From 68c36be2e26813a2a3d7210ae82824de06b3d3ee Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Wed, 8 Mar 2023 23:43:23 -0500
Subject: implement callback for terminal resize request

---
 CHANGELOG.md     |  2 ++
 src/callbacks.rs |  3 +++
 src/screen.rs    | 14 ++++++++++++++
 src/state.rs     | 14 ++++++++++++++
 tests/csi.rs     | 40 ++++++++++++++++++++++++++++++++++++++++
 5 files changed, 73 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 477fc5a..f9fb38a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@
 * `Parser::process_cb`, which works the same as `Parser::process` except that
   it calls callbacks during parsing when it finds a terminal escape which is
   potentially useful but not something that affects the screen itself.
+* Support for xterm window resize request escape codes, via the new callback
+  mechanism.
 
 ### Removed
 
diff --git a/src/callbacks.rs b/src/callbacks.rs
index 256eb58..70331eb 100644
--- a/src/callbacks.rs
+++ b/src/callbacks.rs
@@ -7,6 +7,9 @@ pub trait Callbacks {
     /// This callback is called when the terminal requests an visual bell
     /// (typically with `\eg`).
     fn visual_bell(&mut self, _: &mut crate::Screen) {}
+    /// This callback is called when the terminal requests a resize
+    /// (typically with `\e[8;<rows>;<cols>t`).
+    fn resize(&mut self, _: &mut crate::Screen, _request: (u16, u16)) {}
     /// This callback is called when the terminal receives invalid input
     /// (such as an invalid UTF-8 character or an used control character).
     fn error(&mut self, _: &mut crate::Screen) {}
diff --git a/src/screen.rs b/src/screen.rs
index 9da62c7..c64f8e9 100644
--- a/src/screen.rs
+++ b/src/screen.rs
@@ -1447,6 +1447,19 @@ impl Screen {
         self.grid_mut().set_scroll_region(top - 1, bottom - 1);
     }
 
+    // CSI t
+    #[allow(clippy::unused_self)]
+    fn xtwinops(&self, params: &vte::Params) {
+        let mut iter = params.iter();
+        let op = iter.next().and_then(|x| x.first().copied());
+        match op {
+            Some(8) => {}
+            _ => {
+                log::debug!("unhandled XTWINOPS: {}", param_str(params));
+            }
+        }
+    }
+
     // osc codes
 
     fn osc0(&mut self, s: &[u8]) {
@@ -1544,6 +1557,7 @@ impl vte::Perform for Screen {
                     params,
                     self.grid().size(),
                 )),
+                't' => self.xtwinops(params),
                 _ => {
                     if log::log_enabled!(log::Level::Debug) {
                         log::debug!(
diff --git a/src/state.rs b/src/state.rs
index c84fa2b..5471bdd 100644
--- a/src/state.rs
+++ b/src/state.rs
@@ -42,6 +42,20 @@ impl<'a, T: crate::callbacks::Callbacks> vte::Perform for State<'a, T> {
         ignore: bool,
         c: char,
     ) {
+        if intermediates.first().is_none() && c == 't' {
+            let mut iter = params.iter();
+            let op = iter.next().and_then(|x| x.first().copied());
+            if op == Some(8) {
+                let (screen_rows, screen_cols) = self.screen.size();
+                let rows = iter.next().map_or(screen_rows, |x| {
+                    *x.first().unwrap_or(&screen_rows)
+                });
+                let cols = iter.next().map_or(screen_cols, |x| {
+                    *x.first().unwrap_or(&screen_cols)
+                });
+                self.callbacks.resize(self.screen, (rows, cols));
+            }
+        }
         self.screen.csi_dispatch(params, intermediates, ignore, c);
     }
 
diff --git a/tests/csi.rs b/tests/csi.rs
index 7a409b6..460a03d 100644
--- a/tests/csi.rs
+++ b/tests/csi.rs
@@ -44,3 +44,43 @@ fn il_dl() {
 fn scroll() {
     helpers::fixture("scroll");
 }
+
+#[test]
+fn xtwinops() {
+    struct Callbacks;
+    impl vt100::Callbacks for Callbacks {
+        fn resize(
+            &mut self,
+            screen: &mut vt100::Screen,
+            (rows, cols): (u16, u16),
+        ) {
+            screen.set_size(rows, cols);
+        }
+    }
+
+    let mut vt = vt100::Parser::default();
+    assert_eq!(vt.screen().size(), (24, 80));
+    vt.process_cb(b"\x1b[8;24;80t", &mut Callbacks);
+    assert_eq!(vt.screen().size(), (24, 80));
+    vt.process_cb(b"\x1b[8t", &mut Callbacks);
+    assert_eq!(vt.screen().size(), (24, 80));
+    vt.process_cb(b"\x1b[8;80;24t", &mut Callbacks);
+    assert_eq!(vt.screen().size(), (80, 24));
+    vt.process_cb(b"\x1b[8;24t", &mut Callbacks);
+    assert_eq!(vt.screen().size(), (24, 24));
+
+    let mut vt = vt100::Parser::default();
+    assert_eq!(vt.screen().size(), (24, 80));
+    vt.process_cb(b"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa", &mut Callbacks);
+    assert_eq!(vt.screen().rows(0, 80).next().unwrap(), "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
+    assert_eq!(vt.screen().rows(0, 80).nth(1).unwrap(), "aaaaaaaaaa");
+    vt.process_cb(
+        b"\x1b[H\x1b[8;24;15tbbbbbbbbbbbbbbbbbbbb\x1b[8;24;80tcccccccccccccccccccc",
+        &mut Callbacks,
+    );
+    assert_eq!(vt.screen().rows(0, 80).next().unwrap(), "bbbbbbbbbbbbbbb");
+    assert_eq!(
+        vt.screen().rows(0, 80).nth(1).unwrap(),
+        "bbbbbcccccccccccccccccccc"
+    );
+}
-- 
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