scroll: more consistent scrolling behavior

Scrolling will always anchor the active note to the top of the screen

This is less confusing overall

Changelog-Changed: Clicking on a note will now always scroll it to the top
Signed-off-by: William Casarin <jb55@jb55.com>

damus/Components/EndBlock.swift

@@ -0,0 +1,32 @@
+//
+//  EndBlock.swift
+//  damus
+//
+//  Created by William Casarin on 2022-08-08.
+//
+
+import SwiftUI
+
+struct EndBlock: View {
+    let height: CGFloat
+    
+    init () {
+        self.height = 80.0
+    }
+    
+    init (height: Float) {
+        self.height = CGFloat(height)
+    }
+    
+    var body: some View {
+        Color.white.opacity(0)
+            .id("endblock")
+            .frame(height: height)
+    }
+}
+
+struct EndBlock_Previews: PreviewProvider {
+    static var previews: some View {
+        EndBlock()
+    }
+}

damus/Models/ThreadModel.swift

@@ -189,7 +189,9 @@ class ThreadModel: ObservableObject {
         }
         
         if done {
-            loading = false
+            if (events.contains { ev in ev.id == initial_event.id }) {
+                loading = false
+            }
         }
     }
 

damus/Views/ChatroomView.swift

@@ -14,7 +14,7 @@ struct ChatroomView: View {
     
     var body: some View {
         ScrollViewReader { scroller in
-            ScrollView {
+            ScrollView(.vertical) {
                 LazyVStack(alignment: .leading) {
                     let count = thread.events.count
                     ForEach(Array(zip(thread.events, thread.events.indices)), id: \.0.id) { (ev, ind) in
@@ -34,17 +34,20 @@ struct ChatroomView: View {
                         }
                         .environmentObject(thread)
                     }
+                    
                 }
+                
+                EndBlock()
             }
             .onReceive(NotificationCenter.default.publisher(for: .select_quote)) { notif in
                 let ev = notif.object as! NostrEvent
                 if ev.id != thread.initial_event.id {
                     thread.set_active_event(ev, privkey: damus.keypair.privkey)
                 }
-                scroll_to_event(scroller: scroller, id: ev.id, delay: 0, animate: true, anchor: .top)
+                scroll_to_event(scroller: scroller, id: ev.id, delay: 0, animate: true)
             }
             .onAppear() {
-                scroll_to_event(scroller: scroller, id: thread.initial_event.id, delay: 0.3, animate: false, anchor: .bottom)
+                scroll_to_event(scroller: scroller, id: thread.initial_event.id, delay: 0.1, animate: false)
             }
         }
     }

damus/Views/DMChatView.swift

@@ -21,9 +21,7 @@ struct DMChatView: View {
                         DMView(event: dms.events[ind], damus_state: damus_state)
                             .event_context_menu(ev, privkey: damus_state.keypair.privkey)
                     }
-                    Color.white.opacity(0)
-                        .id("endblock")
-                        .frame(height: 80)
+                    EndBlock()
                 }
             }
             .onAppear {

damus/Views/EventDetailView.swift

@@ -37,11 +37,11 @@ struct EventDetailView: View {
     @StateObject var thread: ThreadModel
     @State var collapsed: Bool = true
     
-    func toggle_collapse_thread(scroller: ScrollViewProxy, id mid: String?, animate: Bool = true, anchor: UnitPoint = .center) {
+    func toggle_collapse_thread(scroller: ScrollViewProxy, id mid: String?, animate: Bool = true) {
         self.collapsed = !self.collapsed
         if let id = mid {
             if !self.collapsed {
-                scroll_to_event(scroller: scroller, id: id, delay: 0.1, animate: animate, anchor: anchor)
+                scroll_to_event(scroller: scroller, id: id, delay: 0.1, animate: animate)
             }
         }
     }
@@ -52,7 +52,7 @@ struct EventDetailView: View {
         print("uncollapsing section at \(c.start) '\(ev.content.prefix(12))...'")
         let start_id = ev.id
         
-        toggle_collapse_thread(scroller: scroller, id: start_id, animate: false, anchor: .top)
+        toggle_collapse_thread(scroller: scroller, id: start_id, animate: false)
     }
     
     func CollapsedEventView(_ cev: CollapsedEvent, scroller: ScrollViewProxy) -> some View {
@@ -76,18 +76,17 @@ struct EventDetailView: View {
                             thread.set_active_event(ev, privkey: damus.keypair.privkey)
                         }
                     }
-                    .onAppear() {
-                        if highlight.is_main {
-                            scroll_to_event(scroller: scroller, id: ev.id, delay: 0.5, animate: true)
-                        }
-                    }
             }
         }
     }
     
     var body: some View {
         ScrollViewReader { proxy in
-            ScrollView {
+            if thread.loading {
+                ProgressView().progressViewStyle(.circular)
+            }
+            
+            ScrollView(.vertical) {
                 let collapsed_events = calculated_collapsed_events(
                     privkey: damus.keypair.privkey,
                     collapsed: self.collapsed,
@@ -97,11 +96,26 @@ struct EventDetailView: View {
                 ForEach(collapsed_events, id: \.id) { cev in
                     CollapsedEventView(cev, scroller: proxy)
                 }
+                
+                EndBlock(height: 600)
+            }
+            .onChange(of: thread.loading) { val in
+                scroll_after_load(proxy)
+            }
+            .onAppear() {
+                scroll_after_load(proxy)
             }
         }
         .navigationBarTitle("Thread")
 
     }
+    
+    func scroll_after_load(_ proxy: ScrollViewProxy) {
+        if !thread.loading {
+            let id = thread.initial_event.id
+            scroll_to_event(scroller: proxy, id: id, delay: 0.1, animate: false)
+        }
+    }
 
     func toggle_thread_view() {
         NotificationCenter.default.post(name: .toggle_thread_view, object: nil)
@@ -273,14 +287,14 @@ func print_event(_ ev: NostrEvent) {
     print(ev.description)
 }
 
-func scroll_to_event(scroller: ScrollViewProxy, id: String, delay: Double, animate: Bool, anchor: UnitPoint = .center) {
+func scroll_to_event(scroller: ScrollViewProxy, id: String, delay: Double, animate: Bool) {
     DispatchQueue.main.asyncAfter(deadline: .now() + delay) {
         if animate {
             withAnimation {
-                scroller.scrollTo(id, anchor: anchor)
+                scroller.scrollTo(id, anchor: .top)
             }
         } else {
-            scroller.scrollTo(id, anchor: anchor)
+            scroller.scrollTo(id, anchor: .top)
         }
     }
 }