collectStyle method

NotusStyle collectStyle(int offset, int length)

Returns style for specified text range.

Only attributes applied to all characters within this range are included in the result. Inline and line level attributes are handled separately, e.g.:

• line attribute X is included in the result only if it exists for every line within this range (partially included lines are counted).
• inline attribute X is included in the result only if it exists for every character within this range (line-break characters excluded).

Implementation

NotusStyle collectStyle(int offset, int length) {
  final local = math.min(this.length - offset, length);

  var result = NotusStyle();
  final excluded = <NotusAttribute>{};

  void _handle(NotusStyle style) {
    if (result.isEmpty) {
      excluded.addAll(style.values);
    } else {
      for (var attr in result.values) {
        if (!style.contains(attr)) {
          excluded.add(attr);
        }
      }
    }
    final remaining = style.removeAll(excluded);
    result = result.removeAll(excluded);
    result = result.mergeAll(remaining);
  }

  final data = lookup(offset, inclusive: true);
  LeafNode? node = data.node as LeafNode?;
  if (node != null) {
    result = result.mergeAll(node.style);
    var pos = node.length - data.offset;
    while (!node!.isLast && pos < local) {
      node = node.next as LeafNode?;
      _handle(node!.style);
      pos += node.length;
    }
  }

  result = result.mergeAll(style);
  if (parent is BlockNode) {
    BlockNode block = parent as BlockNode;
    result = result.mergeAll(block.style);
  }

  final remaining = length - local;
  if (remaining > 0) {
    final rest = nextLine!.collectStyle(0, remaining);
    _handle(rest);
  }

  return result;
}