From 72d2238d1de20e5ea9c212ebc3c90cffda2c13c1 Mon Sep 17 00:00:00 2001
From: Luigi Rosso <luigi@rive.app>
Date: Tue, 27 Jul 2021 15:38:05 -0700
Subject: [PATCH] Applying latest fix from editor for ik constraints with
 skinned bones.

---
 lib/src/rive_core/bones/bone.dart             |  9 ++++
 lib/src/rive_core/bones/skin.dart             | 12 ++++-
 .../rive_core/constraints/ik_constraint.dart  | 45 ++++++++++++++++---
 3 files changed, 60 insertions(+), 6 deletions(-)

diff --git a/lib/src/rive_core/bones/bone.dart b/lib/src/rive_core/bones/bone.dart
index 9d0a604..a82fdca 100644
--- a/lib/src/rive_core/bones/bone.dart
+++ b/lib/src/rive_core/bones/bone.dart
@@ -1,3 +1,4 @@
+import 'package:rive/src/rive_core/constraints/constraint.dart';
 import 'package:rive/src/rive_core/math/mat2d.dart';
 import 'package:rive/src/rive_core/math/vec2d.dart';
 import 'package:rive/src/generated/bones/bone_base.dart';
@@ -6,6 +7,14 @@ export 'package:rive/src/generated/bones/bone_base.dart';
 typedef bool BoneCallback(Bone bone);
 
 class Bone extends BoneBase {
+  /// Child constraints applied to some child of this bone which also affect
+  /// this bone.
+  final Set<Constraint> _peerConstraints = {};
+  Iterable<Constraint> get peerConstraints => _peerConstraints;
+
+  bool addPeerConstraint(Constraint child) => _peerConstraints.add(child);
+  bool removePeerConstraint(Constraint child) => _peerConstraints.remove(child);
+
   @override
   void lengthChanged(double from, double to) {
     for (final child in children) {
diff --git a/lib/src/rive_core/bones/skin.dart b/lib/src/rive_core/bones/skin.dart
index 4512467..266cb88 100644
--- a/lib/src/rive_core/bones/skin.dart
+++ b/lib/src/rive_core/bones/skin.dart
@@ -1,5 +1,6 @@
 import 'dart:typed_data';
 
+import 'package:rive/src/rive_core/bones/bone.dart';
 import 'package:rive/src/rive_core/bones/skinnable.dart';
 import 'package:rive/src/rive_core/bones/tendon.dart';
 import 'package:rive/src/rive_core/component.dart';
@@ -96,7 +97,16 @@ class Skin extends SkinBase {
     // A skin depends on all its bones. N.B. that we don't depend on the parent
     // skinnable. The skinnable depends on us.
     for (final tendon in _tendons) {
-      tendon.bone?.addDependent(this);
+      var bone = tendon.bone;
+      if (bone == null) {
+        continue;
+      }
+      bone.addDependent(this);
+      if (bone is Bone) {
+        for (final childConstraint in bone.peerConstraints) {
+          childConstraint.constrainedComponent?.addDependent(this);
+        }
+      }
     }
   }
 
diff --git a/lib/src/rive_core/constraints/ik_constraint.dart b/lib/src/rive_core/constraints/ik_constraint.dart
index faabdd1..148891a 100644
--- a/lib/src/rive_core/constraints/ik_constraint.dart
+++ b/lib/src/rive_core/constraints/ik_constraint.dart
@@ -35,11 +35,28 @@ class IKConstraint extends IKConstraintBase {
   Iterable<_BoneChainLink> get fkChain => _fkChain;
 
   @override
-  void buildDependencies() {
-    super.buildDependencies();
+  void onAdded() {
+    super.onAdded();
+    _buildFKChain();
+  }
 
-    // Rebuild the FK chain when we update dependencies.
+  @override
+  void onRemoved() {
+    _clearFKChain();
+
+    super.onRemoved();
+  }
+
+  void _clearFKChain() {
+    for (final link in _fkChain) {
+      link.bone.markRebuildDependencies();
+      link.bone.removePeerConstraint(this);
+    }
     _fkChain.clear();
+  }
+
+  bool _buildFKChain() {
+    var nextFKChain = <_BoneChainLink>[];
     var boneCount = parentBoneCount;
     var bone = parent as Bone;
     var bones = <Bone>[bone];
@@ -51,15 +68,33 @@ class IKConstraint extends IKConstraintBase {
     }
     // Now put them in FK order (top to bottom).
     for (final bone in bones.reversed) {
-      _fkChain.add(_BoneChainLink(
-        index: _fkChain.length,
+      bone.addPeerConstraint(this);
+      nextFKChain.add(_BoneChainLink(
+        index: nextFKChain.length,
         bone: bone,
       ));
     }
 
+    _clearFKChain();
+
+    _fkChain.addAll(nextFKChain);
+    for (final link in _fkChain) {
+      link.bone.markRebuildDependencies();
+      link.bone.addPeerConstraint(this);
+    }
+    markRebuildDependencies();
+    return true;
+  }
+
+  @override
+  void buildDependencies() {
+    super.buildDependencies();
+
     // Make sure all of the first level children of each bone depend on the
     // tip (constrainedComponent).
     var tip = parent as Bone;
+
+    var bones = _fkChain.reversed.map((link) => link.bone).toSet();
     for (final bone in bones.skip(1)) {
       for (final child in bone.children) {
         if (child is TransformComponent && !bones.contains(child)) {