在TextView中为特定字符设置下标和上标？

Question

有没有办法在TextView中为特定字符设置下标和上标？我想显示一个如下所示的文本:

所以,我尝试了这段代码:

TextView tv1 = ... ;
String latex = "\u222E";
tv1.setText(Html.fromHtml(latex + "<sup>200</sup><sub>2</sub> f(x)dx"));

但结果如下:

您可以在下标后看到上标.我如何解决这个问题？我可以用SpannableString解决吗？或者我可以改变下标的位置吗？

Answer 1

这个自定义跨度可以帮助您理解基本思想：

class SupSubSpan extends ReplacementSpan {
    private String sup;
    private String sub;

    public SupSubSpan(String sup, String sub) {
        this.sup = sup;
        this.sub = sub;
    }

    @Override
    public int getSize(Paint paint, CharSequence text, int start, int end, FontMetricsInt fm) {
        return (int) Math.max(paint.measureText(sup), paint.measureText(sub));
    }

    @Override
    public void draw(Canvas canvas, CharSequence text, int start, int end, float x, int top, int y, int bottom, Paint paint) {
        canvas.drawText(sup, x, y + paint.ascent() / 2, paint);
        canvas.drawText(sub, x, y - paint.ascent() / 2, paint);
    }
}