Shine - Declarative Graphics for the Web
Shine wraps javascript's drawing functions in a declarative API.
Heavily inspired by gloss.
demo (compiled tests) here
Compiling
You need ghcjs
A great way of building ghcjs packages is to use the reflex platform
Usage
Pictures
To represent your drawing you have to build a tree using the Picture datatype.
pic :: Picture
pic = Rect 10 20 -- represents a 10x20 squareTo compose multiple Pictures you can use Over, which accepts two Pictures
and overlaps them.
Picture is a monoid: <> is an alias for Over and mempty is the empty picture.
-- draw some shapes on top of each other
pic :: Picture
pic = Rect 10 20
<> Translate 30 30 (Circle 15)
<> Colored (Color 255 0 0 0.2) (RectF 4 4)
<> Text "Sans 12px" LeftAlign 200 "The quick brown fox jumps over the lazy dog."Using Foldable you can do things like
concentricCircles :: Picture
concentricCircles = foldMap Circle [1,10..100]
Drawing Pictures
Before drawing anything you need to obtain a CanvasRenderingContext2D (and sometimes a Document).
For this purpose, shine provides two utility functions: fullScreenCanvas and fixedSizeCanvas
{-# LANGUAGE CPP #-}
import Graphics.Shine
import Graphics.Shine.Input
import Graphics.Shine.Picture
import GHCJS.DOM (currentDocumentUnchecked)
-- This is how the ghcjs-dom hello-world does it.
-- It's boilerplate, so in the next shine version there
-- will probably be a ready-to-use run function
#if defined(ghcjs_HOST_OS)
run :: a -> a
run = id
#elif defined(MIN_VERSION_jsaddle_wkwebview)
import Language.Javascript.JSaddle.WKWebView (run)
#else
import Language.Javascript.JSaddle.WebKitGTK (run)
#endif
main :: IO ()
main = run $ do
doc <- currentDocumentUnchecked -- use currentDocument to handle failure
ctx <- fixedSizeCanvas doc 400 400
-- do something with ctx (and maybe doc)To render a Picture on a context you have three options:
render
You can draw it manually using render from Graphics.Shine.Render
main :: IO ()
{- get the context, see before -}
draw ctx concentricCircles
animate
You can draw a Picture that depends on time. That is, a Float -> Picture.
-- An expanding-and-contracting circle.
animation :: Float -> Picture
animation = Translate 200 200
. Circle
. (*100) . (+1) -- bigger positive oscillation
. sin -- the circle's radius oscillates
main :: IO ()
main = do
{- get the context, see before -}
animate ctx 30 animation
play
Finally, you can draw a Picture that depends on time, inputs
(keyboard and mouse) and an internal state. This is especially useful for games,
hence the name.
-- this code draws a black rectangle in the center of the canvas only when the
-- left mouse button is pressed
main :: IO ()
main = do
{- get the context and the document, see before -}
play ctx doc 30 initialState draw handleInput step
where
-- our state represents the state of the left mouse button
initialState = Up
-- we draw a square only if the button is pressed
draw Up = Empty
draw Down = Translate 200 200 $ RectF 200 200
-- when an event is fired we store the button state
handleInput (MouseBtn BtnLeft buttonState _) = const buttonState
handleInput _ = id -- catch-all for all other events
step _ = id -- our state does not depend on time
