Add support for modal windows

Sources/Adwaita/Model/User Interface/App/GTUIApp.swift

@@ -32,8 +32,9 @@ public class GTUIApp: Application {
         let body = body()
         for windowScene in body.scene.windows() {
             for _ in 0..<windowScene.open {
-                sceneStorage.append(windowScene.createWindow(app: self))
+                addWindow(windowScene.id)
             }
+            setParentWindows()
         }
     }
 
@@ -48,9 +49,21 @@ public class GTUIApp: Application {
     /// - Parameters:
     ///     - id: The window's id.
     public func addWindow(_ id: String) {
-        if let window = body().scene.windows().first(where: { $0.id == id }) {
+        State<Any>.updateViews()
-            sceneStorage.append(window.createWindow(app: self))
+        if let window = body().scene.windows().last(where: { $0.id == id }) {
+            let window = window.createWindow(app: self)
+            sceneStorage.append(window)
+            setParentWindows()
             showWindow(id)
         }
     }
+
+    /// Set the parents of every window having a parent window.
+    func setParentWindows() {
+      for window in sceneStorage {
+        if let parent = sceneStorage.first { $0.id == window.parentID } {
+            window.window.setParent(parent.window)
+        }
+      }
+    }
 }

Sources/Adwaita/Model/User Interface/Window/WindowScene.swift

@@ -12,6 +12,8 @@ public protocol WindowScene: WindowSceneGroup {
 
     /// The window type's identifier.
     var id: String { get }
+    /// The identifier of the window's parent window.
+    var parentID: String? { get set }
     /// The number of instances of the window at the startup.
     var `open`: Int { get }
     /// The keyboard shortcuts on the application's level.

Sources/Adwaita/Model/User Interface/Window/WindowStorage.swift

@@ -12,6 +12,8 @@ public class WindowStorage {
 
     /// The window's identifier.
     public var id: String
+    /// The identifier of the window's parent window.
+    public var parentID: String?
     /// Whether the reference to the window should disappear in the next update.
     public var destroy = false
     /// The GTUI window.

Sources/Adwaita/Window/Window.swift

@@ -18,6 +18,8 @@ public struct Window: WindowScene {
     var content: (GTUIApplicationWindow) -> Body
     /// Whether an instance of the window type should be opened when the app is starting up.
     public var `open`: Int
+    /// The identifier of the window's parent.
+    public var parentID: String?
     /// The keyboard shortcuts.
     var shortcuts: [String: (GTUIApplicationWindow) -> Void] = [:]
     /// The keyboard shortcuts on the app level.
@@ -45,6 +47,7 @@ public struct Window: WindowScene {
             windowStorage.destroy = true
             return false
         }
+        windowStorage.parentID = parentID
         return windowStorage
     }
 
@@ -80,6 +83,17 @@ public struct Window: WindowScene {
         }
     }
 
+    /// Add windows that overlay the last instance of this window if presented.
+    /// - Parameter windows: The windows.
+    /// - Returns: The new windows and this window.
+    public func overlay(@SceneBuilder windows: () -> [WindowSceneGroup]) -> [WindowScene] {
+        windows().windows().map { window in
+            var newWindow = window
+            newWindow.parentID = id
+            return newWindow
+        } + [self]
+    }
+
     /// Add a keyboard shortcut.
     /// - Parameters:
     ///     - shortcut: The keyboard shortcut.

Tests/Demo.swift

@@ -20,6 +20,12 @@ struct Demo: App {
         Window(id: "main") { window in
             DemoContent(window: window, app: app)
         }
+        .overlay {
+            Window(id: "overlay", open: 0) { window in
+                OverlayWindowDemo.WindowContent(window: window)
+            }
+            .keyboardShortcut("Escape") { $0.close() }
+        }
         HelperWindows()
     }
 

Tests/OverlayWindowDemo.swift

@@ -0,0 +1,53 @@
+//
+//  OverlayWindowDemo.swift
+//  Adwaita
+//
+//  Created by david-swift on 09.11.23.
+//
+
+// swiftlint:disable missing_docs implicitly_unwrapped_optional no_magic_numbers
+
+import Adwaita
+
+struct OverlayWindowDemo: View {
+
+    var app: GTUIApp!
+
+    var view: Body {
+        VStack {
+            Button("Show Window") {
+                app.showWindow("overlay")
+            }
+            .style("pill")
+            .frame(maxSize: 100)
+            .padding()
+        }
+    }
+
+    struct WindowContent: View {
+
+        var window: GTUIWindow
+
+        var view: Body {
+            VStack {
+                Button("Close Window") {
+                    window.close()
+                }
+                .style("pill")
+                .padding()
+                .frame(maxSize: 100)
+            }
+            .valign(.center)
+            .topToolbar {
+                HeaderBar.empty()
+            }
+            .onAppear {
+                window.setDefaultSize(width: 300, height: 200)
+            }
+        }
+
+    }
+
+}
+
+// swiftlint:enable missing_docs implicitly_unwrapped_optional no_magic_numbers

Tests/Page.swift

@@ -18,13 +18,19 @@ enum Page: String, Identifiable, CaseIterable {
     case toolbar
     case transition
     case dice
+    case overlayWindow
 
     var id: Self {
         self
     }
 
     var label: String {
-        rawValue.capitalized
+        switch self {
+        case .overlayWindow:
+            return "Overlay Window"
+        default:
+            return rawValue.capitalized
+        }
     }
 
     var icon: GTUI.Icon? {
@@ -50,6 +56,8 @@ enum Page: String, Identifiable, CaseIterable {
             return "A slide transition between two views."
         case .dice:
             return "Roll the dice."
+        case .overlayWindow:
+            return "A window on top of another window."
         }
     }
 
@@ -68,6 +76,8 @@ enum Page: String, Identifiable, CaseIterable {
             TransitionDemo()
         case .dice:
             DiceDemo()
+        case .overlayWindow:
+            OverlayWindowDemo(app: app)
         }
     }