Layout system rewrite

Benchmarks/LayoutPerformanceBenchmark/LayoutPerformanceBenchmark.swift

@@ -10,10 +10,13 @@ protocol TestCaseView: View {
 #if BENCHMARK_VIZ
     import DefaultBackend
 
+    @MainActor
+    var visualizationSize: (width: Int?, height: Int?) = (nil, nil)
+
     struct VizApp<V: TestCaseView>: App {
         var body: some Scene {
-            WindowGroup("Benchmark visualisation") {
-                V()
+            WindowGroup("Benchmark visualization") {
+                V().frame(width: visualizationSize.width, height: visualizationSize.height)
             }
         }
     }
@@ -34,36 +37,39 @@ struct Benchmarks {
         }
 
         @MainActor
-        func updateNode<V: View>(_ node: ViewGraphNode<V, DummyBackend>, _ size: SIMD2<Int>) {
-            _ = node.update(proposedSize: size, environment: environment, dryRun: true)
-            _ = node.update(proposedSize: size, environment: environment, dryRun: false)
+        func updateNode<V: View>(_ node: ViewGraphNode<V, DummyBackend>, _ size: ProposedViewSize) {
+            _ = node.computeLayout(proposedSize: size, environment: environment)
+            _ = node.commit()
         }
 
         #if BENCHMARK_VIZ
-            var benchmarkVisualizations: [(name: String, main: () -> Never)] = []
+            var benchmarkVisualizations: [
+                (name: String, size: ProposedViewSize, main: () -> Never)
+            ] = []
         #endif
 
         @MainActor
-        func benchmarkLayout<V: TestCaseView>(of viewType: V.Type, _ size: SIMD2<Int>, _ label: String) {
+        func benchmarkLayout<V: TestCaseView>(of viewType: V.Type, _ size: ProposedViewSize, _ label: String) {
             #if BENCHMARK_VIZ
                 benchmarkVisualizations.append((
                     label,
+                    size,
                     {
                         VizApp<V>.main()
                         exit(0)
                     }
                 ))
             #else
-                let node = makeNode(V())
                 benchmark(label) { @MainActor in
+                    let node = makeNode(V())
                     updateNode(node, size)
                 }
             #endif
         }
 
         // Register benchmarks
-        benchmarkLayout(of: GridView.self, SIMD2(800, 800), "grid")
-        benchmarkLayout(of: ScrollableMessageListView.self, SIMD2(800, 800), "message list")
+        benchmarkLayout(of: GridView.self, ProposedViewSize(800, 800), "grid")
+        benchmarkLayout(of: ScrollableMessageListView.self, ProposedViewSize(800, 800), "message list")
 
         #if BENCHMARK_VIZ
             let names = benchmarkVisualizations.map(\.name).joined(separator: " | ")
@@ -82,6 +88,11 @@ struct Benchmarks {
                 exit(1)
             }
 
+            visualizationSize = (
+                benchmark.size.width.map(Int.init),
+                benchmark.size.height.map(Int.init)
+            )
+
             benchmark.main()
         #else
             await Benchmark.main()

Examples/Sources/NotesExample/ContentView.swift

@@ -130,21 +130,25 @@ struct ContentView: View {
             }
             .frame(minWidth: 200)
         } detail: {
-            ScrollView {
-                VStack(alignment: .center) {
-                    if let selectedNote = selectedNote {
-                        HStack(spacing: 4) {
-                            Text("Title")
-                            TextField("Title", text: selectedNote.title)
-                        }
+            GeometryReader { proxy in
+                ScrollView {
+                    VStack(alignment: .center) {
+                        if let selectedNote = selectedNote {
+                            HStack(spacing: 4) {
+                                Text("Title")
+                                TextField("Title", text: selectedNote.title)
+                            }
 
-                        TextEditor(text: selectedNote.content)
-                            .padding()
-                            .background(textEditorBackground)
-                            .cornerRadius(4)
+                            TextEditor(text: selectedNote.content)
+                                .padding()
+                                .background(textEditorBackground)
+                                .cornerRadius(4)
+                                .frame(maxHeight: .infinity)
+                        }
                     }
+                    .padding()
+                    .frame(minHeight: Int(proxy.size.height))
                 }
-                .padding()
             }
         }
     }

Examples/Sources/PathsExample/PathsApp.swift

@@ -23,17 +23,8 @@ struct ArcShape: StyledShape {
     }
 
     func size(fitting proposal: SIMD2<Int>) -> ViewSize {
-        let diameter = max(11, min(proposal.x, proposal.y))
-        return ViewSize(
-            size: SIMD2(x: diameter, y: diameter),
-            idealSize: SIMD2(x: 100, y: 100),
-            idealWidthForProposedHeight: proposal.y,
-            idealHeightForProposedWidth: proposal.x,
-            minimumWidth: 11,
-            minimumHeight: 11,
-            maximumWidth: nil,
-            maximumHeight: nil
-        )
+        let diameter = Double(max(11, min(proposal.x, proposal.y)))
+        return ViewSize(diameter, diameter)
     }
 }
 

Examples/Sources/WebViewExample/WebViewApp.swift

@@ -13,18 +13,26 @@ struct WebViewApp: App {
 
     @State var url = URL(string: "https://stackotter.dev")!
 
+    func go(_ url: String) {
+        guard let url = URL(string: urlInput) else {
+            return
+        }
+
+        self.url = url
+    }
+
     var body: some Scene {
         WindowGroup("WebViewExample") {
             #hotReloadable {
                 VStack {
                     HStack {
                         TextField("URL", text: $urlInput)
-                        Button("Go") {
-                            guard let url = URL(string: urlInput) else {
-                                return  // disabled
+                            .onSubmit {
+                                go(urlInput)
                             }
 
-                            self.url = url
+                        Button("Go") {
+                            go(urlInput)
                         }.disabled(URL(string: urlInput) == nil)
                     }
                     .padding()
@@ -36,5 +44,6 @@ struct WebViewApp: App {
                 }
             }
         }
+        .defaultSize(width: 800, height: 800)
     }
 }

Examples/Sources/WindowingExample/WindowingApp.swift

@@ -177,6 +177,8 @@ struct WindowingApp: App {
                     }
 
                     Image(Bundle.module.bundleURL.appendingPathComponent("Banner.png"))
+                        .resizable()
+                        .aspectRatio(contentMode: .fit)
 
                     Divider()
 

Package.swift

@@ -163,6 +163,7 @@ let package = Package(
             name: "SwiftCrossUITests",
             dependencies: [
                 "SwiftCrossUI",
+                "DummyBackend",
                 .target(name: "AppKitBackend", condition: .when(platforms: [.macOS])),
             ]
         ),

Sources/AppKitBackend/AppKitBackend.swift

@@ -31,7 +31,7 @@ public final class AppKitBackend: AppBackend {
         // We assume that all scrollers have their controlSize set to `.regular` by default.
         // The internet seems to indicate that this is true regardless of any system wide
         // preferences etc.
-        Int(
+        return Int(
             NSScroller.scrollerWidth(
                 for: .regular,
                 scrollerStyle: NSScroller.preferredScrollerStyle
@@ -523,32 +523,17 @@ public final class AppKitBackend: AppBackend {
     public func size(
         of text: String,
         whenDisplayedIn widget: Widget,
-        proposedFrame: SIMD2<Int>?,
+        proposedWidth: Int?,
+        proposedHeight: Int?,
         environment: EnvironmentValues
     ) -> SIMD2<Int> {
-        if let proposedFrame, proposedFrame.x == 0 {
-            // We want the text to have the same height as it would have if it were
-            // one pixel wide so that the layout doesn't suddely jump when the text
-            // reaches zero width.
-            let size = size(
-                of: text,
-                whenDisplayedIn: widget,
-                proposedFrame: SIMD2(1, proposedFrame.y),
-                environment: environment
-            )
-            return SIMD2(
-                0,
-                size.y
-            )
-        }
-
         let proposedSize = NSSize(
-            width: (proposedFrame?.x).map(CGFloat.init) ?? 0,
-            height: .greatestFiniteMagnitude
+            width: proposedWidth.map(Double.init) ?? .greatestFiniteMagnitude,
+            height: proposedHeight.map(Double.init) ?? .greatestFiniteMagnitude
         )
         let rect = NSString(string: text).boundingRect(
             with: proposedSize,
-            options: [.usesLineFragmentOrigin],
+            options: [.usesLineFragmentOrigin, .truncatesLastVisibleLine],
             attributes: Self.attributes(forTextIn: environment)
         )
         return SIMD2(
@@ -564,6 +549,7 @@ public final class AppKitBackend: AppBackend {
         // styles when clicked (yeah that happens...)
         field.allowsEditingTextAttributes = true
         field.isSelectable = false
+        field.cell?.truncatesLastVisibleLine = true
         return field
     }
 
@@ -2253,7 +2239,9 @@ public class NSCustomWindow: NSWindow {
             }
 
             let contentSize = sender.contentRect(
-                forFrameRect: NSRect(x: 0, y: 0, width: frameSize.width, height: frameSize.height)
+                forFrameRect: NSRect(
+                    x: sender.frame.origin.x, y: sender.frame.origin.y, width: frameSize.width,
+                    height: frameSize.height)
             )
 
             resizeHandler(

Sources/AppKitBackend/NSViewRepresentable.swift

@@ -55,7 +55,7 @@ public protocol NSViewRepresentable: View where Content == Never {
     ///   for the maximum width/height if the view has no maximum size (and
     ///   therefore may occupy the entire screen).
     func determineViewSize(
-        for proposal: SIMD2<Int>,
+        for proposal: ProposedViewSize,
         nsView: NSViewType,
         context: NSViewRepresentableContext<Coordinator>
     ) -> ViewSize
@@ -76,34 +76,16 @@ extension NSViewRepresentable {
     }
 
     public func determineViewSize(
-        for proposal: SIMD2<Int>, nsView: NSViewType,
+        for proposal: ProposedViewSize,
+        nsView: NSViewType,
         context _: NSViewRepresentableContext<Coordinator>
     ) -> ViewSize {
         let intrinsicSize = nsView.intrinsicContentSize
         let sizeThatFits = nsView.fittingSize
 
-        let roundedSizeThatFits = SIMD2(
-            Int(sizeThatFits.width.rounded(.up)),
-            Int(sizeThatFits.height.rounded(.up)))
-        let roundedIntrinsicSize = SIMD2(
-            Int(intrinsicSize.width.rounded(.awayFromZero)),
-            Int(intrinsicSize.height.rounded(.awayFromZero)))
-
         return ViewSize(
-            size: SIMD2(
-                intrinsicSize.width < 0.0 ? proposal.x : roundedSizeThatFits.x,
-                intrinsicSize.height < 0.0 ? proposal.y : roundedSizeThatFits.y
-            ),
-            // The 10 here is a somewhat arbitrary constant value so that it's always the same.
-            // See also `Color` and `Picker`, which use the same constant.
-            idealSize: SIMD2(
-                intrinsicSize.width < 0.0 ? 10 : roundedIntrinsicSize.x,
-                intrinsicSize.height < 0.0 ? 10 : roundedIntrinsicSize.y
-            ),
-            minimumWidth: max(0, roundedIntrinsicSize.x),
-            minimumHeight: max(0, roundedIntrinsicSize.x),
-            maximumWidth: nil,
-            maximumHeight: nil
+            intrinsicSize.width < 0 ? (proposal.width ?? 10) : sizeThatFits.width,
+            intrinsicSize.height < 0 ? (proposal.height ?? 10) : sizeThatFits.height
         )
     }
 }
@@ -139,15 +121,14 @@ extension View where Self: NSViewRepresentable {
         }
     }
 
-    public func update<Backend: AppBackend>(
+    public func computeLayout<Backend: AppBackend>(
         _ widget: Backend.Widget,
         children: any ViewGraphNodeChildren,
-        proposedSize: SIMD2<Int>,
+        proposedSize: ProposedViewSize,
         environment: EnvironmentValues,
-        backend: Backend,
-        dryRun: Bool
-    ) -> ViewUpdateResult {
-        guard let backend = backend as? AppKitBackend else {
+        backend: Backend
+    ) -> ViewLayoutResult {
+        guard backend is AppKitBackend else {
             fatalError("NSViewRepresentable updated by \(Backend.self)")
         }
 
@@ -160,11 +141,17 @@ extension View where Self: NSViewRepresentable {
             context: representingWidget.context!
         )
 
-        if !dryRun {
-            backend.setSize(of: representingWidget, to: size.size)
-        }
+        return ViewLayoutResult.leafView(size: size)
+    }
 
-        return ViewUpdateResult.leafView(size: size)
+    public func commit<Backend: AppBackend>(
+        _ widget: Backend.Widget,
+        children: any ViewGraphNodeChildren,
+        layout: ViewLayoutResult,
+        environment: EnvironmentValues,
+        backend: Backend
+    ) {
+        backend.setSize(of: widget, to: layout.size.vector)
     }
 }