Android GridView Padding and Pagination

package com.myapp;

import java.util.ArrayList;
import java.util.HashMap;


import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends Activity {
	
	public int currentPage = 1;
	public int displayPerPage = 6;  // Display Perpage
	public int indexRowStart = 0;
	public int indexRowEnd = 0;
	public int TotalRows = 0;
	public GridView gridV;
	
	public Button btnNext;
	public Button btnPre;
	
	ArrayList<HashMap<String, String>> myArrList;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
       
        // gridView1
        gridV = (GridView)findViewById(R.id.gridView1); 
        
        // Next
        btnNext = (Button) findViewById(R.id.btnNext);
        // Perform action on click
        btnNext.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
            	currentPage = currentPage + 1;
            	progressShowData();
            }
        });
        
        // Previous
        btnPre = (Button) findViewById(R.id.btnPre);
        // Perform action on click
        btnPre.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
            	currentPage = currentPage - 1;
            	progressShowData();
            }
        });
        
        /*
         * ArrayList Data
         * ArrayList Data
         * ArrayList Data
         */
    	myArrList = new ArrayList<HashMap<String, String>>();
		HashMap<String, String> map;
		for(int i = 1; i<=53; i++)
		{
			map = new HashMap<String, String>();
			map.put("ItemID", "Items " + (i));
			map.put("Name", "Data " + (i));
			map.put("ImagePath", "/mnt/sdcard/mypicture/android.png");
			myArrList.add(map);
			
		}
		
		progressShowData();
		
    }
    
    public void progressShowData()
    {
    		// Total Record
			TotalRows = myArrList.size();
			
			// Start Index
			indexRowStart = ((displayPerPage*currentPage)-displayPerPage);
			
			int TotalPage = 0;
			if(TotalRows<=displayPerPage)
			{
				TotalPage =1;
			}
			else if((TotalRows % displayPerPage)==0)
			{
				TotalPage =(TotalRows/displayPerPage) ;
			}
			else
			{
				TotalPage =(TotalRows/displayPerPage)+1;
				TotalPage = (int)TotalPage;
			}
			
			// Disabled Button Next
			if(currentPage >= TotalPage)
			{
				btnNext.setEnabled(false);
			}
			else
			{
				btnNext.setEnabled(true);
			}
			
			// Disabled Button Previos
			if(currentPage <= 1)
			{
				btnPre.setEnabled(false);
			}
			else
			{
				btnPre.setEnabled(true);
			}
			
			// Show Data in GridView
			gridV.setAdapter(new myAdapter(this));

    }
    
    public class myAdapter extends BaseAdapter 
    {
        private Context context;

        public myAdapter(Context c) 
        {
        	// TODO Auto-generated method stub
            context = c;
        }
 
        public int getCount() {
        	// TODO Auto-generated method stub
        	if(displayPerPage > TotalRows - indexRowStart)
        	{
        		return TotalRows - indexRowStart;
        	}
        	else
        	{
        		return displayPerPage;
        	}
            
        }

 
        public Object getItem(int position) {
        	// TODO Auto-generated method stub
            return position;
        }
 
        public long getItemId(int position) {
        	// TODO Auto-generated method stub
            return position;
        }

		public View getView(final int position, View convertView,
				ViewGroup parent) {
	
			// TODO Auto-generated method stub
			LayoutInflater inflater = (LayoutInflater) context
					.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
		 
			if (convertView == null) {
				convertView = inflater.inflate(R.layout.activity_column, null); 
			}
	
			// ColItemID
			TextView ItemID = (TextView) convertView.findViewById(R.id.ColItemID);
			ItemID.setText(myArrList.get(position+indexRowStart).get("ItemID"));
			
			// ColName
			TextView Name = (TextView) convertView.findViewById(R.id.ColName);
			Name.setText(myArrList.get(position+indexRowStart).get("Name"));

			// ColPhoto
			ImageView Photo = (ImageView) convertView.findViewById(R.id.ColPhoto);
			Bitmap bm = BitmapFactory.decodeFile(myArrList.get(position+indexRowStart).get("ImagePath"));
			Photo.setImageBitmap(bm);
			
			return convertView;
			
		}

    }
    

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
    
}