How to add a touch listener to a surface view?

Question

I am new to Android, so please excuse if it is asked before!

I am playing with some camera code (found online) and I want to show/hide some buttons on screen. When the user touches the screen, I want it to capture the image.

My setup:

1. Main Activity:

public class CameraDemo extends Activity {
/** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main_inuse);

        preview = new Preview(this);

        ((FrameLayout) findViewById(R.id.preview)).addView(preview);

... ...  
// rest of the code that captures the image when a button is pressed.
// the button is defined in main.xml with button id ButtonClicked
}

2. The preview class looks like this:

class Preview extends SurfaceView implements SurfaceHolder.Callback {

    SurfaceHolder mHolder;
    public Camera camera;

    Preview(Context context) {
        super(context);

        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        mHolder = getHolder();
        mHolder.addCallback(this);
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}

My question is,

1. How can I add touch functionality so that the user can touch the preview (say for a second, or just touch quickly) and something happens ? (Say image is saved)

2. And a button will appear on the surface say a "Next" button, for example?

Answer 1

@Override
public boolean onTouchEvent(MotionEvent event) {
    return super.onTouchEvent(event);
}

in your preview class , the MotionEvent object will tell you what kind of touch it is (and position etc etc) and let you do whatever you want to do.