Introduce PathInterpolator to native animators

For interpolators defined with a path, PathInterpolator is more accurate
and likely less costly for longer animations than what are currently
using as a substiute - LUTInterpolator.

Test: manual test and added a unit test
BUG: 32830741
Change-Id: I867c7a28e4261392cce9c45a2992ab4fd120c496

core/java/android/view/animation/PathInterpolator.java

@@ -25,6 +25,9 @@ import android.util.PathParser;
 import android.view.InflateException;
 
 import com.android.internal.R;
+import com.android.internal.view.animation.HasNativeInterpolator;
+import com.android.internal.view.animation.NativeInterpolatorFactory;
+import com.android.internal.view.animation.NativeInterpolatorFactoryHelper;
 
 /**
  * An interpolator that can traverse a Path that extends from <code>Point</code>
@@ -42,7 +45,8 @@ import com.android.internal.R;
  *     path.lineTo(1f, 1f);
  * </pre></blockquote></p>
  */
-public class PathInterpolator extends BaseInterpolator {
+@HasNativeInterpolator
+public class PathInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
 
     // This governs how accurate the approximation of the Path is.
     private static final float PRECISION = 0.002f;
@@ -229,4 +233,11 @@ public class PathInterpolator extends BaseInterpolator {
         float endY = mY[endIndex];
         return startY + (fraction * (endY - startY));
     }
+
+    /** @hide **/
+    @Override
+    public long createNativeInterpolator() {
+        return NativeInterpolatorFactoryHelper.createPathInterpolator(mX, mY);
+    }
+
 }

core/java/com/android/internal/view/animation/NativeInterpolatorFactoryHelper.java

@@ -32,5 +32,6 @@ public final class NativeInterpolatorFactoryHelper {
     public static native long createDecelerateInterpolator(float factor);
     public static native long createLinearInterpolator();
     public static native long createOvershootInterpolator(float tension);
+    public static native long createPathInterpolator(float[] x, float[] y);
     public static native long createLutInterpolator(float[] values);
 }

core/jni/com_android_internal_view_animation_NativeInterpolatorFactoryHelper.cpp

@@ -18,6 +18,7 @@
 
 #include "jni.h"
 #include <nativehelper/JNIHelp.h>
+#include <cutils/log.h>
 #include "core_jni_helpers.h"
 
 #include <Interpolator.h>
@@ -62,6 +63,19 @@ static jlong createOvershootInterpolator(JNIEnv* env, jobject clazz, jfloat tens
     return reinterpret_cast<jlong>(new OvershootInterpolator(tension));
 }
 
+static jlong createPathInterpolator(JNIEnv* env, jobject clazz, jfloatArray jX, jfloatArray jY) {
+    jsize lenX = env->GetArrayLength(jX);
+    jsize lenY = env->GetArrayLength(jY);
+    LOG_ALWAYS_FATAL_IF(lenX != lenY || lenX <= 0, "Invalid path interpolator, x size: %d,"
+            " y size: %d", lenX, lenY);
+    std::vector<float> x(lenX);
+    std::vector<float> y(lenY);
+    env->GetFloatArrayRegion(jX, 0, lenX, x.data());
+    env->GetFloatArrayRegion(jY, 0, lenX, y.data());
+
+    return reinterpret_cast<jlong>(new PathInterpolator(std::move(x), std::move(y)));
+}
+
 static jlong createLutInterpolator(JNIEnv* env, jobject clazz, jfloatArray jlut) {
     jsize len = env->GetArrayLength(jlut);
     if (len <= 0) {
@@ -88,6 +102,7 @@ static const JNINativeMethod gMethods[] = {
     { "createDecelerateInterpolator", "(F)J", (void*) createDecelerateInterpolator },
     { "createLinearInterpolator", "()J", (void*) createLinearInterpolator },
     { "createOvershootInterpolator", "(F)J", (void*) createOvershootInterpolator },
+    { "createPathInterpolator", "([F[F)J", (void*) createPathInterpolator },
     { "createLutInterpolator", "([F)J", (void*) createLutInterpolator },
 };
 

libs/hwui/Android.mk

@@ -294,6 +294,7 @@ LOCAL_SRC_FILES += \
     tests/unit/MeshStateTests.cpp \
     tests/unit/OffscreenBufferPoolTests.cpp \
     tests/unit/OpDumperTests.cpp \
+    tests/unit/PathInterpolatorTests.cpp \
     tests/unit/RenderNodeDrawableTests.cpp \
     tests/unit/RecordingCanvasTests.cpp \
     tests/unit/RenderNodeTests.cpp \

libs/hwui/Interpolator.cpp

@@ -88,6 +88,39 @@ float OvershootInterpolator::interpolate(float t) {
     return t * t * ((mTension + 1) * t + mTension) + 1.0f;
 }
 
+float PathInterpolator::interpolate(float t) {
+    if (t <= 0) {
+        return 0;
+    } else if (t >= 1) {
+        return 1;
+    }
+    // Do a binary search for the correct x to interpolate between.
+    size_t startIndex = 0;
+    size_t endIndex = mX.size() - 1;
+
+    while (endIndex > startIndex + 1) {
+        int midIndex = (startIndex + endIndex) / 2;
+        if (t < mX[midIndex]) {
+            endIndex = midIndex;
+        } else {
+            startIndex = midIndex;
+        }
+    }
+
+    float xRange = mX[endIndex] - mX[startIndex];
+    if (xRange == 0) {
+        return mY[startIndex];
+    }
+
+    float tInRange = t - mX[startIndex];
+    float fraction = tInRange / xRange;
+
+    float startY = mY[startIndex];
+    float endY = mY[endIndex];
+    return startY + (fraction * (endY - startY));
+
+}
+
 LUTInterpolator::LUTInterpolator(float* values, size_t size)
     : mValues(values)
     , mSize(size) {

libs/hwui/Interpolator.h

@@ -20,6 +20,7 @@
 #include <memory>
 
 #include <cutils/compiler.h>
+#include <vector>
 
 namespace android {
 namespace uirenderer {
@@ -100,6 +101,16 @@ private:
     const float mTension;
 };
 
+class ANDROID_API PathInterpolator : public Interpolator {
+public:
+    explicit PathInterpolator(std::vector<float>&& x, std::vector<float>&& y)
+            : mX (x), mY(y) {}
+    virtual float interpolate(float input) override;
+private:
+    std::vector<float> mX;
+    std::vector<float> mY;
+};
+
 class ANDROID_API LUTInterpolator : public Interpolator {
 public:
     LUTInterpolator(float* values, size_t size);

libs/hwui/tests/unit/PathInterpolatorTests.cpp

@@ -0,0 +1,110 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+#include <gtest/gtest.h>
+
+#include <Interpolator.h>
+
+namespace android {
+namespace uirenderer {
+
+struct TestData {
+    const std::vector<float> x;
+    const std::vector<float> y;
+    const std::vector<float> inFraction;
+    const std::vector<float> outFraction;
+};
+
+const static TestData sTestDataSet[] = {
+        {
+                // Straight line as a path.
+                {0.0f, 1.0f},
+                {0.0f, 1.0f},
+                {0.0f, 0.2f, 0.4f, 0.6f, 0.8f, 1.0f},
+                {0.0f, 0.2f, 0.4f, 0.6f, 0.8f, 1.0f},
+        },
+
+        {
+                {
+                        0.0f, 0.5f, 0.5178955f, 0.5341797f, 0.5489991f, 0.5625f, 0.5748291f,
+                        0.5861328f, 0.60625005f, 0.62402344f, 0.640625f, 0.675f, 0.6951172f,
+                        0.71875f, 0.7470703f, 0.78125f, 0.82246095f, 0.84606934f, 0.871875f,
+                        0.9000244f, 0.93066406f, 0.96394044f, 1.0f
+                },
+                {
+                        0.0f, 0.0f, 0.0028686523f, 0.011230469f, 0.024719238f, 0.04296875f,
+                        0.06561279f, 0.092285156f, 0.15625f, 0.2319336f, 0.31640625f, 0.5f,
+                        0.5932617f, 0.68359375f, 0.7680664f, 0.84375f, 0.90771484f, 0.9343872f,
+                        0.95703125f, 0.97528076f, 0.98876953f, 0.99713135f, 1.0f
+                },
+                {
+                        0.0f, 0.03375840187072754f, 0.13503384590148926f, 0.23630905151367188f,
+                        0.336834192276001f, 0.4508626461029053f, 0.564141035079956f,
+                        0.6781694889068604f, 0.7921979427337646f, 0.9054763317108154f, 1.0f
+                },
+                {
+                        0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0459827296435833f,
+                        0.5146934390068054f, 0.8607426285743713f, 0.9776809215545654f, 1.0f
+
+                }
+
+        },
+        {
+                {
+                        0.0f, 0.017895509f, 0.034179688f, 0.048999026f, 0.0625f, 0.0748291f,
+                        0.08613282f, 0.10625f, 0.12402344f, 0.140625f, 0.17500001f, 0.19511719f,
+                        0.21875f, 0.24707031f, 0.28125f, 0.32246095f, 0.34606934f, 0.371875f,
+                        0.4000244f, 0.43066406f, 0.46394044f, 0.5f, 1.0f
+                },
+                {
+                        0.0f, 0.0028686523f, 0.011230469f, 0.024719238f, 0.04296875f, 0.06561279f,
+                        0.092285156f, 0.15625f, 0.2319336f, 0.31640625f, 0.5f, 0.5932617f,
+                        0.68359375f, 0.7680664f, 0.84375f, 0.90771484f, 0.9343872f, 0.95703125f,
+                        0.97528076f, 0.98876953f, 0.99713135f, 1.0f, 1.0f
+                },
+                {
+                        0.0f, 0.102020263671875f, 0.20330810546875f, 0.3165740966796875f,
+                        0.43060302734375f, 0.5318756103515625f, 0.6331634521484375f,
+                        0.746429443359375f, 0.84771728515625f, 0.9617462158203125f, 1.0f
+                },
+                {
+                        0.0f, 0.14280107617378235f, 0.6245699524879456f, 0.8985776901245117f,
+                        0.9887426495552063f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f, 1.0f
+                }
+        },
+
+
+};
+
+static std::vector<float> getX(const TestData& data) {
+    return data.x;
+}
+
+static std::vector<float> getY(const TestData& data) {
+    return data.y;
+}
+
+TEST(Interpolator, pathInterpolation) {
+    for (const TestData& data: sTestDataSet) {
+        PathInterpolator interpolator(getX(data), getY(data));
+        for (size_t i = 0; i < data.inFraction.size(); i++) {
+            EXPECT_FLOAT_EQ(data.outFraction[i], interpolator.interpolate(data.inFraction[i]));
+        }
+    }
+}
+
+}
+}