optimizing for primitive types in animations

The animator classes caused autoboxing by converting primitive types (by far
the most typical types used in animations) to be converted to their
Object equivalents because of various APIs that required Object
(like getValue() to get the animated value). This change creates
factory methods on some classes instead of the former constructors
so that we can create and return private type-specific subclasses
which operate directly on the primitive types instead.

In particular, float and int are natively supported by the animators
now. Support in the APIs for double and long was removed because it
seemed like these less common types did not justify the extra
baggage of the added API and code.

Change-Id: I6008a3883e3d6dd5225005f45f112af148e5a4ea

1 files changed, 133 insertions, 0 deletions

diff --git a/core/java/android/animation/IntKeyframeSet.java b/core/java/android/animation/IntKeyframeSet.java
new file mode 100644
index 000000000000..14a4e3aacc24
--- /dev/null
+++ b/core/java/android/animation/IntKeyframeSet.java
@@ -0,0 +1,133 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.animation;
+
+import android.animation.Keyframe.IntKeyframe;
+
+import java.util.ArrayList;
+
+/**
+ * This class holds a collection of IntKeyframe objects and is called by ValueAnimator to calculate
+ * values between those keyframes for a given animation. The class internal to the animation
+ * package because it is an implementation detail of how Keyframes are stored and used.
+ *
+ * <p>This type-specific subclass of KeyframeSet, along with the other type-specific subclasses for
+ * float, long, and double, exists to speed up the getValue() method when there is no custom
+ * TypeEvaluator set for the animation, so that values can be calculated without autoboxing to the
+ * Object equivalents of these primitive types.</p>
+ */
+class IntKeyframeSet extends KeyframeSet {
+    private int firstValue;
+    private int lastValue;
+    private int deltaValue;
+    private boolean firstTime = true;
+
+    public IntKeyframeSet(IntKeyframe... keyframes) {
+        super(keyframes);
+    }
+
+    @Override
+    public Object getValue(float fraction) {
+        return getIntValue(fraction);
+    }
+
+    @Override
+    public IntKeyframeSet clone() {
+        ArrayList<Keyframe> keyframes = mKeyframes;
+        int numKeyframes = mKeyframes.size();
+        IntKeyframe[] newKeyframes = new IntKeyframe[numKeyframes];
+        for (int i = 0; i < numKeyframes; ++i) {
+            newKeyframes[i] = (IntKeyframe) keyframes.get(i).clone();
+        }
+        IntKeyframeSet newSet = new IntKeyframeSet(newKeyframes);
+        return newSet;
+    }
+
+    public int getIntValue(float fraction) {
+        if (mNumKeyframes == 2) {
+            if (firstTime) {
+                firstTime = false;
+                firstValue = ((IntKeyframe) mKeyframes.get(0)).getIntValue();
+                lastValue = ((IntKeyframe) mKeyframes.get(1)).getIntValue();
+                deltaValue = lastValue - firstValue;
+            }
+            if (mInterpolator != null) {
+                fraction = mInterpolator.getInterpolation(fraction);
+            }
+            if (mEvaluator == null) {
+                return firstValue + (int)(fraction * deltaValue);
+            } else {
+                return ((Number)mEvaluator.evaluate(fraction, firstValue, lastValue)).intValue();
+            }
+        }
+        if (fraction <= 0f) {
+            final IntKeyframe prevKeyframe = (IntKeyframe) mKeyframes.get(0);
+            final IntKeyframe nextKeyframe = (IntKeyframe) mKeyframes.get(1);
+            int prevValue = prevKeyframe.getIntValue();
+            int nextValue = nextKeyframe.getIntValue();
+            float prevFraction = prevKeyframe.getFraction();
+            float nextFraction = nextKeyframe.getFraction();
+            final TimeInterpolator interpolator = nextKeyframe.getInterpolator();
+            if (interpolator != null) {
+                fraction = interpolator.getInterpolation(fraction);
+            }
+            float intervalFraction = (fraction - prevFraction) / (nextFraction - prevFraction);
+            return mEvaluator == null ?
+                    prevValue + (int)(fraction * (nextValue - prevValue)) :
+                    ((Number)mEvaluator.evaluate(intervalFraction, prevValue, nextValue)).
+                            intValue();
+        } else if (fraction >= 1f) {
+            final IntKeyframe prevKeyframe = (IntKeyframe) mKeyframes.get(mNumKeyframes - 2);
+            final IntKeyframe nextKeyframe = (IntKeyframe) mKeyframes.get(mNumKeyframes - 1);
+            int prevValue = prevKeyframe.getIntValue();
+            int nextValue = nextKeyframe.getIntValue();
+            float prevFraction = prevKeyframe.getFraction();
+            float nextFraction = nextKeyframe.getFraction();
+            final TimeInterpolator interpolator = nextKeyframe.getInterpolator();
+            if (interpolator != null) {
+                fraction = interpolator.getInterpolation(fraction);
+            }
+            float intervalFraction = (fraction - prevFraction) / (nextFraction - prevFraction);
+            return mEvaluator == null ?
+                    prevValue + (int)(fraction * (nextValue - prevValue)) :
+                    ((Number)mEvaluator.evaluate(intervalFraction, prevValue, nextValue)).intValue();
+        }
+        IntKeyframe prevKeyframe = (IntKeyframe) mKeyframes.get(0);
+        for (int i = 1; i < mNumKeyframes; ++i) {
+            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();
+                return mEvaluator == null ?
+                        prevValue + (int)(fraction * (nextValue - prevValue)) :
+                        ((Number)mEvaluator.evaluate(intervalFraction, prevValue, nextValue)).
+                                intValue();
+            }
+            prevKeyframe = nextKeyframe;
+        }
+        // shouldn't get here
+        return ((Number)mKeyframes.get(mNumKeyframes - 1).getValue()).intValue();
+    }
+
+}
+