Make RelativeSizeSpan align to top
suggest changeIn order to make a RelativeSizeSpan
align to the top, a custom class can be derived from the class SuperscriptSpan
. In the following example, the derived class is named TopAlignSuperscriptSpan
:
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 );
}
}
Reference screenshot:
Found a mistake? Have a question or improvement idea?
Let me know.
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