Tidy-up FormattedBodyText and MessageBubbleLayout. (#5019)

* Tidy-up FormattedBodyText.

* Switch TimelineBubbleLayout.Priority from .layoutPriority to .layoutValue.

* Rename TimelineBubbleLayout.Priority to TimelineBubbleLayout.Size

ElementX/Sources/Screens/Timeline/View/Style/TimelineBubbleLayout.swift

@@ -20,18 +20,39 @@ struct TimelineBubbleLayout: Layout {
     /// The spacing between the components in the bubble.
     let spacing: CGFloat
     
-    /// Layout priority constants for the bubble content. These priorities are abused within
+    /// Layout size for the bubble content. These sizing types are used within
-    /// `TimelineBubbleLayout` to create the layout we would like. They aren't
+    /// `TimelineBubbleLayout` to create the layout we would like.
-    /// used in the expected way that SwiftUI would normally use layout priorities.
+    enum Size: LayoutValueKey, Equatable {
-    enum Priority {
+        static let defaultValue: Size = .natural
-        /// The priority of hidden quote bubbles/code blocks that are only used for layout calculations.
+        
-        /// Any views given this priority should be made non-greedy for the calculations to work.
+        /// Full width mode used for greedy components like blockquotes and code blocks.
-        static let hiddenGreedyComponent: Double = -1
+        enum BubbleWidthMode {
-        /// The priority of visible quote bubbles/code blocks that are placed in the view with a full width.
+            /// The view has its natural size and will be used for layout calculations only.
-        /// Any views given this priority should remain in their normal greedy form.
+            case layout
-        static let visibleGreedyComponent: Double = 0
+            /// The view has a greedy width and will fill the available space within the bubble.
-        /// The priority of regular text that is used for layout calculations and placed in the view.
+            case rendering
-        static let nonGreedyComponent: Double = 1
+        }
+        
+        /// The view will fill the available width, with different behaviour depending on the mode.
+        /// Views using the `.layout` mode should be hidden and are used only for width calculations.
+        /// Views using the `.rendering` mode should be visible and are placed to fill the bubble's calculated width.
+        case bubbleWidth(mode: BubbleWidthMode)
+        /// The view uses its natural size for both layout calculations and rendering.
+        case natural
+        
+        var shouldLayout: Bool {
+            switch self {
+            case .natural, .bubbleWidth(mode: .layout): true
+            default: false
+            }
+        }
+        
+        var shouldRender: Bool {
+            switch self {
+            case .natural, .bubbleWidth(mode: .rendering): true
+            default: false
+            }
+        }
     }
     
     func makeCache(subviews: Subviews) -> Cache {
@@ -47,7 +68,7 @@ struct TimelineBubbleLayout: Layout {
         guard !subviews.isEmpty else { return .zero }
         
         // Calculate the natural size using the regular text and non-greedy quote bubbles.
-        let layoutSubviews = subviews.filter { $0.priority != Priority.visibleGreedyComponent }
+        let layoutSubviews = subviews.filter { $0[Size.self].shouldLayout }
 
         let subviewSizes = layoutSubviews.map { size(for: $0, subviews: subviews, proposedSize: proposal, cache: &cache) }
         
@@ -62,11 +83,11 @@ struct TimelineBubbleLayout: Layout {
         guard !subviews.isEmpty else { return }
         
         // Calculate the width using the regular text along with non-greedy versions of any greedy components.
-        let layoutSubviews = subviews.filter { $0.priority != Priority.visibleGreedyComponent }
+        let layoutSubviews = subviews.filter { $0[Size.self].shouldLayout }
         let maxWidth = layoutSubviews.map { size(for: $0, subviews: subviews, proposedSize: proposal, cache: &cache).width }.reduce(0, max)
         
         // Place the regular text and greedy components using the calculated width.
-        let visibleSubviews = subviews.filter { $0.priority != Priority.hiddenGreedyComponent }
+        let visibleSubviews = subviews.filter { $0[Size.self].shouldRender }
 
         let subviewSizes = visibleSubviews.map { size(for: $0, subviews: subviews, proposedSize: ProposedViewSize(width: maxWidth, height: proposal.height), cache: &cache) }
         
@@ -101,3 +122,10 @@ struct TimelineBubbleLayout: Layout {
         return size
     }
 }
+
+extension View {
+    /// Sets the layout size for this view when placed within a `TimelineBubbleLayout`.
+    func timelineBubbleLayoutSize(_ size: TimelineBubbleLayout.Size) -> some View {
+        layoutValue(key: TimelineBubbleLayout.Size.self, value: size)
+    }
+}

ElementX/Sources/Screens/Timeline/View/Style/TimelineItemBubbledStylerView.swift

@@ -190,7 +190,7 @@ struct TimelineItemBubbledStylerView<Content: View>: View {
             if !context.viewState.timelineKind.isThread, timelineItem.properties.isThreaded {
                 ThreadDecorator()
                     .padding(.leading, 4)
-                    .layoutPriority(TimelineBubbleLayout.Priority.nonGreedyComponent)
+                    .timelineBubbleLayoutSize(.natural)
             }
             
             if let replyDetails = timelineItem.properties.replyDetails {
@@ -203,7 +203,7 @@ struct TimelineItemBubbledStylerView<Content: View>: View {
                     .frame(maxWidth: .infinity, alignment: .leading)
                     .background(Color.compound.bgCanvasDefault)
                     .cornerRadius(8)
-                    .layoutPriority(TimelineBubbleLayout.Priority.visibleGreedyComponent)
+                    .timelineBubbleLayoutSize(.bubbleWidth(mode: .rendering))
                     .onTapGesture {
                         if context.viewState.timelineKind != .pinned {
                             context.send(viewAction: .focusOnEventID(replyDetails.eventID))
@@ -214,12 +214,12 @@ struct TimelineItemBubbledStylerView<Content: View>: View {
                 TimelineReplyView(placement: .timeline, timelineItemReplyDetails: replyDetails)
                     .fixedSize(horizontal: false, vertical: true)
                     .padding(4.0)
-                    .layoutPriority(TimelineBubbleLayout.Priority.hiddenGreedyComponent)
+                    .timelineBubbleLayoutSize(.bubbleWidth(mode: .layout))
                     .hidden()
             }
             
             content()
-                .layoutPriority(TimelineBubbleLayout.Priority.nonGreedyComponent)
+                .timelineBubbleLayoutSize(.natural)
                 .cornerRadius(timelineItem.contentCornerRadius)
         }
     }

ElementX/Sources/Screens/Timeline/View/TimelineItemViews/FormattedBodyText.swift

@@ -63,14 +63,10 @@ struct FormattedBodyText: View {
     }
     
     var body: some View {
-        mainContent
-            .accessibilityElement(children: .ignore)
-            .accessibilityLabel(Text(attributedString))
-    }
-    
-    var mainContent: some View {
         layout
             .tint(.compound.textLinkExternal)
+            .accessibilityElement(children: .ignore)
+            .accessibilityLabel(Text(attributedString))
     }
     
     /// The attributed components laid out for the bubbles timeline style.
@@ -83,34 +79,11 @@ struct FormattedBodyText: View {
                 } else {
                     switch component.type {
                     case .blockquote:
-                        // The rendered blockquote with a greedy width. The custom layout prevents the
+                        BlockquoteView(attributedString: component.attributedString, mode: .rendering)
-                        // infinite width from increasing the overall width of the view.
+                            .timelineBubbleLayoutSize(.bubbleWidth(mode: .rendering))
-                        MessageText(attributedString: component.attributedString.mergingAttributes(blockquoteAttributes))
-                            .fixedSize(horizontal: false, vertical: true)
-                            .frame(maxWidth: .infinity, alignment: .leading)
-                            .padding(.leading, 12.0)
-                            .overlay(alignment: .leading) {
-                                // User an overlay here so that the rectangle's infinite height doesn't take priority
-                                Capsule()
-                                    .frame(width: 2.0)
-                                    .padding(.leading, 5.0)
-                                    .foregroundColor(.compound.textSecondary)
-                                    .padding(.vertical, 2)
-                            }
-                            .layoutPriority(TimelineBubbleLayout.Priority.visibleGreedyComponent)
                     case .codeBlock:
-                        // The rendered codeblock with a greedy width (due to the scroll view). The custom
+                        CodeBlockView(attributedString: component.attributedString, mode: .rendering)
-                        // layout prevents the scroll view from increasing the overall width of the view.
+                            .timelineBubbleLayoutSize(.bubbleWidth(mode: .rendering))
-                        ScrollView(.horizontal) {
-                            MessageText(attributedString: component.attributedString)
-                                .padding([.horizontal, .top], 4)
-                                .padding(.bottom, 8)
-                        }
-                        .background(.compound._bgCodeBlock)
-                        .scrollBounceBehavior(.basedOnSize, axes: .horizontal)
-                        .scrollIndicatorsFlash(onAppear: true)
-                        .padding(.horizontal, 4)
-                        .layoutPriority(TimelineBubbleLayout.Priority.visibleGreedyComponent)
                             .contextMenu {
                                 Button(L10n.actionCopy) {
                                     UIPasteboard.general.string = component.attributedString.string
@@ -120,24 +93,22 @@ struct FormattedBodyText: View {
                         MessageText(attributedString: component.attributedString)
                             .padding(.horizontal, 4)
                             .fixedSize(horizontal: false, vertical: true)
-                            .layoutPriority(TimelineBubbleLayout.Priority.nonGreedyComponent)
+                            .timelineBubbleLayoutSize(.natural)
                     }
                 }
             }
             
-            // Make a second iteration through the components adding fixed width blockquotes/codeblocks
+            // Make a second iteration through the components adding naturally sized versions of the
-            // which are used for layout calculations but won't be rendered.
+            // block quotes and code blocks which are used for layout calculations but won't be rendered.
             ForEach(attributedComponents) { component in
                 switch component.type {
                 case .blockquote:
-                    MessageText(attributedString: component.attributedString.mergingAttributes(blockquoteAttributes))
+                    BlockquoteView(attributedString: component.attributedString, mode: .layout)
-                        .fixedSize(horizontal: false, vertical: true)
+                        .timelineBubbleLayoutSize(.bubbleWidth(mode: .layout))
-                        .padding(.leading, 12.0)
-                        .layoutPriority(TimelineBubbleLayout.Priority.hiddenGreedyComponent)
                         .hidden()
                 case .codeBlock:
-                    HiddenCodeBlockScrollView(attributedString: component.attributedString)
+                    CodeBlockView(attributedString: component.attributedString, mode: .layout)
-                        .layoutPriority(TimelineBubbleLayout.Priority.hiddenGreedyComponent)
+                        .timelineBubbleLayoutSize(.bubbleWidth(mode: .layout))
                         .hidden()
                 case .plainText:
                     EmptyView()
@@ -146,6 +117,33 @@ struct FormattedBodyText: View {
         }
     }
     
+    // MARK: - Component Views
+    
+    /// The view used to render a blockquote component. It can be configured in one of 2 modes:
+    /// - `.layout`: The view is given it's natural size to be used for layout calculations.
+    /// - `.rendering`: The view has a greedy width that, in combination with the custom layout,
+    /// will fill any available space, whilst remaining constrained by the bubble's calculated width.
+    struct BlockquoteView: View {
+        let attributedString: AttributedString
+        let mode: TimelineBubbleLayout.Size.BubbleWidthMode
+        
+        var body: some View {
+            MessageText(attributedString: attributedString.mergingAttributes(blockquoteAttributes))
+                .fixedSize(horizontal: false, vertical: true)
+                .frame(maxWidth: mode == .rendering ? .infinity : nil, alignment: .leading)
+                .padding(.leading, 12.0)
+                .overlay(alignment: .leading) {
+                    // Use an overlay here so that the rectangle's infinite height doesn't take priority
+                    if mode == .rendering {
+                        Capsule()
+                            .frame(width: 2.0)
+                            .padding(.leading, 5.0)
+                            .foregroundColor(.compound.textSecondary)
+                            .padding(.vertical, 2)
+                    }
+                }
+        }
+        
         private var blockquoteAttributes: AttributeContainer {
             // The paragraph style removes the block style paragraph that the parser adds by default
             // Set directly in the constructor to avoid `Conformance to 'Sendable'` warnings
@@ -156,23 +154,29 @@ struct FormattedBodyText: View {
             
             return container
         }
+    }
     
-    /// A self-sizing version of the code block component's view, necessary
+    /// The view used to render a code block component. It can be configured in one of 2 modes:
-    /// because unlike quote bubbles, code blocks don't wrap when the space
+    /// - `.layout`: The view is given it's natural size to be used for layout calculations.
-    /// is constrained.
+    /// - `.rendering`: The view has a greedy width that, in combination with the custom layout,
-    private struct HiddenCodeBlockScrollView: View {
+    /// will fill any available space, whilst remaining constrained by the bubble's calculated width.
+    private struct CodeBlockView: View {
         let attributedString: AttributedString
+        let mode: TimelineBubbleLayout.Size.BubbleWidthMode
         
-        @State private var maxSize: CGSize = .zero
+        @State private var maxWidth: CGFloat = .zero
         
         var body: some View {
             ScrollView(.horizontal) {
                 MessageText(attributedString: attributedString)
                     .padding([.horizontal, .top], 4)
                     .padding(.bottom, 8)
-                    .onGeometryChange(for: CGSize.self) { $0.size } action: { maxSize = $0 }
+                    .onGeometryChange(for: CGFloat.self) { $0.size.width } action: { maxWidth = $0 }
             }
-            .frame(maxWidth: maxSize.width)
+            .frame(maxWidth: mode == .layout ? maxWidth : nil)
+            .background(.compound._bgCodeBlock)
+            .scrollBounceBehavior(.basedOnSize, axes: .horizontal)
+            .scrollIndicatorsFlash(onAppear: true)
             .padding(.horizontal, 4)
         }
     }