flutter - Flutter 中所有渲染词框的列表

Question

如何获得包含我呈现的所有单词的框列表，我需要它来确定用户长按哪个单词？换句话说，我怎样才能找到maxRange以便我可以在下面的代码中使用getBoxesForRange ？

我的代码：

var pin = Offset(0, 0);
    // To create a paragraph of text, we use ParagraphBuilder.
    final ui.ParagraphBuilder builder = ui.ParagraphBuilder(
      ui.ParagraphStyle(
        textDirection: ui.TextDirection.rtl,
        textAlign: ebookTextAlign,
        fontFamily: "Asan",
        fontSize: ebookMainTextSize,
      ),
    )..pushStyle(ui.TextStyle(color: const ui.Color(0xFF000000)));

    spans.forEach((spn) {
      if (spn.localName == "p") builder.addText("\n");
      builder.addText(spn.text + " ");
    });
    builder.pop();

    paragraph = builder.build()
      ..layout(ui.ParagraphConstraints(width: size.width));

    var list = new List<ExtendedTextBox>();
    var boxes = paragraph.getBoxesForRange(0, maxRange);