Adjusting text alignment using SpannableString

问题:

I have created a SpannableString, with the first character, and last 2 smaller than the rest. It looks like this:

sBBBBss

I would like to align the smaller characters so they are aligned with the top of the bigger text, instead of the bottom (as they appear here).

Is this possible?

I guess I am looking for something like this pseudo-code:

myAmount.setSpan(new RelativeAlignSpan(View.TOP), 0, 1, 0);

My only other alternative is to create a new layout, with multiple TextViews, that I populate independently, and align however I please. I think this is kind of messy, and would prefer to use the SpannableString approach.

回答1:

So I found the answer to this question posting it here to help the next guy.

I created a helper class to contain the methods to adjust the Span, you can call it using this syntax (this is setting the last 2 characters to appear higher on the line):

SpannableString contentAmount = new SpannableString(amount);

contentAmount.setSpan(new SuperscriptSpanAdjuster(3.0/5.0), contentAmount.length() - 2, contentAmount.length(), SpannableString.SPAN_EXCLUSIVE_EXCLUSIVE);

and the helper class is:

/**
 * This is a helper class to help adjust the alignment of a section of text, when using SpannableStrings to set text 
 * formatting dynamically.
 * 
 */
import android.text.TextPaint;
import android.text.style.MetricAffectingSpan;

public class SuperscriptSpanAdjuster extends MetricAffectingSpan {
    double ratio = 0.5;

    public SuperscriptSpanAdjuster() {
    }

    public SuperscriptSpanAdjuster(double ratio) {
        this.ratio = ratio;
    }

    @Override
    public void updateDrawState(TextPaint paint) {
        paint.baselineShift += (int) (paint.ascent() * ratio);
    }

    @Override
    public void updateMeasureState(TextPaint paint) {
        paint.baselineShift += (int) (paint.ascent() * ratio);
    }
}