prevent exception when local hero is disabled and no local hero scope

example/ios/Flutter/AppFrameworkInfo.plist

@@ -21,6 +21,6 @@
   <key>CFBundleVersion</key>
   <string>1.0</string>
   <key>MinimumOSVersion</key>
-  <string>8.0</string>
+  <string>9.0</string>
 </dict>
 </plist>

example/ios/Runner.xcodeproj/project.pbxproj

@@ -3,7 +3,7 @@
 	archiveVersion = 1;
 	classes = {
 	};
-	objectVersion = 46;
+	objectVersion = 50;
 	objects = {
 
 /* Begin PBXBuildFile section */
@@ -135,7 +135,7 @@
 		97C146E61CF9000F007C117D /* Project object */ = {
 			isa = PBXProject;
 			attributes = {
-				LastUpgradeCheck = 1020;
+				LastUpgradeCheck = 1300;
 				ORGANIZATIONNAME = "";
 				TargetAttributes = {
 					97C146ED1CF9000F007C117D = {
@@ -280,7 +280,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				SUPPORTED_PLATFORMS = iphoneos;
@@ -362,7 +362,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = YES;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
@@ -411,7 +411,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				SUPPORTED_PLATFORMS = iphoneos;

example/ios/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1020"
+   LastUpgradeVersion = "1300"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

example/lib/main_example_readme.dart

@@ -5,6 +5,21 @@ void main() {
   runApp(const _LocalHeroApp());
 }
 
+class _Box extends StatelessWidget {
+  const _Box({
+    Key? key,
+  }) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      color: Colors.red,
+      width: 50,
+      height: 50,
+    );
+  }
+}
+
 class _LocalHeroApp extends StatelessWidget {
   const _LocalHeroApp({
     Key? key,
@@ -28,7 +43,6 @@ class _LocalHeroPage extends StatelessWidget {
     return const Scaffold(
       body: SafeArea(
         child: LocalHeroScope(
-          duration: Duration(milliseconds: 300),
           curve: Curves.easeInOut,
           child: _LocalHeroPlayground(),
         ),
@@ -79,18 +93,3 @@ class _LocalHeroPlaygroundState extends State<_LocalHeroPlayground> {
     );
   }
 }
-
-class _Box extends StatelessWidget {
-  const _Box({
-    Key? key,
-  }) : super(key: key);
-
-  @override
-  Widget build(BuildContext context) {
-    return Container(
-      color: Colors.red,
-      width: 50,
-      height: 50,
-    );
-  }
-}

lib/src/rendering/controller.dart

@@ -1,5 +1,4 @@
 import 'package:flutter/animation.dart';
-import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter/scheduler.dart';
 
@@ -16,7 +15,7 @@ class LocalHeroController {
     required this.curve,
     required this.createRectTween,
     required this.tag,
-  })   : link = LayerLink(),
+  })  : link = LayerLink(),
         _vsync = vsync,
         _initialDuration = duration;
 

lib/src/rendering/layer.dart

@@ -30,8 +30,11 @@ class LocalHeroLayer extends ContainerLayer {
 
   Offset? _transformOffset<S>(Offset localPosition) {
     if (_inverseDirty) {
-      _invertedTransform = Matrix4.tryInvert(getLastTransform()!);
-      _inverseDirty = false;
+      final lastTransform = getLastTransform();
+      if (lastTransform != null) {
+        _invertedTransform = Matrix4.tryInvert(lastTransform);
+        _inverseDirty = false;
+      }
     }
     if (_invertedTransform == null) {
       return null;
@@ -51,7 +54,7 @@ class LocalHeroLayer extends ContainerLayer {
     Offset localPosition, {
     required bool onlyFirst,
   }) {
-    if (controller.link.leader == null) {
+    if (!controller.link.leaderConnected) {
       return false;
     }
     final Offset? transformedOffset = _transformOffset<S>(localPosition);
@@ -90,7 +93,9 @@ class LocalHeroLayer extends ContainerLayer {
     // Apply each layer to the matrix in turn, starting from the last layer,
     // and providing the previous layer as the child.
     for (int index = layers.length - 1; index > 0; index -= 1) {
-      layers[index]!.applyTransform(layers[index - 1], result);
+      if (layers[index - 1] != null) {
+        layers[index]!.applyTransform(layers[index - 1], result);
+      }
     }
     return result;
   }
@@ -99,12 +104,13 @@ class LocalHeroLayer extends ContainerLayer {
   void _establishTransform() {
     _lastTransform = null;
     // Check to see if we are linked.
-    if (controller.link.leader == null) {
+    if (!controller.link.leaderConnected) {
       return;
     }
     // If we're linked, check the link is valid.
-    assert(controller.link.leader!.owner == owner,
-        'Linked LeaderLayer anchor is not in the same layer tree as the FollowerLayer.');
+    if (controller.link.debugLeader?.owner != owner) {
+      return;
+    }
     // Collect all our ancestors into a Set so we can recognize them.
     final Set<Layer> ancestors = <Layer>{};
     Layer? ancestor = parent;
@@ -114,7 +120,7 @@ class LocalHeroLayer extends ContainerLayer {
     }
     // Collect all the layers from a hypothetical child (null) of the target
     // layer up to the common ancestor layer.
-    ContainerLayer layer = controller.link.leader!;
+    ContainerLayer layer = controller.link.debugLeader!;
     final List<ContainerLayer?> forwardLayers = <ContainerLayer?>[null, layer];
     do {
       layer = layer.parent!;
@@ -162,7 +168,7 @@ class LocalHeroLayer extends ContainerLayer {
 
   @override
   void addToScene(ui.SceneBuilder builder, [Offset layerOffset = Offset.zero]) {
-    if (controller.link.leader == null) {
+    if (!controller.link.leaderConnected) {
       _lastTransform = null;
       _lastOffset = null;
       _inverseDirty = true;
@@ -187,7 +193,6 @@ class LocalHeroLayer extends ContainerLayer {
   @override
   void applyTransform(Layer? child, Matrix4 transform) {
     assert(child != null);
-    assert(transform != null);
 
     transform.multiply(_lastTransform!);
   }

lib/src/rendering/local_hero_layer.dart

@@ -1,5 +1,4 @@
 import 'package:flutter/animation.dart';
-import 'package:flutter/foundation.dart';
 import 'package:flutter/rendering.dart';
 import 'package:local_hero/src/rendering/controller.dart';
 import 'package:local_hero/src/rendering/layer.dart';

lib/src/widgets/local_hero.dart

@@ -59,27 +59,27 @@ class LocalHero extends StatefulWidget {
 
 class _LocalHeroState extends State<LocalHero>
     with SingleTickerProviderStateMixin<LocalHero> {
-  late LocalHeroController controller;
-  late LocalHeroScopeState scopeState;
+  late LocalHeroController? controller;
+  late LocalHeroScopeState? scopeState;
 
   @override
   void initState() {
     super.initState();
-    scopeState = context.getLocalHeroScopeState();
-    controller = scopeState.track(context, widget);
+    scopeState = widget.enabled ? context.getLocalHeroScopeState() : null;
+    controller = scopeState?.track(context, widget);
   }
 
   @override
   void dispose() {
-    scopeState.untrack(widget);
+    scopeState?.untrack(widget);
     super.dispose();
   }
 
   @override
   Widget build(BuildContext context) {
     return widget.enabled
         ? LocalHeroLeader(
-            controller: controller,
+            controller: controller!,
             child: widget.child,
           )
         : widget.child;

lib/src/widgets/local_hero_scope.dart

@@ -1,6 +1,5 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/scheduler.dart';
-import 'package:flutter/widgets.dart';
 import 'package:local_hero/src/rendering/controller.dart';
 import 'package:local_hero/src/widgets/local_hero.dart';
 import 'package:local_hero/src/widgets/local_hero_layer.dart';