[Android] pinch zoom event with font size change

Android Java code for the pinch zoom event that makes increase font size.

import android.app.Activity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.TextView;


public class Introduce extends Activity implements OnTouchListener{
 
 final static float STEP = 200;
 TextView mtxtRatio1,mtxtRatio2,mtxtRatio3,mtxtRatio4;
 float mRatio = 1.0f;
 int mBaseDist;
 float mBaseRatio;
 float fontsize = 13;

 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.introduce);
  
  mtxtRatio1 = (TextView)findViewById(R.id.intro1);
  mtxtRatio1.setTextSize(mRatio+13);  
 }

 public boolean onTouchEvent(MotionEvent event) {
  if (event.getPointerCount() == 2) {
   int action = event.getAction();
   int pureaction = action & MotionEvent.ACTION_MASK;
   if (pureaction == MotionEvent.ACTION_POINTER_DOWN) {
    mBaseDist = getDistance(event);
    mBaseRatio = mRatio;
   } else {
    float delta = (getDistance(event) - mBaseDist) / STEP;
    float multi = (float)Math.pow(2, delta);
    mRatio = Math.min(1024.0f, Math.max(0.1f, mBaseRatio * multi));
    mtxtRatio1.setTextSize(mRatio+13);
   }
  }
  return true; 
 }

 int getDistance(MotionEvent event) {
  int dx = (int)(event.getX(0) - event.getX(1));
  int dy = (int)(event.getY(0) - event.getY(1));
  return (int)(Math.sqrt(dx * dx + dy * dy));
 }

 public boolean onTouch(View v, MotionEvent event) {
  // TODO Auto-generated method stub
  return false;
 }
}