Solos

So far:
- [x] Editor
- [x] Dart Tests
- [x] Flutter Runtime
- [x] C++ Runtime
- [x] C++ Tests

Hierarchy interaction:
<img width="280" alt="CleanShot 2023-03-24 at 21 44 53@2x" src="https://user-images.githubusercontent.com/454182/227696646-09f9cbe5-c482-4bab-aae9-b0b36c16047e.png">

Nesting:
<img width="394" alt="CleanShot 2023-03-24 at 21 45 23@2x" src="https://user-images.githubusercontent.com/454182/227696653-b1132ba1-5471-4c6d-9b59-20387389ae12.png">

Inspector active solo selection:
<img width="253" alt="CleanShot 2023-03-24 at 21 45 33@2x" src="https://user-images.githubusercontent.com/454182/227696660-6676acfa-15ab-4ae2-a866-4b7898bc1f52.png">

Animatable with timeline hierarchy value too:
<img width="510" alt="CleanShot 2023-03-24 at 21 46 07@2x" src="https://user-images.githubusercontent.com/454182/227696686-255064c9-43fd-4213-9e3f-9cd46cca9de3.png">

Diffs=
daaf140ba Solos (#5047)
44ef23f7e Text fix variable and opacity (#5017)
3c396d3b8 Text style variation at runtime. (#5014)

.rive_head

@@ -1 +1 @@
-41b699beb873be31f4d38ba79bd613cc83f74eca
+daaf140ba0a062ba9ec7f4eafa1e198d9121b220

example/analysis_options.yaml

@@ -1,4 +1,10 @@
 include: package:flutter_lints/flutter.yaml
+analyzer:
+  exclude:
+    - windows/**
+    - ios/**
+    - macos/**
+    - web/**
 
 linter:
   rules:

lib/src/generated/rive_core_context.dart

@@ -123,6 +123,7 @@ import 'package:rive/src/rive_core/shapes/shape.dart';
 import 'package:rive/src/rive_core/shapes/star.dart';
 import 'package:rive/src/rive_core/shapes/straight_vertex.dart';
 import 'package:rive/src/rive_core/shapes/triangle.dart';
+import 'package:rive/src/rive_core/solo.dart';
 import 'package:rive/src/rive_core/text/text.dart';
 import 'package:rive/src/rive_core/text/text_style.dart';
 import 'package:rive/src/rive_core/text/text_style_axis.dart';
@@ -152,6 +153,8 @@ class RiveCoreContext {
         return Node();
       case NestedArtboardBase.typeKey:
         return NestedArtboard();
+      case SoloBase.typeKey:
+        return Solo();
       case AnimationBase.typeKey:
         return Animation();
       case LinearAnimationBase.typeKey:
@@ -508,6 +511,11 @@ class RiveCoreContext {
           object.animationId = value;
         }
         break;
+      case SoloBase.activeComponentIdPropertyKey:
+        if (object is SoloBase && value is int) {
+          object.activeComponentId = value;
+        }
+        break;
       case AnimationBase.namePropertyKey:
         if (object is AnimationBase && value is String) {
           object.name = value;
@@ -1300,6 +1308,7 @@ class RiveCoreContext {
       case DrawableBase.drawableFlagsPropertyKey:
       case NestedArtboardBase.artboardIdPropertyKey:
       case NestedAnimationBase.animationIdPropertyKey:
+      case SoloBase.activeComponentIdPropertyKey:
       case LinearAnimationBase.fpsPropertyKey:
       case LinearAnimationBase.durationPropertyKey:
       case LinearAnimationBase.loopValuePropertyKey:
@@ -1527,6 +1536,8 @@ class RiveCoreContext {
         return (object as NestedArtboardBase).artboardId;
       case NestedAnimationBase.animationIdPropertyKey:
         return (object as NestedAnimationBase).animationId;
+      case SoloBase.activeComponentIdPropertyKey:
+        return (object as SoloBase).activeComponentId;
       case LinearAnimationBase.fpsPropertyKey:
         return (object as LinearAnimationBase).fps;
       case LinearAnimationBase.durationPropertyKey:
@@ -2000,6 +2011,11 @@ class RiveCoreContext {
           object.animationId = value;
         }
         break;
+      case SoloBase.activeComponentIdPropertyKey:
+        if (object is SoloBase) {
+          object.activeComponentId = value;
+        }
+        break;
       case LinearAnimationBase.fpsPropertyKey:
         if (object is LinearAnimationBase) {
           object.fps = value;

lib/src/generated/solo_base.dart

@@ -0,0 +1,54 @@
+/// Core automatically generated lib/src/generated/solo_base.dart.
+/// Do not modify manually.
+
+import 'package:rive/src/generated/component_base.dart';
+import 'package:rive/src/generated/container_component_base.dart';
+import 'package:rive/src/generated/transform_component_base.dart';
+import 'package:rive/src/generated/world_transform_component_base.dart';
+import 'package:rive/src/rive_core/node.dart';
+
+abstract class SoloBase extends Node {
+  static const int typeKey = 147;
+  @override
+  int get coreType => SoloBase.typeKey;
+  @override
+  Set<int> get coreTypes => {
+        SoloBase.typeKey,
+        NodeBase.typeKey,
+        TransformComponentBase.typeKey,
+        WorldTransformComponentBase.typeKey,
+        ContainerComponentBase.typeKey,
+        ComponentBase.typeKey
+      };
+
+  /// --------------------------------------------------------------------------
+  /// ActiveComponentId field with key 296.
+  static const int activeComponentIdInitialValue = 0;
+  int _activeComponentId = activeComponentIdInitialValue;
+  static const int activeComponentIdPropertyKey = 296;
+
+  /// Identifier of the active child in the solo set.
+  int get activeComponentId => _activeComponentId;
+
+  /// Change the [_activeComponentId] field value.
+  /// [activeComponentIdChanged] will be invoked only if the field's value has
+  /// changed.
+  set activeComponentId(int value) {
+    if (_activeComponentId == value) {
+      return;
+    }
+    int from = _activeComponentId;
+    _activeComponentId = value;
+    if (hasValidated) {
+      activeComponentIdChanged(from, value);
+    }
+  }
+
+  void activeComponentIdChanged(int from, int to);
+
+  @override
+  void copy(covariant SoloBase source) {
+    super.copy(source);
+    _activeComponentId = source._activeComponentId;
+  }
+}

lib/src/rive_core/artboard.dart

@@ -138,10 +138,12 @@ class Artboard extends ArtboardBase with ShapePaintContainer {
           Component component = _dependencyOrder[i];
           _dirtDepth = i;
           int d = component.dirt;
-          if (d == 0) {
+
+          if (d == 0 || (d & ComponentDirt.collapsed) != 0) {
             continue;
           }
-          component.dirt = 0;
+
+          component.dirt &= ComponentDirt.collapsed;
           component.update(d);
           if (_dirtDepth < i) {
             break;

lib/src/rive_core/component.dart

@@ -1,5 +1,6 @@
 import 'package:rive/src/generated/component_base.dart';
 import 'package:rive/src/rive_core/artboard.dart';
+import 'package:rive/src/rive_core/component_dirt.dart';
 import 'package:rive/src/rive_core/container_component.dart';
 import 'package:rive_common/utilities.dart';
 
@@ -10,6 +11,23 @@ abstract class Component extends ComponentBase<RuntimeArtboard>
   Artboard? _artboard;
   dynamic _userData;
 
+  /// Whether this Component's update processes at all.
+  bool get isCollapsed => (dirt & ComponentDirt.collapsed) != 0;
+
+  bool propagateCollapse(bool collapse) {
+    if (isCollapsed == collapse) {
+      return false;
+    }
+    if (collapse) {
+      dirt |= ComponentDirt.collapsed;
+    } else {
+      dirt &= ~ComponentDirt.collapsed;
+    }
+    onDirty(dirt);
+    artboard?.onComponentDirty(this);
+    return true;
+  }
+
   /// Override to true if you want some object inheriting from Component to not
   /// have a parent. Most objects will validate that they have a parent during
   /// the onAdded callback otherwise they are considered invalid and are culled
@@ -18,7 +36,7 @@ abstract class Component extends ComponentBase<RuntimeArtboard>
 
   // Used during update process.
   int graphOrder = 0;
-  int dirt = 0xFFFF;
+  int dirt = ComponentDirt.filthy;
 
   // This is really only for sanity and earlying out of recursive loops.
   static const int maxTreeDepth = 5000;
@@ -112,6 +130,7 @@ abstract class Component extends ComponentBase<RuntimeArtboard>
     if (_parent == value) {
       return;
     }
+    dirt &= ~ComponentDirt.collapsed;
     var old = _parent;
     _parent = value;
     parentId = value?.id ?? Core.missingId;

lib/src/rive_core/component_dirt.dart

@@ -1,44 +1,50 @@
 class ComponentDirt {
-  static const int dependents = 1 << 0;
+  /// Means to not process the update!
+  static const int collapsed = 1 << 0;
+
+  static const int dependents = 1 << 1;
 
   /// General flag for components are dirty (if this is up, the update cycle
   /// runs). It gets automatically applied with any other dirt.
-  static const int components = 1 << 1;
+  static const int components = 1 << 2;
 
   /// Draw order needs to be re-computed.
-  static const int drawOrder = 1 << 2;
+  static const int drawOrder = 1 << 3;
 
   /// Draw order needs to be re-computed.
-  static const int naturalDrawOrder = 1 << 3;
+  static const int naturalDrawOrder = 1 << 4;
 
   /// Path is dirty and needs to be rebuilt.
-  static const int path = 1 << 4;
+  static const int path = 1 << 5;
 
   /// Text shape is dirty, the shaper needs to re-run.
-  static const int textShape = 1 << 4;
+  static const int textShape = 1 << 5;
 
   /// Vertices have changed, re-order cached lists.
-  static const int vertices = 1 << 5;
+  static const int vertices = 1 << 6;
 
   /// Used by any component that needs to recompute their local transform.
   /// Usually components that have their transform dirty will also have their
   /// worldTransform dirty.
-  static const int transform = 1 << 6;
+  static const int transform = 1 << 7;
 
   /// Used by any component that needs to update its world transform.
-  static const int worldTransform = 1 << 7;
+  static const int worldTransform = 1 << 8;
 
   /// Dirt used to mark some stored paint needs to be rebuilt or that we just
   /// want to trigger an update cycle so painting occurs.
-  static const int paint = 1 << 8;
+  static const int paint = 1 << 9;
 
   /// Used by the gradients track when the stops need to be re-ordered.
-  static const int stops = 1 << 9;
+  static const int stops = 1 << 10;
 
   /// Used by ClippingShape to help Shape know when to recalculate its list of
   /// clipping sources.
-  static const int clip = 1 << 10;
+  static const int clip = 1 << 11;
 
   /// Set when blend modes need to be updated.
-  static const int blendMode = 1 << 11;
+  static const int blendMode = 1 << 12;
+
+  /// All dirty. Every flag (apart from Collapsed) is set.
+  static const int filthy = 0xFFFE;
 }

lib/src/rive_core/component_flags.dart

@@ -3,47 +3,10 @@ class ComponentFlags {
   /// drawables and paths).
   static const int hidden = 1 << 0;
 
-  // Whether the component was locked for editing in the editor.
+  /// Whether the component was locked for editing in the editor.
   static const int locked = 1 << 1;
 
-  /// These options are used by [TransformComponentConstraint]s, any other
-  /// component that's not in that class hierarchy can re-use these values as
-  /// they won't collide.
-  ///
-  /// -----------
-
-  /// Whether the [TransformComponentConstraint]'s constrained value is offset
-  /// from the design time value (in the matching space).
-  static const int offset = 1 << 2;
-
-  /// Whether the transform component is copied.
-  static const int copy = 1 << 3;
-
-  /// Set when a minimum value should be applied to the constrained value.
-  static const int min = 1 << 4;
-
-  /// Set when a maximum value should be applied to the constrained value.
-  static const int max = 1 << 5;
-
-  /// Whether an X transform component is copied.
-  static const int copyX = 1 << 3;
-
-  /// Set when a minimum value should be applied to the constrained X value.
-  static const int minX = 1 << 4;
-
-  /// Set when a maximum value should be applied to the constrained X value.
-  static const int maxX = 1 << 5;
-
-  /// Whether a Y transform component is copied.
-  static const int copyY = 1 << 6;
-
-  /// Set when a minimum value should be applied to the constrained Y value.
-  static const int minY = 1 << 7;
-
-  /// Set when a maximum value should be applied to the constrained Y value.
-  static const int maxY = 1 << 8;
-
-  /// End of TransformComponentConstraint
-  ///
-  /// ----------
+  /// Whether this Component is disconnected from the hierarchy meaning it won't
+  /// receive any update cycles nor will any drawables draw.
+  static const int disconnected = 1 << 2;
 }

lib/src/rive_core/container_component.dart

@@ -22,7 +22,9 @@ abstract class ContainerComponent extends ContainerComponentBase {
   }
 
   @mustCallSuper
-  void childAdded(Component child) {}
+  void childAdded(Component child) {
+    _propagateCollapseToChildren(isCollapsed);
+  }
 
   void childRemoved(Component child) {}
 
@@ -71,4 +73,19 @@ abstract class ContainerComponent extends ContainerComponentBase {
       }
     }
   }
+
+  void _propagateCollapseToChildren(bool collapse) {
+    for (final child in children) {
+      child.propagateCollapse(collapse);
+    }
+  }
+
+  @override
+  bool propagateCollapse(bool collapse) {
+    if (!super.propagateCollapse(collapse)) {
+      return false;
+    }
+    _propagateCollapseToChildren(collapse);
+    return true;
+  }
 }

lib/src/rive_core/drawable.dart

@@ -85,5 +85,7 @@ abstract class Drawable extends DrawableBase {
   @override
   void drawableFlagsChanged(int from, int to) => addDirt(ComponentDirt.paint);
 
-  bool get isHidden => (drawableFlags & ComponentFlags.hidden) != 0;
+  bool get isHidden =>
+      (drawableFlags & ComponentFlags.hidden) != 0 ||
+      (dirt & ComponentDirt.collapsed) != 0;
 }

lib/src/rive_core/shapes/path_composer.dart

@@ -85,4 +85,18 @@ class PathComposer extends Component {
       _recomputePath();
     }
   }
+
+  void syncCollapse() {
+    var collapsed = (dirt & ComponentDirt.collapsed) != 0;
+    if (collapsed == shape.isCollapsed) {
+      return;
+    }
+    if (collapsed) {
+      dirt |= ComponentDirt.collapsed;
+    } else {
+      dirt &= ~ComponentDirt.collapsed;
+    }
+    onDirty(dirt);
+    artboard?.onComponentDirty(this);
+  }
 }

lib/src/rive_core/shapes/shape.dart

@@ -46,6 +46,12 @@ class Shape extends ShapeBase with ShapePaintContainer {
     _worldBounds = _localBounds = null;
   }
 
+  @override
+  void onDirty(int mask) {
+    pathComposer.syncCollapse();
+    super.onDirty(mask);
+  }
+
   bool addPath(Path path) {
     paintChanged();
     var added = paths.add(path);

lib/src/rive_core/solo.dart

@@ -0,0 +1,53 @@
+import 'package:rive/src/generated/solo_base.dart';
+import 'package:rive/src/rive_core/component.dart';
+import 'package:rive/src/rive_core/container_component.dart';
+
+export 'package:rive/src/generated/solo_base.dart';
+
+class Solo extends SoloBase {
+  Component? _activeComponent;
+  @override
+  void activeComponentIdChanged(int from, int to) =>
+      activeComponent = context.resolve(to);
+
+  Component? get activeComponent => _activeComponent;
+
+  set activeComponent(Component? value) {
+    if (_activeComponent == value) {
+      return;
+    }
+    _activeComponent = value;
+    activeComponentId = value?.id ?? Core.missingId;
+    _updateCollapse();
+  }
+
+  void _updateCollapse() {
+    for (final child in children) {
+      if (child == _activeComponent) {
+        child.propagateCollapse(false);
+      } else {
+        child.propagateCollapse(true);
+      }
+    }
+  }
+
+  @override
+  void childRemoved(Component child) {
+    super.childRemoved(child);
+    _updateCollapse();
+  }
+
+  @override
+  void childAdded(Component child) {
+    super.childAdded(child);
+    _updateCollapse();
+  }
+
+  @override
+  void onAddedDirty() {
+    super.onAddedDirty();
+    if (activeComponentId != Core.missingId) {
+      activeComponent = context.resolve(activeComponentId);
+    }
+  }
+}

lib/src/rive_core/text/text.dart

@@ -329,6 +329,14 @@ class Text extends TextBase with TextStyleContainer {
         computeShape();
       }
     }
+    if (dirt & ComponentDirt.worldTransform != 0) {
+      for (final style in styles) {
+        for (final paint in style.shapePaints) {
+          paint.renderOpacity = renderOpacity;
+        }
+      }
+      markPaintDirty();
+    }
   }
 
   @override

lib/src/rive_core/text/text_style.dart

@@ -104,17 +104,20 @@ class TextStyle extends TextStyleBase
     _variationHelper?.buildDependencies();
   }
 
+  void removeVariations() => _variations.toSet().forEach(context.removeObject);
+
   @override
   set asset(FontAsset? value) {
     if (asset == value) {
       return;
     }
-    _variations.toSet().forEach(context.removeObject);
+
     super.asset = value;
     if (asset?.whenDecoded(_fontDecoded, notifyAlreadyDecoded: false) ??
         false) {
       // Already decoded.
       _markShapeDirty();
+      _variationHelper?.addDirt(ComponentDirt.textShape);
     }
   }