[UIElements] ListView derived class won't show selection highlight

Hi,

I have a rather simple class that I have derived from ListView. It does very little. Its only purpose is to make the ListView reactive so that if its data source is changed the ListView automatically refreshes.

However with this derived class, the ListView does not show the selection highlight when an item is clicked on like the raw ListView does, and for the life of me I can't figure out why. The items DO register the click properly, and the result from the onSelectionChanged action is correct.

My derived class is very simple, and is posted here in its entirety. The ReactiveCollection here comes from UniRx and implements IList.

Code (CSharp):

1.  
2. using System;
3. using System.Collections;
4. using System.Collections.Generic;
5. using UniRx;
6. using UnityEngine.Experimental.UIElements;
7. using UnityEngine;
8.  
9. namespace Genesis.Unity.Tessa
10. {
11.     public class ReactiveListView : ListView
12.     {
13.         private ReactiveCollection<string> m_collection;
14.         public ReactiveCollection<string> SourceCollection
15.         {
16.             get { return m_collection; }
17.             set
18.             {
19.                 if (m_collection == value) return;
20.              
21.                 m_collection = value;
22.                 m_collection.ObserveReset().Subscribe(OnReset);
23.                 m_collection.ObserveCountChanged().Buffer(TimeSpan.FromSeconds(1)).Subscribe(OnCountChanged);
24.             }
25.         }
26.  
27.         public bool SortItems = true;
28.  
29.         public ReactiveListView(ReactiveCollection<string> itemsSource, int itemHeight, Func<VisualElement> makeItem, Action<VisualElement, int> bindItem) : base(itemsSource, itemHeight, makeItem, bindItem)
30.         {
31.             SourceCollection = itemsSource;
32.         }
33.  
34.         private void OnCountChanged(IList<int> obj)
35.         {
36.             if (obj.Count > 0)
37.             {
38.                 Debug.Log($"OnCountChanged {obj.Count}");
39.                 if (SortItems)
40.                 {
41.                     ArrayList.Adapter(m_collection).Sort();
42.                 }
43.                 Refresh();
44.             }
45.         }
46.      
47.         private void OnReset(Unit obj)
48.         {
49.             Debug.Log("OnReset");
50.         }
51.     }
52. }
53.  

 

Thank you for the reply Antoine. I never would have figured out that problem on my own! We are on 2018.3 at the moment, and not sure when 2019.1 will happen sadly.

As for composition, wrapping it up in a new class is fine but we want something that can be dropped inline where a normal ListView would go, in another class that handles the UI. So a VisualElement that just handles itself. I'll have to think about the best way to handle this, or implemented highlighting manually as a fall back option.

Thanks again for helping me understand what the root problem is.

 

Are the default stylesheets available somewhere where I could copy the styling used for ListView?

EDITL Ah nevermind I can just grab it from the UIElements Inspector window.

 

Ok so in case I (or others) run into this again and come here via Google..

This was easily fixed by adding my own stylesheet that picked up ReactiveListView :selected.

ReactiveListView :selected {
background-color: rgba(61, 96, 145, 1.0);
}

This reproduces the exact same behaviour as ListView.

SIDE NOTE: Deconstructing Style rules from the UIElements Inspector is fine, but bear in mind the information shown in that window isn't necessarily exactly what is in the actual rule In my case, I had two small roadbumps in that regard:

1) The UIElements Inspector lists the style as RGBA() when in reality it needs to be lowercase rgba()
2) The UIElements Inspector lists color values in floating point 0-1, but they must be specified in integer 0-255 in the USS file. So if you are copying directly from you inspector and seeing black and white results this is why.

It would be nice if the inspector more precisely showed the value as it is in the USS file.