Add modifiers for modifying child views of a view

Documentation/Reference/README.md

@@ -16,6 +16,7 @@
 -   [Binding](structs/Binding.md)
 -   [Button](structs/Button.md)
 -   [Clamp](structs/Clamp.md)
+-   [ContentModifier](structs/ContentModifier.md)
 -   [EitherView](structs/EitherView.md)
 -   [HStack](structs/HStack.md)
 -   [HeaderBar](structs/HeaderBar.md)
@@ -24,6 +25,7 @@
 -   [Menu](structs/Menu.md)
 -   [MenuButton](structs/MenuButton.md)
 -   [MenuSection](structs/MenuSection.md)
+-   [ModifierStopper](structs/ModifierStopper.md)
 -   [NavigationSplitView](structs/NavigationSplitView.md)
 -   [ScrollView](structs/ScrollView.md)
 -   [State](structs/State.md)

Documentation/Reference/classes/GTUIApp.md

@@ -40,3 +40,7 @@ Focus the window with a certain id. Create the window if it doesn't already exis
 Add a new window with the content of the window with a certain id.
 - Parameters:
     - id: The window's id.
+
+### `setParentWindows()`
+
+Set the parents of every window having a parent window.

Documentation/Reference/classes/WindowStorage.md

@@ -9,6 +9,10 @@ A storage for an app's window.
 
 The window's identifier.
 
+### `parentID`
+
+The identifier of the window's parent window.
+
 ### `destroy`
 
 Whether the reference to the window should disappear in the next update.

Documentation/Reference/extensions/Array.md

@@ -8,16 +8,18 @@
 The array's view body is the array itself.
 
 ## Methods
-### `widget()`
+### `widget(modifiers:)`
 
 Get a widget from a collection of views.
+- Parameter modifiers: Modify views before being updated.
 - Returns: A widget.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update a collection of views with a collection of view storages.
 - Parameters:
     - storage: The collection of view storages.
+    - modifiers: Modify views before being updated.
 
 ### `windows()`
 

Documentation/Reference/extensions/NativeWidgetPeer.md

@@ -3,14 +3,17 @@
 # `NativeWidgetPeer`
 
 ## Methods
-### `update(_:)`
+### `update(_:modifiers:)`
 
 A `GTUI.NativeWidgetPeer` is static.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `container()`
+### `container(modifiers:)`
 
 A `GTUI.NativeWidgetPeer`'s container is itself.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The view storage.
 
 ### `modifier(code:)`

Documentation/Reference/extensions/View.md

@@ -3,27 +3,41 @@
 # `View`
 
 ## Methods
-### `widget()`
+### `widget(modifiers:)`
 
 Wrap the view into a widget.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The widget.
 
-### `updateStorage(_:)`
+### `updateStorage(_:modifiers:)`
 
 Update a storage to a view.
-- Parameter storage: The storage.
+- Parameters:
+    - storage: The storage.
+    - modifiers: Modify views before being updated.
 
-### `storage()`
+### `storage(modifiers:)`
 
 Get a storage.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The storage.
 
+### `getModified(modifiers:)`
+
 ### `frame(maxSize:)`
 
 Set the view's maximal size.
 - Parameter maxSize: The maximal size.
 - Returns: A view.
 
+### `modifyContent(_:modify:)`
+
+Replace every occurrence of a certain view type in the content.
+- Parameters:
+    - type: The view type.
+    - modify: Modify the view.
+- Returns: A view.
+
 ### `inspect(_:)`
 
 Modify a GTUI widget before being displayed and when being updated.
@@ -94,6 +108,11 @@ Run a function when the view appears for the first time.
 - Parameter closure: The function.
 - Returns: A view.
 
+### `stopModifiers()`
+
+Remove all of the content modifiers for the wrapped views.
+- Returns: A view.
+
 ### `topToolbar(visible:_:)`
 
 Add a top toolbar to the view.

Documentation/Reference/protocols/Widget.md

@@ -5,11 +5,14 @@
 A widget is a view that know about its GTUI widget.
 
 ## Methods
-### `container()`
+### `container(modifiers:)`
 
 The view storage.
+- Parameter modifiers: Modify views before being updated.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update the stored content.
-- Parameter storage: The storage to update.
+- Parameters:
+    - storage: The storage to update.
+    - modifiers: Modify views before being updated

Documentation/Reference/protocols/WindowScene.md

@@ -9,6 +9,10 @@ A structure representing the content for a certain window type.
 
 The window type's identifier.
 
+### `parentID`
+
+The identifier of the window's parent window.
+
 ### `open`
 
 The number of instances of the window at the startup.

Documentation/Reference/structs/Button.md

@@ -33,14 +33,17 @@ Initialize a button.
   - label: The buttons label.
   - handler: The button's action handler.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update a button's view storage.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `container()`
+### `container(modifiers:)`
 
 Get a button's view storage.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The button's view storage.
 
 ### `keyboardShortcut(_:window:)`

Documentation/Reference/structs/Clamp.md

@@ -14,12 +14,15 @@ The content.
 The maximum size.
 
 ## Methods
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update a view storage.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `container()`
+### `container(modifiers:)`
 
 Get a view storage.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The view storage.

Documentation/Reference/structs/ContentModifier.md

@@ -0,0 +1,33 @@
+**STRUCT**
+
+# `ContentModifier`
+
+A widget which replaces views of a specific type in its content.
+
+## Properties
+### `content`
+
+The wrapped view.
+
+### `modify`
+
+The closure for the modification.
+
+## Methods
+### `container(modifiers:)`
+
+Get the content's container.
+- Parameter modifiers: Modify views before being updated.
+- Returns: The content's container.
+
+### `update(_:modifiers:)`
+
+Update the content.
+- Parameters:
+    - storage: The content's storage.
+    - modifiers: Modify views before being updated.
+
+### `modifyView(_:)`
+
+Apply the modifier to a view.
+- Parameter view: The view.

Documentation/Reference/structs/EitherView.md

@@ -34,18 +34,21 @@ Initialize an `EitherView`.
   - trueView:  The view that is presented if `isTrue` is true.
   - falseView: The view that is presented if `isTrue` is false.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update an `EitherView`'s storage.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `updateContent(_:state:stack:)`
+### `updateContent(_:state:stack:modifiers:)`
 
 Update the content of a view in the view storage.
 - Parameters:
   - storage: The view storage.
   - state: Whether it is the true or false view.
   - stack: The stack.
+  - modifiers: Modify views before being updated.
 
 ### `setVisible(_:view:)`
 
@@ -54,7 +57,8 @@ Set the visible content page.
   - stack: The stack.
   - view: The visible view.
 
-### `container()`
+### `container(modifiers:)`
 
 Get a GtkStack view storage.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The view storage.

Documentation/Reference/structs/HStack.md

@@ -15,12 +15,15 @@ The content.
 Initialize a `HStack`.
 - Parameter content: The view content.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update a view storage.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `container()`
+### `container(modifiers:)`
 
 Get a view storage.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The view storage.

Documentation/Reference/structs/HeaderBar.md

@@ -59,14 +59,17 @@ Initialize a header bar with only views at the end.
 - Parameter start: The views.
 - Returns: The header bar.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update a header bar's view storage.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `container()`
+### `container(modifiers:)`
 
 Get the container for a header bar.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The view storage.
 
 ### `headerBarTitle(view:)`

Documentation/Reference/structs/InspectorWrapper.md

@@ -14,12 +14,15 @@ The custom code to edit the widget.
 The wrapped view.
 
 ## Methods
-### `container()`
+### `container(modifiers:)`
 
 Get the content's container.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The content's container.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update the content.
-- Parameter storage: The content's storage.
+- Parameters:
+    - storage: The content's storage.
+    - modifiers: Modify views before being updated.

Documentation/Reference/structs/List.md

@@ -26,14 +26,17 @@ Initialize `List`.
   - selection: The identifier of the selected element.
   - content: The view for an element.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update a view storage.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `container()`
+### `container(modifiers:)`
 
 Get a view storage.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The view storage.
 
 ### `updateSelection(box:)`

Documentation/Reference/structs/Menu.md

@@ -45,12 +45,15 @@ Initialize a menu button.
   - window: The application window.
   - content: The menu's content.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update a button's view storage.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `container()`
+### `container(modifiers:)`
 
 Get a button's view storage.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The button's view storage.

Documentation/Reference/structs/ModifierStopper.md

@@ -0,0 +1,24 @@
+**STRUCT**
+
+# `ModifierStopper`
+
+Remove all of the content modifiers for the wrapped views.
+
+## Properties
+### `content`
+
+The wrapped view.
+
+## Methods
+### `container(modifiers:)`
+
+Get the content's container.
+- Parameter modifiers: Modify views before being updated.
+- Returns: The content's container.
+
+### `update(_:modifiers:)`
+
+Update the content.
+- Parameters:
+    - storage: The content's storage.
+    - modifiers: Modify views before being updated.

Documentation/Reference/structs/NavigationSplitView.md

@@ -29,12 +29,15 @@ Initialize a navigation split view.
   - sidebar: The sidebar content.
   - content: The main content.
 
-### `container()`
+### `container(modifiers:)`
 
 Get the container of the navigation split view widget.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The view storage.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update the view storage of the navigation split view widget.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.

Documentation/Reference/structs/ScrollView.md

@@ -15,12 +15,15 @@ The content.
 Initialize a `ScrollView`.
 - Parameter content: The view content.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update a view storage.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `container()`
+### `container(modifiers:)`
 
 Get a view storage.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The view storage.

Documentation/Reference/structs/StateWrapper.md

@@ -26,12 +26,15 @@ Initialize a `StateWrapper`.
   - content: The view content.
   - state: The state information.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update a view storage.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `container()`
+### `container(modifiers:)`
 
 Get a view storage.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The view storage.

Documentation/Reference/structs/StatusPage.md

@@ -31,12 +31,15 @@ Initialize a status page widget.
   - description: Additional details.
   - content: Additional content.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update the view storage of the text widget.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `container()`
+### `container(modifiers:)`
 
 Get the container of the text widget.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The view storage.

Documentation/Reference/structs/Text.md

@@ -15,12 +15,14 @@ The content.
 Initialize a text widget.
 - Parameter text: The content.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update the view storage of the text widget.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `container()`
+### `container(modifiers:)`
 
 Get the container of the text widget.
 - Returns: The view storage.

Documentation/Reference/structs/ToolbarView.md

@@ -26,12 +26,15 @@ Whether the toolbar is visible.
 The identifier of the toolbar content.
 
 ## Methods
-### `container()`
+### `container(modifiers:)`
 
 Get the container of the toolbar view widget.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The view storage.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update the view storage of the toolbar view widget.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.

Documentation/Reference/structs/UpdateObserver.md

@@ -14,12 +14,15 @@ The function.
 The content.
 
 ## Methods
-### `container()`
+### `container(modifiers:)`
 
 Get the content's container.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The content's container.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update the content.
-- Parameter storage: The content's storage.
+- Parameters:
+    - storage: The content's storage.
+    - modifiers: Modify views before being updated.

Documentation/Reference/structs/VStack.md

@@ -15,12 +15,15 @@ The content.
 Initialize a `VStack`.
 - Parameter content: The view content.
 
-### `update(_:)`
+### `update(_:modifiers:)`
 
 Update a view storage.
-- Parameter storage: The view storage.
+- Parameters:
+    - storage: The view storage.
+    - modifiers: Modify views before being updated.
 
-### `container()`
+### `container(modifiers:)`
 
 Get a view storage.
+- Parameter modifiers: Modify views before being updated.
 - Returns: The view storage.

Documentation/Reference/structs/Window.md

@@ -19,6 +19,10 @@ The window's content.
 
 Whether an instance of the window type should be opened when the app is starting up.
 
+### `parentID`
+
+The identifier of the window's parent.
+
 ### `shortcuts`
 
 The keyboard shortcuts.
@@ -59,6 +63,12 @@ Get the storage of the content view.
 Update a window storage's content.
 - Parameter storage: The storage to update.
 
+### `overlay(windows:)`
+
+Add windows that overlay the last instance of this window if presented.
+- Parameter windows: The windows.
+- Returns: The new windows and this window.
+
 ### `keyboardShortcut(_:action:)`
 
 Add a keyboard shortcut.

README.md

@@ -103,6 +103,8 @@ If you want to use _Adwaita_ in a project, but there are widgets missing, open a
 | `onAppear(_:)`               | Run when the view is rendered for the first time.                                       |
 | `topToolbar(visible:_:)`     | Add a native toolbar to the view. Normally, it contains a HeaderBar.                    |
 | `bottomToolbar(visible:_:)`  | Add a native bottom toolbar to the view.                                                |
+| `modifyContent(_:modify:)`   | Replace all occurrences of a certain view type with another view.                       |
+| `stopModifiers()`            | Ignore all the `modifyContent(_:modify:)` modifiers from higher above in the view tree. |
 
 ### `Button` Modifiers
 | Syntax                       | Description                                                                             |

Sources/Adwaita/Model/Extensions/Array.swift

@@ -13,22 +13,30 @@ extension Array: View where Element == View {
     public var view: Body { self }
 
     /// Get a widget from a collection of views.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: A widget.
-    public func widget() -> Widget {
+    public func widget(modifiers: [(View) -> View]) -> Widget {
-        if count == 1, let widget = self[safe: 0]?.widget() {
+        if count == 1, let widget = self[safe: 0]?.widget(modifiers: modifiers) {
             return widget
         } else {
-            return VStack { self }
+            var modified = self
+            for (index, view) in modified.enumerated() {
+                for modifier in modifiers {
+                    modified[index] = modifier(view)
+                }
+            }
+            return VStack { modified }
         }
     }
 
     /// Update a collection of views with a collection of view storages.
     /// - Parameters:
     ///     - storage: The collection of view storages.
-    public func update(_ storage: [ViewStorage]) {
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: [ViewStorage], modifiers: [(View) -> View]) {
         for (index, element) in enumerated() {
             if let storage = storage[safe: index] {
-                element.widget().updateStorage(storage)
+                element.widget(modifiers: modifiers).updateStorage(storage, modifiers: modifiers)
             }
         }
     }

Sources/Adwaita/Model/Extensions/NativeWidgetPeer.swift

@@ -10,12 +10,15 @@ import GTUI
 extension NativeWidgetPeer: Widget {
 
     /// A `GTUI.NativeWidgetPeer` is static.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) { }
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) { }
 
     /// A `GTUI.NativeWidgetPeer`'s container is itself.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
         let bold = "\(modifier(code: 1))"
         let yellow = 33
         let warning = "\(modifier(code: yellow))\(bold)"

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

@@ -61,7 +61,7 @@ public class GTUIApp: Application {
     /// 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 } {
+        if let parent = sceneStorage.first(where: { $0.id == window.parentID }) {
             window.window.setParent(parent.window)
         }
       }

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

@@ -30,9 +30,11 @@ public protocol View {
 extension View {
 
     /// Wrap the view into a widget.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The widget.
-    public func widget() -> Widget {
+    public func widget(modifiers: [(View) -> View]) -> Widget {
-        if let peer = self as? Widget {
+        let modified = getModified(modifiers: modifiers)
+        if let peer = modified as? Widget {
             return peer
         } else {
             var state: [String: StateProtocol] = [:]
@@ -46,19 +48,31 @@ extension View {
     }
 
     /// Update a storage to a view.
-    /// - Parameter storage: The storage.
+    /// - Parameters:
-    func updateStorage(_ storage: ViewStorage) {
+    ///     - storage: The storage.
-        if let widget = self as? Widget {
+    ///     - modifiers: Modify views before being updated.
-            widget.update(storage)
+    func updateStorage(_ storage: ViewStorage, modifiers: [(View) -> View]) {
+        let modified = getModified(modifiers: modifiers)
+        if let widget = modified as? Widget {
+            widget.update(storage, modifiers: modifiers)
         } else {
-            StateWrapper { self }.update(storage)
+            StateWrapper { self }.update(storage, modifiers: modifiers)
         }
     }
 
     /// Get a storage.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The storage.
-    func storage() -> ViewStorage {
+    func storage(modifiers: [(View) -> View]) -> ViewStorage {
-        widget().container()
+        widget(modifiers: modifiers).container(modifiers: modifiers)
+    }
+
+    func getModified(modifiers: [(View) -> View]) -> View {
+        var modified: View = self
+        for modifier in modifiers {
+            modified = modifier(modified)
+        }
+        return modified
     }
 
 }

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

@@ -11,10 +11,13 @@ import GTUI
 public protocol Widget: View {
 
     /// The view storage.
-    func container() -> ViewStorage
+    /// - Parameter modifiers: Modify views before being updated.
+    func container(modifiers: [(View) -> View]) -> ViewStorage
     /// Update the stored content.
-    /// - Parameter storage: The storage to update.
+    /// - Parameters:
-    func update(_ storage: ViewStorage)
+    ///     - storage: The storage to update.
+    ///     - modifiers: Modify views before being updated
+    func update(_ storage: ViewStorage, modifiers: [(View) -> View])
 
 }
 

Sources/Adwaita/View/Button.swift

@@ -40,8 +40,10 @@ public struct Button: Widget {
     }
 
     /// Update a button's view storage.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         if let button = storage.view as? GTUI.Button {
             let content = button.getContent()
             if let label {
@@ -58,8 +60,9 @@ public struct Button: Widget {
     }
 
     /// Get a button's view storage.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The button's view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
         if let icon {
             return .init(GTUI.Button(label, icon: icon).handler(handler))
         } else {

Sources/Adwaita/View/EitherView.swift

@@ -42,11 +42,13 @@ public struct EitherView: Widget {
     }
 
     /// Update an `EitherView`'s storage.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         let stack = storage.view as? Stack
-        updateContent(storage, state: true, stack: stack)
+        updateContent(storage, state: true, stack: stack, modifiers: modifiers)
-        updateContent(storage, state: false, stack: stack)
+        updateContent(storage, state: false, stack: stack, modifiers: modifiers)
         if isTrue, let trueView = storage.content["\(true)"]?.last?.view {
             setVisible(stack, view: trueView)
         } else if !isTrue, let falseView = storage.content["\(false)"]?.last?.view {
@@ -59,11 +61,12 @@ public struct EitherView: Widget {
     ///   - storage: The view storage.
     ///   - state: Whether it is the true or false view.
     ///   - stack: The stack.
-    private func updateContent(_ storage: ViewStorage, state: Bool, stack: Stack?) {
+    ///   - modifiers: Modify views before being updated.
-        let activeView = (state ? trueView : falseView)?.widget()
+    private func updateContent(_ storage: ViewStorage, state: Bool, stack: Stack?, modifiers: [(View) -> View]) {
+        let activeView = (state ? trueView : falseView)?.widget(modifiers: modifiers)
         if let view = storage.content["\(state)"]?[safe: 0] {
-            activeView?.updateStorage(view)
+            activeView?.updateStorage(view, modifiers: modifiers)
-        } else if let view = activeView?.storage() {
+        } else if let view = activeView?.storage(modifiers: modifiers) {
             _ = stack?.append(view.view)
             storage.content["\(state)"] = [view]
         }
@@ -78,17 +81,18 @@ public struct EitherView: Widget {
     }
 
     /// Get a GtkStack view storage.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
         let stack = Stack()
         var content: [String: [ViewStorage]] = [:]
         if let trueView {
-            let view = trueView.widget().storage()
+            let view = trueView.widget(modifiers: modifiers).storage(modifiers: modifiers)
             _ = stack.append(view.view)
             content["\(true)"] = [view]
         }
         if let falseView {
-            let view = falseView.widget().storage()
+            let view = falseView.widget(modifiers: modifiers).storage(modifiers: modifiers)
             _ = stack.append(view.view)
             content["\(false)"] = [view]
         }

Sources/Adwaita/View/HStack.swift

@@ -20,18 +20,21 @@ public struct HStack: Widget {
     }
 
     /// Update a view storage.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
-        content().update(storage.content[.mainContent] ?? [])
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
+        content().update(storage.content[.mainContent] ?? [], modifiers: modifiers)
     }
 
     /// Get a view storage.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
         let box: Box = .init(horizontal: true)
         var content: [ViewStorage] = []
         for element in self.content() {
-            let widget = element.storage()
+            let widget = element.storage(modifiers: modifiers)
             _ = box.append(widget.view)
             content.append(widget)
         }

Sources/Adwaita/View/HeaderBar.swift

@@ -58,35 +58,38 @@ public struct HeaderBar: Widget {
     }
 
     /// Update a header bar's view storage.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         if let bar = storage.view as? GTUI.HeaderBar {
             _ = bar.showTitleButtons(titleButtons)
         }
-        start.update(storage.content[startID] ?? [])
+        start.update(storage.content[startID] ?? [], modifiers: modifiers)
-        end.update(storage.content[endID] ?? [])
+        end.update(storage.content[endID] ?? [], modifiers: modifiers)
         if let first = storage.content[titleID]?.first {
-            headerBarTitle?.widget().update(first)
+            headerBarTitle?.widget(modifiers: modifiers).update(first, modifiers: modifiers)
         }
     }
 
     /// Get the container for a header bar.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
         let bar: GTUI.HeaderBar = .init()
         var startContent: [ViewStorage] = []
         var endContent: [ViewStorage] = []
         for element in start {
-            let element = element.storage()
+            let element = element.storage(modifiers: modifiers)
             _ = bar.packStart(element.view)
             startContent.append(element)
         }
         for element in end {
-            let element = element.storage()
+            let element = element.storage(modifiers: modifiers)
             _ = bar.packEnd(element.view)
             endContent.append(element)
         }
-        let title = headerBarTitle?.widget().container()
+        let title = headerBarTitle?.widget(modifiers: modifiers).container(modifiers: modifiers)
         let titleStorage: [ViewStorage]
         if let title {
             _ = bar.titleWidget(title.view)

Sources/Adwaita/View/List.swift

@@ -33,20 +33,23 @@ public struct List<Element>: Widget where Element: Identifiable {
     }
 
     /// Update a view storage.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         if let box = storage.view as? ListBox {
             updateSelection(box: box)
         }
     }
 
     /// Get a view storage.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
         let box: ListBox = .init()
         var content: [ViewStorage] = []
         for element in elements {
-            let widget = self.content(element).widget().container()
+            let widget = self.content(element).widget(modifiers: modifiers).container(modifiers: modifiers)
             _ = box.append(widget.view)
             content.append(widget)
         }

Sources/Adwaita/View/Menu.swift

@@ -63,8 +63,10 @@ public struct Menu: Widget {
     }
 
     /// Update a button's view storage.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         if let button = storage.view as? GTUI.MenuButton {
             let content = button.getContent()
             if let label {
@@ -81,8 +83,9 @@ public struct Menu: Widget {
     }
 
     /// Get a button's view storage.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The button's view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
         let button: GTUI.MenuButton
         if let icon {
             button = .init(label, icon: icon)

Sources/Adwaita/View/Modifiers/Clamp.swift

@@ -16,20 +16,23 @@ struct Clamp: Widget {
     var maxSize: Int
 
     /// Update a view storage.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         if let clamp = storage.view as? GTUI.Clamp {
             _ = clamp.maximumSize(maxSize)
         }
         if let storage = storage.content[.mainContent]?[safe: 0] {
-            content.widget().update(storage)
+            content.widget(modifiers: modifiers).update(storage, modifiers: modifiers)
         }
     }
 
     /// Get a view storage.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The view storage.
-    func container() -> ViewStorage {
+    func container(modifiers: [(View) -> View]) -> ViewStorage {
-        let container = content.storage()
+        let container = content.storage(modifiers: modifiers)
         let clamp: GTUI.Clamp = .init(container.view)
         _ = clamp.maximumSize(maxSize)
         return .init(clamp, content: [.mainContent: [container]])

Sources/Adwaita/View/Modifiers/ContentModifier.swift

@@ -0,0 +1,60 @@
+//
+//  ContentModifier.swift
+//  Adwaita
+//
+//  Created by david-swift on 11.11.23.
+//
+
+import GTUI
+
+/// A widget which replaces views of a specific type in its content.
+struct ContentModifier<Content>: Widget where Content: View {
+
+    /// The wrapped view.
+    var content: View
+    /// The closure for the modification.
+    var modify: (Content) -> View
+
+    /// Get the content's container.
+    /// - Parameter modifiers: Modify views before being updated.
+    /// - Returns: The content's container.
+    func container(modifiers: [(View) -> View]) -> ViewStorage {
+        let storage = content.storage(modifiers: modifiers + [modifyView])
+        return storage
+    }
+
+    /// Update the content.
+    /// - Parameters:
+    ///     - storage: The content's storage.
+    ///     - modifiers: Modify views before being updated.
+    func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
+        content.updateStorage(storage, modifiers: modifiers + [modifyView])
+    }
+
+    /// Apply the modifier to a view.
+    /// - Parameter view: The view.
+    func modifyView(_ view: View) -> View {
+        if let view = view as? Content {
+            return modify(view).stopModifiers()
+        } else {
+            return view
+        }
+    }
+
+}
+
+extension View {
+
+    /// Replace every occurrence of a certain view type in the content.
+    /// - Parameters:
+    ///     - type: The view type.
+    ///     - modify: Modify the view.
+    /// - Returns: A view.
+    public func modifyContent<Content>(
+        _ type: Content.Type,
+        modify: @escaping (Content) -> View
+    ) -> View where Content: View {
+        ContentModifier(content: self, modify: modify)
+    }
+
+}

Sources/Adwaita/View/Modifiers/InspectorWrapper.swift

@@ -16,17 +16,20 @@ struct InspectorWrapper: Widget {
     var content: View
 
     /// Get the content's container.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The content's container.
-    func container() -> ViewStorage {
+    func container(modifiers: [(View) -> View]) -> ViewStorage {
-        let storage = content.storage()
+        let storage = content.storage(modifiers: modifiers)
         modify(storage.view)
         return storage
     }
 
     /// Update the content.
-    /// - Parameter storage: The content's storage.
+    /// - Parameters:
-    func update(_ storage: ViewStorage) {
+    ///     - storage: The content's storage.
-        content.updateStorage(storage)
+    ///     - modifiers: Modify views before being updated.
+    func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
+        content.updateStorage(storage, modifiers: modifiers)
         modify(storage.view)
     }
 

Sources/Adwaita/View/Modifiers/ModifierStopper.swift

@@ -0,0 +1,42 @@
+//
+//  ModifierStopper.swift
+//  Adwaita
+//
+//  Created by david-swift on 11.11.23.
+//
+
+import GTUI
+
+/// Remove all of the content modifiers for the wrapped views.
+struct ModifierStopper: Widget {
+
+    /// The wrapped view.
+    var content: View
+
+    /// Get the content's container.
+    /// - Parameter modifiers: Modify views before being updated.
+    /// - Returns: The content's container.
+    func container(modifiers: [(View) -> View]) -> ViewStorage {
+        let storage = content.storage(modifiers: [])
+        return storage
+    }
+
+    /// Update the content.
+    /// - Parameters:
+    ///     - storage: The content's storage.
+    ///     - modifiers: Modify views before being updated.
+    func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
+        content.updateStorage(storage, modifiers: [])
+    }
+
+}
+
+extension View {
+
+    /// Remove all of the content modifiers for the wrapped views.
+    /// - Returns: A view.
+    public func stopModifiers() -> View {
+        ModifierStopper(content: self)
+    }
+
+}

Sources/Adwaita/View/Modifiers/ToolbarView.swift

@@ -23,13 +23,14 @@ struct ToolbarView: Widget {
     let toolbarID = "toolbar"
 
     /// Get the container of the toolbar view widget.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The view storage.
-    func container() -> ViewStorage {
+    func container(modifiers: [(View) -> View]) -> ViewStorage {
-        let content = content.storage()
+        let content = content.storage(modifiers: modifiers)
         let view = GTUI.ToolbarView(content.view)
         var toolbarContent: [ViewStorage] = []
         for item in toolbar() {
-            let storage = item.storage()
+            let storage = item.storage(modifiers: modifiers)
             toolbarContent.append(storage)
             if bottom {
                 _ = view.addBottomBar(storage.view)
@@ -46,14 +47,16 @@ struct ToolbarView: Widget {
     }
 
     /// Update the view storage of the toolbar view widget.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         if let mainContent = storage.content[.mainContent]?.first {
-            content.widget().update(mainContent)
+            content.widget(modifiers: modifiers).update(mainContent, modifiers: modifiers)
         }
         if let toolbar = storage.content[toolbarID] {
             for (index, content) in toolbar.enumerated() {
-                self.toolbar()[safe: index]?.updateStorage(content)
+                self.toolbar()[safe: index]?.updateStorage(content, modifiers: modifiers)
             }
         }
         if let view = storage.view as? GTUI.ToolbarView {

Sources/Adwaita/View/Modifiers/UpdateObserver.swift

@@ -16,17 +16,20 @@ struct UpdateObserver: Widget {
     var content: View
 
     /// Get the content's container.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The content's container.
-    func container() -> ViewStorage {
+    func container(modifiers: [(View) -> View]) -> ViewStorage {
         onUpdate()
-        return content.storage()
+        return content.storage(modifiers: modifiers)
     }
 
     /// Update the content.
-    /// - Parameter storage: The content's storage.
+    /// - Parameters:
-    func update(_ storage: ViewStorage) {
+    ///     - storage: The content's storage.
+    ///     - modifiers: Modify views before being updated.
+    func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         onUpdate()
-        content.updateStorage(storage)
+        content.updateStorage(storage, modifiers: modifiers)
     }
 
 }

Sources/Adwaita/View/NavigationSplitView.swift

@@ -30,17 +30,18 @@ public struct NavigationSplitView: Widget {
     }
 
     /// Get the container of the navigation split view widget.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
         let splitView: GTUI.NavigationSplitView = .init()
         var content: [String: [ViewStorage]] = [:]
 
-        let sidebar = sidebar().widget().container()
+        let sidebar = sidebar().widget(modifiers: modifiers).container(modifiers: modifiers)
         let label = sidebar.view.fields[.navigationLabel] as? String ?? ""
         _ = splitView.sidebar(sidebar.view, title: label)
         content[sidebarID] = [sidebar]
 
-        let mainContent = self.content().widget().container()
+        let mainContent = self.content().widget(modifiers: modifiers).container(modifiers: modifiers)
         let mainLabel = mainContent.view.fields[.navigationLabel] as? String ?? ""
         _ = splitView.content(mainContent.view, title: mainLabel)
         content[contentID] = [mainContent]
@@ -49,13 +50,15 @@ public struct NavigationSplitView: Widget {
     }
 
     /// Update the view storage of the navigation split view widget.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         if let storage = storage.content[contentID]?[safe: 0] {
-            content().widget().update(storage)
+            content().widget(modifiers: modifiers).update(storage, modifiers: modifiers)
         }
         if let storage = storage.content[sidebarID]?[safe: 0] {
-            sidebar().widget().update(storage)
+            sidebar().widget(modifiers: modifiers).update(storage, modifiers: modifiers)
         }
     }
 

Sources/Adwaita/View/ScrollView.swift

@@ -20,17 +20,20 @@ public struct ScrollView: Widget {
     }
 
     /// Update a view storage.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         if let first = storage.content[.mainContent]?.first {
-          content().widget().update(first)
+          content().widget(modifiers: modifiers).update(first, modifiers: modifiers)
         }
     }
 
     /// Get a view storage.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
-        let container = content().widget().container()
+        let container = content().widget(modifiers: modifiers).container(modifiers: modifiers)
         return .init(Scrolled().setChild(container.view), content: [.mainContent: [container]])
     }
 

Sources/Adwaita/View/StateWrapper.swift

@@ -31,22 +31,25 @@ public struct StateWrapper: Widget {
     }
 
     /// Update a view storage.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         for property in state {
             if let value = storage.state[property.key]?.value {
                 property.value.value = value
             }
         }
         if let storage = storage.content[.mainContent]?.first {
-            content().widget().update(storage)
+            content().widget(modifiers: modifiers).update(storage, modifiers: modifiers)
         }
     }
 
     /// Get a view storage.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
-        let content = content().widget().container()
+        let content = content().widget(modifiers: modifiers).container(modifiers: modifiers)
         return .init(content.view, content: [.mainContent: [content]], state: state)
     }
 

Sources/Adwaita/View/StatusPage.swift

@@ -38,20 +38,23 @@ public struct StatusPage: Widget {
     }
 
     /// Update the view storage of the text widget.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         if let statusPage = storage.view as? GTUI.StatusPage {
             _ = statusPage.title(title).description(description).icon(icon)
         }
         if let storage = storage.content[.mainContent]?.first {
-            content.widget().update(storage)
+            content.widget(modifiers: modifiers).update(storage, modifiers: modifiers)
         }
     }
 
     /// Get the container of the text widget.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
-        let child = content.widget().container()
+        let child = content.widget(modifiers: []).container(modifiers: modifiers)
         return .init(
             GTUI.StatusPage().title(title).description(description).icon(icon).child(child.view),
             content: [.mainContent: [child]]

Sources/Adwaita/View/Text.swift

@@ -20,8 +20,10 @@ public struct Text: Widget {
     }
 
     /// Update the view storage of the text widget.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
         if let label = storage.view as? MarkupLabel {
             label.setText(text)
         }
@@ -29,7 +31,7 @@ public struct Text: Widget {
 
     /// Get the container of the text widget.
     /// - Returns: The view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
         .init(MarkupLabel(self.text))
     }
 

Sources/Adwaita/View/VStack.swift

@@ -20,18 +20,21 @@ public struct VStack: Widget {
     }
 
     /// Update a view storage.
-    /// - Parameter storage: The view storage.
+    /// - Parameters:
-    public func update(_ storage: ViewStorage) {
+    ///     - storage: The view storage.
-        content().update(storage.content[.mainContent] ?? [])
+    ///     - modifiers: Modify views before being updated.
+    public func update(_ storage: ViewStorage, modifiers: [(View) -> View]) {
+        content().update(storage.content[.mainContent] ?? [], modifiers: modifiers)
     }
 
     /// Get a view storage.
+    /// - Parameter modifiers: Modify views before being updated.
     /// - Returns: The view storage.
-    public func container() -> ViewStorage {
+    public func container(modifiers: [(View) -> View]) -> ViewStorage {
         let box: Box = .init(horizontal: false)
         var content: [ViewStorage] = []
         for element in self.content() {
-            let widget = element.storage()
+            let widget = element.storage(modifiers: modifiers)
             _ = box.append(widget.view)
             content.append(widget)
         }

Sources/Adwaita/Window/Window.swift

@@ -66,7 +66,7 @@ public struct Window: WindowScene {
     /// - Returns: The storage of the content of the window.
     func getViewStorage(window: GTUIApplicationWindow) -> ViewStorage {
         let content = content(window)
-        let storage = content.widget().container()
+        let storage = content.widget(modifiers: []).container(modifiers: [])
         window.setChild(storage.view)
         updateShortcuts(window: window)
         return storage
@@ -77,7 +77,7 @@ public struct Window: WindowScene {
     public func update(_ storage: WindowStorage, app: GTUIApp) {
         if let window = storage.window as? GTUIApplicationWindow {
             let content = content(window)
-            content.widget().updateStorage(storage.view)
+            content.widget(modifiers: []).updateStorage(storage.view, modifiers: [])
             updateShortcuts(window: window)
             updateAppShortcuts(app: app)
         }

Tests/Demo.swift

@@ -46,7 +46,7 @@ struct Demo: App {
 
     struct DemoContent: View {
 
-        @State private var selection: Page = .welcome
+        @State private var selection: Page = .transition
         var window: GTUIApplicationWindow
         var app: GTUIApp!
 

Tests/TransitionDemo.swift

@@ -16,15 +16,16 @@ struct TransitionDemo: View {
     var view: Body {
         VStack {
             if firstView {
-                content("First View")
+                Text("First View")
                     .transition(.slideDown)
                     .style("accent")
             } else {
-                content("Second View")
+                Text("Second View")
                     .transition(.slideUp)
                     .style("success")
             }
         }
+        .modifyContent(Text.self) { $0.style("title-2").padding() }
         .style("card")
         .frame(maxSize: 200)
         .padding()
@@ -36,12 +37,6 @@ struct TransitionDemo: View {
         .frame(maxSize: 100)
     }
 
-    private func content(_ text: String) -> View {
-        Text(text)
-            .style("title-2")
-            .padding()
-    }
-
 }
 
 // swiftlint:enable missing_docs no_magic_numbers