[Android GridView Full Image] รบกวนด้วยครับ อยากถามเกี่ยวกับ Gridview ครับ

public class MainActivity extends Activity {

    List <String> ImageList;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        /*** Get Images from SDCard ***/
        ImageList = getSD();

        // gridView1
        final  GridView gView1 = (GridView)findViewById(R.id.gridView1);

        gView1.setAdapter(new ImageAdapter(this,ImageList));


        // OnClick
        gView1.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View v,
                                    int position, long id) {

                View layout = inflater.inflate(R.layout.custom_full_imagedialog,
                        (ViewGroup) findViewById(R.id.layout_root));
                ImageView image = (ImageView) layout.findViewById(R.id.fullimage);
                Toast.makeText(getApplicationContext(),
                        "Your selected : " + ImageList.get(position).toString(), Toast.LENGTH_SHORT).show();

            }
        });

    }

    private List <String> getSD()
    {
        List <String> it = new ArrayList <String>();
        File f = new  File(
            android.os.Environment.getExternalStorageDirectory()
                    + File.separator + Constance.PHOTO_ALBUM);
        File[] files = f.listFiles ();


        for (int i = 0; i <files.length; i++)
        {
            File  file = files[i];
            Log.d("Count",file.getPath());
            it.add (file.getPath());
        }
        return it;
    }

    public class ImageAdapter extends BaseAdapter
    {
        private Context context;
        private List <String> lis;

        public ImageAdapter(Context c, List <String> li)
        {
            // TODO Auto-generated method stub
            context = c;
            lis = li;
        }



        public int getCount() {
            // TODO Auto-generated method stub
            return lis.size();
        }

        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(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.show_image, null);
            }

            TextView textView = (TextView) convertView.findViewById(R.id.textView1);
            String strPath = lis.get(position).toString();

            // Get File Name
            String fileName = strPath.substring( strPath.lastIndexOf('/')+1, strPath.length() );
            textView.setText(fileName);

            // Image Resource
            ImageView imageView = (ImageView) convertView.findViewById(R.id.imageView1);
            Bitmap bm = BitmapFactory.decodeFile(strPath);
            imageView.setImageBitmap(bm);

            return convertView;

        }