Add support for custom renderable types

README.md

@@ -32,8 +32,8 @@ It knows the following layers of UI:
 
 - An app is the entry point of the executable, containing the windows.
 - A scene element is a template for a container holding one or multiple views (e.g. a window).
-- A view is a part of the actual UI inside a window, another view or a menu.
-- A menu is a list of buttons, other menus, and views. Certain views (such as menu buttons) allow menus to be used.
+- A view is a part of the actual UI inside a window, another view, or another renderable component.
+- Custom renderable components can be used for more restrictive UI elements, such as menus.
 
 Detailed information can be found in the [docs](https://aparokshaui.github.io/meta/).
 

Sources/Meta.docc/Meta.md

@@ -14,5 +14,5 @@ It knows the following layers of UI:
 
 - An app is the entry point of the executable, containing the windows.
 - A scene element is a template for a container holding one or multiple views (e.g. a window).
-- A view is a part of the actual UI inside a window, another view or a menu.
-- A menu is a list of buttons, other menus, and views. Certain views (such as menu buttons) allow menus to be used.
+- A view is a part of the actual UI inside a window, another view, or another renderable component.
+- Custom renderable components can be used for more restrictive UI elements, such as menus.

Sources/Model/Extensions/Array.swift

@@ -36,18 +36,18 @@ extension Array: AnyView where Element == AnyView {
 
     /// Update a collection of views with a collection of view storages.
     /// - Parameters:
-    ///     - storage: The collection of view storages.
+    ///     - storages: The collection of view storages.
     ///     - modifiers: Modify views before being updated.
     ///     - updateProperties: Whether to update properties.
     ///     - type: The type of the app storage.
     public func update<Storage>(
-        _ storage: [ViewStorage],
+        _ storages: [ViewStorage],
         modifiers: [(AnyView) -> AnyView],
         updateProperties: Bool,
         type: Storage.Type
     ) where Storage: AppStorage {
         for (index, element) in filter({ $0.renderable(type: type, modifiers: modifiers) }).enumerated() {
-            if let storage = storage[safe: index] {
+            if let storage = storages[safe: index] {
                 element
                     .widget(modifiers: modifiers, type: type)
                     .updateStorage(storage, modifiers: modifiers, updateProperties: updateProperties, type: type)
@@ -114,3 +114,44 @@ extension Array where Element: Identifiable {
     }
 
 }
+
+extension Array where Element == Renderable {
+
+    /// Update a collection of renderable elements.
+    /// - Parameters:
+    ///     - storage: The collection of renderable storages.
+    ///     - updateProperties: Whether to update properties.
+    ///     - type: The type of the renderable element.
+    ///     - fields: Additional information.
+    public func update<RenderableType>(
+        _ storages: [RenderableStorage],
+        updateProperties: Bool,
+        type: RenderableType.Type,
+        fields: [String: Any]
+    ) {
+        for (index, element) in filter({ $0 as? RenderableType != nil }).enumerated() {
+            if let storage = storages[safe: index] {
+                element
+                    .update(storage, updateProperties: updateProperties, type: type, fields: fields)
+            }
+        }
+    }
+
+    /// Get the renderable storages of a collection of renderable elements.
+    /// - Parameters:
+    ///     - type: The type of the renderable element.
+    ///     - fields: Additional information.
+    /// - Returns: The storages.
+    public func storages<RenderableType>(
+        type: RenderableType.Type,
+        fields: [String: Any]
+    ) -> [RenderableStorage] {
+        compactMap { element in
+            if element as? RenderableType != nil {
+                return element.container(type: type, fields: fields)
+            }
+            return nil
+        }
+    }
+
+}

Sources/Model/User Interface/Renderable/Builder.swift

@@ -0,0 +1,68 @@
+//
+//  Builder.swift
+//  Meta
+//
+//  Created by david-swift on 03.07.24.
+//
+
+import Foundation
+
+/// The ``Builder`` is a result builder for scenes.
+@resultBuilder
+public enum Builder<RenderableType> {
+
+    /// A component used in the ``MenuBuilder``.
+    public enum Component {
+
+        /// A renderable element as a component.
+        case element(_: RenderableType)
+        /// An array of components as a component.
+        case components(_: [Self])
+
+    }
+
+    /// Build combined results from statement blocks.
+    /// - Parameter components: The components.
+    /// - Returns: The components in a component.
+    public static func buildBlock(_ elements: Component...) -> Component {
+        .components(elements)
+    }
+
+    /// Translate an element into a ``MenuBuilder.Component``.
+    /// - Parameter element: The element to translate.
+    /// - Returns: A component created from the element.
+    public static func buildExpression(_ element: RenderableType) -> Component {
+        .element(element)
+    }
+
+    /// Translate an array of elements into a ``MenuBuilder.Component``.
+    /// - Parameter elements: The elements to translate.
+    /// - Returns: A component created from the element.
+    public static func buildExpression(_ elements: [RenderableType]) -> Component {
+        var components: [Component] = []
+        for element in elements {
+            components.append(.element(element))
+        }
+        return .components(components)
+    }
+
+    /// Fetch a component.
+    /// - Parameter component: A component.
+    /// - Returns: The component.
+    public static func buildExpression(_ component: Component) -> Component {
+        component
+    }
+
+    /// Convert a component to an array of elements.
+    /// - Parameter component: The component to convert.
+    /// - Returns: The generated array of elements.
+    public static func buildFinalResult(_ component: Component) -> [RenderableType] {
+        switch component {
+        case let .element(element):
+            return [element]
+        case let .components(components):
+            return components.flatMap { buildFinalResult($0) }
+        }
+    }
+
+}

Sources/Model/User Interface/Renderable/Renderable.swift

@@ -0,0 +1,30 @@
+//
+//  Renderable.swift
+//  Meta
+//
+//  Created by david-swift on 03.07.24.
+//
+
+/// A structure conforming to `Renderable` is a more limited UI type similar to a view, e.g. a menu.
+public protocol Renderable {
+
+    /// The view storage.
+    /// - Parameters:
+    ///     - type: The type of the renderable elements.
+    ///     - fields: More information.
+    func container<RenderableType>(type: RenderableType.Type, fields: [String: Any]) -> RenderableStorage
+
+    /// Update the stored content.
+    /// - Parameters:
+    ///     - storage: The storage to update.
+    ///     - updateProperties: Whether to update the properties.
+    ///     - type: The type of the renderable elements.
+    ///     - fields:
+    func update<RenderableType>(
+        _ storage: RenderableStorage,
+        updateProperties: Bool,
+        type: RenderableType.Type,
+        fields: [String: Any]
+    )
+
+}

Sources/Model/User Interface/Renderable/RenderableStorage.swift

@@ -0,0 +1,34 @@
+//
+//  ViewStorage.swift
+//  Meta
+//
+//  Created by david-swift on 26.05.24.
+//
+
+/// Store a reference to a rendered view in a view storage.
+public class RenderableStorage {
+
+    /// The pointer.
+    ///
+    /// It can be a C pointer, a Swift class, or other information depending on the backend and renderable type.
+    public var pointer: Any?
+    /// Various properties of a widget.
+    public var fields: [String: Any] = [:]
+
+    /// The pointer as an opaque pointer, as this is may be needed with backends interoperating with C or C++.
+    public var opaquePointer: OpaquePointer? {
+        get {
+            pointer as? OpaquePointer
+        }
+        set {
+            pointer = newValue
+        }
+    }
+
+    /// Initialize a renderable storage.
+    /// - Parameter pointer: The pointer to the renderable element, its type depends on the backend.
+    public init(_ pointer: Any?, content: [String: [ViewStorage]] = [:]) {
+        self.pointer = pointer
+    }
+
+}

Sources/Model/User Interface/View/ViewStorage.swift

@@ -14,6 +14,8 @@ public class ViewStorage {
     public var pointer: Any?
     /// The view's content for container widgets.
     public var content: [String: [ViewStorage]]
+    /// The view's renderable content.
+    public var renderableContent: [String: [RenderableStorage]] = [:]
     /// The view's state (used in `StateWrapper`).
     var state: [String: StateProtocol] = [:]
     /// Various properties of a widget.

Sources/Model/User Interface/View/Widget.swift

@@ -19,6 +19,7 @@ public protocol Widget: AnyView {
         modifiers: [(AnyView) -> AnyView],
         type: Storage.Type
     ) -> ViewStorage where Storage: AppStorage
+
     /// Update the stored content.
     /// - Parameters:
     ///     - storage: The storage to update.

Tests/DemoApp/DemoApp.swift

@@ -71,6 +71,10 @@ struct TestView: View {
                 test = "\(Int.random(in: 1...10))"
             }
         }
+        Backend1.Menu("Hi") {
+            Backend1.Menu("World") {
+            }
+        }
     }
 
 }

Tests/SampleBackends/Backend1.swift

@@ -70,6 +70,39 @@ public enum Backend1 {
 
     }
 
+    public struct Menu: BackendWidget, MenuElement {
+
+        var label: String
+        var content: MenuContent
+
+        public init(_ label: String, @Builder<MenuElement> content: @escaping () -> MenuContent) {
+            self.label = label
+            self.content = content()
+        }
+
+        public func container<RenderableType>(type: RenderableType.Type, fields: [String : Any]) -> RenderableStorage {
+            .init(nil)
+        }
+
+        public func update<RenderableType>(_ storage: RenderableStorage, updateProperties: Bool, type: RenderableType.Type, fields: [String : Any]) {
+            print("Update renderable")
+        }
+
+        public func container<Storage>(modifiers: [(any AnyView) -> any AnyView], type: Storage.Type) -> ViewStorage where Storage: AppStorage {
+            let storage = ViewStorage(nil)
+            storage.renderableContent[.mainContent] = (content as [Renderable]).storages(type: MenuElement.self, fields: [:]) ?? []
+            return storage
+        }
+
+        public func update<Storage>(_ storage: ViewStorage, modifiers: [(any AnyView) -> any AnyView], updateProperties: Bool, type: Storage.Type) {
+            guard updateProperties, let content = storage.renderableContent[.mainContent] else {
+                return
+            }
+            (self.content as [Renderable]).update(content, updateProperties: updateProperties, type: MenuElement.self, fields: [:])
+        }
+
+    }
+
     public struct Window: BackendSceneElement {
 
         public var id: String
@@ -133,6 +166,10 @@ public enum Backend1 {
 
     public protocol BackendSceneElement: SceneElement { }
 
+    public protocol MenuElement: Renderable { }
+
+    public typealias MenuContent = [MenuElement]
+
     public class Backend1App: AppStorage {
 
         public typealias SceneElementType = BackendSceneElement