Bug Label of a DropdownField sends ChangeEvent

I'm trying to implement localization in my game and I have a drop-down field with the different languages that can be selected.

When the

DropdownField

field changes, it sends a

ChangeEvent<string>

which I register to update the text of the UI.

When I update the

Label

of the

DropdownField

, it also sends a

ChangeEvent<string>

using the same callback function!

I try to filter the event using

event.target

, but it's always the

DropdownField

and never the

Label

.

Populate the language drop-down with the available languages:

Code (CSharp):

1.     IEnumerator Start()
2.     {
3.         yield return LocalizationSettings.InitializationOperation;
4.  
5.         // Populate the Languages drop-down with the available locales.
6.         var languages = new List<string>();
7.         var selected = 0;
8.         for (int i = 0; i < LocalizationSettings.AvailableLocales.Locales.Count; ++i)
9.         {
10.             var locale = LocalizationSettings.AvailableLocales.Locales[i];
11.             if (LocalizationSettings.SelectedLocale == locale)
12.                 selected = i;
13.  
14.             languages.Add(locale.LocaleName);
15.         }
16.  
17.         // Populate the drop-down menu with the available languages.
18.         var dropdown = uiDocument.rootVisualElement.Q<DropdownField>("Language");
19.         dropdown.choices = languages;
20.         dropdown.value = languages[selected];
21.     }
22.  

Register the value changed event on the language drop-down and query the lable:

Code (CSharp):

1.         languageDropdown = menu.rootVisualElement.Q<DropdownField>("Language");
2.         languageDropdown.RegisterValueChangedCallback(LanguageChanged);
3.         languageDropdownLabel = languageDropdown.Q<Label>();
4.  

Change the locale based on the value in the drop-down:

Code (CSharp):

1.     void LanguageChanged(ChangeEvent<string> e)
2.     {
3.         // Ignore change events on the label of the drop-down.
4.         if (e.target == languageDropdownLabel) return; // This doesn't work!!
5.  
6.         Debug.Log($"Language changed to: {e.newValue}");
7.         PlayerPrefs.SetString(LANGUAGE_KEY, e.newValue);
8.  
9.         LocalizationSettings.SelectedLocale = LocalizationSettings.AvailableLocales.Locales[languageDropdown.index];
10.         UpdateLocale();
11.     }
12.  

Update the label text:

Code (CSharp):

1.     void UpdateLocale()
2.     {
3.         // This also fires the "LaguageChanged" callback function!
4.         languageDropdownLabel.text = languageString.GetLocalizedString();
5.         // etc...
6.     }
7.  

So how can I ignore the

ChangeEvent

on the Label of the

DropdownField

?

 

This is not a method on a

Label

.

 

A bit messy, but it seems to work...

Thanks @karl_jones

 

It feels like there are some slight inconveniences to the api as of current. Why we are unable to filter the change event on label vs. value, is not clear to me. The very verbose cast to make a change in the label text not cascade to a changeEvent in the dropDown, is something I would be hard pressed to figure out without googling into the depths of the forum.

My expectations of the DropdownField was to be able to do this :

Code (CSharp):

1. _dropDownField.RegisterCallback<ChangeEvent<int>>(ev =>
2.                 {
3.                    Debug.Log($"We changed {ev.newValue}");
4.                 });
5.  

And get an index into the choices-list of the DropdownField.