terminal: add ESC [ 22 J (scroll and clear)

src/terminal/Screen.zig

@@ -6421,6 +6421,34 @@ test "Screen: resize less cols with reflow previously wrapped and scrollback" {
     try testing.expectEqual(@as(usize, 2), s.cursor.y);
 }
 
+// test "Screen: resize less cols with scrollback keeps cursor row" {
+//     const testing = std.testing;
+//     const alloc = testing.allocator;
+//
+//     var s = try init(alloc, 3, 5, 5);
+//     defer s.deinit();
+//     const str = "1A\n2B\n3C\n4D\n5E";
+//     try s.testWriteString(str);
+//
+//     // Put our cursor on the end
+//     s.cursor.x = 1;
+//     s.cursor.y = s.rows - 1;
+//     try testing.expectEqual(@as(u32, 'E'), s.getCell(.active, s.cursor.y, s.cursor.x).char);
+//
+//     try s.resize(3, 3);
+//
+//     {
+//         const contents = try s.testString(alloc, .viewport);
+//         defer alloc.free(contents);
+//         const expected = "3C\n4D\n5E";
+//         try testing.expectEqualStrings(expected, contents);
+//     }
+//
+//     // Cursor should be on the last line
+//     try testing.expectEqual(@as(usize, 1), s.cursor.x);
+//     try testing.expectEqual(@as(usize, 2), s.cursor.y);
+// }
+//
 test "Screen: resize more rows, less cols with reflow with scrollback" {
     const testing = std.testing;
     const alloc = testing.allocator;

src/terminal/Terminal.zig

@@ -1144,6 +1144,20 @@ pub fn eraseDisplay(
     const protected = self.screen.protected_mode == .iso or protected_req;
 
     switch (mode) {
+        .scroll_complete => {
+            self.screen.scroll(.{ .clear = {} }) catch |err| {
+                log.warn("scroll clear failed, doing a normal clear err={}", .{err});
+                self.eraseDisplay(alloc, .complete, protected_req);
+                return;
+            };
+
+            // Unsets pending wrap state
+            self.screen.cursor.pending_wrap = false;
+
+            // Clear all Kitty graphics state for this screen
+            self.screen.kitty_images.delete(alloc, self, .{ .all = true });
+        },
+
         .complete => {
             var it = self.screen.rowIterator(.active);
             while (it.next()) |row| {
@@ -6017,6 +6031,23 @@ test "Terminal: eraseDisplay protected above" {
     var t = try init(alloc, 10, 5);
     defer t.deinit(alloc);
 
+    try t.print('A');
+    t.carriageReturn();
+    try t.linefeed();
+    t.eraseDisplay(alloc, .scroll_complete, false);
+
+    {
+        const str = try t.plainString(testing.allocator);
+        defer testing.allocator.free(str);
+        try testing.expectEqualStrings("", str);
+    }
+}
+
+test "Terminal: eraseDisplay scroll complete" {
+    const alloc = testing.allocator;
+    var t = try init(alloc, 10, 3);
+    defer t.deinit(alloc);
+
     try t.print('A');
     t.carriageReturn();
     try t.linefeed();

src/terminal/csi.zig

@@ -4,6 +4,10 @@ pub const EraseDisplay = enum(u8) {
     above = 1,
     complete = 2,
     scrollback = 3,
+
+    /// This is an extension added by Kitty to move the viewport into the
+    /// scrollback and then erase the display.
+    scroll_complete = 22,
 };
 
 // Modes for the EL CSI command.