How to implement progress reporting for Portable HttpClient

Question

I\'m writing a library with intentions to use it in desktop (.Net 4.0 and up), phone (WP 7.5 and up) and Windows Store (Windows 8 and up) apps.

The library has the c

Answer 1

I wrote the following code to implement progress reporting. The code supports all the platforms I wanted; however, you need to reference the following NuGet packages:

• Microsoft.Net.Http
• Microsoft.Bcl.Async

Here is the code:

public async Task DownloadFileAsync(string url, IProgress<double> progress, CancellationToken token)
{
    var response = await client.GetAsync(url, HttpCompletionOption.ResponseHeadersRead, token);

    if (!response.IsSuccessStatusCode)
    {
        throw new Exception(string.Format("The request returned with HTTP status code {0}", response.StatusCode));
    }

    var total = response.Content.Headers.ContentLength.HasValue ? response.Content.Headers.ContentLength.Value : -1L;
    var canReportProgress = total != -1 && progress != null;

    using (var stream = await response.Content.ReadAsStreamAsync())
    {
        var totalRead = 0L;
        var buffer = new byte[4096];
        var isMoreToRead = true;

        do
        {
            token.ThrowIfCancellationRequested();

            var read = await stream.ReadAsync(buffer, 0, buffer.Length, token);

            if (read == 0)
            {
                isMoreToRead = false;
            }
            else
            {
                var data = new byte[read];
                buffer.ToList().CopyTo(0, data, 0, read);

                // TODO: put here the code to write the file to disk

                totalRead += read;

                if (canReportProgress)
                {
                    progress.Report((totalRead * 1d) / (total * 1d) * 100);
                }
            }
        } while (isMoreToRead);
    }
}

The using it is as simple as:

var progress = new Microsoft.Progress<double>();
progress.ProgressChanged += (sender, value) => System.Console.Write("\r%{0:N0}", value);

var cancellationToken = new CancellationTokenSource();

await DownloadFileAsync("http://www.dotpdn.com/files/Paint.NET.3.5.11.Install.zip", progress, cancellationToken.Token);

Answer 2

You can specify HttpCompletionOption.ResponseHeadersRead and then get the stream and report progress while you read from the stream. See this similar question.