encodeAlternateScrollLines function

Uint8List encodeAlternateScrollLines({
  1. required int lines,
  2. required bool up,
})

Batch lines × SS3 cursor-up/down for alternate-scroll / alt-screen TUI. Matches alacritty scroll_terminal alternate-scroll branch (always SS3).

Implementation

Uint8List encodeAlternateScrollLines({required int lines, required bool up}) {
  if (lines <= 0) return Uint8List(0);
  final cmd = up ? 0x41 : 0x42;
  final out = BytesBuilder(copy: false);
  for (var i = 0; i < lines; i++) {
    out.addByte(0x1b);
    out.addByte(0x4f);
    out.addByte(cmd);
  }
  return out.toBytes();
}