Question

I have 8 buttons I would like the app to detect the buttons by just scrolling on the screen and not by touching? like the accessibility feature in Jelly bean? I am not sure how to call that feature as? Gesture? Motion sense?

Is this possible? What should I look for?

Thanks!

Answer 1

By default the UI elements in Android are focusable by scrollballs, arrow keys, etc… The Views have an View.setOnFocusChangedListener callback. You can also set focus on elements programmatically.

Some example code I quickly wrote and did not test.

float initialX = 0;
float initialY = 0;
int currentFocusedChild = 0;
List<View> children;

public void walkElements() {
    final LinearLayout mainLayout = (LinearLayout) findViewById(R.id.main_layout);
    children = mainLayout.getFocusables(View.FOCUS_FORWARD);
    mainLayout.setOnTouchListener(new OnTouchListener() {

        @Override
        public boolean onTouch(View v, MotionEvent event) {
            switch(event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    initialX = event.getX();
                    initialY = event.getY();                        
                    break;
                case MotionEvent.ACTION_MOVE:
                    float diffX = event.getX() - initialX;
                    float diffY = event.getY() - initialY;

                    if(diffY > 0) {
                        if (currentFocusedChild < children.size() - 1) {
                            currentFocusedChild++;
                        }
                    } else {
                        if (currentFocusedChild > 0) {
                            currentFocusedChild--;
                        }
                    }
                    children.get(currentFocusedChild).setSelected(true);

                    //Sleep for a period of time so the selection is slow enough for the user.
                    Thread.sleep(300);
                    break;
                case MotionEvent.ACTION_UP:
                    children.get(currentFocusedChild).performClick();
                    break;
            }
            return false;
        }
    });

}