Question

这是我到目前为止所做的，但是对于我改变进度条的数字并不重要。值也改变了，我仍然得到相同的结果0.我猜这个问题在于时间表可变，但我无法弄清楚。

import { InMemoryDbService } from 'angular-in-memory-web-api';

export class InMemoryDataService implements InMemoryDbService {
    createDb() {
        let videos = [
            {
                "kind": "youtube#searchResult",
                "etag": "\"m2yskBQFythfE4irbTIeOgYYfBU/QkoKhBZWzraVqpegM1PMjSXcsNk\"",
                "id": {
                    "kind": "youtube#video",
                    "videoId": "10V6xet5ODk"
                },
                "snippet": {
                    "publishedAt": "2017-02-03T14:38:23.000Z",
                    "channelId": "UCNqFDjYTexJDET3rPDrmJKg",
                    "title": "Electro Swing Radio 2017 |  24/7 Music Live Stream | Gaming Music",
                    "description": "Electro Swing Radio 2017 | 24/7 Music Live Stream | Gaming Music.",
                    "thumbnails": {
                        "default": {
                            "url": "https://i.ytimg.com/vi/10V6xet5ODk/default_live.jpg",
                            "width": 120,
                            "height": 90
                        },
                        "medium": {
                            "url": "https://i.ytimg.com/vi/10V6xet5ODk/mqdefault_live.jpg",
                            "width": 320,
                            "height": 180
                        },
                        "high": {
                            "url": "https://i.ytimg.com/vi/10V6xet5ODk/hqdefault_live.jpg",
                            "width": 480,
                            "height": 360
                        }
                    },
                    "channelTitle": "7clouds",
                    "liveBroadcastContent": "live"
                }
            }, 
            { ... some other data }
        ];
        return {videos};
    }
}

Answer 1

试试这个。

public static void Main(string[] args)
{            
  DateTime StartTime = DateTime.Now;

  /// do something here... that actually takes time
  Thread.Sleep(TimeSpan.FromSeconds(1));

  /// next estimate update
  {
    double WorkDone = 0.10; // e.g. 10%... give some indication how much work has been done between 0 and 1

    TimeSpan TimeSpent = DateTime.Now - StartTime;
    TimeSpan TimeOverall = TimeSpan.FromTicks((long) (TimeSpent.Ticks / WorkDone));
    TimeSpan TimeRemaining = TimeOverall - TimeSpent;

    Console.WriteLine(TimeRemaining.TotalSeconds);
  }
}

DateTime.Now分辨率为Ticks或1E-7秒，如果您经常请求时间，则没有时间过去。要获得更高的分辨率，您需要能够测量CPU周期的性能计数器。

Answer 2

您拥有的代码相当接近，但是您有一个错误：您的starttime变量是一个局部变量，您可以在尝试使用它来计算经过的时间之前将其重置为当前时间。因此，经过的时间总是零，或非常接近。

您应该将变量移动为实例字段，以便它可以在进度更新之间保留：

DateTime starttime;

private void backgroundWorker1_DoWork(
    object sender, System.ComponentModel.DoWorkEventArgs e)
{
    int sum = 0;

    // Using UtcNow will ensure the time calculation is correct even if
    // the work occurs during a daylight saving time change-over
    starttimme = DateTime.UtcNow;

    for (int i = 1; i <= 100; i++)
    {
        // run the process here
       Thread.Sleep(100);
        // end process
        sum = sum + i;
        backgroundWorker1.ReportProgress(i);

        if (backgroundWorker1.CancellationPending)
        {
            e.Cancel = true;
            backgroundWorker1.ReportProgress(0);
            return;
        }
    }
    // displays the sum of the process
    e.Result = sum;
}

private void backgroundWorker1_ProgressChanged(
    object sender, System.ComponentModel.ProgressChangedEventArgs e)
{
    progressBar1.Value = e.ProgressPercentage;
    label5.Text = e.ProgressPercentage.ToString() + "%";

    var timespent = DateTime.UtcNow - starttime;

    // Casting to double here is superfluous. TotalSeconds is already a
    // double, and its presence in the expression results in the rest of
    // the values being promoted to double and the expression type being double.
    double secondsremaining =
        (double)(timespent.TotalSeconds / progressBar1.Value) *
        (progressBar1.Maximum - progressBar1.Value);
    label7.Text = "Time remaining:" + (int)secondsremaining;
    Console.WriteLine(secondsremaining);

}

如何计算完成一项操作的剩余时间？

2 个答案: