WebClient.UploadValuesAsync 未正确更新进度

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问题描述

我有一个 WebClient，用于通过以下方式上传文件，base64Encoded 是编码为 base64 字符串的图片，这是 imgur 服务器所期望的:

I have a WebClient which I use to upload a file in the following way, base64Encoded is a picture encoded as a base64 string as that is what the imgur server expects:

    public Upload()
    {
        WebClient webClient = new WebClient();
        webClient.UploadProgressChanged += new UploadProgressChangedEventHandler(webClient_UploadProgressChanged);
        webClient.UploadValuesCompleted += new UploadValuesCompletedEventHandler(webClient_UploadValuesCompleted);

        NameValueCollection values = new NameValueCollection();
        values.Add("key", "imgur api key");
        values.Add("image", base64Encoded);
        webClient.UploadValuesAsync(new Uri("http://api.imgur.com/2/upload"), "POST", values);
    }

这是 UploadProgressChanged 的事件处理程序:

This is the event handler for the UploadProgressChanged:

    private void webClient_UploadProgressChanged(object sender, UploadProgressChangedEventArgs e)
    {
        int percentage = e.ProgressPercentage * 2;

        progressBar.Value = percentage;
        percentageTextBlock.Text = (percentage).ToString() + "%";
    }

现在我的问题是事件处理程序在开始时只调用一次，报告 ProgressPercentage 为 50，然后不再被调用.文件上传成功，但我的进度条不工作.这不是因为我正在上传一个小文件，因为我也尝试了几个 mb 的文件，这些文件也立即报告了 50 的 ProgressPercentage.e.BytesSent 也没有帮助，因为它也等于 e.TotalBytesToSend.这是怎么回事?

Now my problem is that the event handler is only called once right at the start, reports a ProgressPercentage of 50 and is then not being called anymore. The file uploads successfully, but my progressbar is not working. This is not because I'm uploading a small file as I've also tried this with files of several mb which also report a ProgressPercentage of 50 right away. e.BytesSent is no help either because that one is equal to e.TotalBytesToSend right away as well. What is going on here?

UploadValuesAsync

WebClient.UploadValuesAsync 未正确更新进度

问题描述

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