added code from unity

Runtime/PopupTriggerView.cs

@@ -0,0 +1,54 @@
+using System;
+using Jovian.PopupSystem.UI;
+using UnityEngine;
+
+namespace Jovian.PopupSystem {
+    /// <summary>
+    /// Handles popup behavior for a <see cref="PopupTrigger"/>. Holds the content callback and
+    /// forwards pointer events to the <see cref="IPopupSystem"/>. This is the behavior layer;
+    /// the MonoBehaviour trigger is the reference holder that forwards events here.
+    /// </summary>
+    public sealed class PopupTriggerView {
+        readonly IPopupSystem popupSystem;
+        Action<PopupContentBuilder> contentCallback;
+
+        /// <summary>
+        /// Creates a new trigger view bound to the given popup system.
+        /// </summary>
+        public PopupTriggerView(IPopupSystem popupSystem) {
+            this.popupSystem = popupSystem;
+        }
+
+        /// <summary>
+        /// Sets the content builder callback that will be invoked when the popup is shown.
+        /// </summary>
+        public void SetContent(Action<PopupContentBuilder> callback) {
+            contentCallback = callback;
+        }
+
+        /// <summary>
+        /// Called by <see cref="PopupTrigger"/> when the pointer enters. Reads the trigger's
+        /// category, anchor side, and position mode to show the popup.
+        /// </summary>
+        public void OnPointerEnter(PopupTrigger trigger) {
+            if(popupSystem == null || contentCallback == null) {
+                return;
+            }
+
+            if(trigger.PositionMode == PopupPositionMode.AnchorToElement) {
+                popupSystem.Show(trigger.Category, contentCallback, (RectTransform)trigger.transform, trigger.AnchorSide);
+            }
+            else {
+                popupSystem.Show(trigger.Category, contentCallback);
+            }
+        }
+
+        /// <summary>
+        /// Called by <see cref="PopupTrigger"/> when the pointer exits. Hides the popup
+        /// for the trigger's category.
+        /// </summary>
+        public void OnPointerExit(PopupTrigger trigger) {
+            popupSystem?.Hide(trigger.Category);
+        }
+    }
+}