如何使用 DownloadFileAsync 进度百分比更新 listView 中的文本？

Question

我目前正在制作一个播客客户端来下载剧集。我有一个 listView 填充了一个提要的剧集，然后当你双击一个时，它会将它放入一个单独的“下载”lisview，它有一个“名称”和一个“进度”列。我遇到的问题是尝试在异步下载时单独更新每个进度。因为我不确定如何跟踪每个 ListViewItem 的进度以及如何在 downloadProgressChanged 函数中引用它。        private void lvPodDownloads_SelectionChanged(object sender, SelectionChangedEventArgs e)    {        if (lvPodEpisodes.SelectedItems.Count == 1) // Check if an item is selected just to be safe        {            ListViewItem item = (ListViewItem)lvPodEpisodes.SelectedItem;            string[] epInfo = (string[])item.Tag;            txtTitle.Text = epInfo[0];            txtDesc.Text = epInfo[1];            try            {                imgFeedImage.Source = new BitmapImage(new Uri((Environment.CurrentDirectory + "\\..\\..\\feedImages\\" + epInfo[3])));            }            catch (Exception) // If it fails to set the image (Eg. It's non-existent) It will leave it blank            {                imgFeedImage.Source = null;            }        }    }    private void lvPodEpisodes_MouseDoubleClick(object sender, MouseButtonEventArgs e) // Downloading the episode in here    {        if (e.ChangedButton == MouseButton.Left) // Left button was double clicked        {            ListViewItem selected = (ListViewItem)lvPodEpisodes.SelectedItem;            string[] epInfo = (string[])selected.Tag;            Uri downloadUrl = new Uri(epInfo[2]);            List<Episode> downloading = new List<Episode>();            downloading.Add(new Episode() { Title = epInfo[0], Progress = "0%" });            lvPodDownloads.Items.Add((new Episode() { Title = epInfo[0], Progress = "0%" }));            using (WebClient client = new WebClient())            {                client.DownloadProgressChanged += new DownloadProgressChangedEventHandler(ProgressChanged);            }        }    }这是程序下载部分的代码示例。这是我到目前为止所拥有的图像：https : //s33.postimg.cc/gthzioxlr/image.png

Answer 1

您应该向 ProgressChanged 方法添加一个额外的参数。

private void ProgressChanged(object sender, DownloadProgressChangedEventArgs e, Episode curEpisode)

{

    curEpisode.Progress = $"{e.ProgressPercentage} %";

}

并像这样修改处理程序设置：

List<Episode> downloading = new List<Episode>();

var newEpisode = new Episode() { Title = epInfo[0], Progress = "0%" };  

downloading.Add(newEpisode);

lvPodDownloads.Items.Add(newEpisode);

using (WebClient client = new WebClient())

{

    client.DownloadProgressChanged += new DownloadProgressChangedEventHandler((sender, e) => ProgressChanged(sender, e, newEpisode));

}

静态属性intDownloadProgress就没有用了。

您还应该考虑将可观察集合用于剧集列表，并通过 XAML 代码将其用于绑定。