How to make RelativeSizeSpan align to top

However I did in this way:

activity_main.xml:

<TextView
    android:id="@+id/txtView"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginTop="50dp"
    android:textSize="26sp" />

MainActivity.java:

TextView txtView = (TextView) findViewById(R.id.txtView);

SpannableString spannableString = new SpannableString("RM123.456");
spannableString.setSpan( new TopAlignSuperscriptSpan( (float)0.35 ), 0, 2, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE );
txtView.setText(spannableString);

TopAlignSuperscriptSpan.java:

private class TopAlignSuperscriptSpan extends SuperscriptSpan {
        //divide superscript by this number
        protected int fontScale = 2;

        //shift value, 0 to 1.0
        protected float shiftPercentage = 0;

        //doesn't shift
        TopAlignSuperscriptSpan() {}

        //sets the shift percentage
        TopAlignSuperscriptSpan( float shiftPercentage ) {
            if( shiftPercentage > 0.0 && shiftPercentage < 1.0 )
                this.shiftPercentage = shiftPercentage;
        }

        @Override
        public void updateDrawState( TextPaint tp ) {
            //original ascent
            float ascent = tp.ascent();

            //scale down the font
            tp.setTextSize( tp.getTextSize() / fontScale );

            //get the new font ascent
            float newAscent = tp.getFontMetrics().ascent;

            //move baseline to top of old font, then move down size of new font
            //adjust for errors with shift percentage
            tp.baselineShift += ( ascent - ascent * shiftPercentage )
                    - (newAscent - newAscent * shiftPercentage );
        }

        @Override
        public void updateMeasureState( TextPaint tp ) {
            updateDrawState( tp );
        }
    }

Hope this will help you.