) where
104− mempty = VtyWidgetOut mempty mempty
105− mappend wo wo' = wo <> wo'
106−
107−instance Reflex t => Switchable t (VtyWidgetOut t) where
108− switching e0 e = do
109− shutdown <- switching (_vtyWidgetOut_shutdown e0) $ fmap _vtyWidgetOut_shutdown e
110− images <- switching (_vtyWidgetOut_images e0) $ fmap _vtyWidgetOut_images e
111− return $ VtyWidgetOut
112− { _vtyWidgetOut_images = images
113− , _vtyWidgetOut_shutdown = shutdown
114− }
115−
116−-- | A widget that can read its context and produce image output
117−newtype VtyWidget t m a = VtyWidget
118− { unVtyWidget :: WriterT (VtyWidgetOut t) (ReaderT (VtyWidgetCtx t) m) a
119− }
120− deriving (Functor, Applicative, Monad, MonadSample t, MonadHold t, MonadFix, NotReady t)
121−
122−instance (PostBuild t m, Reflex t) => PostBuild t (VtyWidget t m) where
123− getPostBuild = VtyWidget $ lift getPostBuild
124−
125−instance (Adjustable t m, MonadHold t m, Reflex t) => Adjustable t (VtyWidget t m) where
126− runWithReplace a0 a' = VtyWidget $ runWithReplace (unVtyWidget a0) $ fmap unVtyWidget a'
127− traverseIntMapWithKeyWithAdjust f dm0 dm' = VtyWidget $
128− traverseIntMapWithKeyWithAdjust (\k v -> unVtyWidget (f k v)) dm0 dm'
129− traverseDMapWithKeyWithAdjust f dm0 dm' = VtyWidget $ do
130− traverseDMapWithKeyWithAdjust (\k v -> unVtyWidget (f k v)) dm0 dm'
131− traverseDMapWithKeyWithAdjustWithMove f dm0 dm' = VtyWidget $ do
132− traverseDMapWithKeyWithAdjustWithMove (\k v -> unVtyWidget (f k v)) dm0 dm'
133−
134−-- | Runs a 'VtyWidget' with a given context
135−runVtyWidget
136− :: Reflex t
137− => VtyWidgetCtx t
138− -> VtyWidget t m a
139− -> m (a, VtyWidgetOut t)
140−runVtyWidget ctx w = runReaderT (runWriterT (unVtyWidget w)) ctx
26+-- * Running a vty application
14127
142−-- | 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
14329mainWidgetWithHandle
14430 :: V.Vty
145− -> (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 ()))
14640 -> IO ()
14741mainWidgetWithHandle vty child =
14842 runVtyAppWithHandle vty $ \dr0 inp -> do
@@ -152,71 +46,178 @@ mainWidgetWithHandle vty child =
15246 let inp' = fforMaybe inp $ \case
15347 V.EvResize {} -> Nothing
15448 x -> Just x
155− let ctx = VtyWidgetCtx
156− { _vtyWidgetCtx_size = size
157− , _vtyWidgetCtx_input = inp'
158− , _vtyWidgetCtx_focus = constDyn True
159− }
160− ((), wo) <- runVtyWidget ctx $ do
161− tellImages . ffor (current size) $ \(w, h) -> [V.charFill V.defAttr ' ' w h]
162− 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
16357 return $ VtyResult
164− { _vtyResult_picture = fmap (V.picForLayers . reverse) (_vtyWidgetOut_images wo)
165− , _vtyResult_shutdown = _vtyWidgetOut_shutdown wo
58+ { _vtyResult_picture = fmap (V.picForLayers . reverse) images
59+ , _vtyResult_shutdown = shutdown
16660 }
16761
62+-- | The output of a vty widget
63+data VtyWidgetOut t = VtyWidgetOut
64+ { _vtyWidgetOut_shutdown :: Event t ()
65+ }
66+
16867-- | Like 'mainWidgetWithHandle', but uses a default vty configuration
16968mainWidget
170− :: (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 ()))
17178 -> IO ()
17279mainWidget child = do
17380 vty <- getDefaultVty
17481 mainWidgetWithHandle vty child
17582
176−-- | A class for things that know their own display size dimensions
177−class (Reflex t, Monad m) => HasDisplaySize t m | m -> t where
178− displaySize :: m (Dynamic t (Int, Int))
179−
180−instance (Reflex t, Monad m) => HasDisplaySize t (VtyWidget t m) where
181− displaySize = VtyWidget . lift $ asks _vtyWidgetCtx_size
182−
183−-- | Retrieve the display width (columns)
184−displayWidth :: HasDisplaySize t m => m (Dynamic t Int)
185−displayWidth = fmap fst <$> displaySize
186−
187−-- | Retrieve the display height (rows)
188−displayHeight :: HasDisplaySize t m => m (Dynamic t Int)
189−displayHeight = fmap snd <$> displaySize
83+-- * Input Events
19084
19185-- | A class for things that can receive vty events as input
192−class HasVtyInput t m | m -> t where
86+class HasInput t m | m -> t where
19387 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
194180
195−instance (Reflex t, Monad m) => HasVtyInput t (VtyWidget t m) where
196− input = VtyWidget . lift $ asks _vtyWidgetCtx_input
197−
198−-- | A class for things that can dynamically gain and lose focus
199−class HasFocus t m | m -> t where
200− focus :: m (Dynamic t Bool)
201−
202−instance (Reflex t, Monad m) => HasFocus t (VtyWidget t m) where
203− focus = VtyWidget . lift $ asks _vtyWidgetCtx_focus
204−
205−-- | A class for widgets that can produce images to draw to the display
206−class (Reflex t, Monad m) => ImageWriter t m | m -> t where
207− -- | Send images upstream for rendering
208− tellImages :: Behavior t [Image] -> m ()
209−
210−instance (Reflex t, Monad m) => ImageWriter t (VtyWidget t m) where
211− tellImages imgs = VtyWidget $ tell (mempty { _vtyWidgetOut_images = imgs })
212−
213−-- | A class for things that can shut down the vty application
214−class (Reflex t, Monad m) => Shutdown t m where
215− -- | Signals that the vty application should shut down
216− 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
217219
218−instance (Reflex t, Monad m) => Shutdown t (VtyWidget t m) where
219− tellShutdown sd = VtyWidget $ tell (mempty { _vtyWidgetOut_shutdown = sd })
220+-- * Getting and setting the display region
220221
221222-- | A chunk of the display area
222223data Region = Region
@@ -227,14 +228,293 @@ data Region = Region
227228 }
228229 deriving (Show, Read, Eq, Ord)
229230
231+-- | A region that occupies no space.
232+nilRegion :: Region
233+nilRegion = Region 0 0 0 0
234+
230235-- | The width and height of a 'Region'
231236regionSize :: Region -> (Int, Int)
232237regionSize (Region _ _ w h) = (w, h)
233238
234239-- | Produces an 'Image' that fills a region with space characters
235−regionBlankImage :: Region -> Image
236−regionBlankImage r@(Region _ _ width height) =
237− 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
238518
239519-- | Translates and crops an 'Image' so that it is contained by
240520-- the given 'Region'.
@@ -246,7 +526,17 @@ withinImage (Region left top width height)
246526 | width < 0 || height < 0 = withinImage (Region left top 0 0)
247527 | otherwise = V.translate left top . V.crop width height
248528
249−-- | 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
250540-- a given region and context. This widget filters and modifies the input
251541-- that the child widget receives such that:
252542-- * unfocused widgets receive no key events
@@ -254,298 +544,18 @@ withinImage (Region left top width height)
254544-- * mouse inputs inside the region have their coordinates translated such
255545-- that (0,0) is the top-left corner of the region
256546pane
257− :: (Reflex t, Monad m)
258− => 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
259549 -> Dynamic t Bool -- ^ Whether the widget should be focused when the parent is.
260− -> VtyWidget t m a
261− -> VtyWidget t m a
262−pane reg foc child = VtyWidget $ do
263− ctx <- lift ask
264− let ctx' = VtyWidgetCtx
265− { _vtyWidgetCtx_input = leftmost -- TODO: think about this leftmost more.
266− [ fmapMaybe id $
267− attachWith (\(r,f) e -> filterInput r f e)
268− (liftA2 (,) (current reg) (current foc))
269− (_vtyWidgetCtx_input ctx)
270− ]
271− , _vtyWidgetCtx_focus = liftA2 (&&) (_vtyWidgetCtx_focus ctx) foc
272− , _vtyWidgetCtx_size = fmap regionSize reg }
273− (result, wo) <- lift . lift $ runVtyWidget ctx' child
274− let images = _vtyWidgetOut_images wo
275− images' = liftA2 (\r is -> map (withinImage r) is) (current reg) images
276− wo' = wo { _vtyWidgetOut_images = images' }
277− tell wo'
278− return result
279− where
280− filterInput :: Region -> Bool -> VtyEvent -> Maybe VtyEvent
281− filterInput (Region l t w h) focused e = case e of
282− V.EvKey _ _ | not focused -> Nothing
283− V.EvMouseDown x y btn m -> mouse (\u v -> V.EvMouseDown u v btn m) x y
284− V.EvMouseUp x y btn -> mouse (\u v -> V.EvMouseUp u v btn) x y
285− _ -> Just e
286− where
287− mouse con x y
288− | or [ x < l
289− , y < t
290− , x >= l + w
291− , y >= t + h ] = Nothing
292− | otherwise =
293− Just (con (x - l) (y - t))
294−
295−-- | Information about a drag operation
296−data Drag = Drag
297− { _drag_from :: (Int, Int) -- ^ Where the drag began
298− , _drag_to :: (Int, Int) -- ^ Where the mouse currently is
299− , _drag_button :: V.Button -- ^ Which mouse button is dragging
300− , _drag_modifiers :: [V.Modifier] -- ^ What modifiers are held
301− , _drag_end :: Bool -- ^ Whether the drag ended (the mouse button was released)
302− }
303− deriving (Eq, Ord, Show)
304−
305−-- | Converts raw vty mouse drag events into an event stream of 'Drag's
306−drag
307− :: (Reflex t, MonadFix m, MonadHold t m)
308− => V.Button
309− -> VtyWidget t m (Event t Drag)
310−drag btn = do
311− inp <- input
312− let f :: Maybe Drag -> V.Event -> Maybe Drag
313− f Nothing = \case
314− V.EvMouseDown x y btn' mods
315− | btn == btn' -> Just $ Drag (x,y) (x,y) btn' mods False
316− | otherwise -> Nothing
317− _ -> Nothing
318− f (Just (Drag from _ _ mods end)) = \case
319− V.EvMouseDown x y btn' mods'
320− | end -> Just $ Drag (x,y) (x,y) btn' mods' False
321− | btn == btn' -> Just $ Drag from (x,y) btn mods' False
322− | otherwise -> Nothing -- Ignore other buttons.
323− V.EvMouseUp x y (Just btn')
324− | end -> Nothing
325− | btn == btn' -> Just $ Drag from (x,y) btn mods True
326− | otherwise -> Nothing
327− V.EvMouseUp x y Nothing -- Terminal doesn't specify mouse up button,
328− -- assume it's the right one.
329− | end -> Nothing
330− | otherwise -> Just $ Drag from (x,y) btn mods True
331− _ -> Nothing
332− rec let newDrag = attachWithMaybe f (current dragD) inp
333− dragD <- holdDyn Nothing $ Just <$> newDrag
334− return (fmapMaybe id $ updated dragD)
335−
336−-- | Mouse down events for a particular mouse button
337−mouseDown
338− :: (Reflex t, Monad m)
339− => V.Button
340− -> VtyWidget t m (Event t MouseDown)
341−mouseDown btn = do
342− i <- input
343− return $ fforMaybe i $ \case
344− V.EvMouseDown x y btn' mods -> if btn == btn'
345− then Just $ MouseDown btn' (x, y) mods
346− else Nothing
347− _ -> Nothing
348−
349−-- | Mouse up events for a particular mouse button
350−mouseUp
351− :: (Reflex t, Monad m)
352− => VtyWidget t m (Event t MouseUp)
353−mouseUp = do
354− i <- input
355− return $ fforMaybe i $ \case
356− V.EvMouseUp x y btn' -> Just $ MouseUp btn' (x, y)
357− _ -> Nothing
358−
359−-- | Information about a mouse down event
360−data MouseDown = MouseDown
361− { _mouseDown_button :: V.Button
362− , _mouseDown_coordinates :: (Int, Int)
363− , _mouseDown_modifiers :: [V.Modifier]
364− }
365− deriving (Eq, Ord, Show)
366−
367−-- | Information about a mouse up event
368−data MouseUp = MouseUp
369− { _mouseUp_button :: Maybe V.Button
370− , _mouseUp_coordinates :: (Int, Int)
371− }
372− deriving (Eq, Ord, Show)
373−
374−-- | A plain split of the available space into vertically stacked panes.
375−-- No visual separator is built in here.
376−splitV :: (Reflex t, Monad m)
377− => Dynamic t (Int -> Int)
378− -- ^ Function used to determine size of first pane based on available size
379− -> Dynamic t (Bool, Bool)
380− -- ^ How to focus the two sub-panes, given that we are focused.
381− -> VtyWidget t m a
382− -- ^ Widget for first pane
383− -> VtyWidget t m b
384− -- ^ Widget for second pane
385− -> VtyWidget t m (a,b)
386−splitV sizeFunD focD wA wB = do
387− sz <- displaySize
388− let regA = (\f (w,h) -> Region 0 0 w (f h)) <$> sizeFunD <*> sz
389− regB = (\(w,h) (Region _ _ _ hA) -> Region 0 hA w (h - hA)) <$> sz <*> regA
390− ra <- pane regA (fst <$> focD) wA
391− rb <- pane regB (snd <$> focD) wB
392− return (ra,rb)
393−
394−-- | A split of the available space into two parts with a draggable separator.
395−-- Starts with half the space allocated to each, and the first pane has focus.
396−-- Clicking in a pane switches focus.
397−splitVDrag :: (Reflex t, MonadFix m, MonadHold t m)
398− => VtyWidget t m ()
399− -> VtyWidget t m a
400− -> VtyWidget t m b
401− -> VtyWidget t m (a,b)
402−splitVDrag wS wA wB = do
403− sz <- displaySize
404− (_, h0) <- sample $ current sz
405− dragE <- drag V.BLeft
406− let splitter0 = h0 `div` 2
407− rec splitterCheckpoint <- holdDyn splitter0 $ leftmost [fst <$> ffilter snd dragSplitter, resizeSplitter]
408− splitterPos <- holdDyn splitter0 $ leftmost [fst <$> dragSplitter, resizeSplitter]
409− splitterFrac <- holdDyn ((1::Double) / 2) $ ffor (attach (current sz) (fst <$> dragSplitter)) $ \((_,h),x) ->
410− fromIntegral x / fromIntegral h
411− let dragSplitter = fforMaybe (attach (current splitterCheckpoint) dragE) $
412− \(splitterY, Drag (_, fromY) (_, toY) _ _ end) ->
413− if splitterY == fromY then Just (toY, end) else Nothing
414− regA = (\(w,_) sp -> Region 0 0 w sp) <$> sz <*> splitterPos
415− regS = (\(w,_) sp -> Region 0 sp w 1) <$> sz <*> splitterPos
416− regB = (\(w,h) sp -> Region 0 (sp + 1) w (h - sp - 1)) <$> sz <*> splitterPos
417− resizeSplitter = ffor (attach (current splitterFrac) (updated sz)) $
418− \(frac, (_,h)) -> round (frac * fromIntegral h)
419− focA <- holdDyn True $ leftmost
420− [ True <$ mA
421− , False <$ mB
422− ]
423− (mA, rA) <- pane regA focA $ withMouseDown wA
424− pane regS (pure False) wS
425− (mB, rB) <- pane regB (not <$> focA) $ withMouseDown wB
426− return (rA, rB)
427− where
428− withMouseDown x = do
429− m <- mouseDown V.BLeft
430− x' <- x
431− return (m, x')
432−
433−-- | Fill the background with a particular character.
434−fill :: (Reflex t, Monad m) => Char -> VtyWidget t m ()
435−fill c = do
436− sz <- displaySize
437− let fillImg = ffor (current sz) $ \(w,h) -> [V.charFill V.defAttr c w h]
438− tellImages fillImg
439−
440−-- | Fill the background with the bottom
441−hRule :: (Reflex t, Monad m) => BoxStyle -> VtyWidget t m ()
442−hRule boxStyle = fill (_boxStyle_s boxStyle)
443−
444−-- | Transform the images produces by a widget
445−modifyImages
446− :: (Reflex t, MonadHold t m, MonadFix m)
447− => Behavior t ([Image] -> [Image])
448− -> VtyWidget t m a
449− -> VtyWidget t m a
450−modifyImages f (VtyWidget w) = VtyWidget $ flip censor w $ \wo ->
451− wo { _vtyWidgetOut_images = f <*> (_vtyWidgetOut_images wo) }
452−
453−-- | Defines a set of symbols to use to draw the outlines of boxes
454−-- C.f. https://en.wikipedia.org/wiki/Box-drawing_character
455−data BoxStyle = BoxStyle
456− { _boxStyle_nw :: Char
457− , _boxStyle_n :: Char
458− , _boxStyle_ne :: Char
459− , _boxStyle_e :: Char
460− , _boxStyle_se :: Char
461− , _boxStyle_s :: Char
462− , _boxStyle_sw :: Char
463− , _boxStyle_w :: Char
464− }
465−
466−instance Default BoxStyle where
467− def = singleBoxStyle
468−
469−-- | A box style that uses hyphens and pipe characters. Doesn't handle
470−-- corners very well.
471−hyphenBoxStyle :: BoxStyle
472−hyphenBoxStyle = BoxStyle '-' '-' '-' '|' '-' '-' '-' '|'
473−
474−-- | A single line box style
475−singleBoxStyle :: BoxStyle
476−singleBoxStyle = BoxStyle '┌' '─' '┐' '│' '┘' '─' '└' '│'
477−
478−-- | A thick single line box style
479−thickBoxStyle :: BoxStyle
480−thickBoxStyle = BoxStyle '┏' '━' '┓' '┃' '┛' '━' '┗' '┃'
481−
482−-- | A double line box style
483−doubleBoxStyle :: BoxStyle
484−doubleBoxStyle = BoxStyle '╔' '═' '╗' '║' '╝' '═' '╚' '║'
485−
486−-- | A single line box style with rounded corners
487−roundedBoxStyle :: BoxStyle
488−roundedBoxStyle = BoxStyle '╭' '─' '╮' '│' '╯' '─' '╰' '│'
489−
490−-- | Draws a box in the provided style and a child widget inside of that box
491−box :: (Monad m, Reflex t)
492− => BoxStyle
493− -> VtyWidget t m a
494− -> VtyWidget t m a
495−box style child = do
496− sz <- displaySize
497− let boxReg = ffor (current sz) $ \(w,h) -> Region 0 0 w h
498− innerReg = ffor sz $ \(w,h) -> Region 1 1 (w - 2) (h - 2)
499− tellImages (fmap boxImages boxReg)
500− tellImages (fmap (\r -> [regionBlankImage r]) (current innerReg))
501− pane innerReg (pure True) child
502− where
503− boxImages :: Region -> [Image]
504− boxImages (Region left top width height) =
505− let right = left + width - 1
506− bottom = top + height - 1
507− sides =
508− [ withinImage (Region (left + 1) top (width - 2) 1) $
509− V.charFill V.defAttr (_boxStyle_n style) (width - 2) 1
510− , withinImage (Region right (top + 1) 1 (height - 2)) $
511− V.charFill V.defAttr (_boxStyle_e style) 1 (height - 2)
512− , withinImage (Region (left + 1) bottom (width - 2) 1) $
513− V.charFill V.defAttr (_boxStyle_s style) (width - 2) 1
514− , withinImage (Region left (top + 1) 1 (height - 2)) $
515− V.charFill V.defAttr (_boxStyle_w style) 1 (height - 2)
516− ]
517− corners =
518− [ withinImage (Region left top 1 1) $
519− V.char V.defAttr (_boxStyle_nw style)
520− , withinImage (Region right top 1 1) $
521− V.char V.defAttr (_boxStyle_ne style)
522− , withinImage (Region right bottom 1 1) $
523− V.char V.defAttr (_boxStyle_se style)
524− , withinImage (Region left bottom 1 1) $
525− V.char V.defAttr (_boxStyle_sw style)
526− ]
527− in sides ++ if width > 1 && height > 1 then corners else []
528−
529−-- | Renders text, wrapped to the container width
530−text
531− :: (Reflex t, Monad m)
532− => Behavior t Text
533− -> VtyWidget t m ()
534−text msg = do
535− dw <- displayWidth
536− let img = (\w s -> [wrapText w V.defAttr s]) <$> current dw <*> msg
537− tellImages img
538− where
539− wrapText maxWidth attrs = V.vertCat
540− . concatMap (fmap (V.string attrs . T.unpack) . TZ.wrapWithOffset maxWidth 0)
541− . T.split (=='\n')
542−
543−-- | Renders any behavior whose value can be converted to
544−-- 'String' as text
545−display
546− :: (Reflex t, Monad m, Show a)
547− => Behavior t a
548− -> VtyWidget t m ()
549−display a = text $ T.pack . show <$> a
550−
551−
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 ()