android - 如何在多行文本的行尾添加 ImageSpan

Question

我想在多行字符串的每一行末尾添加一个跨度。我试着只画一个字符，但行尾什么也没有出现。但是当设置了ImageSpan时，可以增加行高，但行内仍然没有图像。

private void addSpansAtEnd() {
    String s = "First line\nSecond line\Third line\n";
    SpannableStringBuilder e = new SpannableStringBuilder(s);
    int stop = start + count;
    for (int start = -1;
        (start = s.indexOf("\n", start)) > -1 && start < stop;
        ++start) {
            e.setSpan(
                    /*new ImageSpan(getContext(), R.drawable.ic_line),*/
                    new NewLineSpan(),
                    start,
                    start + 1,
                    Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
    }
}

/* Trying to replace \\n with other character. */
private class NewLineSpan extends ReplacementSpan {
    @Override
    public int getSize(
            Paint paint,
            CharSequence text,
            int start,
            int end,
            Paint.FontMetricsInt fm) {
        return 0;
    }

    @Override
    public void draw(
            Canvas canvas,
            CharSequence text,
            int start,
            int end,
            float x,
            int top,
            int y,
            int bottom,
            Paint paint) {
        paint.setColor(0xFF666666);
        canvas.drawText("o", x, y, paint);
    }
}

如何在行尾绘制？

Answer 1

将跨度放在换行符上似乎有点奇怪。换行符跨越两行但没有任何宽度。我认为如果在换行符之前添加一个空格然后将 span 放在空格周围，你可能会更幸运:

for (int start = -1;
    (start = s.indexOf("\n", start)) > -1 && start < stop;
    start += 2) { // increment by 2 to skip the displaced newline
        e.insert(start, " ");  // insert a space for the span
        e.setSpan(new ImageSpan(getContext(), R.drawable.ic_line),
                start,
                start + 1,
                Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
        stop++;  // because a space was added
}