[skottie] Hierarchical animators

Instead of a flat animator space, introduce animator groups.

This allows us to encapsulate layer animators and only dispatch ticks
when their owning layer is active.

TBR=

Change-Id: I1fc8a55abf68a712b71969bb1a11275dbe54c236
Reviewed-on: https://skia-review.googlesource.com/101201
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>

1 files changed, 14 insertions, 2 deletions

diff --git a/experimental/sksg/SkSGScene.h b/experimental/sksg/SkSGScene.h
index 32186498d2..2081c1d747 100644
--- a/experimental/sksg/SkSGScene.h
+++ b/experimental/sksg/SkSGScene.h
@@ -39,6 +39,20 @@ private:
     using INHERITED = SkNoncopyable;
 };
 
+using AnimatorList = std::vector<std::unique_ptr<Animator>>;
+
+class GroupAnimator : public Animator {
+protected:
+    explicit GroupAnimator(AnimatorList&&);
+
+    void onTick(float t) override;
+
+private:
+    const AnimatorList fAnimators;
+
+    using INHERITED = Animator;
+};
+
 /**
  * Holds a scene root and a list of animators.
  *
@@ -47,8 +61,6 @@ private:
  */
 class Scene final : SkNoncopyable {
 public:
-    using AnimatorList = std::vector<std::unique_ptr<Animator>>;
-
     static std::unique_ptr<Scene> Make(sk_sp<RenderNode> root, AnimatorList&& animators);
     ~Scene();