android - 如何使更新进度中的ProgressBar "smoother"

Question

如何让 ProgressBar 显示进度更流畅？

目前我正在使用它(它以秒为单位计算到指定时间，在此示例中 secondsToRun = 120):

public void startBrushing(View view) {
    progressBar = (ProgressBar) findViewById(R.id.progressBar);

    int secondsToRun = 120;
    progressBar.setMax(secondsToRun);

    runner = new AsyncTaskRunner();
    runner.execute(secondsToRun);
}

private class AsyncTaskRunner extends AsyncTask<Integer, Integer, Void> {

    private String resp;

    @Override
    protected Void doInBackground(Integer... params) {
        try {
            for(int i = 0; i <= params[0]; i++) {
                publishProgress(i);
                Thread.sleep(1000);

                if (i == params[0]) {
                    Log.d("CyCy", "Finished Countdown!");
                    chronometer.stop();
                }
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        return null;
    }

    @Override
    protected void onProgressUpdate(Integer... status) {
        progressBar.setProgress(status[0]);
    }
}

如果我增加更新时间(secondsToRun = 1200 并且每 100 毫秒更新一次，而不是每 1000 毫秒更新一次)它也能正常工作，但会有点不准确。

如果我使用 secondsToRun = 12000 并每 10 毫秒更新一次，那将非常不准确。当循环实时显示“30 秒完成”时，它是 37 秒。

感谢您的帮助，抱歉我的英语不好。

Answer 1

正如我在上面的评论中所建议的那样，您可以根据实时而不是您自己的计数器来更新 ProgressBar:

我还没有测试过这个，所以把它看作是温和的伪代码:

private class AsyncTaskRunner extends AsyncTask<Void, Long, Void> {

    private long startTime;
    private long progressDurationMillis;
    private long updateFrequencyMillis = 200;     // default 0.2 secs

    // pass in the progress bar max duration in the constructor
    //    so you can set the dialog max value in onPreExecute()
    public AsyncTaskRunner(long progressDurationMillis) {
        this.progressDurationMillis = progressDurationMillis;
    }

    // a second constructor for easy testing of different update values
    // you could test a bunch together in a loop and see which looks best
    public AsyncTaskRunner(long progressDurationMillis, long updateFrequencyMillis) {
        this(progressDurationMillis);
        this.updateFrequencyMillis = updateFrequencyMillis;
    }

    @Override
    public void onPreExecute() {
        this.startTime = System.getCurrentMillis();
        // set up your dialog here and display
    }

    @Override
    protected Void doInBackground(Void... params) {
        long timeExpired = 0;
        try {
            while(true) {
                timeExpired = progressDurationMillis - (System.getCurrentMillis() - startTime)
                publishProgress(timeExpired);
                Thread.sleep(updateFrequencyMillis);

                if (timeExpired >= progressDurationMillis) {
                    Log.d("CyCy", "Finished Countdown!");
                    chronometer.stop();
                    // exit the while loop
                    break;
                }
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onProgressUpdate(Long... status) {
        progressBar.setProgress(status[0]);
    }

    @Override
    public void onPostExecute() {
        // dismiss your dialog here
    }
}