From c9f2f806ec73aa2586e4faef731af4d0a8df4baa Mon Sep 17 00:00:00 2001
From: Tim Culverhouse <tim@timculverhouse.com>
Date: Tue, 5 Dec 2023 10:34:25 -0600
Subject: [PATCH] terminal: implement mode 1047 (alternate screen)

Implement handling of mode 1047, which enters the alternate screen. This
is not used often, typically applications will favor 1049 (enter alt
screen, save cursor, clear alt screen).
---
 src/terminal/modes.zig |  1 +
 src/termio/Exec.zig    | 15 +++++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/src/terminal/modes.zig b/src/terminal/modes.zig
index dcd7f0071..9168cdb89 100644
--- a/src/terminal/modes.zig
+++ b/src/terminal/modes.zig
@@ -209,6 +209,7 @@ const entries: []const ModeEntry = &.{
     .{ .name = "alt_esc_prefix", .value = 1036, .default = true },
     .{ .name = "alt_sends_escape", .value = 1039 },
     .{ .name = "reverse_wrap_extended", .value = 1045 },
+    .{ .name = "alt_screen", .value = 1047 },
     .{ .name = "alt_screen_save_cursor_clear_enter", .value = 1049 },
     .{ .name = "bracketed_paste", .value = 2004 },
     .{ .name = "synchronized_output", .value = 2026 },
diff --git a/src/termio/Exec.zig b/src/termio/Exec.zig
index e1eb96956..dc6b7d6d3 100644
--- a/src/termio/Exec.zig
+++ b/src/termio/Exec.zig
@@ -1772,6 +1772,21 @@ const StreamHandler = struct {
                 self.terminal.scrolling_region.right = self.terminal.cols - 1;
             },
 
+            .alt_screen => {
+                const opts: terminal.Terminal.AlternateScreenOptions = .{
+                    .cursor_save = false,
+                    .clear_on_enter = false,
+                };
+
+                if (enabled)
+                    self.terminal.alternateScreen(self.alloc, opts)
+                else
+                    self.terminal.primaryScreen(self.alloc, opts);
+
+                // Schedule a render since we changed screens
+                try self.queueRender();
+            },
+
             .alt_screen_save_cursor_clear_enter => {
                 const opts: terminal.Terminal.AlternateScreenOptions = .{
                     .cursor_save = true,