Add View Traits and transitions

NativeDemo/TokamakDemo.xcodeproj/project.pbxproj

@@ -9,6 +9,8 @@
 /* Begin PBXBuildFile section */
 		207C05702610E16E00BBBE54 /* DatePickerDemo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 207C056F2610E16E00BBBE54 /* DatePickerDemo.swift */; };
 		207C05712610E16E00BBBE54 /* DatePickerDemo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 207C056F2610E16E00BBBE54 /* DatePickerDemo.swift */; };
+		26136823269E8EB5006F372E /* TransitionDemo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 26136822269E8EB5006F372E /* TransitionDemo.swift */; };
+		26136824269E8EB5006F372E /* TransitionDemo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 26136822269E8EB5006F372E /* TransitionDemo.swift */; };
 		262DA7B32695D99500CABEAE /* ShapeStyleDemo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 262DA7B22695D99500CABEAE /* ShapeStyleDemo.swift */; };
 		262DA7B42695D99500CABEAE /* ShapeStyleDemo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 262DA7B22695D99500CABEAE /* ShapeStyleDemo.swift */; };
 		26A3BFB0269BD18A0004DA16 /* AnimationDemo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 26A3BFAF269BD18A0004DA16 /* AnimationDemo.swift */; };
@@ -101,6 +103,7 @@
 
 /* Begin PBXFileReference section */
 		207C056F2610E16E00BBBE54 /* DatePickerDemo.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DatePickerDemo.swift; sourceTree = "<group>"; };
+		26136822269E8EB5006F372E /* TransitionDemo.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TransitionDemo.swift; sourceTree = "<group>"; };
 		262DA7B22695D99500CABEAE /* ShapeStyleDemo.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ShapeStyleDemo.swift; sourceTree = "<group>"; };
 		26A3BFAF269BD18A0004DA16 /* AnimationDemo.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AnimationDemo.swift; sourceTree = "<group>"; };
 		3DCDE44324CA6AD400910F17 /* SidebarDemo.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = SidebarDemo.swift; sourceTree = "<group>"; };
@@ -197,6 +200,7 @@
 		85ED189924AD425E0085DFA0 /* TokamakDemo */ = {
 			isa = PBXGroup;
 			children = (
+				26136822269E8EB5006F372E /* TransitionDemo.swift */,
 				26A3BFAF269BD18A0004DA16 /* AnimationDemo.swift */,
 				262DA7B22695D99500CABEAE /* ShapeStyleDemo.swift */,
 				D120FDDA257E7145008FFBAD /* TextEditorDemo.swift */,
@@ -375,6 +379,7 @@
 				B5DBA22B24D509B4003D3347 /* RedactDemo.swift in Sources */,
 				B56F22E024BC89FD001738DF /* ColorDemo.swift in Sources */,
 				26A3BFB0269BD18A0004DA16 /* AnimationDemo.swift in Sources */,
+				26136823269E8EB5006F372E /* TransitionDemo.swift in Sources */,
 				B51F215024B920B400CF2583 /* PathDemo.swift in Sources */,
 				85ED18AF24AD425E0085DFA0 /* EnvironmentDemo.swift in Sources */,
 				85ED18A324AD425E0085DFA0 /* SpacerDemo.swift in Sources */,
@@ -410,6 +415,7 @@
 				D1D6B62424D817350041E1D9 /* GeometryReaderDemo.swift in Sources */,
 				B5DBA22C24D509B4003D3347 /* RedactDemo.swift in Sources */,
 				26A3BFB1269BD18A0004DA16 /* AnimationDemo.swift in Sources */,
+				26136824269E8EB5006F372E /* TransitionDemo.swift in Sources */,
 				B56F22E124BC89FD001738DF /* ColorDemo.swift in Sources */,
 				B51F215124B920B400CF2583 /* PathDemo.swift in Sources */,
 				85ED18A424AD425E0085DFA0 /* SpacerDemo.swift in Sources */,

Sources/TokamakCore/Animation/Transaction.swift

@@ -26,7 +26,7 @@ public struct Transaction {
 
   public init(animation: Animation?) {
     self.animation = animation
-    disablesAnimations = true
+    disablesAnimations = false
   }
 }
 

Sources/TokamakCore/Modifiers/ViewModifier.swift

@@ -18,7 +18,9 @@ public protocol ViewModifier {
   func body(content: Content) -> Self.Body
 }
 
-public struct _ViewModifier_Content<Modifier>: View where Modifier: ViewModifier {
+public struct _ViewModifier_Content<Modifier>: View
+  where Modifier: ViewModifier
+{
   public let modifier: Modifier
   public let view: AnyView
 
@@ -27,7 +29,7 @@ public struct _ViewModifier_Content<Modifier>: View where Modifier: ViewModifier
     self.view = view
   }
 
-  public var body: AnyView {
+  public var body: some View {
     view
   }
 }

Sources/TokamakCore/MountedViews/MountedApp.swift

@@ -22,21 +22,33 @@ import OpenCombineShim
 // `View`s
 final class MountedApp<R: Renderer>: MountedCompositeElement<R> {
   override func mount(
-    before _: R.TargetType? = nil,
-    on _: MountedElement<R>? = nil,
-    with reconciler: StackReconciler<R>
+    before sibling: R.TargetType? = nil,
+    on parent: MountedElement<R>? = nil,
+    in reconciler: StackReconciler<R>,
+    with transaction: Transaction
   ) {
+    super.prepareForMount()
+
     // `App` elements have no siblings, hence the `before` argument is discarded.
     // They also have no parents, so the `parent` argument is discarded as well.
     let childBody = reconciler.render(mountedApp: self)
 
     let child: MountedElement<R> = mountChild(reconciler.renderer, childBody)
     mountedChildren = [child]
-    child.mount(before: nil, on: self, with: reconciler)
+    child.transaction = transaction
+    child.mount(before: nil, on: self, in: reconciler, with: transaction)
+
+    super.mount(before: sibling, on: parent, in: reconciler, with: transaction)
   }
 
-  override func unmount(with reconciler: StackReconciler<R>) {
-    mountedChildren.forEach { $0.unmount(with: reconciler) }
+  override func unmount(
+    in reconciler: StackReconciler<R>,
+    with transaction: Transaction,
+    parentTask: UnmountTask<R>?
+  ) {
+    super.unmount(in: reconciler, with: transaction, parentTask: parentTask)
+    mountedChildren
+      .forEach { $0.unmount(in: reconciler, with: transaction, parentTask: parentTask) }
   }
 
   /// Mounts a child scene within the app.

Sources/TokamakCore/MountedViews/MountedCompositeElement.swift

@@ -61,10 +61,11 @@ class MountedCompositeElement<R: Renderer>: MountedElement<R> {
     _ view: AnyView,
     _ parentTarget: R.TargetType,
     _ environmentValues: EnvironmentValues,
+    _ viewTraits: _ViewTraitStore,
     _ parent: MountedElement<R>?
   ) {
     self.parentTarget = parentTarget
-    super.init(view, environmentValues, parent)
+    super.init(view, environmentValues, viewTraits, parent)
   }
 }
 

Sources/TokamakCore/MountedViews/MountedCompositeView.swift

@@ -21,20 +21,32 @@ final class MountedCompositeView<R: Renderer>: MountedCompositeElement<R> {
   override func mount(
     before sibling: R.TargetType? = nil,
     on parent: MountedElement<R>? = nil,
-    with reconciler: StackReconciler<R>
+    in reconciler: StackReconciler<R>,
+    with transaction: Transaction
   ) {
+    super.prepareForMount()
+
+    var transaction = transaction
     (view.view as? _TransactionModifierProtocol)?.modifyTransaction(&transaction)
+    // Disable animations on mount so `animation(_:)` doesn't try to animate
+    // until the transition finishes.
+    transaction.disablesAnimations = true
+    self.transaction = transaction
 
     let childBody = reconciler.render(compositeView: self)
 
+    if let traitModifier = view.view as? _TraitWritingModifierProtocol {
+      traitModifier.modifyViewTraitStore(&viewTraits)
+    }
     let child: MountedElement<R> = childBody.makeMountedView(
       reconciler.renderer,
       parentTarget,
       environmentValues,
+      viewTraits,
       self
     )
     mountedChildren = [child]
-    child.mount(before: sibling, on: self, with: reconciler)
+    child.mount(before: sibling, on: self, in: reconciler, with: transaction)
 
     // `_TargetRef` (and `TargetRefType` generic eraser protocol it conforms to) is a composite
     // view, so it's enough check for it only here.
@@ -73,10 +85,25 @@ final class MountedCompositeView<R: Renderer>: MountedCompositeElement<R> {
         preferenceReader.preferenceStore(self.preferenceStore)
       }
     })
+
+    super.mount(before: sibling, on: parent, in: reconciler, with: transaction)
   }
 
-  override func unmount(with reconciler: StackReconciler<R>) {
-    mountedChildren.forEach { $0.unmount(with: reconciler) }
+  override func unmount(
+    in reconciler: StackReconciler<R>,
+    with transaction: Transaction,
+    parentTask: UnmountTask<R>?
+  ) {
+    super.unmount(in: reconciler, with: transaction, parentTask: parentTask)
+
+    var transaction = transaction
+    transaction.disablesAnimations = false
+    (view.view as? _TransactionModifierProtocol)?.modifyTransaction(&transaction)
+
+    mountedChildren.forEach {
+      $0.viewTraits = self.viewTraits
+      $0.unmount(in: reconciler, with: transaction, parentTask: parentTask)
+    }
 
     if let appearanceAction = view.view as? AppearanceActionType {
       appearanceAction.disappear?()
@@ -85,6 +112,7 @@ final class MountedCompositeView<R: Renderer>: MountedCompositeElement<R> {
 
   override func update(in reconciler: StackReconciler<R>, with transaction: Transaction) {
     var transaction = transaction
+    transaction.disablesAnimations = false
     (view.view as? _TransactionModifierProtocol)?.modifyTransaction(&transaction)
     let element = reconciler.render(compositeView: self)
     reconciler.reconcile(
@@ -98,7 +126,13 @@ final class MountedCompositeView<R: Renderer>: MountedCompositeElement<R> {
         $0.transaction = transaction
       },
       mountChild: {
-        $0.makeMountedView(reconciler.renderer, parentTarget, environmentValues, self)
+        $0.makeMountedView(
+          reconciler.renderer,
+          parentTarget,
+          environmentValues,
+          viewTraits,
+          self
+        )
       }
     )
   }

Sources/TokamakCore/MountedViews/MountedElement.swift

@@ -86,9 +86,13 @@ public class MountedElement<R: Renderer> {
 
   var mountedChildren = [MountedElement<R>]()
 
-  public internal(set) var transaction: Transaction = .init(animation: nil)
+  public var transaction: Transaction = .init(animation: nil)
+  /// Where this element is the process of mounting/unmounting.
+  var transitionPhase = TransitionPhase.willMount
+  /// The current `UnmountTask` of this element.
+  var unmountTask: UnmountTask<R>?
 
-  var environmentValues: EnvironmentValues
+  public internal(set) var environmentValues: EnvironmentValues
 
   unowned var parent: MountedElement<R>?
   /// `didSet` on this field propagates the preference changes up the view tree.
@@ -98,24 +102,34 @@ public class MountedElement<R: Renderer> {
     }
   }
 
+  public internal(set) var viewTraits: _ViewTraitStore
+
   init(_ app: _AnyApp, _ environmentValues: EnvironmentValues, _ parent: MountedElement<R>?) {
     element = .app(app)
     self.parent = parent
     self.environmentValues = environmentValues
+    viewTraits = .init()
     updateEnvironment()
   }
 
   init(_ scene: _AnyScene, _ environmentValues: EnvironmentValues, _ parent: MountedElement<R>?) {
     element = .scene(scene)
     self.parent = parent
     self.environmentValues = environmentValues
+    viewTraits = .init()
     updateEnvironment()
   }
 
-  init(_ view: AnyView, _ environmentValues: EnvironmentValues, _ parent: MountedElement<R>?) {
+  init(
+    _ view: AnyView,
+    _ environmentValues: EnvironmentValues,
+    _ viewTraits: _ViewTraitStore,
+    _ parent: MountedElement<R>?
+  ) {
     element = .view(view)
     self.parent = parent
     self.environmentValues = environmentValues
+    self.viewTraits = viewTraits
     updateEnvironment()
   }
 
@@ -131,16 +145,43 @@ public class MountedElement<R: Renderer> {
     }
   }
 
+  /// You must call `super.prepareForMount` before all other mounting work.
+  func prepareForMount() {
+    // Allow the root of a mount to transition
+    // (if their parent isn't mounting, then they are the root of the mount).
+    if parent?.transitionPhase == .normal {
+      viewTraits.insert(true, forKey: CanTransitionTraitKey.self)
+    }
+  }
+
+  /// You must call `super.mount` after all other mounting work.
   func mount(
     before sibling: R.TargetType? = nil,
     on parent: MountedElement<R>? = nil,
-    with reconciler: StackReconciler<R>
+    in reconciler: StackReconciler<R>,
+    with transaction: Transaction
   ) {
-    fatalError("implement \(#function) in subclass")
+    // Set the phase to `normal` after finished mounting.
+    transitionPhase = .normal
   }
 
-  func unmount(with reconciler: StackReconciler<R>) {
-    fatalError("implement \(#function) in subclass")
+  /// You must call `super.unmount` before all other unmounting work.
+  func unmount(
+    in reconciler: StackReconciler<R>,
+    with transaction: Transaction,
+    parentTask: UnmountTask<R>?
+  ) {
+    if !(self is MountedHostView<R>) {
+      unmountTask = parentTask?.appendChild()
+    }
+
+    // Set the phase to `willUnmount` before unmounting.
+    transitionPhase = .willUnmount
+    // Allow the root of an unmount to transition
+    // (if their parent isn't unmounting, then they are the root of the unmount).
+    if parent?.transitionPhase == .normal {
+      viewTraits.insert(true, forKey: CanTransitionTraitKey.self)
+    }
   }
 
   func update(in reconciler: StackReconciler<R>, with transaction: Transaction) {
@@ -228,14 +269,15 @@ extension AnyView {
     _ renderer: R,
     _ parentTarget: R.TargetType,
     _ environmentValues: EnvironmentValues,
+    _ viewTraits: _ViewTraitStore,
     _ parent: MountedElement<R>?
   ) -> MountedElement<R> {
     if type == EmptyView.self {
-      return MountedEmptyView(self, environmentValues, parent)
+      return MountedEmptyView(self, environmentValues, viewTraits, parent)
     } else if bodyType == Never.self && !renderer.isPrimitiveView(type) {
-      return MountedHostView(self, parentTarget, environmentValues, parent)
+      return MountedHostView(self, parentTarget, environmentValues, viewTraits, parent)
     } else {
-      return MountedCompositeView(self, parentTarget, environmentValues, parent)
+      return MountedCompositeView(self, parentTarget, environmentValues, viewTraits, parent)
     }
   }
 }

Sources/TokamakCore/MountedViews/MountedEmptyView.swift

@@ -19,10 +19,20 @@ final class MountedEmptyView<R: Renderer>: MountedElement<R> {
   override func mount(
     before sibling: R.TargetType? = nil,
     on parent: MountedElement<R>? = nil,
-    with reconciler: StackReconciler<R>
-  ) {}
+    in reconciler: StackReconciler<R>,
+    with transaction: Transaction
+  ) {
+    super.prepareForMount()
+    super.mount(before: sibling, on: parent, in: reconciler, with: transaction)
+  }
 
-  override func unmount(with reconciler: StackReconciler<R>) {}
+  override func unmount(
+    in reconciler: StackReconciler<R>,
+    with transaction: Transaction,
+    parentTask: UnmountTask<R>?
+  ) {
+    super.unmount(in: reconciler, with: transaction, parentTask: parentTask)
+  }
 
   override func update(in reconciler: StackReconciler<R>, with transaction: Transaction?) {}
 }