如何从进度条动画（计时器）中获取剩余秒数？

我在Fragment中实现了一个10秒的进度条递减动画（从100到0），每次进入Fragment都会启动。现在需要在点击退出按钮时，获取并打印剩余的秒数（比如剩余4秒就打印4），当前代码仅实现了进度条动画，没有这个功能。

原代码如下：

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                          savedInstanceState: Bundle?): View? {
        val binding = DataBindingUtil.inflate<FragmentGameBinding>(
            inflater, R.layout.fragment_game, container, false)

        binding.game = this
        timer(binding)
        
        // when user clicks submitButton, it will exit current fragment
        binding.submitButton.setOnClickListener{ view: View ->
           Log.d("asd","print seconds left when exit the fragment : ") //print here
           view.findNavController().navigate(GameFragmentDirections.actionGameFragmentToGameOverFragment())
        }
        
        return binding.root
}
private fun timer(binding:FragmentGameBinding){
    val mProgressBar = binding.progressBar
    val progressAnimator = ObjectAnimator.ofInt(mProgressBar, "progress", 100, 0) //max 100, min 0
    progressAnimator.duration = 10000 //10 s = 10000 ms
    progressAnimator.interpolator = LinearInterpolator()
    progressAnimator.start()
}

实现步骤 #

• 将progressAnimator声明为Fragment的类成员变量，确保在按钮点击事件中能访问到它。
• 在按钮点击时，通过currentPlayTime获取动画已运行的毫秒数，用总时长减去已运行时长得到剩余毫秒数，再转换为秒数（取整）。
• 打印计算出的剩余秒数。

修改后的完整代码：

class GameFragment : Fragment() {
    // 声明为类成员变量，方便点击事件中访问
    private lateinit var progressAnimator: ObjectAnimator

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                              savedInstanceState: Bundle?): View? {
        val binding = DataBindingUtil.inflate<FragmentGameBinding>(
            inflater, R.layout.fragment_game, container, false)

        binding.game = this
        timer(binding)
        
        binding.submitButton.setOnClickListener{ view: View ->
            // 计算剩余秒数
            val elapsedMs = progressAnimator.currentPlayTime
            val remainingMs = progressAnimator.duration - elapsedMs
            val remainingSeconds = (remainingMs / 1000).toInt()
            Log.d("asd","print seconds left when exit the fragment : $remainingSeconds")
            
            view.findNavController().navigate(GameFragmentDirections.actionGameFragmentToGameOverFragment())
        }
        
        return binding.root
    }

    private fun timer(binding:FragmentGameBinding){
        val mProgressBar = binding.progressBar
        progressAnimator = ObjectAnimator.ofInt(mProgressBar, "progress", 100, 0)
        progressAnimator.duration = 10000
        progressAnimator.interpolator = LinearInterpolator()
        progressAnimator.start()
    }
}

关键说明 #

• progressAnimator.currentPlayTime：获取动画已经运行的毫秒数，动画未启动时返回0，结束后返回总时长。
• 因为使用了LinearInterpolator线性插值，进度和时间完全对应，所以剩余时间的计算是准确的。
• 最后将剩余毫秒数除以1000取整，得到剩余的整秒数。

内容的提问来源于stack exchange，提问作者HaveMercyOnMe