brick/programs/ListViDemo.hs
Jonathan Daugherty bd89f787d2 Support GHC 8.4 (fixes #162)
This change splits up Monoid instances into Monoid and Semigroup. It
also conditionally imports Data.Monoid on GHCs prior to 8.4.
2018-03-17 09:03:59 -07:00

94 lines
3.0 KiB
Haskell

{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE CPP #-}
module Main where
import Control.Monad (void)
import Data.Maybe (fromMaybe)
#if !(MIN_VERSION_base(4,11,0))
import Data.Monoid
#endif
import qualified Graphics.Vty as V
import Lens.Micro ((^.))
import qualified Brick.AttrMap as A
import qualified Brick.Main as M
import Brick.Types (Widget)
import qualified Brick.Types as T
import Brick.Util (fg, on)
import qualified Brick.Widgets.Border as B
import qualified Brick.Widgets.Center as C
import Brick.Widgets.Core (hLimit, str, vBox, vLimit, withAttr, (<+>))
import qualified Brick.Widgets.List as L
import qualified Data.Vector as Vec
drawUI :: (Show a) => L.List () a -> [Widget ()]
drawUI l = [ui]
where
label = str "Item " <+> cur <+> str " of " <+> total
cur = case l^.(L.listSelectedL) of
Nothing -> str "-"
Just i -> str (show (i + 1))
total = str $ show $ Vec.length $ l^.(L.listElementsL)
box = B.borderWithLabel label $
hLimit 25 $
vLimit 15 $
L.renderList listDrawElement True l
ui = C.vCenter $ vBox [ C.hCenter box
, str " "
, C.hCenter $ str "Press +/- to add/remove list elements."
, C.hCenter $ str "Press Esc to exit."
]
appEvent :: L.List () Char -> T.BrickEvent () e -> T.EventM () (T.Next (L.List () Char))
appEvent l (T.VtyEvent e) =
case e of
V.EvKey (V.KChar '+') [] ->
let el = nextElement (L.listElements l)
pos = Vec.length $ l^.(L.listElementsL)
in M.continue $ L.listInsert pos el l
V.EvKey (V.KChar '-') [] ->
case l^.(L.listSelectedL) of
Nothing -> M.continue l
Just i -> M.continue $ L.listRemove i l
V.EvKey V.KEsc [] -> M.halt l
ev -> M.continue =<< (L.handleListEventVi L.handleListEvent) ev l
where
nextElement :: Vec.Vector Char -> Char
nextElement v = fromMaybe '?' $ Vec.find (flip Vec.notElem v) (Vec.fromList ['a' .. 'z'])
appEvent l _ = M.continue l
listDrawElement :: (Show a) => Bool -> a -> Widget ()
listDrawElement sel a =
let selStr s = if sel
then withAttr customAttr (str $ "<" <> s <> ">")
else str s
in C.hCenter $ str "Item " <+> (selStr $ show a)
initialState :: L.List () Char
initialState = L.list () (Vec.fromList ['a','b','c']) 1
customAttr :: A.AttrName
customAttr = L.listSelectedAttr <> "custom"
theMap :: A.AttrMap
theMap = A.attrMap V.defAttr
[ (L.listAttr, V.white `on` V.blue)
, (L.listSelectedAttr, V.blue `on` V.white)
, (customAttr, fg V.cyan)
]
theApp :: M.App (L.List () Char) e ()
theApp =
M.App { M.appDraw = drawUI
, M.appChooseCursor = M.showFirstCursor
, M.appHandleEvent = appEvent
, M.appStartEvent = return
, M.appAttrMap = const theMap
}
main :: IO ()
main = void $ M.defaultMain theApp initialState