在安卓中放大和缩小到文本视图

xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">
    <TextView
        android:id="@+id/zoomin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="40dp"
        android:gravity="center"
        android:text="GeeksForGeeks"
        android:textColor="#CE1D59"
        android:textSize="32sp" />
LinearLayout>


import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity implements View.OnTouchListener {
    TextView text;
    final static float move = 200;
    float ratio = 1.0f;
    int bastDst;
    float baseratio;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        text = findViewById(R.id.zoomin);
        text.setTextSize(ratio + 15);
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (event.getPointerCount() == 2) {
            int action = event.getAction();
            int mainaction = action & MotionEvent.ACTION_MASK;
            if (mainaction == MotionEvent.ACTION_POINTER_DOWN) {
                bastDst = getDistance(event);
                baseratio = ratio;
            } else {
                // if ACTION_POINTER_UP then after finding the distance
                // we will increase the text size by 15
                float scale = (getDistance(event) - bastDst) / move;
                float factor = (float) Math.pow(2, scale);
                ratio = Math.min(1024.0f, Math.max(0.1f, baseratio * factor));
                text.setTextSize(ratio + 15);
            }
        }
        return true;
    }
    // get distance between the touch event
    private 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);
    }
    @Override
    public boolean onTouch(View v, MotionEvent event) {
        return false;
    }
}