{-# LANGUAGE PatternGuards #-}
{-| Simple picture drawing application.
Like MSPaint, but you can only draw lines.
-}
module Main where
import Brillo
import Brillo.Interface.Pure.Game
main :: IO ()
main =
do
let state = State Nothing []
play
(InWindow "Draw" (600, 600) (0, 0))
white
100
state
makePicture
handleEvent
stepWorld
-- | The game state.
data State
= State
(Maybe Path) -- The current line being drawn.
[Picture] -- All the lines drawn previously.
-- | A Line Segment
type Segment = ((Float, Float), (Float, Float))
-- | Convert our state to a picture.
makePicture :: State -> Picture
makePicture (State m xs) =
Pictures (maybe xs (\x -> Line x : xs) m)
-- | Handle mouse click and motion events.
handleEvent :: Event -> State -> State
handleEvent event state
-- If the mouse has moved, then extend the current line.
| EventMotion (x, y) <- event
, State (Just ps) ss <- state =
State (Just ((x, y) : ps)) ss
-- Start drawing a new line.
| EventKey (MouseButton LeftButton) Down _ pt@(x, y) <- event
, State Nothing ss <- state =
State
(Just [pt])
((Translate x y $ Scale 0.1 0.1 $ Text "Down") : ss)
-- Finish drawing a line, and add it to the picture.
| EventKey (MouseButton LeftButton) Up _ pt@(x, y) <- event
, State (Just ps) ss <- state =
State
Nothing
((Translate x y $ Scale 0.1 0.1 $ Text "up") : Line (pt : ps) : ss)
| otherwise =
state
stepWorld :: Float -> State -> State
stepWorld _ = id