Add scroll queue detection in notification view

This will stop injecting events into the timeline if you're scrolling

damus/Models/NotificationsModel.swift

@@ -45,7 +45,8 @@ enum NotificationItem {
     }
 }
 
-class NotificationsModel: ObservableObject {
+class NotificationsModel: ObservableObject, ScrollQueue {
+    
     var incoming_zaps: [Zap]
     var incoming_events: [NostrEvent]
     var should_queue: Bool
@@ -73,6 +74,10 @@ class NotificationsModel: ObservableObject {
         self.notifications = []
     }
     
+    func set_should_queue(_ val: Bool) {
+        self.should_queue = val
+    }
+    
     func uniq_pubkeys() -> [String] {
         var pks = Set<String>()
         

damus/Util/EventHolder.swift

@@ -8,12 +8,16 @@
 import Foundation
 
 /// Used for holding back events until they're ready to be displayed
-class EventHolder: ObservableObject {
+class EventHolder: ObservableObject, ScrollQueue {
     private var has_event: Set<String>
     @Published var events: [NostrEvent]
     @Published var incoming: [NostrEvent]
     var should_queue: Bool
     
+    func set_should_queue(_ val: Bool) {
+        self.should_queue = val
+    }
+    
     var queued: Int {
         return incoming.count
     }

damus/Views/Notifications/NotificationsView.swift

@@ -22,6 +22,12 @@ struct NotificationsView: View {
                         NotificationItemView(state: state, item: item)
                     }
                 }
+                .background(GeometryReader { proxy -> Color in
+                    DispatchQueue.main.async {
+                        handle_scroll_queue(proxy, queue: self.notifications)
+                    }
+                    return Color.clear
+                })
                 .padding(.horizontal)
             }
             .onReceive(handle_notify(.scroll_to_top)) { notif in

damus/Views/TimelineView.swift

@@ -27,17 +27,6 @@ struct TimelineView: View {
         MainContent
     }
     
-    func handle_scroll(_ proxy: GeometryProxy) {
-        let offset = -proxy.frame(in: .named("scroll")).origin.y
-        guard offset >= 0 else {
-            return
-        }
-        let val = offset > 0
-        if self.events.should_queue != val {
-            self.events.should_queue = val
-        }
-    }
-    
     var realtime_bar_opacity: Double {
         colorScheme == .dark ? 0.2 : 0.1
     }
@@ -55,7 +44,7 @@ struct TimelineView: View {
                     .disabled(loading)
                     .background(GeometryReader { proxy -> Color in
                         DispatchQueue.main.async {
-                            handle_scroll(proxy)
+                            handle_scroll_queue(proxy, queue: self.events)
                         }
                         return Color.clear
                     })
@@ -82,3 +71,18 @@ struct TimelineView_Previews: PreviewProvider {
 }
 
 
+protocol ScrollQueue {
+    var should_queue: Bool { get }
+    func set_should_queue(_ val: Bool)
+}
+    
+func handle_scroll_queue(_ proxy: GeometryProxy, queue: ScrollQueue) {
+    let offset = -proxy.frame(in: .named("scroll")).origin.y
+    guard offset >= 0 else {
+        return
+    }
+    let val = offset > 0
+    if queue.should_queue != val {
+        queue.set_should_queue(val)
+    }
+}