[Animations] Add a utility method to get the number of milliseconds for

/*

 * 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.util.animation

import kotlin.math.roundToLong

/** A generic util class for animations in SysUI. */

class AnimationUtil {

    companion object {

        /**

         * Returns the number of milliseconds there are in [numFrames] for a 60 fps device.

         *

         * Note that this method can be used on any device, not just 60 fps devices. Animation

         * lengths are typically specified in terms of number of frames for a 60 fps device, and

         * the value "5 frames" is often more meaningful than "83ms". This method allows us to

         * write animation code in terms of the more meaningful "5" number.

         *

         * @param numFrames must be >= 0.

         */

        fun getMsForFrames(numFrames: Int): Long {

            if (numFrames < 0) {

                throw IllegalArgumentException("numFrames must be >= 0")

            }

            return (numFrames * 1000f / 60f).roundToLong()

        }

    }

}

/*

 * 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.util.animation

import androidx.test.filters.SmallTest

import com.android.systemui.SysuiTestCase

import com.google.common.truth.Truth.assertThat

import org.junit.Test

import java.lang.IllegalArgumentException

@SmallTest

class AnimationUtilTest : SysuiTestCase() {

    @Test

    fun getMsForFrames_5frames_returns83() {

        assertThat(AnimationUtil.getMsForFrames(5)).isEqualTo(83L)

    }

    @Test

    fun getMsForFrames_7frames_returns117() {

        assertThat(AnimationUtil.getMsForFrames(7)).isEqualTo(117L)

    }

    @Test

    fun getMsForFrames_30frames_returns500() {

        assertThat(AnimationUtil.getMsForFrames(30)).isEqualTo(500L)

    }

    @Test

    fun getMsForFrames_60frames_returns1000() {

        assertThat(AnimationUtil.getMsForFrames(60)).isEqualTo(1000L)

    }

    @Test(expected = IllegalArgumentException::class)

    fun getMsForFrames_negativeFrames_throwsException() {

        AnimationUtil.getMsForFrames(-1)

    }

}