collectStyle method

Style collectStyle(int offset, int len)

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).

In essence, it is INTERSECTION of each individual segment's styles

Implementation

Style collectStyle(int offset, int len) {
  final local = math.min(length - offset, len);
  var result = Style();
  final excluded = <Attribute>{};

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

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

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

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

  return result;
}