From bdb79bf5e014fa033c7f13429a7a0f42df100b0b Mon Sep 17 00:00:00 2001
From: Justin Bedo <cu@cua0.org>
Date: Sat, 30 Nov 2024 22:34:35 +1100
Subject: don't redraw when cursor offscreen

---
 jterm.hs | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/jterm.hs b/jterm.hs
index 7790942..1fe3c7e 100644
--- a/jterm.hs
+++ b/jterm.hs
@@ -310,8 +310,11 @@ waitEvent display event = do
 handleEvent :: Display -> Drawable -> XftColor -> XftColor -> XftColor -> XftColor -> XftFont -> HandledEvent -> StateT Buffer IO ()
 handleEvent display win bgcolour fgcolour linecolour selcolour font event = do
   b <- get
+  (_, _, _, _, m, _, _) <- lift $ getGeometry display win
   let (start, end) = cursor b
       selstr = R.splitAt end (content b) & fst & R.splitAt start & snd
+      (height, _) = fontSize display font
+      pageheight = fromIntegral m `div` fromIntegral height
   case event of
     Key (_, _, time, x, y, _, _, mod, keycode, _) -> do
       keysym <- lift $ keycodeToKeysym display keycode 0
@@ -330,9 +333,6 @@ handleEvent display win bgcolour fgcolour linecolour selcolour font event = do
           -- right click down
           case search selstr (content b) (1 + end) of
             Just p -> do
-              (_, _, _, _, m, _, _) <- lift $ getGeometry display win
-              let (height, _) = fontSize display font
-                  pageheight = fromIntegral m `div` fromIntegral height
               put $ b {cursor = (p, p + end - start), pos = max (pos b) $ R.lengthInLines (R.splitAt p (content b) & fst) + 1 -. pageheight}
             Nothing -> pure ()
         (0, 2) ->
@@ -403,14 +403,8 @@ handleEvent display win bgcolour fgcolour linecolour selcolour font event = do
                 (_, 65362) -> scrollup 1
                 (_, 65364) -> scrolldown 1
                 (_, 65365) -> do
-                  (_, _, _, _, m, _, _) <- lift $ getGeometry display win
-                  let (height, _) = fontSize display font
-                      pageheight = fromIntegral m `div` fromIntegral height
                   scrollup ((681 * pageheight) `div` 1000)
                 (_, 65366) -> do
-                  (_, _, _, _, m, _, _) <- lift $ getGeometry display win
-                  let (height, _) = fontSize display font
-                      pageheight = fromIntegral m `div` fromIntegral height
                   scrolldown ((681 * pageheight) `div` 1000)
                 (_, 65288) -> do
                   -- backspace
@@ -422,8 +416,11 @@ handleEvent display win bgcolour fgcolour linecolour selcolour font event = do
     T toAppend -> do
       let noesc = stripAnsiEscapeCodes toAppend
           expandedTabs = T.intercalate "\n" $ map expandTabs $ T.splitOn "\n" noesc
+          pl = pos b & linePos
+          cl = ptycursor b & linePos
+          linePos p = content b & R.splitAt p & fst & R.lengthAsPosition & posLine
       delins' True (ptycursor b) (ptycursor b) $ R.fromText expandedTabs
-      redraw
+      when (pl + pageheight > cl) redraw
     Notify -> do
       prop <- lift $ internAtom display "JTERM_CLIPBOARD" False
       lift (getWindowProperty8 display prop win) >>= \case
-- 
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