module Hbro.Gtk.ScrolledWindow where
import Hbro.Util
import Hbro.Types
import Control.Monad.IO.Class
import Control.Monad.Reader
import Graphics.UI.Gtk.Misc.Adjustment
import Graphics.UI.Gtk.Scrolling.ScrolledWindow
getAdjustment :: (MonadIO m) => Axis -> ScrolledWindow -> m Adjustment
getAdjustment Horizontal = io . scrolledWindowGetHAdjustment
getAdjustment Vertical = io . scrolledWindowGetVAdjustment
scroll' :: (MonadIO m) => Axis -> Position -> ScrolledWindow -> m ()
scroll' axis percentage scrollWindow = io $ do
adj <- io . getAdjustment axis $ scrollWindow
page <- io $ adjustmentGetPageSize adj
current <- io $ adjustmentGetValue adj
lower <- io $ adjustmentGetLower adj
upper <- io $ adjustmentGetUpper adj
let shift (Absolute x) = lower + x/100 * (upper page lower)
shift (Relative x) = current + x/100 * page
limit x = (x `max` lower) `min` (upper page)
io $ adjustmentSetValue adj $ limit (shift percentage)
scroll :: (MonadIO m, MonadReader r m, HasScrollWindow r) => Axis -> Position -> m ()
scroll axis percentage = scroll' axis percentage =<< asks _scrollwindow