Fix compose reply view not working after ContentTextView refactor, use named CoordinateSpace for calculating scroll offset in reply avatar view

Tusker/Screens/Compose/ComposeReplyContentView.swift

@@ -23,6 +23,7 @@ struct ComposeReplyContentView: UIViewRepresentable {
         view.setTextFrom(status: status)
         view.isUserInteractionEnabled = false
         view.backgroundColor = .clear
+        view.setContentCompressionResistancePriority(.defaultLow, for: .horizontal)
         
         return view
     }

Tusker/Screens/Compose/ComposeReplyView.swift

@@ -11,8 +11,8 @@ import SwiftUI
 struct ComposeReplyView: View {
     let status: StatusMO
     let stackPadding: CGFloat
-    let outerMinY: CGFloat
     
+    @State private var displayNameHeight: CGFloat?
     @State private var contentHeight: CGFloat?
     
     @ObservedObject private var preferences = Preferences.shared
@@ -37,23 +37,25 @@ struct ComposeReplyView: View {
 
                     Spacer()
                 }
-
-                ComposeReplyContentView(status: status) { (newHeight) in
-                    self.contentHeight = newHeight
+                .background(GeometryReader { proxy in
+                    Color.clear
+                        .preference(key: DisplayNameHeightPrefKey.self, value: proxy.size.height)
+                        .onPreferenceChange(DisplayNameHeightPrefKey.self) { newValue in
+                            displayNameHeight = newValue
+                        }
+                })
+ 
+                ComposeReplyContentView(status: status) { newHeight in
+                    contentHeight = newHeight
                 }
-                    .offset(x: -4, y: -8)
-                    .padding(.bottom, -8)
+                .frame(height: contentHeight ?? 0)
             }
-            .frame(height: max(50, contentHeight ?? 0) + 8)
         }
-        .padding(.bottom, -8)
     }
     
     private func replyAvatarImage(geometry: GeometryProxy) -> some View {
-        // using named coordinate spaces produces an incorrect scroll offset on iOS 13,
-        // so simply compare the geometry inside and outside the scroll view in the global coordinate space
-        let scrollOffset = outerMinY - geometry.frame(in: .global).minY
-        
+        let scrollOffset = -geometry.frame(in: .named(ComposeView.coordinateSpaceOutsideOfScrollView)).minY
+
         // add stackPadding so that the image is always at least stackPadding away from the top
         var offset = scrollOffset + stackPadding
         
@@ -61,7 +63,7 @@ struct ComposeReplyView: View {
         offset = max(offset, 0)
         
         // subtract 50, because we care about where the bottom of the view is but the offset is relative to the top of the view
-        let maxOffset = (contentHeight ?? 0) - 50
+        let maxOffset = (contentHeight ?? 0) + (displayNameHeight ?? 0) - 50
         
         // once you scroll past the in-reply-to-content, the bottom of the avatar should be pinned to the bottom of the content
         offset = min(offset, maxOffset)
@@ -74,6 +76,13 @@ struct ComposeReplyView: View {
     
 }
 
+private struct DisplayNameHeightPrefKey: PreferenceKey {
+    static var defaultValue: CGFloat = 0
+    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) {
+        value = nextValue()
+    }
+}
+
 //struct ComposeReplyView_Previews: PreviewProvider {
 //    static var previews: some View {
 //        ComposeReplyView()

Tusker/Screens/Compose/ComposeView.swift

@@ -42,6 +42,8 @@ import Combine
 }
 
 struct ComposeView: View {
+    static let coordinateSpaceOutsideOfScrollView = "coordinateSpaceOutsideOfScrollView"
+    
     @ObservedObject var draft: Draft
     @EnvironmentObject var mastodonController: MastodonController
     @EnvironmentObject var uiState: ComposeUIState
@@ -77,20 +79,12 @@ struct ComposeView: View {
     }
     
     var body: some View {
-        mostOfTheBody.toolbar {
-            ToolbarItem(placement: .cancellationAction) { cancelButton }
-            ToolbarItem(placement: .confirmationAction) { postButton }
-        }
-    }
-    
-    var mostOfTheBody: some View {
         ZStack(alignment: .top) {
-            GeometryReader { (outer) in
-                ScrollView(.vertical) {
-                    mainStack(outerMinY: outer.frame(in: .global).minY)
-                }
-                .scrollDismissesKeyboardInteractivelyIfAvailable()
+            ScrollView(.vertical) {
+                mainStack
             }
+            .coordinateSpace(name: ComposeView.coordinateSpaceOutsideOfScrollView)
+            .scrollDismissesKeyboardInteractivelyIfAvailable()
             
             if let poster = poster {
                 // can't use SwiftUI.ProgressView because there's no UIProgressView.Style.bar equivalent, see FB8587149
@@ -108,6 +102,10 @@ struct ComposeView: View {
                 dismissButton: .default(Text("OK"))
             )
         }
+        .toolbar {
+            ToolbarItem(placement: .cancellationAction) { cancelButton }
+            ToolbarItem(placement: .confirmationAction) { postButton }
+        }
     }
     
     @ViewBuilder
@@ -122,14 +120,13 @@ struct ComposeView: View {
         .animation(.default, value: uiState.autocompleteState)
     }
     
-    func mainStack(outerMinY: CGFloat) -> some View {
+    var mainStack: some View {
         VStack(alignment: .leading, spacing: 8) {
             if let id = draft.inReplyToID,
                let status = mastodonController.persistentContainer.status(for: id) {
                 ComposeReplyView(
                     status: status,
-                    stackPadding: stackPadding,
-                    outerMinY: outerMinY
+                    stackPadding: stackPadding
                 )
             }