From 7609f7f27d756dea7c19fd51d1171f44f1829582 Mon Sep 17 00:00:00 2001
From: Kyle Carlstrom <kylecarlstrom@google.com>
Date: Mon, 16 Aug 2021 16:46:47 -0700
Subject: [PATCH] Create Vec2ExpressionAnimator

Change-Id: I056eb5ca61c14dd58c2edeadcd122f383094fcb9
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/439976
Commit-Queue: Kyle Carlstrom <kylecarlstrom@google.com>
Commit-Queue: Avinash Parchuri <aparchur@google.com>
Reviewed-by: Avinash Parchuri <aparchur@google.com>
Reviewed-by: Florin Malita <fmalita@chromium.org>
---
 .../src/animator/Vec2KeyframeAnimator.cpp     | 29 +++++++++++++++++--
 modules/skottie/tests/Expression.cpp          | 23 +++++++++++++--
 2 files changed, 47 insertions(+), 5 deletions(-)

diff --git a/modules/skottie/src/animator/Vec2KeyframeAnimator.cpp b/modules/skottie/src/animator/Vec2KeyframeAnimator.cpp
index 0652ce6e52..891e24d5d2 100644
--- a/modules/skottie/src/animator/Vec2KeyframeAnimator.cpp
+++ b/modules/skottie/src/animator/Vec2KeyframeAnimator.cpp
@@ -101,6 +101,29 @@ private:
     using INHERITED = KeyframeAnimator;
 };
 
+class Vec2ExpressionAnimator final : public Animator {
+public:
+    Vec2ExpressionAnimator(sk_sp<ExpressionEvaluator<std::vector<float>>> expression_evaluator,
+        Vec2Value* target_value)
+        : fExpressionEvaluator(std::move(expression_evaluator))
+        , fTarget(target_value) {}
+
+private:
+
+    StateChanged onSeek(float t) override {
+        auto old_value = *fTarget;
+
+        std::vector<float> result = fExpressionEvaluator->evaluate(t);
+        fTarget->x = result.size() > 0 ? result[0] : 0;
+        fTarget->y = result.size() > 1 ? result[1] : 0;
+
+        return *fTarget != old_value;
+    }
+
+    sk_sp<ExpressionEvaluator<std::vector<float>>> fExpressionEvaluator;
+    Vec2Value* fTarget;
+};
+
 class Vec2AnimatorBuilder final : public AnimatorBuilder {
     public:
         Vec2AnimatorBuilder(Vec2Value* vec_target, float* rot_target)
@@ -125,8 +148,10 @@ class Vec2AnimatorBuilder final : public AnimatorBuilder {
                                                  fRotTarget));
         }
 
-        sk_sp<Animator> makeFromExpression(ExpressionManager&, const char*) override {
-            return nullptr;
+        sk_sp<Animator> makeFromExpression(ExpressionManager& em, const char* expr) override {
+            sk_sp<ExpressionEvaluator<std::vector<SkScalar>>> expression_evaluator =
+                em.createArrayExpressionEvaluator(expr);
+            return sk_make_sp<Vec2ExpressionAnimator>(expression_evaluator, fVecTarget);
         }
 
         bool parseValue(const AnimationBuilder&, const skjson::Value& jv) const override {
diff --git a/modules/skottie/tests/Expression.cpp b/modules/skottie/tests/Expression.cpp
index 29d2177b1e..fba3f6b34d 100644
--- a/modules/skottie/tests/Expression.cpp
+++ b/modules/skottie/tests/Expression.cpp
@@ -22,6 +22,13 @@ public:
     }
 };
 
+class FakeVectorExpressionEvaluator : public ExpressionEvaluator<std::vector<float>> {
+public:
+    std::vector<float> evaluate(float t) override {
+        return {1.0f, 2.0f};
+    }
+};
+
 class FakeExpressionManager : public ExpressionManager {
 public:
     sk_sp<ExpressionEvaluator<float>> createNumberExpressionEvaluator(
@@ -36,18 +43,24 @@ public:
 
     sk_sp<ExpressionEvaluator<std::vector<float>>> createArrayExpressionEvaluator(
         const char expression[]) override {
-        return nullptr;
+        return sk_make_sp<FakeVectorExpressionEvaluator>();
     }
 };
 
 class FakePropertyObserver : public PropertyObserver {
     public:
         void onOpacityProperty(const char node_name[],
-                                     const LazyHandle<OpacityPropertyHandle>& opacity_handle) override {
+                               const LazyHandle<OpacityPropertyHandle>& opacity_handle) override {
             opacity_handle_.reset(opacity_handle().release());
         }
 
+        void onTransformProperty(const char node_name[],
+                                 const LazyHandle<TransformPropertyHandle>& transform_handle) override {
+            transform_handle_.reset(transform_handle().release());
+        }
+
     std::unique_ptr<OpacityPropertyHandle> opacity_handle_;
+    std::unique_ptr<TransformPropertyHandle> transform_handle_;
 };
 } // namespace
 
@@ -97,7 +110,8 @@ DEF_TEST(Skottie_ScalarExpression, r) {
                             0
                         ],
                         "ix": 1,
-                        "l": 2
+                        "l": 2,
+                        "x": "fake; return value is specified by the FakeArrayExpressionEvaluator."
                     },
                     "s": {
                         "a": 0,
@@ -135,4 +149,7 @@ DEF_TEST(Skottie_ScalarExpression, r) {
     anim->seekFrameTime(0);
 
     REPORTER_ASSERT(r, SkScalarNearlyEqual(observer->opacity_handle_->get(), 7.0f));
+    SkPoint anchor_point = observer->transform_handle_->get().fAnchorPoint;
+    REPORTER_ASSERT(r, SkScalarNearlyEqual(anchor_point.fX, 1.0f));
+    REPORTER_ASSERT(r, SkScalarNearlyEqual(anchor_point.fY, 2.0f));
 }