android -属性动画的应用 旋转的专辑封面

class MainActivity : AppCompatActivity() {

    private var timer: Timer? = null

    private var task: TimerTask? = null

    var isPause = true

    private var i = 0.0f

    private lateinit var animator: ObjectAnimator


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        iv_rotate.setImageResource(R.mipmap.ic_launcher_round)

        animator  = ObjectAnimator.ofFloat(iv_rotate, "rotation", 0.0f, 360.0f)

        with(animator) {
            duration = 10*1000
            interpolator = LinearInterpolator()
            repeatCount = -1
            repeatMode = ObjectAnimator.RESTART
        }

        btn_start.setOnClickListener {
            startTimer()
        }

        btn_stop.setOnClickListener {
            stopTimer()
        }

        btn_anim_reset.setOnClickListener {

            animator.end()
        }

        btn_anim_start.setOnClickListener {

            animator.start()
        }

        btn_anim_resume.setOnClickListener {

            animator.resume()
        }
        btn_anim_stop.setOnClickListener {

            animator.pause()
        }

    }

    private fun startTimer() {
        if (isPause) {
            if (timer == null) {
                timer = Timer()
            }

            if (task == null) {
                task = object : TimerTask() {
                    override fun run() {
                        runOnUiThread {
                            i += 0.2f
                            iv_rotate.rotation = i % 360f
                        }

                    }
                }
            }

            timer?.schedule(task, 5, 5)
            isPause = false
        }
    }

    private fun stopTimer() {
        if (!isPause) {
            timer?.cancel()
            timer = null
            task?.cancel()
            task = null
            isPause = true

        }
    }


}

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">

    <ImageView
            android:layout_marginStart="168dp"
            android:layout_marginBottom="312dp"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            android:id="@+id/iv_rotate"
            android:layout_width="80dp"
            android:layout_height="80dp"
            tools:ignore="ContentDescription"/>


    <Button
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintBottom_toBottomOf="parent"
            android:id="@+id/btn_start"
            android:text="@string/start_rotate_text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:layout_marginStart="16dp"/>

    <Button
            app:layout_constraintStart_toEndOf="@id/btn_start"
            app:layout_constraintBottom_toBottomOf="parent"
            android:id="@+id/btn_stop"
            android:text="@string/stop_rotate_text"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" android:layout_marginStart="128dp"/>


    <Button
            android:textSize="12sp"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent"
            android:id="@+id/btn_anim_start"
            android:text="@string/start_anim"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

    <Button
            android:textSize="12sp"
            app:layout_constraintStart_toEndOf="@id/btn_anim_start"
            app:layout_constraintTop_toTopOf="parent"
            android:id="@+id/btn_anim_stop"
            android:text="@string/stop_anim"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>
    <Button

            android:textSize="12sp"
            app:layout_constraintStart_toEndOf="@id/btn_anim_stop"
            app:layout_constraintTop_toTopOf="parent"
            android:id="@+id/btn_anim_reset"
            android:text="@string/reset_anim"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

    <Button
            android:textSize="12sp"
            app:layout_constraintStart_toEndOf="@id/btn_anim_reset"
            app:layout_constraintTop_toTopOf="parent"
            android:id="@+id/btn_anim_resume"
            android:text="@string/resume_anim"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>

</androidx.constraintlayout.widget.ConstraintLayout>