Detect pinch zoom using ScaleGestureDetector

For Android 2.2 (Froyo) android.view.ScaleGestureDetector was added for processing the most commonly requested two-finger gesture: pinch zooming.

package com.exercise.AndroidScaleGestureDetector;

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

public class AndroidScaleGestureDetectorActivity extends Activity {

TextView scaleGesture;
ScaleGestureDetector scaleGestureDetector;

   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);
       scaleGesture = (TextView)findViewById(R.id.ScaleGesture);
      
       scaleGestureDetector = new ScaleGestureDetector(this, new simpleOnScaleGestureListener());
   }
  
@Override
public boolean onTouchEvent(MotionEvent event) {
 // TODO Auto-generated method stub
 scaleGestureDetector.onTouchEvent(event);
 return true;
}

public class simpleOnScaleGestureListener extends
  SimpleOnScaleGestureListener {

 @Override
 public boolean onScale(ScaleGestureDetector detector) {
  // TODO Auto-generated method stub
  scaleGesture.setText(String.valueOf(detector.getScaleFactor()));
  return true;
 }

 @Override
 public boolean onScaleBegin(ScaleGestureDetector detector) {
  // TODO Auto-generated method stub
  scaleGesture.setVisibility(View.VISIBLE);
  return true;
 }

 @Override
 public void onScaleEnd(ScaleGestureDetector detector) {
  // TODO Auto-generated method stub
  scaleGesture.setVisibility(View.INVISIBLE);
 }

}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:orientation="vertical" >

   <TextView
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:text="@string/hello" />
   <TextView
       android:id="@+id/ScaleGesture"
       android:layout_width="fill_parent"
       android:layout_height="wrap_content" />

</LinearLayout>

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next:
- Scale bitmap according to ScaleGestureDetector

Thank you for reading this article Detect pinch zoom using ScaleGestureDetector With URL http://x-tutorials.blogspot.com/2011/11/detect-pinch-zoom-using.html. Also a time to read the other articles.