How to add a Drawable onClick / onTouch Listener?

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.Interpolator;
import android.view.animation.LinearInterpolator;
import android.view.animation.TranslateAnimation;
import android.widget.Toast;

public class SnowFall extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        SnowFallView snowFallView = new SnowFallView(this);
        setContentView(snowFallView);
        snowFallView.setBackgroundDrawable(getResources().getDrawable(R.drawable.winter));
    }

    private class SnowFallView extends View {
        private int snow_flake_count = 10;
        private final List<Drawable> drawables = new ArrayList<Drawable>();
        private int[][] coords;
        private final Drawable snow_flake;

        public SnowFallView(Context context) {
            super(context);
            setFocusable(true);
            setFocusableInTouchMode(true);

            snow_flake = context.getResources().getDrawable(R.drawable.snow_flake);
            snow_flake.setBounds(0, 0, snow_flake.getIntrinsicWidth(), snow_flake
                    .getIntrinsicHeight());
        }

        @Override
        protected void onSizeChanged(int width, int height, int oldw, int oldh) {
            super.onSizeChanged(width, height, oldw, oldh);
            Random random = new Random();
            Interpolator interpolator = new LinearInterpolator();

            snow_flake_count = Math.max(width, height) /100;
            coords = new int[snow_flake_count][];
            drawables.clear();
            for (int i = 0; i < snow_flake_count; i++) {
                Animation animation = new TranslateAnimation(20, height / 10
                        - random.nextInt(height / 5), -65, height + 30);
                animation.setDuration(10 * height + random.nextInt(5 * height));
                animation.setRepeatCount(-1);
                animation.initialize(10, 10, 10, 10);
                animation.setInterpolator(interpolator);

                coords[i] = new int[] { random.nextInt(width - 30), -30 };
                drawables.add(new AnimateDrawable(snow_flake, animation));

                animation.setStartOffset(random.nextInt(20 * height));
                animation.startNow();
            }
        }


        @Override
        protected void onDraw(Canvas canvas) {
            for (int i = 0; i < snow_flake_count; i++) {
                Drawable drawable = drawables.get(i);
                canvas.save();
                canvas.translate(coords[i][0], coords[i][1]);
                drawable.draw(canvas);
                canvas.restore();
            }
            invalidate();
        }


        @Override
        public boolean onTouchEvent(MotionEvent event) {
            //  --->  ????
            return super.onTouchEvent(event);
        }


    }
}