Set scroll limit in android leanback

Question

I'm working on an AndroidTV app, using the Leanback library.

How can I slow down the speed at which it scrolls by leaving the button pressed?

I want to slow scrolling speed in my leanback project but i don't no how its possible?

my code -

@Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT || keyCode == KeyEvent.KEYCODE_DPAD_RIGHT
                || keyCode == KeyEvent.KEYCODE_DPAD_DOWN || keyCode == KeyEvent.KEYCODE_DPAD_UP) {
            // Add shadow over topShelfImage at here
            topShelfImg.setAlpha(0.3f);
        }

        if (mTeamSclFragment != null) {
            mTeamSclFragment.onMyKeyDown(keyCode, event);
        }
        return false;
    }