Scrolling - Store actual buffer lines displayed in a window.

In order for scrolling to work we have to differentiate between the height
of the window in display lines and the number of actual buffer lines
displayed in a window. This patch stores that information in a window.

src/Yi/Buffer/HighLevel.hs

@@ -388,7 +388,7 @@ pointScreenRelPosition p rs re
   | p < rs = Above
   | p > re = Below
 pointScreenRelPosition _ _ _ = Within -- just to disable the non-exhaustive pattern match warning
- 
+
 -- | Move the visible region to include the point
 snapScreenB :: BufferM Bool
 snapScreenB = do
@@ -397,12 +397,13 @@ snapScreenB = do
     if movePoint w then return False else do
         inWin <- pointInWindowB =<< pointB
         if inWin then return False else do
-            h <- askWindow height
+            h <- askWindow actualLines
+            --h <- askWindow height
             r <- winRegionB
             p <- pointB
             let gap = case pointScreenRelPosition p (regionStart r) (regionEnd r) of
                         Above  -> 0
-                        Below  -> h - 2
+                        Below  -> h - 1
                         Within -> 0 -- Impossible but handle it anyway
             i <- indexOfSolAbove gap
             f <- fromMark <$> askMarks
@@ -435,7 +436,7 @@ middleB = do
 pointInWindowB :: Point -> BufferM Bool
 pointInWindowB p = nearRegion p <$> winRegionB
 --  do w <- winRegionB;  trace ("pointInWindowB " ++ show w ++ " p = " ++ show p)
-
+          
 -----------------------------
 -- Region-related operations
 

src/Yi/Editor.hs

@@ -444,9 +444,13 @@ alternateBufferE n = do
       then fail "no alternate buffer"
       else switchToBufferE $ lst!!n
 
+-- | Create a new zero size window on a given buffer
+newZeroSizeWindow ::Bool -> BufferRef -> WindowRef -> Window
+newZeroSizeWindow mini bk ref = Window mini bk [] 0 emptyRegion ref 0
+
 -- | Create a new window onto the given buffer.
 newWindowE :: Bool -> BufferRef -> EditorM Window
-newWindowE mini bk = Window mini bk [] 0 emptyRegion <$> newRef
+newWindowE mini bk = newZeroSizeWindow mini bk <$> newRef
 
 -- | Attach the specified buffer to the current window
 switchToBufferE :: BufferRef -> EditorM ()

src/Yi/UI/Vty.hs

@@ -178,7 +178,8 @@ layout ui e = do
                            -- Discard this field, otherwise we keep retaining reference to
                            -- old Window objects (leak)
       apply win = win {
-          winRegion = getRegionImpl win (configUI $ config ui) e cols (height win)
+          winRegion   = getRegionImpl win (configUI $ config ui) e cols (height win)
+         ,actualLines = windowLinesDisp win (configUI $ config ui) e cols (height win) 
         }
 
   return $ windowsA ^= ws'' $ e
@@ -252,20 +253,25 @@ scanrT (+*+) k t = fst $ runState (mapM f t) k
                    put s'
                    return s
 
+windowLinesDisp :: Window -> UIConfig -> Editor -> Int -> Int -> Int
+windowLinesDisp win cfg e w h = dispCount
+  where (_,_,dispCount) = drawWindow cfg e (error "focus must not be used")  win w h
+
 getRegionImpl :: Window -> UIConfig -> Editor -> Int -> Int -> Region
-getRegionImpl win cfg e w h = snd $
-                              drawWindow cfg e (error "focus must not be used")  win w h
+getRegionImpl win cfg e w h = region
+  where (_,region,_) = drawWindow cfg e (error "focus must not be used")  win w h
 
 -- | Return a rendered wiew of the window.
 renderWindow :: UIConfig -> Editor -> Int -> (Window, Bool) -> Rendered
 renderWindow cfg e width (win,hasFocus) =
-    let (rendered,_) = drawWindow cfg e hasFocus win width (height win)
+    let (rendered,_,_) = drawWindow cfg e hasFocus win width (height win)
     in rendered
 
 -- | Draw a window
 -- TODO: horizontal scrolling.
-drawWindow :: UIConfig -> Editor -> Bool -> Window -> Int -> Int -> (Rendered, Region)
-drawWindow cfg e focused win w h = (Rendered { picture = pict,cursor = cur}, mkRegion fromMarkPoint toMarkPoint')
+-- TODO(jwall): Store display line counts so scrolling has all the necesary info
+drawWindow :: UIConfig -> Editor -> Bool -> Window -> Int -> Int -> (Rendered, Region, Int)
+drawWindow cfg e focused win w h = (Rendered { picture = pict,cursor = cur}, mkRegion fromMarkPoint toMarkPoint', dispLnCount)
     where
         b = findBufferWith (bufkey win) e
         sty = configStyle cfg
@@ -298,7 +304,7 @@ drawWindow cfg e focused win w h = (Rendered { picture = pict,cursor = cur}, mkR
         tabWidth = tabSize . fst $ runBuffer win b indentSettingsB
         prompt = if isMini win then miniIdentString b else ""
 
-        (rendered,toMarkPoint',cur) = drawText h' w
+        (rendered,toMarkPoint',cur,dispLnCount) = drawText h' w
                                 fromMarkPoint
                                 point 
                                 tabWidth
@@ -315,20 +321,23 @@ drawWindow cfg e focused win w h = (Rendered { picture = pict,cursor = cur}, mkR
 -- | Renders text in a rectangle.
 -- This also returns 
 -- * the index of the last character fitting in the rectangle
--- * the position of the Point in (x,y) coordinates, if in the window.
+-- * the position of the Point in (x,y) coordinates, if in the window,
+-- * the number of display lines for this drawing.
 drawText :: Int    -- ^ The height of the part of the window we are in
          -> Int    -- ^ The width of the part of the window we are in
          -> Point  -- ^ The position of the first character to draw
          -> Point  -- ^ The position of the cursor
          -> Int    -- ^ The number of spaces to represent a tab character with.
          -> [(Char,(Vty.Attr,Point))]  -- ^ The data to draw.
-         -> ([Image], Point, Maybe (Int,Int))
+         -> ([Image], Point, Maybe (Int,Int), Int)
 drawText h w topPoint point tabWidth bufData
-    | h == 0 || w == 0 = ([], topPoint, Nothing)
-    | otherwise        = (rendered_lines, bottomPoint, pntpos)
+    | h == 0 || w == 0 = ([], topPoint, Nothing, 0)
+    | otherwise        = (rendered_lines, bottomPoint, pntpos, h - (length wrapped - h))
   where 
 
-  lns0 = take h $ concatMap (wrapLine w) $ map (concatMap expandGraphic) $ take h $ lines' $ bufData
+  -- the actual lines to display, can get line count from here.
+  wrapped = concatMap (wrapLine w) $ map (concatMap expandGraphic) $ take h $ lines' $ bufData
+  lns0 = take h wrapped
 
   bottomPoint = case lns0 of 
                  [] -> topPoint 

src/Yi/Window.hs

@@ -21,18 +21,19 @@ data Window = Window {
                       isMini    :: !Bool   -- ^ regular or mini window?
                      ,bufkey    :: !BufferRef -- ^ the buffer this window opens to
                      ,bufAccessList :: ![BufferRef] -- ^ list of last accessed buffers (former bufKeys). Last accessed one is first element
-                     ,height    :: Int    -- ^ height of the window (in number of lines displayed)
+                     ,height    :: Int    -- ^ height of the window (in number of screen lines displayed)
                      ,winRegion    :: Region -- ^ view area.
                                               -- note that the top point is also available as a buffer mark.
                      ,wkey      :: !WindowRef -- ^ identifier for the window (for UI sync)
+                     ,actualLines :: Int-- ^ The actual number of lines displayed. Taking into account line wrapping
                      }
         deriving (Typeable)
 
 instance Binary Window where
-    put (Window mini bk bl _h _rgn key) = put mini >> put bk >> put bl >> put key
+    put (Window mini bk bl _h _rgn key lns) = put mini >> put bk >> put bl >> put key >> put lns
     get = Window <$> get <*> get <*> get
                    <*> return 0 <*> return emptyRegion
-                   <*> get
+                   <*> get <*> get
 
 
 -- | Get the identification of a window.
@@ -58,5 +59,5 @@ dummyWindowKey = (-1)
 
 -- | Return a "fake" window onto a buffer.
 dummyWindow :: BufferRef -> Window
-dummyWindow b = Window False b [] 0 emptyRegion dummyWindowKey
+dummyWindow b = Window False b [] 0 emptyRegion dummyWindowKey 0