SneathLane

Widgets

data Widget z

Atom of a sneath lane application

Constructors

Finish z

Continue (Output (Widget z)) (Maybe (MouseOut (Widget z))) (Maybe (Animate (Widget z))) (WidgetFocus z)

Instances

Monad Widget

Functor Widget

Applicative Widget

data WidgetFocus z

Determines the focus behavior of the widget

Constructors

NotFocusable

Widget can not take keyboard focus

Focusable (Widget z) (Widget z)

Widget can take keyboard focus, but does not have it now

Focused (Widget z) (Widget z, Bool) (Widget z, Bool) (HandleKey (Widget z))

Widget has keyboard focus

zipW :: CombineGraphics ((Point, MouseButton) -> Widget z) -> Widget z -> Widget z -> Widget z

Combine two widgets to run in parallel as a single widget

Build Widgets

graphicWidget :: GraphicTree () -> Widget a

A widget which just shows a constant graphic output.

above :: Widget z -> Widget z -> Widget z

Combine two widgets one above the other

beside :: Widget z -> Widget z -> Widget z

Combine two widgets side by side

Run Widgets

runOnCanvas :: String -> Double -> Double -> (forall z. Widget z) -> IO ()

Run the widget on the canvas element with ID "canvas"

Graphics

data GraphicTree :: * -> * where

A tree of graphics, used as widget output type. FMap functions are stored in the tree instead of being mapped over the leaves, so that tree reconstruction is fast when a widget changes. This is why GraphicTree is a GADT.

Offset: a sub-tree translated by a point

Branch: Two sub-trees; graphicTreeBounds are cached for each

Leaf: A leaf, consisting of a single graphic element

FMap: A graphic tree composed with a function.

Constructors

Offset :: Point -> GraphicTree a -> GraphicTree a

Branch :: Rect -> GraphicTree a -> Rect -> GraphicTree a -> GraphicTree a

Leaf :: Graphic -> GraphicTree ()

FMap :: (a -> b) -> GraphicTree a -> GraphicTree b

Instances

Functor GraphicTree

graphicList :: [Graphic] -> GraphicTree ()

Construct a graphic tree from a nonempty list of graphics.

graphicTreeBounds :: GraphicTree a -> Rect

Find a rectangle containing the entire contents of the graphic tree

Events

data MouseButton

Which mouse button (if any) was being pressed

Constructors

NoButton

LeftButton

type Key = Int

Utility

balancedFold :: (a -> a -> a) -> [a] -> a

Apply a fold in a balanced fashion over a list. Recommended for combining lists of widgets, so that the widget tree has logarithmic depth.

Type synonyms

type Output a = GraphicTree ((Point, MouseButton) -> a)

type CombineGraphics a = GraphicTree a -> GraphicTree a -> GraphicTree a

type Animate a = TimeDifference -> a

type MouseOut a = a

type HandleKey a = Key -> a

type TimeDifference = Double