lottie: fix position property animation along path.

Change-Id: I5b30f96a0e8358d2f6b75685ad9025dcdd4dee60

diff --git a/src/lottie/lottiemodel.h b/src/lottie/lottiemodel.h
index 05c888c3f1873f3991cc9eccbfda3bcb4e975190..b3dba6063e0b801adefa80a0f54036fe0f82e250 100644 (file)
--- a/src/lottie/lottiemodel.h
+++ b/src/lottie/lottiemodel.h
@@ -151,8 +151,14 @@ struct LOTKeyFrameValue<VPointF>
 
     VPointF value(float t) const {
         if (mPathKeyFrame) {
-            return VBezier::fromPoints(mStartValue, mStartValue + mOutTangent,
-                                       mEndValue + mInTangent, mEndValue).pointAt(t);
+            /*
+             * position along the path calcualated
+             * using bezier at progress length (t * bezlen)
+             */
+            VBezier b = VBezier::fromPoints(mStartValue, mStartValue + mOutTangent,
+                                       mEndValue + mInTangent, mEndValue);
+            return b.pointAt(b.tAtLength(t * b.length()));
+
         } else {
             return lerp(mStartValue, mEndValue, t);
         }