Graphics.Blank

Starting blank-canvas

blankCanvas :: Int -> (Context -> IO ()) -> IO ()

blankCanvas is the main entry point into blank-canvas. A typical invocation would be

module Main where

import Graphics.Blank

main = blankCanvas 3000 $ \ context -> do
        send context $ do
                moveTo(50,50)
                lineTo(200,100)
                lineWidth 10
                strokeStyle "red"
                stroke()

launch single-canvas app on specified port

blankCanvasMany :: Int -> [(String, Context -> IO ())] -> IO ()

launch multiple canvas apps, each with a prefix, like `/myprefix/foo/bar`

blankCanvasManyParams :: Int -> [(String, Context -> IO ())] -> FilePath -> Bool -> IO ()

as blankCanvasMany but takes customization parameters dataDir and performLogging

blankCanvasParams :: Int -> (Context -> IO ()) -> FilePath -> Bool -> String -> IO ()

as blankCanvas but takes customization parameters dataDir and performLogging

blankCanvasParamsScotty :: (Context -> IO ()) -> FilePath -> Bool -> String -> IO (ScottyM ())

parametrised version of blankCanvas, also returns ScottyM application instead of running a server. use scotty to run it.

Graphics Context

data Context

Context is our abstact handle into a specific 2d-context inside a browser.

send :: Context -> Canvas a -> IO a

Sends a set of Canvas commands to the canvas. Attempts to common up as many commands as possible.

events :: Context -> EventName -> IO EventQueue

events gets the raw event queue for a specific event type.

Drawing pictures using the Canvas DSL

data Canvas

Instances

Monad Canvas

Functor Canvas

Applicative Canvas

arc :: (Float, Float, Float, Float, Float, Bool) -> Canvas ()

see http://www.w3schools.com/tags/canvas_arc.asp

beginPath :: Canvas ()

see http://www.w3schools.com/tags/canvas_beginpath.asp

bezierCurveTo :: (Float, Float, Float, Float, Float, Float) -> Canvas ()

see http://www.w3schools.com/tags/canvas_beziercurveto.asp

clearRect :: (Float, Float, Float, Float) -> Canvas ()

see http://www.w3schools.com/tags/canvas_clearrect.asp

closePath :: Canvas ()

see http://www.w3schools.com/tags/canvas_closepath.asp

custom :: String -> Canvas ()

sends command (JS) unchanged. useful for extending this library with functionality it doesn't currently have. example:

 custom $ unlines $ [
       "var grd=c.createRadialGradient(0,0,3,20,20,10); "
      ,"grd.addColorStop(0,\"white\");"
      ,"grd.addColorStop(1,\"red\");"
      ,"c.fillStyle=grd;"]

fill :: Canvas ()

see http://www.w3schools.com/tags/canvas_fill.asp

fillRect :: (Float, Float, Float, Float) -> Canvas ()

see http://www.w3schools.com/tags/canvas_fillrect.asp

fillStyle :: String -> Canvas ()

see http://www.w3schools.com/tags/canvas_fillstyle.asp

fillText :: (String, Float, Float) -> Canvas ()

see http://www.w3schools.com/tags/canvas_filltext.asp

font :: String -> Canvas ()

see http://www.w3schools.com/tags/canvas_font.asp

globalAlpha :: Float -> Canvas ()

see http://www.w3schools.com/tags/canvas_globalalpha.asp

lineCap :: String -> Canvas ()

see http://www.w3schools.com/tags/canvas_linecap.asp

lineJoin :: String -> Canvas ()

see http://www.w3schools.com/tags/canvas_linejoin.asp

lineTo :: (Float, Float) -> Canvas ()

see http://www.w3schools.com/tags/canvas_lineto.asp

lineWidth :: Float -> Canvas ()

see http://www.w3schools.com/tags/canvas_linewidth.asp

miterLimit :: Float -> Canvas ()

see http://www.w3schools.com/tags/canvas_miterlimit.asp

moveTo :: (Float, Float) -> Canvas ()

see http://www.w3schools.com/tags/canvas_moveto.asp

restore :: Canvas ()

see bottom of http://www.w3schools.com/tags/ref_canvas.asp

rotate :: Float -> Canvas ()

see http://www.w3schools.com/tags/canvas_rotate.asp

scale :: (Float, Float) -> Canvas ()

http://www.w3schools.com/tags/canvas_scale.asp

save :: Canvas ()

see bottom of http://www.w3schools.com/tags/ref_canvas.asp

stroke :: Canvas ()

see http://www.w3schools.com/tags/canvas_stroke.asp

strokeRect :: (Float, Float, Float, Float) -> Canvas ()

see http://www.w3schools.com/tags/canvas_strokerect.asp

strokeText :: (String, Float, Float) -> Canvas ()

see http://www.w3schools.com/tags/canvas_stroketext.asp

strokeStyle :: String -> Canvas ()

see http://www.w3schools.com/tags/canvas_strokestyle.asp

textAlign :: String -> Canvas ()

see http://www.w3schools.com/tags/canvas_textalign.asp

textBaseline :: String -> Canvas ()

see http://www.w3schools.com/tags/canvas_textbaseline.asp

transform :: (Float, Float, Float, Float, Float, Float) -> Canvas ()

see http://www.w3schools.com/tags/canvas_transform.asp

translate :: (Float, Float) -> Canvas ()

see http://www.w3schools.com/tags/canvas_translate.asp

readEvent :: EventName -> Canvas Event

read a specific event; wait for it if the event is not in queue.

tryReadEvent :: EventName -> Canvas (Maybe Event)

read a specific event; or return Nothing if the event is not in queue.

size :: Canvas (Float, Float)

size of the canvas

Events

data Event

Basic Event from Browser, the code is event-type specific.

Constructors

Event

Fields

jsCode :: Int

jsMouse :: Maybe (Int, Int)

Instances

Show Event

data EventName

EventName mirrors event names from jquery, where 'map toLower (show name)' gives the jquery event name.

Constructors

KeyPress

KeyDown

KeyUp

MouseDown

MouseEnter

MouseMove

MouseOut

MouseOver

MouseUp

Instances

Bounded EventName

Enum EventName

Eq EventName

Ord EventName

Show EventName

type EventQueue = TChan Event

EventQueue is a STM channel (TChan) of Events. Intentionally, EventQueue is not abstract.

readEventQueue :: EventQueue -> IO Event

tryReadEventQueue :: EventQueue -> IO (Maybe Event)