[skottie] Clamp keyframe values

We can skip interpolation if |t| is out of range or the interval is
constant ("hold").

TBR=
Change-Id: I0602d36557f46592ab673201ed2b4a96d40dc461
Reviewed-on: https://skia-review.googlesource.com/99420
Reviewed-by: Florin Malita <fmalita@chromium.org>
Commit-Queue: Florin Malita <fmalita@chromium.org>

2 files changed, 18 insertions, 18 deletions

diff --git a/experimental/skottie/SkottieAnimator.cpp b/experimental/skottie/SkottieAnimator.cpp
index da00beb2fe..13f14dbf75 100644
--- a/experimental/skottie/SkottieAnimator.cpp
+++ b/experimental/skottie/SkottieAnimator.cpp
@@ -69,19 +69,12 @@ bool KeyframeIntervalBase::parse(const Json::Value& k, KeyframeIntervalBase* pre
 
 float KeyframeIntervalBase::localT(float t) const {
     SkASSERT(this->isValid());
-
-    // 'hold' pins to v0
-    if (fHold) {
-        return 0;
-    }
+    SkASSERT(!this->isHold());
+    SkASSERT(t > fT0 && t < fT1);
 
     auto lt = (t - fT0) / (fT1 - fT0);
 
-    if (fCubicMap) {
-        lt = fCubicMap->computeYFromX(lt);
-    }
-
-    return SkTPin<float>(lt, 0, 1);
+    return fCubicMap ? fCubicMap->computeYFromX(lt) : lt;
 }
 
 template <>
diff --git a/experimental/skottie/SkottieAnimator.h b/experimental/skottie/SkottieAnimator.h
index c03449d11a..062a4d8969 100644
--- a/experimental/skottie/SkottieAnimator.h
+++ b/experimental/skottie/SkottieAnimator.h
@@ -65,21 +65,28 @@ public:
             return false;
         }
 
-        if (this->isHold()) {
-            // Hold v1 == v0.
-            fV1 = fV0;
-        } else if (!ValueTraits<T>::Parse(k["e"], &fV1)) {
+        if (!this->isHold() &&
+            (!ValueTraits<T>::Parse(k["e"], &fV1) ||
+             ValueTraits<T>::Cardinality(fV0) != ValueTraits<T>::Cardinality(fV1))) {
             return false;
         }
 
+        return !prev || ValueTraits<T>::Cardinality(fV0) == ValueTraits<T>::Cardinality(prev->fV0);
+    }
 
-        return ValueTraits<T>::Cardinality(fV0) == ValueTraits<T>::Cardinality(fV1) &&
-            (!prev || ValueTraits<T>::Cardinality(fV0) == ValueTraits<T>::Cardinality(prev->fV0));
+    void eval(float t, T* v) const {
+        if (this->isHold() || t <= this->t0()) {
+            *v = fV0;
+        } else if (t >= this->t1()) {
+            *v = fV1;
+        } else {
+            this->lerp(t, v);
+        }
     }
 
+private:
     void lerp(float t, T*) const;
 
-private:
     // Start/end values.
     T fV0,
       fV1;
@@ -134,7 +141,7 @@ public:
         const auto& frame = this->findFrame(t);
 
         ValT val;
-        frame.lerp(t, &val);
+        frame.eval(t, &val);
 
         fFunc(fTarget.get(), val);
     }