Controls, environment, observation, and the first gallery screens

AndroidSwiftUICore/Package.swift

@@ -8,7 +8,7 @@ import PackageDescription
 // ClassicUI-style desktop renderer it shares its design with).
 let package = Package(
     name: "AndroidSwiftUICore",
-    platforms: [.macOS(.v13)],
+    platforms: [.macOS(.v14)],
     products: [
         .library(name: "AndroidSwiftUICore", targets: ["AndroidSwiftUICore"])
     ],

AndroidSwiftUICore/Sources/AndroidSwiftUICore/Environment.swift

@@ -0,0 +1,82 @@
+//
+//  Environment.swift
+//  AndroidSwiftUICore
+//
+//  Object environment: values flow DOWN the evaluation (they shape body
+//  evaluation) and never cross the bridge. `@Environment(Model.self)` reads an
+//  object a parent injected with `.environment(model)`.
+//
+
+/// Per-subtree environment values, keyed by object type.
+public struct EnvironmentStorage {
+
+    var objects: [ObjectIdentifier: AnyObject] = [:]
+
+    public init() {}
+
+    mutating func set(_ object: AnyObject) {
+        objects[ObjectIdentifier(type(of: object))] = object
+    }
+
+    func object<T: AnyObject>(of type: T.Type) -> T? {
+        objects[ObjectIdentifier(type)] as? T
+    }
+}
+
+/// Reads an object from the environment.
+@propertyWrapper
+public struct Environment<Value: AnyObject> {
+
+    internal let box = EnvironmentBox<Value>()
+
+    public init(_ type: Value.Type) {}
+
+    public var wrappedValue: Value {
+        guard let value = box.value else {
+            fatalError("@Environment(\(Value.self).self) read before injection — missing .environment(_:)?")
+        }
+        return value
+    }
+}
+
+internal final class EnvironmentBox<Value: AnyObject> {
+    var value: Value?
+}
+
+/// Type-erased injection hook, discovered via the reflection seam.
+public protocol _EnvironmentProperty {
+    func _inject(from storage: EnvironmentStorage)
+}
+
+extension Environment: _EnvironmentProperty {
+    public func _inject(from storage: EnvironmentStorage) {
+        box.value = storage.object(of: Value.self)
+    }
+}
+
+/// The `.environment(_:)` wrapper: sets an object for the subtree.
+public struct _EnvironmentWriterView<Content: View>: View {
+
+    internal let object: AnyObject
+    internal let content: Content
+
+    public typealias Body = Never
+}
+
+public extension View {
+    func environment<T: AnyObject>(_ object: T) -> _EnvironmentWriterView<Self> {
+        _EnvironmentWriterView(object: object, content: self)
+    }
+}
+
+/// Injects environment values into a view's `@Environment` properties.
+public enum EnvironmentInjector {
+
+    public static func inject(_ storage: EnvironmentStorage, into view: any View) {
+        for child in Mirror(reflecting: view).children {
+            if let property = child.value as? _EnvironmentProperty {
+                property._inject(from: storage)
+            }
+        }
+    }
+}

AndroidSwiftUICore/Sources/AndroidSwiftUICore/Evaluator.swift

@@ -14,22 +14,44 @@ public struct ResolveContext {
 
     public let storage: StateStorage
     public let callbacks: CallbackRegistry
+    public var environment: EnvironmentStorage
     public var path: String
     public var depth: Int
 
-    public init(storage: StateStorage, callbacks: CallbackRegistry, path: String = "", depth: Int = 0) {
+    public init(
+        storage: StateStorage,
+        callbacks: CallbackRegistry,
+        environment: EnvironmentStorage = EnvironmentStorage(),
+        path: String = "",
+        depth: Int = 0
+    ) {
         self.storage = storage
         self.callbacks = callbacks
+        self.environment = environment
         self.path = path
         self.depth = depth
     }
 
     /// Context for a child at a structurally stable position.
     public func descending(_ component: String) -> ResolveContext {
-        ResolveContext(storage: storage, callbacks: callbacks, path: path + "/" + component, depth: depth + 1)
+        var context = self
+        context.path += "/" + component
+        context.depth += 1
+        return context
     }
 }
 
+/// Type-erased access to the environment-writer wrapper.
+internal protocol _AnyEnvironmentWriter {
+    var _object: AnyObject { get }
+    var _content: any View { get }
+}
+
+extension _EnvironmentWriterView: _AnyEnvironmentWriter {
+    var _object: AnyObject { object }
+    var _content: any View { content }
+}
+
 // MARK: - Primitive / dispatch protocols
 
 /// A view that resolves directly to a node (leaf or container).
@@ -78,9 +100,14 @@ public enum Evaluator {
             return primitive._render(in: context)
         case let anyView as AnyView:
             return resolve(anyView.storage, context.descending("any"))
+        case let writer as _AnyEnvironmentWriter:
+            var child = context.descending("env")
+            child.environment.set(writer._object)
+            return resolve(writer._content, child)
         default:
             let child = context.descending("\(type(of: view))")
             child.storage.install(in: view, path: child.path)
+            EnvironmentInjector.inject(child.environment, into: view)
             return resolve(body(of: view), child)
         }
     }
@@ -113,6 +140,10 @@ public enum Evaluator {
             }
         case let anyView as AnyView:
             flatten(anyView.storage, into: &nodes, context: context.descending("any"))
+        case let writer as _AnyEnvironmentWriter:
+            var child = context.descending("env")
+            child.environment.set(writer._object)
+            flatten(writer._content, into: &nodes, context: child)
         default:
             nodes.append(resolve(view, context))
         }

AndroidSwiftUICore/Sources/AndroidSwiftUICore/Modifiers/Modifiers.swift

@@ -104,3 +104,79 @@ public extension View {
         modifier(_BackgroundColorModifier(color: color))
     }
 }
+
+// MARK: - Corner radius
+
+public struct _CornerRadiusModifier: RenderModifier {
+    let radius: Double
+    public var _modifierNode: ModifierNode {
+        ModifierNode(kind: "cornerRadius", args: ["radius": .double(radius)])
+    }
+}
+
+public extension View {
+    func cornerRadius(_ radius: Double) -> ModifiedContent<Self, _CornerRadiusModifier> {
+        modifier(_CornerRadiusModifier(radius: radius))
+    }
+}
+
+// MARK: - Offset
+
+public struct _OffsetModifier: RenderModifier {
+    let x: Double
+    let y: Double
+    public var _modifierNode: ModifierNode {
+        ModifierNode(kind: "offset", args: ["x": .double(x), "y": .double(y)])
+    }
+}
+
+public extension View {
+    func offset(x: Double = 0, y: Double = 0) -> ModifiedContent<Self, _OffsetModifier> {
+        modifier(_OffsetModifier(x: x, y: y))
+    }
+}
+
+// MARK: - Rotation
+
+public struct _RotationModifier: RenderModifier {
+    let degrees: Double
+    public var _modifierNode: ModifierNode {
+        ModifierNode(kind: "rotation", args: ["degrees": .double(degrees)])
+    }
+}
+
+public extension View {
+    func rotationEffect(_ angle: Angle) -> ModifiedContent<Self, _RotationModifier> {
+        modifier(_RotationModifier(degrees: angle.degrees))
+    }
+}
+
+// MARK: - Scale
+
+public struct _ScaleModifier: RenderModifier {
+    let scale: Double
+    public var _modifierNode: ModifierNode {
+        ModifierNode(kind: "scale", args: ["scale": .double(scale)])
+    }
+}
+
+public extension View {
+    func scaleEffect(_ scale: Double) -> ModifiedContent<Self, _ScaleModifier> {
+        modifier(_ScaleModifier(scale: scale))
+    }
+}
+
+// MARK: - Opacity
+
+public struct _OpacityModifier: RenderModifier {
+    let opacity: Double
+    public var _modifierNode: ModifierNode {
+        ModifierNode(kind: "opacity", args: ["opacity": .double(opacity)])
+    }
+}
+
+public extension View {
+    func opacity(_ opacity: Double) -> ModifiedContent<Self, _OpacityModifier> {
+        modifier(_OpacityModifier(opacity: opacity))
+    }
+}

AndroidSwiftUICore/Sources/AndroidSwiftUICore/Primitives/Picker.swift

@@ -0,0 +1,61 @@
+//
+//  Picker.swift
+//  AndroidSwiftUICore
+//
+
+/// Associates a selection value with a picker row.
+public struct _TagModifier: RenderModifier {
+    let value: String
+    public var _modifierNode: ModifierNode {
+        ModifierNode(kind: "tag", args: ["value": .string(value)])
+    }
+}
+
+public extension View {
+    func tag<V: Hashable>(_ value: V) -> ModifiedContent<Self, _TagModifier> {
+        modifier(_TagModifier(value: identityString(value)))
+    }
+}
+
+/// A control for selecting one of several tagged options.
+///
+/// Selection values round-trip the bridge as strings, so they must be
+/// `LosslessStringConvertible` (String and Int both are).
+public struct Picker<SelectionValue: Hashable & LosslessStringConvertible, Content: View>: View {
+
+    internal let title: String
+    internal let selection: Binding<SelectionValue>
+    internal let content: Content
+
+    public init<S: StringProtocol>(
+        _ title: S,
+        selection: Binding<SelectionValue>,
+        @ViewBuilder content: () -> Content
+    ) {
+        self.title = String(title)
+        self.selection = selection
+        self.content = content()
+    }
+
+    public typealias Body = Never
+}
+
+extension Picker: PrimitiveView {
+    public func _render(in context: ResolveContext) -> RenderNode {
+        let binding = selection
+        let callbackID = context.callbacks.register(.string { raw in
+            guard let value = SelectionValue(raw) else { return }
+            binding.wrappedValue = value
+        })
+        return RenderNode(
+            type: "Picker",
+            id: context.path,
+            props: [
+                "title": .string(title),
+                "selection": .string(identityString(selection.wrappedValue)),
+                "onChange": .int(Int(callbackID)),
+            ],
+            children: Evaluator.resolveChildren(content, context.descending("content"))
+        )
+    }
+}

AndroidSwiftUICore/Sources/AndroidSwiftUICore/Primitives/Text.swift

@@ -16,6 +16,10 @@ public struct Text: View {
         self.content = String(content)
     }
 
+    public init(verbatim content: String) {
+        self.content = content
+    }
+
     public typealias Body = Never
 }