android.view.FocusFinder#getInstance ( )源码实例Demo

@Override
public View focusSearch(View focused, int direction) {
    if (focused != null) {
        final FocusFinder ff = FocusFinder.getInstance();
        final View found = ff.findNextFocus(this, focused, direction);
        if (direction == View.FOCUS_LEFT || direction == View.FOCUS_RIGHT) {
            if ((found == null || found.getId() != R.id.tv_main_title)
                    && getScrollState() == SCROLL_STATE_IDLE) {
                if (shakeX == null) {
                    shakeX = AnimationUtils.loadAnimation(getContext(), R.anim.host_shake);
                }
                focused.clearAnimation();
                focused.startAnimation(shakeX);
                return null;
            }
        }
    }
    return super.focusSearch(focused, direction);
}
 

@Override
protected void setUp() throws Exception {
    super.setUp();

    mFocusFinder = FocusFinder.getInstance();

    // inflate the layout
    final Context context = getContext();
    final LayoutInflater inflater = LayoutInflater.from(context);
    mRoot = (ViewGroup) inflater.inflate(R.layout.focus_2, null);

    // manually measure it, and lay it out
    mRoot.measure(500, 500);
    mRoot.layout(0, 0, 500, 500);

    mLeftButton = (Button) mRoot.findViewById(R.id.leftButton);
    mCenterButton = (Button) mRoot.findViewById(R.id.centerButton);
    mRightButton = (Button) mRoot.findViewById(R.id.rightButton);
}
 

/**
 * Request natural focus.
 *
 * @param direction             direction in which focus is changing
 * @param previouslyFocusedRect previously focus rectangle
 */
private void requestNaturalFocus(int direction, Rect previouslyFocusedRect) {
    FocusFinder ff = FocusFinder.getInstance();
    previouslyFocusedRect = previouslyFocusedRect == null
            ? new Rect(0, 0, 0, 0) : previouslyFocusedRect;
    View toFocus = ff.findNextFocusFromRect(this, previouslyFocusedRect, direction);
    toFocus = toFocus == null ? getChildAt(0) : toFocus;
    if (toFocus != null) {
        toFocus.requestFocus();
    }
}