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Unity Engine

OverlayIcon

Gets the VisualElement that represents an icon that overlays over the icon of the item. This element is hidden by default.
Read time 3 minutesLast updated a month ago

Definition

  • Type: Property
  • Namespace: Unity.Hierarchy
  • Assembly: UnityEngine.HierarchyModule
public VisualElement OverlayIcon { get; }

Remarks

Typically used to add an icon that indicates the state of the item. For example, you can use this to display an icon over a GameObject's icon that indicates a prefab has a broken reference.
The following example adds a custom tooltip that displays in the Hierarchy window when you hover over any GameObject that has a custom component named 
Notes
attached to it. It uses 
OverlayIcon
to add the custom overlay indicator to the icon of the GameObject.
The example requires a USS file called 
CustomTooltip.uss
and a custom MonoBehaviour script called 
Notes.cs
.
To use this example:
  1. Save the script in a folder called 
    Assets/Editor/CustomTooltip
    . Scripts in an 
    Editor
    folder can use the Hierarchy module API without additional setup. If you save the script outside of an 
    Editor
    folder, you must enable the Hierarchy built-in module in the Package Manager window, which also adds the module to your Player builds.
  2. Copy the styles from the USS example on this page. Save them in a USS file called 
    CustomTooltip.uss
    in the same 
    Assets/Editor/CustomTooltip
    folder.
  3. Save the 
    Notes.cs
    script outside of an 
    Editor
    folder, because MonoBehaviour scripts in an 
    Editor
    folder can't be attached to GameObjects.
  4. Add the 
    Notes
    component to a GameObject.
  5. In the Inspector window, enter text in the Note field of the 
    Notes
    component.
  6. In the Hierarchy window, hover over the name of the GameObject to display the text as a tooltip. A small overlay indicator also displays in the corner of the icon of any GameObject that has a note.
using System.Text;
using Unity.Hierarchy;
using Unity.Hierarchy.Editor;
using UnityEditor;
using UnityEngine;
using UnityEngine.UIElements;

namespace Unity.HierarchySamples.Editor
{
 class CustomTooltip
 {
 const string k_NotesOverlayUssClassName = "hierarchy-item__notes-overlay";

 [InitializeOnLoadMethod]
 static void Initialize()
 {
 HierarchyWindow.BindView += OnBindView;
 HierarchyWindow.BindViewItem += OnBindViewItem;
 HierarchyWindow.GetTooltip += OnGetTooltip;
 }

 static void OnBindView(HierarchyWindow window, HierarchyView view)
 => view.styleSheets.Add(AssetDatabase.LoadAssetAtPath<StyleSheet>("Assets/Editor/CustomTooltip/CustomTooltip.uss"));

 static void OnBindViewItem(HierarchyWindow window, HierarchyView view, HierarchyViewItem item)
 {
 if (item.Handler is not HierarchyGameObjectHandler handler)
 return;

 GameObject gameObject = handler.GetGameObject(item.Node);

 bool hasNotes = gameObject.TryGetComponent<Notes>(out Notes notes) && !string.IsNullOrWhiteSpace(notes.note);

 VisualElement notesOverlay = item.OverlayIcon.Q(className: k_NotesOverlayUssClassName);

 if (hasNotes)
 {
 if (notesOverlay == null)
 {
 notesOverlay = new VisualElement();
 notesOverlay.AddToClassList(k_NotesOverlayUssClassName);
 item.OverlayIcon.Add(notesOverlay);
 }
 }
 else if (notesOverlay != null)
 {
 notesOverlay.RemoveFromHierarchy();
 }
 }

 static void OnGetTooltip(HierarchyWindow window, HierarchyView view, HierarchyViewItem item, StringBuilder tooltip, bool filtering)
 {
 if (item.Handler is not HierarchyGameObjectHandler handler)
 return;

 GameObject gameObject = handler.GetGameObject(item.Node);

 if (!gameObject.TryGetComponent<Notes>(out Notes notes) || string.IsNullOrWhiteSpace(notes.note))
 return;

 if (filtering)
 {
 // When filtering, append the note to the existing tooltip.
 tooltip.Append("\nNote: ");
 tooltip.Append(notes.note);
 }
 else
 {
 // When not filtering, fully override the tooltip.
 tooltip.Clear();
 tooltip.Append("Note: ");
 tooltip.Append(notes.note);
 }
 }
 }
}
The following example shows how to style 
CustomTooltip.uss
.
.hierarchy-item__notes-overlay {
 position: absolute;
 width: 100%;
 height: 100%;
 background-size: 8px 8px;
 background-position: top left;
 background-repeat: no-repeat;
 background-image: var(--unity-icons-console_entry_info_small);
}
The following example shows the 
Notes
component that the CustomTooltip example uses.
using UnityEngine;

namespace Unity.HierarchySamples
{
 // Simple component that allows attaching notes to GameObjects for display in custom tooltips.
 public class Notes : MonoBehaviour
 {
 [TextArea(3, 10)]
 public string note;
 }
}