Price Tag TextView

PriceTagSpan.java

import android.text.TextPaint;
import android.text.style.SuperscriptSpan;

public class PriceTagSpan extends SuperscriptSpan {
    @Override
    public void updateDrawState(TextPaint tp) {
        tp.baselineShift += (int) (tp.ascent() * 0.33f);
    }

    @Override
    public void updateMeasureState(TextPaint tp) {
        tp.baselineShift += (int) (tp.ascent() * 0.33f);
    }
}

PriceTagTextView.java

import android.content.Context;
import android.text.Spannable;
import android.text.SpannableStringBuilder;
import android.text.style.RelativeSizeSpan;
import android.util.AttributeSet;
import android.widget.TextView;

public class PriceTagTextView extends TextView {
    private final static String DEFAULT_CURRENCY_TEXT = "$";
    private CharSequence currency;

    public PriceTagTextView(Context context) {
        this(context, null);
    }

    public PriceTagTextView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public PriceTagTextView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        currency = DEFAULT_CURRENCY_TEXT;
    }

    public void setCurrency(CharSequence currency) {
        this.currency = currency;
    }

    public CharSequence getCurrency() {
        return currency;
    }

    @Override
    public void setText(CharSequence text, BufferType type) {
        SpannableStringBuilder spannableStringBuilder = new SpannableStringBuilder(text);

        if (!isEmpty(text) && !isEmpty(currency)) {
            if (text.toString().contains(currency)) {
                int currencyFound = 0;
                while ((currencyFound = text.toString().indexOf(String.valueOf(currency), currencyFound)) != -1) {
                    spannableStringBuilder = setSpans(spannableStringBuilder, currencyFound, currency.length());
                    currencyFound += currency.length();
                }
            } else {
                spannableStringBuilder.append(currency);
                spannableStringBuilder = setSpans(spannableStringBuilder, spannableStringBuilder.length() - currency.length(), currency.length());
            }
        }
        super.setText(spannableStringBuilder, type);
    }

    private SpannableStringBuilder setSpans(SpannableStringBuilder spannableStringBuilder, int start, int length) {
        spannableStringBuilder.setSpan(new PriceTagSpan(), start, start + length, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
        spannableStringBuilder.setSpan(new RelativeSizeSpan(0.5f), start, start + length, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
        return spannableStringBuilder;
    }

    private boolean isEmpty(CharSequence text) {
        return text == null || text.toString().trim().length() == 0;
    }
}