ui: C-z suspend now restores the terminal cleanly

hledger-ui/Hledger/UI/AccountsScreen.hs

@@ -278,7 +278,7 @@ asHandle ui0@UIState{
         VtyEvent (EvKey KEnter []) -> continue $ regenerateScreens j d $ setFilter s $ closeMinibuffer ui
                             where s = chomp $ unlines $ map strip $ getEditContents ed
         VtyEvent (EvKey (KChar 'l') [MCtrl]) -> redraw ui
-        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspendAndRedraw ui
+        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
         VtyEvent ev        -> do ed' <- handleEditorEvent ev ed
                                  continue $ ui{aMode=Minibuffer ed'}
         AppEvent _        -> continue ui
@@ -289,7 +289,7 @@ asHandle ui0@UIState{
       case ev of
         VtyEvent (EvKey (KChar 'q') []) -> halt ui
         VtyEvent (EvKey (KChar 'l') [MCtrl]) -> redraw ui
-        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspendAndRedraw ui
+        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
         _                    -> helpHandle ui ev
 
     Normal ->
@@ -343,7 +343,7 @@ asHandle ui0@UIState{
         VtyEvent (EvKey k           []) | k `elem` [KBS, KDel] -> (continue $ regenerateScreens j d $ resetFilter ui)
         VtyEvent e | e `elem` moveLeftEvents -> continue $ popScreen ui
         VtyEvent (EvKey (KChar 'l') [MCtrl]) -> scrollSelectionToMiddle _asList >> redraw ui
-        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspendAndRedraw ui
+        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
 
         -- enter register screen for selected account (if there is one), 
         -- centering its selected transaction if possible

hledger-ui/Hledger/UI/ErrorScreen.hs

@@ -86,7 +86,7 @@ esHandle ui@UIState{aScreen=ErrorScreen{..}
       case ev of
         VtyEvent (EvKey (KChar 'q') []) -> halt ui
         VtyEvent (EvKey (KChar 'l') [MCtrl]) -> redraw ui
-        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspendAndRedraw ui
+        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
         _                    -> helpHandle ui ev
 
     _ -> do
@@ -108,7 +108,7 @@ esHandle ui@UIState{aScreen=ErrorScreen{..}
 --             Right j' -> continue $ regenerateScreens j' d $ popScreen ui  -- return to previous screen, and reload it
         VtyEvent (EvKey (KChar 'I') []) -> continue $ uiCheckBalanceAssertions d (popScreen $ toggleIgnoreBalanceAssertions ui)
         VtyEvent (EvKey (KChar 'l') [MCtrl]) -> redraw ui
-        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspendAndRedraw ui
+        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
         _ -> continue ui
 
 esHandle _ _ = error "event handler called with wrong screen type, should not happen"

hledger-ui/Hledger/UI/RegisterScreen.hs

@@ -282,7 +282,7 @@ rsHandle ui@UIState{
         VtyEvent (EvKey KEnter []) -> continue $ regenerateScreens j d $ setFilter s $ closeMinibuffer ui
                             where s = chomp $ unlines $ map strip $ getEditContents ed
         VtyEvent (EvKey (KChar 'l') [MCtrl]) -> redraw ui
-        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspendAndRedraw ui
+        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
         VtyEvent ev              -> do ed' <- handleEditorEvent ev ed
                                        continue $ ui{aMode=Minibuffer ed'}
         AppEvent _        -> continue ui
@@ -293,7 +293,7 @@ rsHandle ui@UIState{
       case ev of
         VtyEvent (EvKey (KChar 'q') []) -> halt ui
         VtyEvent (EvKey (KChar 'l') [MCtrl]) -> redraw ui
-        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspendAndRedraw ui
+        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
         _                    -> helpHandle ui ev
 
     Normal ->
@@ -338,7 +338,7 @@ rsHandle ui@UIState{
         VtyEvent (EvKey k           []) | k `elem` [KBS, KDel] -> (continue $ regenerateScreens j d $ resetFilter ui)
         VtyEvent e | e `elem` moveLeftEvents  -> continue $ popScreen ui
         VtyEvent (EvKey (KChar 'l') [MCtrl]) -> scrollSelectionToMiddle rsList >> redraw ui
-        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspendAndRedraw ui
+        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
 
         -- enter transaction screen for selected transaction
         VtyEvent e | e `elem` moveRightEvents -> do

hledger-ui/Hledger/UI/TransactionScreen.hs

@@ -120,7 +120,7 @@ tsHandle ui@UIState{aScreen=s@TransactionScreen{tsTransaction=(i,t)
       case ev of
         VtyEvent (EvKey (KChar 'q') []) -> halt ui
         VtyEvent (EvKey (KChar 'l') [MCtrl]) -> redraw ui
-        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspendAndRedraw ui
+        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
         _                    -> helpHandle ui ev
 
     _ -> do
@@ -181,7 +181,7 @@ tsHandle ui@UIState{aScreen=s@TransactionScreen{tsTransaction=(i,t)
             ui'@UIState{aScreen=scr} = popScreen ui
             ui'' = ui'{aScreen=rsSelect (fromIntegral i) scr}
         VtyEvent (EvKey (KChar 'l') [MCtrl]) -> redraw ui
-        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspendAndRedraw ui
+        VtyEvent (EvKey (KChar 'z') [MCtrl]) -> suspend ui
         _ -> continue ui
 
 tsHandle _ _ = error "event handler called with wrong screen type, should not happen"

hledger-ui/Hledger/UI/UIUtils.hs

@@ -22,7 +22,6 @@ module Hledger.UI.UIUtils (
   ,replaceHiddenAccountsNameWith
   ,scrollSelectionToMiddle
   ,suspend
-  ,suspendAndRedraw
   ,redraw
 )
 where
@@ -52,39 +51,27 @@ import Hledger.Cli.DocFiles
 import Hledger.UI.UITypes
 import Hledger.UI.UIState
 
--- | On posix platforms, suspend the program using the system STOP signal
+-- | On posix platforms, send the system STOP signal to suspend the
--- (as control-z usually does in bash). On windows, does nothing.
+-- current program. On windows, does nothing.
 #ifdef mingw32_HOST_OS
-suspend :: IO ()
+suspendSignal :: IO ()
-suspend = return ()
+suspendSignal = return ()
 #else
 import System.Posix.Signals
-suspend :: IO ()
+suspendSignal :: IO ()
-suspend = raiseSignal sigSTOP 
+suspendSignal = raiseSignal sigSTOP 
 #endif
 
--- | On posix platforms, suspend the program using the system STOP
+-- | On posix platforms, suspend the program using the STOP signal,
--- signal, returning to the original shell prompt
+-- like control-z in bash, returning to the original shell prompt,
--- (TODO: and restore the original terminal attributes).
+-- and when resumed, continue where we left off.
--- When the program is resumed, redraw the screen and continue.
+-- On windows, does nothing.
--- On windows, just redraws the screen.
+suspend :: s -> EventM a (Next s)
-suspendAndRedraw :: s -> EventM a (Next s)
+suspend st = suspendAndResume $ suspendSignal >> return st
-suspendAndRedraw ui = do
-  -- reset terminal attributes using vty ?
-  -- Vty{outputIface=output} <- getVtyHandle
-  -- r <- displayBounds output
-  -- DisplayContext{writeDefaultAttr=_reset} <- liftIO $ (mkDisplayContext output) output r
-  -- runWrite (reset True) _someptr
-
-  -- suspend..
-  liftIO suspend
-
-  -- ..and resume
-  redraw ui
 
 -- | Tell vty to redraw the whole screen, and continue.
 redraw :: s -> EventM a (Next s)
-redraw ui = getVtyHandle >>= liftIO . refresh >> continue ui
+redraw st = getVtyHandle >>= liftIO . refresh >> continue st
 
 -- ui