如何优化大量图片的加载？

Question

我从 REST 服务上传大量图像，并通过定期任务使用它们创建各种 gif 图像。我想知道如何优化我的代码，改进它并使其更快。

 public class WebcamListViewModel : BaseViewModel

{

    public ICommand InitializeWebcamsCommand { set; get; }

    public ICommand OpenVideoWebcamCommand { set; get; }

private List<Webcam> _ListOfWebcam { get; set; }

public List<Webcam> ListOfWebcam

{

    get { return _ListOfWebcam; }

    set

    {

        _ListOfWebcam = value;

        OnPropertyChanged();

    }

}

private IFolder folder;

private int _Counter { get; set; }

public int Counter

{

    get { return _Counter; }

    set

    {

        _Counter = value;

        OnPropertyChanged();

    }

}

private Task SetFrameOnViewTask;

private Task DownloadFramesTask;

CancellationTokenSource tokenSourceSetFrame = new CancellationTokenSource();

CancellationTokenSource tokenSourceDownloadFrames = new CancellationTokenSource();

CancellationToken cancellationTokenSetFrame;

CancellationToken cancellationTokenDownloadFrames;

public WebcamListViewModel(INavigationService navigationService, IApiAutostradeManagerFactory apiAutostradeManagerFactory) : base(navigationService,apiAutostradeManagerFactory)

{

    OpenVideoWebcamCommand = new Command<Webcam>(async (webcam) => {

        await navigationService.NavigateAsync(Locator.WebcamVideoPopUpPage);

        Messenger.Default.Send(new InfoWebcamVideoMessage(webcam.c_mpr, webcam.c_uuid, webcam.t_str_vid));

    });

    InitializeWebcamsCommand = new Command(async () => await RunSafe(InitializeWebcams()));

    InitializeWebcamsCommand.Execute(null);

    cancellationTokenDownloadFrames = tokenSourceDownloadFrames.Token;

    DownloadFramesTask = new Task(async () => {

        cancellationTokenDownloadFrames.ThrowIfCancellationRequested();

在我的 viewModel 中，我有两个任务：DownloadFramesTask 和 SetFrameOnViewTask，每 500 毫秒增加一个计数器，用于显示轮流中的四个帧之一。

Answer 1

而不是这个：foreach (var web in ListOfWebcam){&nbsp; &nbsp; web.image1 = await GetWebcamFrame(web.frame1);&nbsp; &nbsp; web.image2 = await GetWebcamFrame(web.frame2);&nbsp; &nbsp; web.image3 = await GetWebcamFrame(web.frame3);&nbsp; &nbsp; web.image4 = await GetWebcamFrame(web.frame4);}您可以一次执行所有异步任务：var tasks = new List<Task>();tasks.Add(GetWebcamFrame(web.frame1));// add more tasks hereawait Task.WhenAll(tasks);Task.Delay()您还可以删除对;的使用。目前还不清楚为什么有必要这样做。