Question

我有应用程序页面从街道摄像机查看。照片形式相机每30秒刷新一次我创建了一个用于刷新照片的按钮我想添加进度指示器，每次下载照片时都会显示我不知道如何以及在何处添加代码我尝试过很多例子，但都失败了因为我不太懂得如何打开和关闭它。

public void downloading()
{
    WebClient webClient = new WebClient();
    webClient.OpenReadCompleted += new   OpenReadCompletedEventHandler(ImageOpenReadCompleted);
    webClient.OpenReadAsync(new Uri("http://przeprawa.swi.pl/cgi-bin/kam.cgi?6&1399042906515&" + Guid.NewGuid()));
}
private void ImageOpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
    if (!e.Cancelled && e.Error == null)
    {
        BitmapImage bmp = new BitmapImage();
        bmp.SetSource(e.Result);
        image1.Source = bmp;
    }
}
public void Refresh(object sender, EventArgs e)
{
    downloading();
}

Answer 1

对您的代码进行此更改：

public void downloading()
{
    WebClient webClient = new WebClient();
    webClient.OpenReadCompleted += new   OpenReadCompletedEventHandler(ImageOpenReadCompleted);
    webClient.OpenReadAsync(new Uri("http://przeprawa.swi.pl/cgi-bin/kam.cgi?6&1399042906515&" + Guid.NewGuid()));
    var _progressIndicator = new ProgressIndicator
        {
            IsIndeterminate = true,
            IsVisible = true,
            Text = "Downloading...",
        };
    SystemTray.SetProgressIndicator(this, _progressIndicator);
}
private void ImageOpenReadCompleted(object sender, OpenReadCompletedEventArgs e)
{
    if (!e.Cancelled && e.Error == null)
    {
        BitmapImage bmp = new BitmapImage();
        bmp.SetSource(e.Result);
        image1.Source = bmp;
        var _progressIndicator = new ProgressIndicator
        {
            IsVisible = false,
        };
        SystemTray.SetProgressIndicator(this, _progressIndicator);
    }
}
public void Refresh(object sender, EventArgs e)
{
    downloading();
}

添加进度指示器到图像下载

1 个答案: