GTK_Chart.hs

module Main where

import Graphics.Rendering.Chart.Easy
import Graphics.Rendering.Chart.Gtk 
import qualified Graphics.UI.Gtk as G
import qualified Graphics.Rendering.Cairo as C
import qualified Graphics.UI.Gtk.Gdk.Events as GE


import Graphics.Rendering.Chart.Renderable
import Graphics.Rendering.Chart.Geometry
import Graphics.Rendering.Chart.Drawing
import Graphics.Rendering.Chart.Backend.Cairo

import Data.IORef
import Control.Monad(when)
import System.IO.Unsafe(unsafePerformIO)


-- Yuck. But we really want the convenience function
-- renderableToWindow as to be callable without requiring
-- initGUI to be called first. But newer versions of
-- gtk insist that initGUI is only called once
guiInitVar :: IORef Bool
{-# NOINLINE guiInitVar #-}
guiInitVar = unsafePerformIO (newIORef False)

initGuiOnce :: IO ()
initGuiOnce = do
    v <- readIORef guiInitVar
    when (not v) $ do
        -- G.initGUI
        G.unsafeInitGUIForThreadedRTS
        writeIORef guiInitVar True

linechart list = toRenderable layout
  where
    lineplot = plot_lines_values .~ list
              $ plot_lines_style  . line_color .~ opaque blue
              $ plot_lines_title .~ "Plot"
              $ def

    layout = layout_title .~ "Amplitude Modulation"
           $ layout_plots .~ [toPlot lineplot]
           $ def

func :: Double -> Double
func x = (sin (x*3.14159/45) + 1) / 2 * (sin (x*3.14159/5))

createWindowAndCanvas :: Renderable a -> Int -> Int -> IO (G.Window, G.DrawingArea)
createWindowAndCanvas chart windowWidth windowHeight = do
  window <- G.windowNew
  canvas <- G.drawingAreaNew
  G.widgetSetSizeRequest window windowWidth windowHeight
  G.onExpose canvas $ const (updateCanvas chart canvas)
  G.set window [G.containerChild G.:= canvas]
  return (window, canvas)

getSerialDataAndUpdateCanvas :: G.DrawingArea ->IO(Bool)
getSerialDataAndUpdateCanvas canvas = do
  -- I Thought that here, i could do the fetching of the data from
  -- the UART/Serialport and then give the data to "x"
  umpdateCanvas (linechart [[ (x, func x) | x <- [0,0.5 .. 40.0 ]]]) canvas 
  return True

umpdateCanvas :: Renderable a -> G.DrawingArea  -> IO Bool
umpdateCanvas chart canvas = do
  win <- G.widgetGetDrawWindow canvas
  (width, height) <- G.widgetGetSize canvas
  regio <- G.regionRectangle $ GE.Rectangle 0 0 width height
  let sz = (fromIntegral width, fromIntegral height)
  G.drawWindowBeginPaintRegion win regio
  G.renderWithDrawable win $ runBackend (defaultEnv bitmapAlignmentFns) (render chart sz) 
  G.drawWindowEndPaint win
  return True

main :: IO ()
main = do
  let emptyList = [[]] :: [[(Double, Double)]]
      emptyChart = linechart emptyList

  initGuiOnce

  (window, canvas) <- createWindowAndCanvas emptyChart 400 400
  G.set window [G.containerChild G.:= canvas]
  
  window `G.on` G.keyPressEvent $ do
    C.liftIO (G.widgetDestroy window)
    return True

  window `G.on` G.objectDestroy $ G.mainQuit

  -- Calls function with the timeout in ms
  G.timeoutAdd (getSerialDataAndUpdateCanvas canvas) 20
  
  G.widgetShowAll window
  G.mainGUI