feat: add event interfaces IOnAttachToPanel, IOnDetachFromPanel & IOn…

…GeometryChanged

Assets/UIComponents.Tests/Editor/Interfaces/InterfacesTestEditorWindow.cs

@@ -0,0 +1,18 @@
+using UnityEditor;
+using UnityEngine.UIElements;
+
+namespace UIComponents.Tests.Editor.Interfaces
+{
+    public class InterfacesTestEditorWindow : EditorWindow
+    {
+        private void CreateGUI()
+        {
+            rootVisualElement.Add(new Label("Hello world"));    
+        }
+
+        public void AddTestComponent(UIComponent component)
+        {
+            rootVisualElement.Add(component);
+        }
+    }
+}

Assets/UIComponents.Tests/Editor/Interfaces/UIComponentInterfaceTests.cs

@@ -0,0 +1,65 @@
+using NUnit.Framework;
+using UnityEditor;
+using UnityEngine;
+using UnityEngine.UIElements;
+
+namespace UIComponents.Tests.Editor.Interfaces
+{
+    [TestFixture]
+    public class UIComponentInterfaceTests
+    {
+        private class BaseTestComponent : UIComponent
+        {
+            public bool Fired { get; protected set; }
+        }
+
+        private static void Assert_Registers_Event_Callback<TComponent, TEvent>()
+            where TComponent : BaseTestComponent, new()
+            where TEvent : EventBase<TEvent>, new()
+        {
+            var window = EditorWindow.GetWindow<InterfacesTestEditorWindow>();
+            var component = new TComponent();
+            Assert.That(component.Fired, Is.False);
+            window.AddTestComponent(component);
+
+            using (var evt = new TEvent() { target = component })
+                component.SendEvent(evt);
+
+            Assert.That(component.Fired, Is.True);
+            window.Close();
+        }
+
+        private class UIComponentWithOnGeometryChanged : BaseTestComponent, IOnGeometryChanged
+        {
+            public void OnGeometryChanged(GeometryChangedEvent evt) => Fired = true;
+        }
+
+        [Test]
+        public void IOnGeometryChanged_Registers_GeometryChangedEvent_Callback()
+        {
+            Assert_Registers_Event_Callback<UIComponentWithOnGeometryChanged, GeometryChangedEvent>();
+        }
+
+        private class UIComponentWithOnAttachToPanel : BaseTestComponent, IOnAttachToPanel
+        {
+            public void OnAttachToPanel(AttachToPanelEvent evt) => Fired = true;
+        }
+
+        [Test]
+        public void IOnAttachToPanel_Registers_AttachToPanelEvent_Callback()
+        {
+            Assert_Registers_Event_Callback<UIComponentWithOnAttachToPanel, AttachToPanelEvent>();
+        }
+
+        private class UIComponentWithOnDetachFromPanel : BaseTestComponent, IOnDetachFromPanel
+        {
+            public void OnDetachFromPanel(DetachFromPanelEvent evt) => Fired = true;
+        }
+
+        [Test]
+        public void IOnDetachFromPanel_Registers_DetachFromPanelEvent_Callback()
+        {
+            Assert_Registers_Event_Callback<UIComponentWithOnDetachFromPanel, DetachFromPanelEvent>();
+        }
+    }
+}

Assets/UIComponents/Core/EventInterfaces/IOnAttachToPanel.cs

@@ -0,0 +1,15 @@
+using JetBrains.Annotations;
+using UnityEngine.UIElements;
+
+namespace UIComponents
+{
+    /// <summary>
+    /// When implemented by a <see cref="UIComponent"/>,
+    /// a callback for <see cref="AttachToPanelEvent"/> is
+    /// automatically registered in the UIComponent constructor.
+    /// </summary>
+    public interface IOnAttachToPanel
+    {
+        void OnAttachToPanel([NotNull] AttachToPanelEvent evt);
+    }
+}

Assets/UIComponents/Core/EventInterfaces/IOnDetachFromPanel.cs

@@ -0,0 +1,15 @@
+using JetBrains.Annotations;
+using UnityEngine.UIElements;
+
+namespace UIComponents
+{
+    /// <summary>
+    /// When implemented by a <see cref="UIComponent"/>,
+    /// a callback for <see cref="DetachFromPanelEvent"/> is
+    /// automatically registered in the UIComponent constructor.
+    /// </summary>
+    public interface IOnDetachFromPanel
+    {
+        void OnDetachFromPanel([NotNull] DetachFromPanelEvent evt);
+    }
+}

Assets/UIComponents/Core/EventInterfaces/IOnGeometryChanged.cs

@@ -0,0 +1,15 @@
+using JetBrains.Annotations;
+using UnityEngine.UIElements;
+
+namespace UIComponents
+{
+    /// <summary>
+    /// When implemented by a <see cref="UIComponent"/>,
+    /// a callback for <see cref="GeometryChangedEvent"/> is
+    /// automatically registered in the UIComponent constructor.
+    /// </summary>
+    public interface IOnGeometryChanged
+    {
+        void OnGeometryChanged([NotNull] GeometryChangedEvent evt);
+    }
+}

Assets/UIComponents/Core/UIComponent.cs

@@ -83,6 +83,20 @@ protected UIComponent()
             QueryFieldsSetupProfilerMarker.Begin();
             PopulateQueryFields();
             QueryFieldsSetupProfilerMarker.End();
+
+            RegisterEventInterfaceCallbacks();
+        }
+
+        private void RegisterEventInterfaceCallbacks()
+        {
+            if (this is IOnAttachToPanel onAttachToPanel)
+                RegisterCallback<AttachToPanelEvent>(onAttachToPanel.OnAttachToPanel);
+
+            if (this is IOnDetachFromPanel onDetachFromPanel)
+                RegisterCallback<DetachFromPanelEvent>(onDetachFromPanel.OnDetachFromPanel);
+
+            if (this is IOnGeometryChanged onGeometryChanged)
+                RegisterCallback<GeometryChangedEvent>(onGeometryChanged.OnGeometryChanged);
         }
 
         /// <summary>

README.md

@@ -145,6 +145,37 @@ Stylesheets will be applied to `ChildComponent` in the following order:
 
 This means that child components can override styles from their parents.
 
+## Event interfaces
+
+UIComponents supports a number of event interfaces. When implemented, the callbacks
+are automatically registered in the UIComponent constructor.
+
+The interfaces are:
+- `IOnAttachToPanel` for `AttachToPanelEvent`
+- `IOnDetachFromPanel` for `DetachFromPanelEvent`
+- `IOnGeometryChanged` for `GeometryChangedEvent`
+
+```c#
+public class ComponentWithCallbacks : UIComponent, IOnAttachToPanel, IOnGeometryChanged, IOnDetachFromPanel
+{
+    public void OnAttachToPanel(AttachToPanelEvent evt)
+    {
+        Debug.Log("Hello world");
+    }
+
+    public void OnGeometryChanged(GeometryChangedEvent evt)
+    {
+        Debug.Log("Geometry changed");
+        UnregisterCallback<GeometryChangedEvent>(OnGeometryChanged);
+    }
+
+    public void OnDetachFromPanel(DetachFromPanelEvent evt)
+    {
+        Debug.Log("Goodbye world");
+    }
+}
+```
+
 ## Experimental features
 
 `[Query]` is an experimental feature that allows for populating fields automatically.