From 6a9c90da0e093cec1d4903924eb0f6a33be489cb Mon Sep 17 00:00:00 2001
From: Jonathan Daugherty <cygnus@foobox.com>
Date: Wed, 15 Jul 2020 13:49:05 -0700
Subject: [PATCH] Output: add setDisplayBounds field and implementation for
 TerminfoBased backend

---
 cbits/gwinsz.c                           |  9 +++++++++
 cbits/gwinsz.h                           |  1 +
 src/Graphics/Vty/Output/Interface.hs     |  2 ++
 src/Graphics/Vty/Output/Mock.hs          |  1 +
 src/Graphics/Vty/Output/TerminfoBased.hs | 11 +++++++++++
 5 files changed, 24 insertions(+)

diff --git a/cbits/gwinsz.c b/cbits/gwinsz.c
index 0aa7ef6..14bb573 100644
--- a/cbits/gwinsz.c
+++ b/cbits/gwinsz.c
@@ -7,3 +7,12 @@ unsigned long vty_c_get_window_size(int fd) {
 	else
 		return 0x190050;
 }
+
+void vty_c_set_window_size(int fd, unsigned long val) {
+    struct winsize w;
+    if (ioctl(fd, TIOCGWINSZ, &w) >= 0) {
+        w.ws_row = val >> 16;
+        w.ws_col = val & 0xFFFF;
+        ioctl(fd, TIOCSWINSZ, &w);
+    }
+}
diff --git a/cbits/gwinsz.h b/cbits/gwinsz.h
index 4cd4b71..934deb9 100644
--- a/cbits/gwinsz.h
+++ b/cbits/gwinsz.h
@@ -1 +1,2 @@
 unsigned long vty_c_get_window_size(void);
+unsigned long vty_c_set_window_size(int fd, unsigned long val);
diff --git a/src/Graphics/Vty/Output/Interface.hs b/src/Graphics/Vty/Output/Interface.hs
index 72a3b06..42ff289 100644
--- a/src/Graphics/Vty/Output/Interface.hs
+++ b/src/Graphics/Vty/Output/Interface.hs
@@ -73,6 +73,8 @@ data Output = Output
       -- | Return the display to the state before `reserveDisplay` If no
       -- previous state then set the display state to the initial state.
     , releaseDisplay :: IO ()
+      -- | Sets the current display bounds (width, height).
+    , setDisplayBounds :: (Int, Int) -> IO ()
       -- | Returns the current display bounds.
     , displayBounds :: IO DisplayRegion
       -- | Output the bytestring to the terminal device.
diff --git a/src/Graphics/Vty/Output/Mock.hs b/src/Graphics/Vty/Output/Mock.hs
index 3024e2a..c33d93f 100644
--- a/src/Graphics/Vty/Output/Mock.hs
+++ b/src/Graphics/Vty/Output/Mock.hs
@@ -48,6 +48,7 @@ mockTerminal r = liftIO $ do
             , releaseDisplay = return ()
             , ringTerminalBell = return ()
             , supportsBell = return False
+            , setDisplayBounds = const $ return ()
             , displayBounds = return r
             , outputByteBuffer = \bytes -> do
                 putStrLn $ "mock outputByteBuffer of " ++ show (BS.length bytes) ++ " bytes"
diff --git a/src/Graphics/Vty/Output/TerminfoBased.hs b/src/Graphics/Vty/Output/TerminfoBased.hs
index 1d71224..4c722ef 100644
--- a/src/Graphics/Vty/Output/TerminfoBased.hs
+++ b/src/Graphics/Vty/Output/TerminfoBased.hs
@@ -10,10 +10,12 @@
 -- Copyright Corey O'Connor (coreyoconnor@gmail.com)
 module Graphics.Vty.Output.TerminfoBased
   ( reserveTerminal
+  , setWindowSize
   )
 where
 
 import Control.Monad (when)
+import Data.Bits (shiftL)
 import qualified Data.ByteString as BS
 import Data.ByteString.Internal (toForeignPtr)
 import Data.Terminfo.Parse
@@ -174,6 +176,8 @@ reserveTerminal termName outFd = do
             , releaseDisplay = do
                 maybeSendCap rmcup []
                 maybeSendCap cnorm []
+            , setDisplayBounds = \(w, h) ->
+                setWindowSize outFd (w, h)
             , displayBounds = do
                 rawSize <- getWindowSize outFd
                 case rawSize of
@@ -244,6 +248,13 @@ getWindowSize fd = do
     (a,b) <- (`divMod` 65536) `fmap` c_getWindowSize fd
     return (fromIntegral b, fromIntegral a)
 
+foreign import ccall "gwinsz.h vty_c_set_window_size" c_setWindowSize :: Fd -> CLong -> IO ()
+
+setWindowSize :: Fd -> (Int, Int) -> IO ()
+setWindowSize fd (w, h) = do
+    let val = (h `shiftL` 16) + w
+    c_setWindowSize fd $ fromIntegral val
+
 terminfoDisplayContext :: Output -> TerminfoCaps -> DisplayRegion -> IO DisplayContext
 terminfoDisplayContext tActual terminfoCaps r = return dc
     where dc = DisplayContext