How to make the image translucent and change the bounds in JAVA using Eclipse Android API level 2? - overlays

Question

I used the HelloItemizedOverlay code from Google to create and overlay item and it works but now I need to make the image translucent and change the bounds and I do not know how that works exactly.
I found the method getOpacity() but I do not know how to implement it in my ItemizedOverlay class or in my Map class. I am also aware of getIntrinsicHeight() and getIntrinsicWidth() methods but like the getOpacity() I do not know how to use it correctly. The code I have used for my ItemizedOverlay is :
import java.util.ArrayList;
import android.app.AlertDialog;
import android.content.Context;
import android.graphics.PixelFormat;
import android.graphics.drawable.Drawable;
import com.google.android.maps.ItemizedOverlay;
import com.google.android.maps.OverlayItem;
public class ContourItemizedOverlay extends ItemizedOverlay {
Context mContext;
private ArrayList<OverlayItem> mOverlays = new ArrayList<OverlayItem>();
public ContourItemizedOverlay(Drawable defaultMarker, Context context) {
super(boundCenter(defaultMarker));
mContext = context;
// TODO Auto-generated constructor stub
}
public int getOpacity()
{
return PixelFormat.TRANSPARENT;
}
#Override
protected boolean onTap(int index) {
OverlayItem item = mOverlays.get(index);
AlertDialog.Builder dialog = new AlertDialog.Builder(mContext);
dialog.setTitle(item.getTitle());
dialog.setMessage(item.getSnippet());
dialog.show();
return true;
}
public void addOverlay(OverlayItem overlay) {
mOverlays.add(overlay);
populate();
}
#Override
protected OverlayItem createItem(int i) {
// TODO Auto-generated method stub
return mOverlays.get(i);
}
#Override
public int size() {
// TODO Auto-generated method stub
return mOverlays.size();
}
}