tests/tests/view/src/android/view/animation/cts/AccelerateInterpolatorTest.java

/*
 * Copyright (C) 2008 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.view.animation.cts;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

import android.app.Activity;
import android.app.Instrumentation;
import android.content.res.XmlResourceParser;
import android.util.AttributeSet;
import android.util.Xml;
import android.view.View;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.AlphaAnimation;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.Interpolator;
import android.view.animation.Transformation;
import android.view.cts.R;

import androidx.test.InstrumentationRegistry;
import androidx.test.filters.MediumTest;
import androidx.test.rule.ActivityTestRule;
import androidx.test.runner.AndroidJUnit4;

import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.runner.RunWith;

@MediumTest
@RunWith(AndroidJUnit4.class)
public class AccelerateInterpolatorTest {
    private static final float ALPHA_DELTA = 0.001f;

    /** It is defined in R.anim.accelerate_alpha */
    private static final long ACCELERATE_ALPHA_DURATION = 1000;

    private Instrumentation mInstrumentation;
    private Activity mActivity;

    @Rule
    public ActivityTestRule<AnimationTestCtsActivity> mActivityRule =
            new ActivityTestRule<>(AnimationTestCtsActivity.class);

    @Before
    public void setup() {
        mInstrumentation = InstrumentationRegistry.getInstrumentation();
        mActivity = mActivityRule.getActivity();
    }

    @Test
    public void testConstructor() {
        new AccelerateInterpolator();

        new AccelerateInterpolator(1.0f);

        XmlResourceParser parser = mActivity.getResources().getAnimation(R.anim.accelerate_alpha);
        AttributeSet attrs = Xml.asAttributeSet(parser);
        new AccelerateInterpolator(mActivity, attrs);
    }

    @Test
    public void testAccelerateInterpolator() throws Throwable {
        final View animWindow = mActivity.findViewById(R.id.anim_window);

        // XML file of R.anim.accelerate_alpha
        // <alpha xmlns:android="http://schemas.android.com/apk/res/android"
        //      android:interpolator="@android:anim/accelerate_interpolator"
        //      android:fromAlpha="0.1"
        //      android:toAlpha="0.9"
        //      android:duration="1000" />
        final Animation anim = AnimationUtils.loadAnimation(mActivity, R.anim.accelerate_alpha);

        assertEquals(ACCELERATE_ALPHA_DURATION, anim.getDuration());
        assertTrue(anim instanceof AlphaAnimation);

        // factor is 1.0f
        Interpolator interpolator = new AccelerateInterpolator(1.0f);
        anim.setInterpolator(interpolator);
        assertFalse(anim.hasStarted());

        AnimationTestUtils.assertRunAnimation(mInstrumentation, mActivityRule, animWindow, anim);

        Transformation transformation = new Transformation();
        long startTime = anim.getStartTime();
        anim.getTransformation(startTime, transformation);
        float alpha1 = transformation.getAlpha();
        assertEquals(0.1f, alpha1, ALPHA_DELTA);

        anim.getTransformation(startTime + 250, transformation);
        float alpha2 = transformation.getAlpha();

        anim.getTransformation(startTime + 500, transformation);
        float alpha3 = transformation.getAlpha();

        anim.getTransformation(startTime + 750, transformation);
        float alpha4 = transformation.getAlpha();

        anim.getTransformation(startTime + ACCELERATE_ALPHA_DURATION, transformation);
        float alpha5 = transformation.getAlpha();
        assertEquals(0.9f, alpha5, ALPHA_DELTA);

        // check accelerating delta alpha
        float delta1 = alpha2 - alpha1;
        float delta2 = alpha3 - alpha2;
        float delta3 = alpha4 - alpha3;
        float delta4 = alpha5 - alpha4;
        assertTrue(delta1 < delta2);
        assertTrue(delta2 < delta3);
        assertTrue(delta3 < delta4);

        // factor is 1.5f, it starts even slower and ends even faster than 1.0f
        interpolator = new AccelerateInterpolator(1.5f);
        anim.setInterpolator(interpolator);

        AnimationTestUtils.assertRunAnimation(mInstrumentation, mActivityRule, animWindow, anim);

        transformation = new Transformation();
        startTime = anim.getStartTime();
        anim.getTransformation(startTime, transformation);
        float alpha6 = transformation.getAlpha();
        assertEquals(0.1f, alpha1, ALPHA_DELTA);

        anim.getTransformation(startTime + 250, transformation);
        float alpha7 = transformation.getAlpha();

        anim.getTransformation(startTime + 500, transformation);
        float alpha8 = transformation.getAlpha();

        anim.getTransformation(startTime + 750, transformation);
        float alpha9 = transformation.getAlpha();

        anim.getTransformation(startTime + ACCELERATE_ALPHA_DURATION, transformation);
        float alpha10 = transformation.getAlpha();
        assertEquals(0.9f, alpha5, ALPHA_DELTA);

        // check accelerating delta alpha
        float delta5 = alpha7 - alpha6;
        float delta6 = alpha8 - alpha7;
        float delta7 = alpha9 - alpha8;
        float delta8 = alpha10 - alpha9;
        assertTrue(delta5 < delta6);
        assertTrue(delta6 < delta7);
        assertTrue(delta7 < delta8);

        // check whether it starts even slower
        assertTrue(delta5 < delta1);
    }

    @Test
    public void testGetInterpolation() {
        final float input = 0.25f;
        Interpolator interpolator1 = new AccelerateInterpolator(1.0f);
        // factor is 2.0f, it starts even slower and ends even faster than 1.0f
        Interpolator interpolator2 = new AccelerateInterpolator(2.0f);

        float delta1 = interpolator1.getInterpolation(input);
        float delta2 = interpolator2.getInterpolation(input);

        // check whether it starts even slower
        assertTrue(delta2 < delta1);

        // call directly
        Interpolator interpolator = new AccelerateInterpolator();

        float alpha1 = interpolator.getInterpolation(0f);
        float alpha2 = interpolator.getInterpolation(0.25f);
        float alpha3 = interpolator.getInterpolation(0.5f);
        float alpha4 = interpolator.getInterpolation(0.75f);
        float alpha5 = interpolator.getInterpolation(1f);
        // check accelerating and decelerating delta alpha
        // starts and ends slowly, accelerates through middle
        float delta3 = alpha2 - alpha1;
        float delta4 = alpha3 - alpha2;
        float delta5 = alpha4 - alpha3;
        float delta6 = alpha5 - alpha4;
        assertTrue(delta3 < delta4);
        assertTrue(delta4 < delta5);
        assertTrue(delta5 < delta6);
    }
}