Button.Select(); does not highlight?

Question

Hi.

For using a gamepad I have what ought to be a handy script going. When a menu comes up, I want a specific button to be selected and highlighted so the player can start navigating.

I put the following script on a GameObject (like the panel Parent that contains the buttons) which is inactive in the scene (or it's activeSelf but its parent is inactive, either way..).

 using UnityEngine;
 using UnityEngine.UI;
 
 public class ButtonSelector : MonoBehaviour {
 
     public Button selectButton;
 
     void OnEnable()
     {
         if(selectButton != null)
         {
             selectButton.Select();    
             print("selected button");
         }
         else
             Debug.Log ("SelectButton was null");
     }
 }

The button does select, as in if I press a Submit button (spacebar, enter, Gamepad A, etc) it will activate, but the button is usually not highlighted. If I start to navigate, like move on to the next button, the next button does highlight (and select) and then I can move back to the original and it will appear highlighted. But why doesn't it highlight the first time?

Is Select() meant to select AND highlight? If not, what do I use?

Thanks Kevin

Answer 1

Answer by noio · Mar 11, 2016 at 10:42 AM

I am not happy with this, but I solved it by waiting a frame before selecting the button.

     IEnumerator SelectContinueButtonLater()
     {
         yield return null;
         _eventSystem.SetSelectedGameObject(null);
         _eventSystem.SetSelectedGameObject(continueButton.gameObject);
     }

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xxZap · Jun 13, 2016 at 12:41 PM 0

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This is terrible butIi'm very glad to solve my issue. Thank you.

PS: so it's a Unity bug.

mirrorlink · Jun 21, 2016 at 12:27 AM 0

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THAN$$anonymous$$S FOX!

kamathaj · Nov 03, 2018 at 09:16 AM 0

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This is definitely a bug. Thanks for this fix though!

wlwl2 · Aug 26, 2019 at 11:43 PM 0

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I've tried many other solutions over a long period of time, this one seems to finally work for me. Thank you!

Bvenjamin · Nov 22, 2020 at 06:21 PM 0

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using 2019.4 and the new input system, it did not highlight when I called Select when I had an object targeted in the EventSystem's "First Selected" field, but when I set it to None I no longer had to wait a frame for the highlight to work.

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Answer 2

Answer by valtterip · Nov 11, 2016 at 08:32 AM

Ran into this and tried different solution proposals, got it working with the yield-workaround, but it didn't seem to make much sense. So I noticed you don't need to wait the frame, just reset the selected GO before setting it selected again. So something along these lines does the trick for me

 private void setButtonsActive(bool set)
 {   
     buttons.SetActive(set);
     if (set)
         EventSystem.current.SetSelectedGameObject(buttons.GetComponentInChildren<Button>().gameObject, null);        
     else
         EventSystem.current.SetSelectedGameObject(null);
 }

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angrypenguin · Nov 25, 2016 at 04:05 AM 0

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I had something similar myself...

In my case I had a GUI that I was turning on and off dy deactivating and re-activating a root level GameObject as necessary. The first time I opened it in this fashion it worked fine. If I closed and re-opened it the default button would behave as if it were selected, but would not be highlighted even after re-setting the selection.

$$anonymous$$y guess is that the EvenySystem checks to see if the GameObject is already selected before it applies the selection, but that the Button script loses its highlight when deactivated and reactivated. With this in $$anonymous$$d, as with @valtterip's post, I found that nulling the selection and re-applying it seemed to do the trick.

This suggests a $$anonymous$$or issue with the Button component, if my guess above is correct. If it is supposed to maintain its selected status through re-activation then it should re-apply its highlight appropriately (I would assume this is the intent). If it's not supposed to maintain its selected status then it should de-select itself upon deactivation so that the overall system has a consistent representation of its current state.

Answer 3

I know it's a really old post, but to anyone who like me ends up here..

It is not a bug. EventSystem is a component, just another component. Unity lifecycle says that on initializaton, all components Awake and OnEnable are called (in this order), only then all components Start is called.

So, EventSystem Awake and OnEnable may not have been called when our button.Select() was called* if we do it inside Awake or OnEnable (I had this kind of trouble with my components, where one needs to be ready first for others to start calling it).

Also, if your button game object is not enabled, trying to do

 button.Select(); //button is a Button component 
 button.gameObject.SetActive(true);

won't work either (lost some good hours with this). Instead, make sure the gameObject is enabled first

 button.gameObject.SetActive(true);
 button.Select();

of course, if your button.Select() is being called some point after scene initialization, EventSystem might probably be there ready to go.

Answer 4

Answer by Pythalic · Apr 04, 2017 at 02:58 PM

For anyone who doesn't like the presented workaround:

Putting Select() or EventSystem.SetSelectedGameObject(...) into the Start() method, rather than Awake() or OnEnable() solved it for me.

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thatCamelCode · Feb 28, 2018 at 02:59 AM 0

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Yes, this is what I've been doing in my projects where I allow the use of a controller for navigation. I get the thinking that you want to do it as soon as possible, so you put it in OnEnable, but visually the user won't notice the difference between whether it's in OnEnable or in Awake/Start. Personally, I also see this method as being a lot nicer than a fiddle with a coroutine.

Answer 5

Answer by Arclite83 · May 11, 2020 at 08:23 AM

I also wasn't a huge fan of the above solutions. I have no idea if this is correct or ideal but it solves the problem of "I toggle a menu closed/open so I want to re-select my default button, but if I was already ON that button it shows as not selected".

 private void ForceSelectGameObject(GameObject gameObject)
 {
     if (EventSystem.current.currentSelectedGameObject == gameObject)
     {
         EventSystem.current.SetSelectedGameObject(null);            
     }
     EventSystem.current.SetSelectedGameObject(gameObject);    
 }

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Button.Select(); does not highlight?

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