mirror of
https://github.com/jtdaugherty/brick.git
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fc8cfe3b4a
This change makes it possible for brick to extent the event space using its own event notions in addition those provided by Vty and the application itself. This means we no longer need the user to provide the type and appLiftVtyEvent went away. This makes pattern-matching in event handlers a little noisier with the benefit that we can now add events like mouse clicks or drags to the event type.
81 lines
2.5 KiB
Haskell
81 lines
2.5 KiB
Haskell
{-# LANGUAGE OverloadedStrings #-}
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module Main where
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#if !MIN_VERSION_base(4,8,0)
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import Control.Applicative
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#endif
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import Control.Monad (void)
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import Data.Monoid ((<>))
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import qualified Graphics.Vty as V
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import qualified Brick.Types as T
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import qualified Brick.Main as M
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import qualified Brick.Widgets.Center as C
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import Brick.Types
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( Widget
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, BrickEvent(..)
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)
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import Brick.Widgets.Core
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( vBox
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, padTopBottom
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, withDefAttr
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, cached
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, padBottom
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, str
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)
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import Brick (on)
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import Brick.Widgets.Center
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( hCenter
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)
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import Brick.AttrMap
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( AttrName
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, attrMap
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)
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data Name = ExpensiveWidget
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deriving (Ord, Show, Eq)
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drawUi :: Int -> [Widget Name]
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drawUi i = [ui]
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where
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ui = C.vCenter $
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vBox $ hCenter <$>
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[ str "This demo shows how cached widgets behave. The top widget below"
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, str "is cacheable, so once it's rendered, brick re-uses the rendering"
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, str "each time it is drawn. The bottom widget is not cacheable so it is"
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, str "drawn on every request. Brick supports cache invalidation to force"
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, str "a redraw of cached widgets; we can trigger that here with 'i'. Notice"
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, str "how state changes with '+' aren't reflected in the cached widget"
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, str "until the cache is invalidated with 'i'."
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, padTopBottom 1 $
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cached ExpensiveWidget $
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withDefAttr emphAttr $ str $ "This widget is cached (state = " <> show i <> ")"
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, padBottom (T.Pad 1) $
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withDefAttr emphAttr $ str $ "This widget is not cached (state = " <> show i <> ")"
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, hCenter $ str "Press 'i' to invalidate the cache,"
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, str "'+' to change the state value, and"
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, str "'Esc' to quit."
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]
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appEvent :: Int -> BrickEvent Name e -> T.EventM Name (T.Next Int)
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appEvent i (VtyEvent (V.EvKey (V.KChar '+') [])) = M.continue $ i + 1
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appEvent i (VtyEvent (V.EvKey (V.KChar 'i') [])) = M.invalidateCacheEntry ExpensiveWidget >> M.continue i
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appEvent i (VtyEvent (V.EvKey V.KEsc [])) = M.halt i
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appEvent i _ = M.continue i
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emphAttr :: AttrName
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emphAttr = "emphasis"
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app :: M.App Int e Name
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app =
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M.App { M.appDraw = drawUi
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, M.appStartEvent = return
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, M.appHandleEvent = appEvent
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, M.appAttrMap = const $ attrMap V.defAttr [(emphAttr, V.white `on` V.blue)]
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, M.appChooseCursor = M.neverShowCursor
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}
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main :: IO ()
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main = void $ M.defaultMain app 0
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