Update ComposeView content and Compose function to return a value.

See comments in ComposeView for explanation

README.md

@@ -79,6 +79,7 @@ class V: View {
             } else {
                 Text("Goodbye!").Compose(context: composectx)
             }
+            ComposeResult.ok
         }
     }
 
@@ -188,6 +189,7 @@ VStack {
     Text("Hello from SwiftUI")
     ComposeView { _ in
         androidx.compose.material3.Text("Hello from Compose")
+        return .ok
     }
 }
 ```
@@ -196,10 +198,11 @@ Skip also enhances all SwiftUI views with a `Compose()` method, allowing you to
 
 ```swift
 ComposeView { context in 
-    androidx.compose.foundation.layout.Column {
+    androidx.compose.foundation.layout.Column(modifier: context.modifier) {
         Text("Hello from SwiftUI").Compose(context: context.content())
         androidx.compose.material3.Text("Hello from Compose")
     }
+    return .ok
 }
 ```
 
@@ -210,7 +213,7 @@ ComposeView { context in
     VStack {
         Text("Hello from SwiftUI").Compose(context: context.content())
         androidx.compose.material3.Text("Hello from Compose")
-    }.Compose(context: context.content())
+    }.Compose(context: context) // Returns .ok
 }
 ```
 

Sources/SkipUI/SkipUI/Compose/ComposeContainer.swift

@@ -73,5 +73,4 @@ import androidx.compose.ui.Modifier
         content(modifier)
     }
 }
-
 #endif

Sources/SkipUI/SkipUI/Compose/ComposeContext.swift

@@ -30,12 +30,20 @@ public struct ComposeContext {
     }
 }
 
+/// The result of composing content.
+///
+/// Reserved for future use. Having a return value also expands recomposition scope. See `ComposeView` for details.
+public struct ComposeResult {
+    public static let ok = ComposeResult()
+}
+
 /// Mechanism for a parent view to change how a child view is composed.
 public protocol Composer {
     /// Called before a `ComposeView` composes its content.
-    ///
-    /// Reset state gathered during sibling view composition.
-    public func reset()
+    public func willCompose()
+
+    /// Called after a `ComposeView` composes its content.
+    public func didCompose(result: ComposeResult)
 
     /// Compose the given view.
     ///
@@ -44,32 +52,25 @@ public protocol Composer {
 }
 
 extension Composer {
-    public func reset() {
+    public func willCompose() {
+    }
+
+    public func didCompose(result: ComposeResult) {
     }
 }
 
 /// Builtin composer that executes a closure to compose.
 ///
 /// - Warning: Child composables may recompose at any time. Be careful with relying on block capture.
 struct ClosureComposer: Composer {
-    private let resetClosure: () -> Void
-    private let composeClosure: @Composable (inout View, (Bool) -> ComposeContext) -> Void
-
-    init(reset: () -> Void, compose: @Composable (inout View, (Bool) -> ComposeContext) -> Void) {
-        self.resetClosure = reset
-        self.composeClosure = compose
-    }
-
-    convenience init(compose: @Composable (inout View, (Bool) -> ComposeContext) -> Void) {
-        self.init(reset: {}, compose: compose)
-    }
+    private let compose: @Composable (inout View, (Bool) -> ComposeContext) -> Void
 
-    override func reset() {
-        resetClosure()
+    init(compose: @Composable (inout View, (Bool) -> ComposeContext) -> Void) {
+        self.compose = compose
     }
 
     @Composable override func Compose(view: inout View, context: (Bool) -> ComposeContext) {
-        composeClosure(&view, context)
+        compose(&view, context)
     }
 }
 

Sources/SkipUI/SkipUI/Compose/ComposeView.swift

@@ -9,19 +9,28 @@ import androidx.compose.runtime.Composable
 ///
 /// Used to wrap the content of SwiftUI `@ViewBuilders`, and may be used manually to embed raw Compose code.
 public struct ComposeView: View {
-    private let content: @Composable (ComposeContext) -> Void
+    private let content: @Composable (ComposeContext) -> ComposeResult
 
-    public init(content: @Composable (ComposeContext) -> Void) {
+    /// Constructor
+    ///
+    /// The supplied `content` is the content to compose. When transpiling SwiftUI code, this is the logic embedded in the user's `body` and within each container view in
+    /// that `body`, as well as within other `@ViewBuilders`.
+    ///
+    /// - Note: Returning a result from `content` is important. This prevents Compose from recomposing `content` on its own. Instead, a change that would recompose
+    ///   `content` elevates to our void `ComposeContent` function. This allows us to prepare for recompositions, e.g. making the proper callbacks to the context's `composer`.
+    public init(content: @Composable (ComposeContext) -> ComposeResult) {
         self.content = content
     }
 
-    @Composable public override func Compose(context: ComposeContext) {
-        context.composer?.reset()
+    @Composable public override func Compose(context: ComposeContext) -> ComposeResult {
         ComposeContent(context)
+        return .ok
     }
 
     @Composable public override func ComposeContent(context: ComposeContext) {
-        content(context)
+        context.composer?.willCompose()
+        let result = content(context)
+        context.composer?.didCompose(result: result)
     }
 }
 #endif

Sources/SkipUI/SkipUI/Containers/Group.swift

@@ -15,11 +15,12 @@ public struct Group<Content> : View where Content : View {
 
     #if SKIP
     @Composable public override func ComposeContent(context: ComposeContext) {
-        content.Compose(context: context)
+        let _ = content.Compose(context: context)
     }
 
-    @Composable public override func Compose(context: ComposeContext) {
+    @Composable public override func Compose(context: ComposeContext) -> ComposeResult {
         ComposeContent(context: context)
+        return .ok
     }
     #else
     public var body: some View {

Sources/SkipUI/SkipUI/Containers/List.swift

@@ -114,7 +114,7 @@ public struct List<SelectionValue, Content> : View where SelectionValue: Hashabl
     private static let verticalInset = 32.0
     private static let minimumItemHeight = 44.0
     private static let horizontalItemInset = 16.0
-    private static let verticalItemInset = 4.0
+    private static let verticalItemInset = 6.0
 
     @Composable private func ComposeItem(view: inout View, context: ComposeContext, style: ListStyle) {
         let contentModifier = Modifier.padding(horizontal: Self.horizontalItemInset.dp, vertical: Self.verticalItemInset.dp).fillWidth().requiredHeightIn(min: Self.minimumItemHeight.dp)

Sources/SkipUI/SkipUI/Containers/Navigation.swift

@@ -408,7 +408,7 @@ public struct NavigationLink : View, ListItemAdapting {
 
     #if SKIP
     @Composable public override func ComposeContent(context: ComposeContext) {
-        label.Compose(context: context.content(modifier: NavigationModifier(context.modifier)))
+        let _ = label.Compose(context: context.content(modifier: NavigationModifier(context.modifier)))
     }
 
     @Composable func shouldComposeListItem() -> Bool {

Sources/SkipUI/SkipUI/Containers/TabView.swift

@@ -129,7 +129,7 @@ struct TabItem: View {
     }
 
     @Composable public override func ComposeContent(context: ComposeContext) {
-        view.Compose(context: context)
+        let _ = view.Compose(context: context)
     }
 
     @Composable func ComposeTitle(context: ComposeContext) {
@@ -163,7 +163,7 @@ class TabIndexComposer: Composer {
         self.index = index
     }
 
-    override func reset() {
+    override func willCompose() {
         currentIndex = 0
     }
 

Sources/SkipUI/SkipUI/Containers/VStack.swift

@@ -5,9 +5,7 @@
 #if SKIP
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.IntrinsicSize
-import androidx.compose.foundation.layout.padding
-import androidx.compose.foundation.layout.width
+import androidx.compose.foundation.layout.height
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.unit.dp
@@ -55,16 +53,8 @@ public struct VStack<Content> : View where Content : View {
             contentContext = context.content()
             columnArrangement = Arrangement.spacedBy(spacing.dp)
         } else {
-            contentContext = context.content()
-            columnArrangement = Arrangement.spacedBy(Self.defaultSpacing.dp)
-
-//            var lastViewWasText: Bool? = nil
-//            contentContext = context.content(composer: { view, context in
-//                lastViewWasText = ComposeDefaultSpacedItem(view: &view, context: context, lastViewWasText: lastViewWasText)
-//            })
-//            //~~~
-////            columnArrangement = Arrangement.Center
-//            columnArrangement = Arrangement.spacedBy(Self.defaultSpacing.dp)
+            contentContext = context.content(composer: VStackComposer())
+            columnArrangement = Arrangement.spacedBy(0.dp)
         }
         ComposeContainer(modifier: context.modifier) { modifier in
             Column(modifier: modifier, verticalArrangement: columnArrangement, horizontalAlignment: columnAlignment) {
@@ -77,30 +67,38 @@ public struct VStack<Content> : View where Content : View {
             }
         }
     }
+    #else
+    public var body: some View {
+        stubView()
+    }
+    #endif
+}
 
+#if SKIP
+class VStackComposer: Composer {
     private static let defaultSpacing = 8.0
     // SwiftUI spaces adaptively based on font, etc, but this is at least closer to SwiftUI than our defaultSpacing
     private static let textSpacing = 1.0
 
-//    @Composable private func ComposeDefaultSpacedItem(view: inout View, context: ComposeContext, lastViewWasText: Bool?) -> Bool {
-//        // If the Text has spacing modifiers, no longer special case its spacing
-//        let isText = view.strippingModifiers(until: { $0 == .spacing }) { $0 is Text }
-//        //~~~
-//        if let lastViewWasText {
-//            let spacing = lastViewWasText && isText ? Self.textSpacing : Self.defaultSpacing
-//            let modifier = Modifier.padding(top: spacing.dp).then(context.modifier)
-//            view.ComposeContent(context: context.content(modifier: modifier))
-//        } else {
-//            view.ComposeContent(context: context)
-//        }
-//        return isText
-//    }
-    #else
-    public var body: some View {
-        stubView()
+    private var lastViewWasText: Bool? = nil
+
+    override func willCompose() {
+        lastViewWasText = nil
+    }
+
+    @Composable override func Compose(view: inout View, context: (Bool) -> ComposeContext) {
+        // If the Text has spacing modifiers, no longer special case its spacing
+        let isText = view.strippingModifiers(until: { $0 == .spacing }) { $0 is Text }
+        var contentContext = context(false)
+        if let lastViewWasText {
+            let spacing = lastViewWasText && isText ? Self.textSpacing : Self.defaultSpacing
+            androidx.compose.foundation.layout.Spacer(modifier: Modifier.height(spacing.dp))
+        }
+        view.ComposeContent(context: contentContext)
+        lastViewWasText = isText
     }
-    #endif
 }
+#endif
 
 #if !SKIP
 

Sources/SkipUI/SkipUI/Text/Label.swift

@@ -73,13 +73,13 @@ public struct Label : View, ListItemAdapting {
     }
 
     /// Compose only the title of this label.
-    @Composable func ComposeTitle(context: ComposeContext) {
-        title.Compose(context: context)
+    @Composable func ComposeTitle(context: ComposeContext) -> ComposeResult {
+        return title.Compose(context: context)
     }
 
     /// Compose only the image of this label.
-    @Composable func ComposeImage(context: ComposeContext) {
-        image.Compose(context: context)
+    @Composable func ComposeImage(context: ComposeContext) -> ComposeResult {
+        return image.Compose(context: context)
     }
 
     @Composable func shouldComposeListItem() -> Bool {

Sources/SkipUI/SkipUI/View/View.swift

@@ -39,12 +39,12 @@ public protocol View {
 #if SKIP
 extension View {
     /// Compose this view without an existing context - typically called when integrating a SwiftUI view tree into pure Compose.
-    @Composable public func Compose() {
-        Compose(context: ComposeContext())
+    @Composable public func Compose() -> ComposeResult {
+        return Compose(context: ComposeContext())
     }
 
     /// Calls to `Compose` are added by the transpiler.
-    @Composable public func Compose(context: ComposeContext) {
+    @Composable public func Compose(context: ComposeContext) -> ComposeResult {
         if let composer = context.composer {
             composer.Compose(view: &self, context: { retain in
                 guard !retain else {
@@ -57,6 +57,7 @@ extension View {
         } else {
             ComposeContent(context: context)
         }
+        return .ok
     }
 
     /// Compose this view's content.

Tests/SkipUITests/CanvasTests.swift

@@ -75,6 +75,7 @@ final class CanvasTests: XCSnapshotTestCase {
             androidx.compose.foundation.layout.Box(modifier: androidx.compose.ui.Modifier.background(androidx.compose.ui.graphics.Color.White).size(12.dp), contentAlignment: androidx.compose.ui.Alignment.Center) {
                 androidx.compose.foundation.layout.Box(modifier: androidx.compose.ui.Modifier.background(androidx.compose.ui.graphics.Color.Black).size(6.dp, 6.dp))
             }
+            return .ok
         })).pixmap,
         plaf("""
         F F F F F F F F F F F F
@@ -101,6 +102,7 @@ final class CanvasTests: XCSnapshotTestCase {
             androidx.compose.foundation.layout.Box(modifier: androidx.compose.ui.Modifier.size(12.dp).background(androidx.compose.ui.graphics.Color.White), contentAlignment: androidx.compose.ui.Alignment.Center) {
                 androidx.compose.foundation.layout.Box(modifier: androidx.compose.ui.Modifier.size(6.dp, 6.dp).background(androidx.compose.ui.graphics.Color.Black))
             }
+            return .ok
         })).pixmap,
         plaf("""
         F F F F F F F F F F F F