Auto scrolling to a selected UI element?

Unity Engine
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1

Is there an example of a recommended way to handle scrolling to a selected UI item for controller navigation? I’ve recently run into this problem and have been experimenting with ways to solve it.

2

You are probably looking for ScrollView.ScrollTo. It needs the element in parameter and it will scroll to it, assuming it lives in the ScrollView.

1 Like
3

Isn’t that only for UItoolkit? Good to know it has a solution tho :thinking:

4

Yes, I assumed you were working with UI Toolkit based on the title, sorry. For uGUI, I think you can use what is suggested here: user interface - How to scroll to a specific element in ScrollRect with Unity UI? - Stack Overflow

5

Yeah i tried that one but it’s really jank. Needs a lot of additional stuff. Plus need to separate it from mouse input, etc.

6

I’ve posted code that centers an element in a scroll view here:

You can call it in ISelectHandler.OnSelect to center an item when it’s selected through navigation.

public void OnSelect(BaseEventData eventData)
{
    var scrollRect = GetComponentInParent<ScrollRect>();
    if (scrollRect != null) {
        scrollRect.ScrollToCenter(transform as RectTransform);
    }
}

I think you can check if the eventData is a PointerEventData instead of a AxisExtentData to filter out selection through mouse/touch.

But I use a custom button class extending Selectable that disables selecting it with pointers:

public override void OnPointerDown(PointerEventData eventData)
{
    // Temporarily disable navigation to avoid button being selected
    var originalNav = navigation;

    var nav = navigation;
    nav.mode = Navigation.Mode.None;
    navigation = nav;

    base.OnPointerDown(eventData);

    navigation = originalNav;
}

This makes selection exclusive to gamepad/keyboard, which I think is much cleaner anyway.

1 Like
7

Oh neat, I will try this and report back.

8

This works wonderfully!

As an FYI i use a different method with the new input system.


    private void OnEnable()
    {
        InputSystem.onEvent += OnAnyButtonPressed;
    }

    private void OnDisable()
    {
        InputSystem.onEvent -= OnAnyButtonPressed;
    }
    private void OnAnyButtonPressed(InputEventPtr eventPtr, InputDevice device)
    {
        if(device is Keyboard or Gamepad)
            UpdateScroll();
    }