Add androidx.core.animation dependency for better testability

Using ObjectAnimator, ValueAnimator or Interpolators from `androidx.core.animation` has the advantage of improving the testability compared to using them from `android.view.animation`. The `core-animation-testing` dependency (not included in this CL), and specifically the AnimatorTestRule (https://developer.android.com/reference/androidx/core/animation/AnimatorTestRule) allows for things such as `animatorTestRule.advanceTimeBy(500L)`. This enables us to fast forward animations and verify things that happen after an animation has ended.

Test: atest InterpolatorsAndroidXTest
Bug: 259063937
Change-Id: I196eb325e4c99dda163445e6fed84327bebecfb2
diff --git a/packages/SystemUI/animation/Android.bp b/packages/SystemUI/animation/Android.bp
index f7bcf1f..5df79e1 100644
--- a/packages/SystemUI/animation/Android.bp
+++ b/packages/SystemUI/animation/Android.bp
@@ -36,8 +36,29 @@
 
     static_libs: [
         "PluginCoreLib",
+        "androidx.core_core-animation-nodeps",
     ],
 
     manifest: "AndroidManifest.xml",
     kotlincflags: ["-Xjvm-default=all"],
 }
+
+android_test {
+    name: "SystemUIAnimationLibTests",
+
+    static_libs: [
+        "SystemUIAnimationLib",
+        "androidx.test.ext.junit",
+        "androidx.test.rules",
+        "testables",
+    ],
+    libs: [
+        "android.test.base",
+    ],
+    srcs: [
+        "**/*.java",
+        "**/*.kt",
+    ],
+    kotlincflags: ["-Xjvm-default=all"],
+    test_suites: ["general-tests"],
+}
diff --git a/packages/SystemUI/animation/TEST_MAPPING b/packages/SystemUI/animation/TEST_MAPPING
new file mode 100644
index 0000000..3dc8510
--- /dev/null
+++ b/packages/SystemUI/animation/TEST_MAPPING
@@ -0,0 +1,7 @@
+{
+  "presubmit": [
+    {
+      "name": "SystemUIAnimationLibTests"
+    }
+  ]
+}
diff --git a/packages/SystemUI/animation/src/com/android/systemui/animation/Interpolators.java b/packages/SystemUI/animation/src/com/android/systemui/animation/Interpolators.java
index 8063483..9dbb920 100644
--- a/packages/SystemUI/animation/src/com/android/systemui/animation/Interpolators.java
+++ b/packages/SystemUI/animation/src/com/android/systemui/animation/Interpolators.java
@@ -27,7 +27,10 @@
 import android.view.animation.PathInterpolator;
 
 /**
- * Utility class to receive interpolators from
+ * Utility class to receive interpolators from.
+ *
+ * Make sure that changes made to this class are also reflected in {@link InterpolatorsAndroidX}.
+ * Please consider using the androidx dependencies featuring better testability altogether.
  */
 public class Interpolators {
 
diff --git a/packages/SystemUI/animation/src/com/android/systemui/animation/InterpolatorsAndroidX.java b/packages/SystemUI/animation/src/com/android/systemui/animation/InterpolatorsAndroidX.java
new file mode 100644
index 0000000..8da87feb
--- /dev/null
+++ b/packages/SystemUI/animation/src/com/android/systemui/animation/InterpolatorsAndroidX.java
@@ -0,0 +1,219 @@
+/*
+ * Copyright (C) 2022 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 com.android.systemui.animation;
+
+import android.graphics.Path;
+import android.util.MathUtils;
+
+import androidx.core.animation.AccelerateDecelerateInterpolator;
+import androidx.core.animation.AccelerateInterpolator;
+import androidx.core.animation.BounceInterpolator;
+import androidx.core.animation.DecelerateInterpolator;
+import androidx.core.animation.Interpolator;
+import androidx.core.animation.LinearInterpolator;
+import androidx.core.animation.PathInterpolator;
+
+/**
+ * Utility class to receive interpolators from. (androidx compatible version)
+ *
+ * This is the androidx compatible version of {@link Interpolators}. Make sure that changes made to
+ * this class are also reflected in {@link Interpolators}.
+ *
+ * Using the androidx versions of {@link androidx.core.animation.ValueAnimator} or
+ * {@link androidx.core.animation.ObjectAnimator} improves animation testability. This file provides
+ * the androidx compatible versions of the interpolators defined in {@link Interpolators}.
+ * AnimatorTestRule can be used in Tests to manipulate the animation under test (e.g. artificially
+ * advancing the time).
+ */
+public class InterpolatorsAndroidX {
+
+    /*
+     * ============================================================================================
+     * Emphasized interpolators.
+     * ============================================================================================
+     */
+
+    /**
+     * The default emphasized interpolator. Used for hero / emphasized movement of content.
+     */
+    public static final Interpolator EMPHASIZED = createEmphasizedInterpolator();
+
+    /**
+     * The accelerated emphasized interpolator. Used for hero / emphasized movement of content that
+     * is disappearing e.g. when moving off screen.
+     */
+    public static final Interpolator EMPHASIZED_ACCELERATE = new PathInterpolator(
+            0.3f, 0f, 0.8f, 0.15f);
+
+    /**
+     * The decelerating emphasized interpolator. Used for hero / emphasized movement of content that
+     * is appearing e.g. when coming from off screen
+     */
+    public static final Interpolator EMPHASIZED_DECELERATE = new PathInterpolator(
+            0.05f, 0.7f, 0.1f, 1f);
+
+
+    /*
+     * ============================================================================================
+     * Standard interpolators.
+     * ============================================================================================
+     */
+
+    /**
+     * The standard interpolator that should be used on every normal animation
+     */
+    public static final Interpolator STANDARD = new PathInterpolator(
+            0.2f, 0f, 0f, 1f);
+
+    /**
+     * The standard accelerating interpolator that should be used on every regular movement of
+     * content that is disappearing e.g. when moving off screen.
+     */
+    public static final Interpolator STANDARD_ACCELERATE = new PathInterpolator(
+            0.3f, 0f, 1f, 1f);
+
+    /**
+     * The standard decelerating interpolator that should be used on every regular movement of
+     * content that is appearing e.g. when coming from off screen.
+     */
+    public static final Interpolator STANDARD_DECELERATE = new PathInterpolator(
+            0f, 0f, 0f, 1f);
+
+    /*
+     * ============================================================================================
+     * Legacy
+     * ============================================================================================
+     */
+
+    /**
+     * The default legacy interpolator as defined in Material 1. Also known as FAST_OUT_SLOW_IN.
+     */
+    public static final Interpolator LEGACY = new PathInterpolator(0.4f, 0f, 0.2f, 1f);
+
+    /**
+     * The default legacy accelerating interpolator as defined in Material 1.
+     * Also known as FAST_OUT_LINEAR_IN.
+     */
+    public static final Interpolator LEGACY_ACCELERATE = new PathInterpolator(0.4f, 0f, 1f, 1f);
+
+    /**
+     * The default legacy decelerating interpolator as defined in Material 1.
+     * Also known as LINEAR_OUT_SLOW_IN.
+     */
+    public static final Interpolator LEGACY_DECELERATE = new PathInterpolator(0f, 0f, 0.2f, 1f);
+
+    /**
+     * Linear interpolator. Often used if the interpolator is for different properties who need
+     * different interpolations.
+     */
+    public static final Interpolator LINEAR = new LinearInterpolator();
+
+    /*
+    * ============================================================================================
+    * Custom interpolators
+    * ============================================================================================
+    */
+
+    public static final Interpolator FAST_OUT_SLOW_IN = LEGACY;
+    public static final Interpolator FAST_OUT_LINEAR_IN = LEGACY_ACCELERATE;
+    public static final Interpolator LINEAR_OUT_SLOW_IN = LEGACY_DECELERATE;
+
+    /**
+     * Like {@link #FAST_OUT_SLOW_IN}, but used in case the animation is played in reverse (i.e. t
+     * goes from 1 to 0 instead of 0 to 1).
+     */
+    public static final Interpolator FAST_OUT_SLOW_IN_REVERSE =
+            new PathInterpolator(0.8f, 0f, 0.6f, 1f);
+    public static final Interpolator SLOW_OUT_LINEAR_IN = new PathInterpolator(0.8f, 0f, 1f, 1f);
+    public static final Interpolator ALPHA_IN = new PathInterpolator(0.4f, 0f, 1f, 1f);
+    public static final Interpolator ALPHA_OUT = new PathInterpolator(0f, 0f, 0.8f, 1f);
+    public static final Interpolator ACCELERATE = new AccelerateInterpolator();
+    public static final Interpolator ACCELERATE_DECELERATE = new AccelerateDecelerateInterpolator();
+    public static final Interpolator DECELERATE_QUINT = new DecelerateInterpolator(2.5f);
+    public static final Interpolator CUSTOM_40_40 = new PathInterpolator(0.4f, 0f, 0.6f, 1f);
+    public static final Interpolator ICON_OVERSHOT = new PathInterpolator(0.4f, 0f, 0.2f, 1.4f);
+    public static final Interpolator ICON_OVERSHOT_LESS = new PathInterpolator(0.4f, 0f, 0.2f,
+            1.1f);
+    public static final Interpolator PANEL_CLOSE_ACCELERATED = new PathInterpolator(0.3f, 0, 0.5f,
+            1);
+    public static final Interpolator BOUNCE = new BounceInterpolator();
+    /**
+     * For state transitions on the control panel that lives in GlobalActions.
+     */
+    public static final Interpolator CONTROL_STATE = new PathInterpolator(0.4f, 0f, 0.2f,
+            1.0f);
+
+    /**
+     * Interpolator to be used when animating a move based on a click. Pair with enough duration.
+     */
+    public static final Interpolator TOUCH_RESPONSE =
+            new PathInterpolator(0.3f, 0f, 0.1f, 1f);
+
+    /**
+     * Like {@link #TOUCH_RESPONSE}, but used in case the animation is played in reverse (i.e. t
+     * goes from 1 to 0 instead of 0 to 1).
+     */
+    public static final Interpolator TOUCH_RESPONSE_REVERSE =
+            new PathInterpolator(0.9f, 0f, 0.7f, 1f);
+
+    /*
+     * ============================================================================================
+     * Functions / Utilities
+     * ============================================================================================
+     */
+
+    /**
+     * Calculate the amount of overshoot using an exponential falloff function with desired
+     * properties, where the overshoot smoothly transitions at the 1.0f boundary into the
+     * overshoot, retaining its acceleration.
+     *
+     * @param progress a progress value going from 0 to 1
+     * @param overshootAmount the amount > 0 of overshoot desired. A value of 0.1 means the max
+     *                        value of the overall progress will be at 1.1.
+     * @param overshootStart the point in (0,1] where the result should reach 1
+     * @return the interpolated overshoot
+     */
+    public static float getOvershootInterpolation(float progress, float overshootAmount,
+            float overshootStart) {
+        if (overshootAmount == 0.0f || overshootStart == 0.0f) {
+            throw new IllegalArgumentException("Invalid values for overshoot");
+        }
+        float b = MathUtils.log((overshootAmount + 1) / (overshootAmount)) / overshootStart;
+        return MathUtils.max(0.0f,
+                (float) (1.0f - Math.exp(-b * progress)) * (overshootAmount + 1.0f));
+    }
+
+    /**
+     * Similar to {@link #getOvershootInterpolation(float, float, float)} but the overshoot
+     * starts immediately here, instead of first having a section of non-overshooting
+     *
+     * @param progress a progress value going from 0 to 1
+     */
+    public static float getOvershootInterpolation(float progress) {
+        return MathUtils.max(0.0f, (float) (1.0f - Math.exp(-4 * progress)));
+    }
+
+    // Create the default emphasized interpolator
+    private static PathInterpolator createEmphasizedInterpolator() {
+        Path path = new Path();
+        // Doing the same as fast_out_extra_slow_in
+        path.moveTo(0f, 0f);
+        path.cubicTo(0.05f, 0f, 0.133333f, 0.06f, 0.166666f, 0.4f);
+        path.cubicTo(0.208333f, 0.82f, 0.25f, 1f, 1f, 1f);
+        return new PathInterpolator(path);
+    }
+}
diff --git a/packages/SystemUI/animation/tests/com/android/systemui/animation/InterpolatorsAndroidXTest.kt b/packages/SystemUI/animation/tests/com/android/systemui/animation/InterpolatorsAndroidXTest.kt
new file mode 100644
index 0000000..389eed0
--- /dev/null
+++ b/packages/SystemUI/animation/tests/com/android/systemui/animation/InterpolatorsAndroidXTest.kt
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2022 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 com.android.systemui.animation
+
+import androidx.test.filters.SmallTest
+import java.lang.reflect.Modifier
+import junit.framework.Assert.assertEquals
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+
+@SmallTest
+@RunWith(JUnit4::class)
+class InterpolatorsAndroidXTest {
+
+    @Test
+    fun testInterpolatorsAndInterpolatorsAndroidXPublicMethodsAreEqual() {
+        assertEquals(
+            Interpolators::class.java.getPublicMethods(),
+            InterpolatorsAndroidX::class.java.getPublicMethods()
+        )
+    }
+
+    @Test
+    fun testInterpolatorsAndInterpolatorsAndroidXPublicFieldsAreEqual() {
+        assertEquals(
+            Interpolators::class.java.getPublicFields(),
+            InterpolatorsAndroidX::class.java.getPublicFields()
+        )
+    }
+
+    private fun <T> Class<T>.getPublicMethods() =
+        declaredMethods
+            .filter { Modifier.isPublic(it.modifiers) }
+            .map { it.toString().replace(name, "") }
+            .toSet()
+
+    private fun <T> Class<T>.getPublicFields() =
+        fields.filter { Modifier.isPublic(it.modifiers) }.map { it.name }.toSet()
+}