Image.hs

{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE TypeSynonymInstances #-}

{-# OPTIONS_GHC -fno-warn-orphans #-}

module IHaskell.Display.Widgets.Image
  ( -- * The Image Widget
    ImageWidget
    -- * Constructor
  , mkImageWidget
  ) where

-- To keep `cabal repl` happy when running from the ihaskell repo
import           Prelude

import           Data.Aeson
import           Data.IORef (newIORef)
import           Data.Monoid (mempty)
import           Data.Vinyl (Rec(..), (<+>))

import           IHaskell.Display
import           IHaskell.Eval.Widgets
import           IHaskell.IPython.Message.UUID as U

import           IHaskell.Display.Widgets.Types
import           IHaskell.Display.Widgets.Common

-- | An 'ImageWidget' represents a Image widget from IPython.html.widgets.
type ImageWidget = IPythonWidget 'ImageType

-- | Create a new image widget
mkImageWidget :: IO ImageWidget
mkImageWidget = do
  -- Default properties, with a random uuid
  wid <- U.random

  let dom = defaultDOMWidget "ImageView" "ImageModel"
      img = (ImageFormat =:: PNG)
            :& (Width =:+ 0)
            :& (Height =:+ 0)
            :& (B64Value =:: mempty)
            :& RNil
      widgetState = WidgetState (dom <+> img)

  stateIO <- newIORef widgetState

  let widget = IPythonWidget wid stateIO

  -- Open a comm for this widget, and store it in the kernel state
  widgetSendOpen widget $ toJSON widgetState

  -- Return the image widget
  return widget

instance IHaskellDisplay ImageWidget where
  display b = do
    widgetSendView b
    return $ Display []

instance IHaskellWidget ImageWidget where
  getCommUUID = uuid