Android Pich zoom Image how add ImageButton listner

Question

I have Code Image with Pich zoom

package com.androidtutorialpoint;
import com.androidtutorialpoint.imageview.PhotoView;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;

public class MainActivity extends Activity {

  private ViewPager mViewPager;

  @Override



public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);

   mViewPager = new HackyViewPager(this);
  setContentView(mViewPager);

   mViewPager.setAdapter(new SamplePagerAdapter());
 }

  static class SamplePagerAdapter extends PagerAdapter {

   private static int[] sDrawables = {
   R.drawable.ic_launcher,R.drawable.ic_launcher,
   };

   @Override
  public int getCount() {
   return sDrawables.length;
  }

   @Override
  public View instantiateItem(ViewGroup container, int position) {
   PhotoView photoView = new PhotoView(container.getContext());
   photoView.setImageResource(sDrawables[position]);

    // Now just add PhotoView to ViewPager and return it
   container.addView(photoView, LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT);

    return photoView;
  }

   @Override
  public void destroyItem(ViewGroup container, int position, Object object) {
   container.removeView((View) object);
  }



      @Override
      public boolean isViewFromObject(View view, Object object) {
       return view == object;
      }

      }

    }

I have add imageButton listner ale marker with function switching to a new activity My Image button lister have Code

public class MainActivity extends Activity {
    private ImageView mainBtn;  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);     
        mainBtn = (ImageView) findViewById(R.id.button);    
        mainBtn.setOnClickListener(new OnClickListener() 
                                    {           
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                openAlert(v);
            }
        });
    }
        private void openAlert(View view) {
         AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(MainActivity.this);
                 alertDialogBuilder.setTitle(this.getTitle()+ " ");
                 // set positive button: Yes message
         alertDialogBuilder.setPositiveButton("więcej",new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog,int id) {
                    // go to a new activity of the app
                    Intent positveActivity = new Intent(getApplicationContext(), PositiveActivity.class);
                    startActivity(positveActivity); 
                }
              });
         // set negative button: No message
         alertDialogBuilder.setNegativeButton("wyjście",new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog,int id) {
                    // cancel the alert box and put a Toast to the user
                    dialog.cancel();
        Toast.makeText(getApplicationContext(), "Mapa Budnik", 
                Toast.LENGTH_LONG).show();
                }
            });     
         AlertDialog alertDialog = alertDialogBuilder.create();
         // show alert
         alertDialog.show();
    }
}

My Ask how to add a tag to the image Button and when you click the trigger Activity? When my Image Button is in layaut.xml there is invisible.please help me