insertLines method

Implementation

void insertLines(int count) {
  if (!isInVerticalMargin) {
    return;
  }

  setCursorX(0);
  _invalidateCurrentLine();

  // Number of lines from the cursor to the bottom of the scrollable region
  // including the cursor itself.
  final linesBelow = absoluteMarginBottom - absoluteCursorY + 1;

  // Number of empty lines to insert.
  final linesToInsert = min(count, linesBelow);

  // Number of lines to move up.
  final linesToMove = linesBelow - linesToInsert;

  for (var i = 0; i < linesToMove; i++) {
    final index = absoluteMarginBottom - i;
    lines[index] = lines.swap(index - linesToInsert, _newEmptyLine());
  }

  for (var i = linesToMove; i < linesToInsert; i++) {
    lines[absoluteCursorY + i] = _newEmptyLine();
  }
}