android - Html.fromHtml() 设置文本大小

Question

我正在使用Html.fromHtml()在 TextView 中显示一些简单的 Html。就我的口味而言，<h2>标题的字体有点太大了，所以我想知道如何做到这一点，Html 类没有相应的方法。我将深入研究源代码，看看我是否可以扩展一个类、覆盖一个方法或其他东西，但也许有人已经实现了为某些 Html 标签设置字体大小？

Answer 1

It is certianly possible. You just have to use Html.fromHtml() with your own Handler sent with it.

You could do it like this:

CharSequence html = Html.fromHtml(markdownString, null, new TitleHandler());

...

static class TitleHandler implements TagHandler {

  @Override
  public void handleTag(boolean opening, String tag, Editable output,
      XMLReader xmlReader) {
    if (tag.equalsIgnoreCase("h2")) {
      processH2(opening, output);
    }
  }

  public void processH2(boolean opening, Editable output) {
    int len = output.length();
    if (opening) {
      output.setSpan(new RelativeSizeSpan(0.8f), len, len,
          Spannable.SPAN_MARK_MARK);
    } else {
      Object obj = getLast(output, RelativeSizeSpan.class);
      int where = output.getSpanStart(obj);
      output.removeSpan(obj);
      if (where != len) {
        output.setSpan(new RelativeSizeSpan(0.8f), where, len,
            Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
      }
    }
  }

  @SuppressWarnings({ "unchecked", "rawtypes" })
  private Object getLast(Editable text, Class kind) {
    Object[] objs = text.getSpans(0, text.length(), kind);

    if (objs.length == 0) {
      return null;
    } else {
      for (int i = objs.length; i > 0; i--) {
        if (text.getSpanFlags(objs[i - 1]) == Spannable.SPAN_MARK_MARK) {
          return objs[i - 1];
        }
      }
      return null;
    }
  }
}

Using new RelativeSizeSpan(0.8f), you draw the Span in the TextView inside the <h2> elements with a relative size of 80% as it is now.

All the HTML tag handlers of Android are also defined like this.