Fix per-keyframe interpolators

Support different interpolators on every keyframe by running
interpolators on proportional duration instead of raw fraction.

Bug: 19928396

Change-Id: Ifb8c3a3b56785582cd6b0121d7bfb44534866300

3 files changed, 12 insertions, 10 deletions

diff --git a/core/java/android/animation/FloatKeyframeSet.java b/core/java/android/animation/FloatKeyframeSet.java
index 56da940..0173079 100644
--- a/core/java/android/animation/FloatKeyframeSet.java
+++ b/core/java/android/animation/FloatKeyframeSet.java
@@ -118,13 +118,14 @@ class FloatKeyframeSet extends KeyframeSet implements Keyframes.FloatKeyframes {
             FloatKeyframe nextKeyframe = (FloatKeyframe) mKeyframes.get(i);
             if (fraction < nextKeyframe.getFraction()) {
                 final TimeInterpolator interpolator = nextKeyframe.getInterpolator();
-                if (interpolator != null) {
-                    fraction = interpolator.getInterpolation(fraction);
-                }
                 float intervalFraction = (fraction - prevKeyframe.getFraction()) /
                     (nextKeyframe.getFraction() - prevKeyframe.getFraction());
                 float prevValue = prevKeyframe.getFloatValue();
                 float nextValue = nextKeyframe.getFloatValue();
+                // Apply interpolator on the proportional duration.
+                if (interpolator != null) {
+                    intervalFraction = interpolator.getInterpolation(intervalFraction);
+                }
                 return mEvaluator == null ?
                         prevValue + intervalFraction * (nextValue - prevValue) :
                         ((Number)mEvaluator.evaluate(intervalFraction, prevValue, nextValue)).
diff --git a/core/java/android/animation/IntKeyframeSet.java b/core/java/android/animation/IntKeyframeSet.java
index 12a4bf9..73f9af1 100644
--- a/core/java/android/animation/IntKeyframeSet.java
+++ b/core/java/android/animation/IntKeyframeSet.java
@@ -117,13 +117,14 @@ class IntKeyframeSet extends KeyframeSet implements Keyframes.IntKeyframes {
             IntKeyframe nextKeyframe = (IntKeyframe) mKeyframes.get(i);
             if (fraction < nextKeyframe.getFraction()) {
                 final TimeInterpolator interpolator = nextKeyframe.getInterpolator();
-                if (interpolator != null) {
-                    fraction = interpolator.getInterpolation(fraction);
-                }
                 float intervalFraction = (fraction - prevKeyframe.getFraction()) /
                     (nextKeyframe.getFraction() - prevKeyframe.getFraction());
                 int prevValue = prevKeyframe.getIntValue();
                 int nextValue = nextKeyframe.getIntValue();
+                // Apply interpolator on the proportional duration.
+                if (interpolator != null) {
+                    intervalFraction = interpolator.getInterpolation(intervalFraction);
+                }
                 return mEvaluator == null ?
                         prevValue + (int)(intervalFraction * (nextValue - prevValue)) :
                         ((Number)mEvaluator.evaluate(intervalFraction, prevValue, nextValue)).
diff --git a/core/java/android/animation/KeyframeSet.java b/core/java/android/animation/KeyframeSet.java
index c80e162..32edd4d 100644
--- a/core/java/android/animation/KeyframeSet.java
+++ b/core/java/android/animation/KeyframeSet.java
@@ -201,7 +201,6 @@ class KeyframeSet implements Keyframes {
      * @return The animated value.
      */
     public Object getValue(float fraction) {
-
         // Special-case optimization for the common case of only two keyframes
         if (mNumKeyframes == 2) {
             if (mInterpolator != null) {
@@ -238,12 +237,13 @@ class KeyframeSet implements Keyframes {
             Keyframe nextKeyframe = mKeyframes.get(i);
             if (fraction < nextKeyframe.getFraction()) {
                 final TimeInterpolator interpolator = nextKeyframe.getInterpolator();
-                if (interpolator != null) {
-                    fraction = interpolator.getInterpolation(fraction);
-                }
                 final float prevFraction = prevKeyframe.getFraction();
                 float intervalFraction = (fraction - prevFraction) /
                     (nextKeyframe.getFraction() - prevFraction);
+                // Apply interpolator on the proportional duration.
+                if (interpolator != null) {
+                    intervalFraction = interpolator.getInterpolation(intervalFraction);
+                }
                 return mEvaluator.evaluate(intervalFraction, prevKeyframe.getValue(),
                         nextKeyframe.getValue());
             }