From 2234d94b5066d96a97e266c9cb32937f46893f19 Mon Sep 17 00:00:00 2001
From: Michael Davis <mcarsondavis@gmail.com>
Date: Fri, 28 Mar 2025 12:49:27 -0400
Subject: [PATCH] crossterm: Render with synchronized output

This takes advantage of the synchronized output commands from crossterm
to tell the terminal emulator when to pause and resume drawing. This
should feel snappier and have fewer visual artifacts like tearing when
we update the screen with many changes (scrolling or changing theme for
example).
---
 helix-tui/src/backend/crossterm.rs | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/helix-tui/src/backend/crossterm.rs b/helix-tui/src/backend/crossterm.rs
index 5b41585e9..acb0fdfeb 100644
--- a/helix-tui/src/backend/crossterm.rs
+++ b/helix-tui/src/backend/crossterm.rs
@@ -146,6 +146,10 @@ where
             }
         }
     }
+
+    fn supports_synchronized_output(&self) -> bool {
+        self.features().synchronized_output_mode != SynchronizedOutputMode::NotSupported
+    }
 }
 
 impl<W> Write for CrosstermBackend<W>
@@ -268,6 +272,10 @@ where
     where
         I: Iterator<Item = (u16, u16, &'a Cell)>,
     {
+        if self.supports_synchronized_output() {
+            queue!(self.buffer, terminal::BeginSynchronizedUpdate)?;
+        }
+
         let mut fg = Color::Reset;
         let mut bg = Color::Reset;
         let mut underline_color = Color::Reset;
@@ -326,7 +334,13 @@ where
             SetForegroundColor(CColor::Reset),
             SetBackgroundColor(CColor::Reset),
             SetAttribute(CAttribute::Reset)
-        )
+        )?;
+
+        if self.supports_synchronized_output() {
+            execute!(self.buffer, terminal::EndSynchronizedUpdate)?;
+        }
+
+        Ok(())
     }
 
     fn hide_cursor(&mut self) -> io::Result<()> {