Progress manager and aggregator
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Gress is a library that makes progress reporting and aggregation easier.



  • Manages and aggregates progress from multiple operations
  • Supports weighted operations
  • Implements INotifyPropertyChanged
  • Implements IProgress<double>
  • Targets .NET Framework 4.5+ and .NET Standard 1.0+
  • No external dependencies


Basic example

Progress is reported using the Report() method. When a ProgressOperation is disposed, it's marked as completed and cannot report progress anymore.

var manager = new ProgressManager();

// Create an operation and execute a long-running process
using (var operation = manager.CreateOperation())
    for (var i = 0; i < 100; i++)
        await Task.Delay(200); // simulate time-consuming task
        operation.Report((i+1)/100); // report progress

Using weight

Operations may have custom weight which defines how much its own progress affects the total progress, compared to other operations. This is useful, for example, when you know that one of the operations takes less time to complete and want to make total progress look a bit more linear.

var manager = new ProgressManager();

// Create a light operation
var operationLight = manager.CreateOperation(1);

// Create a heavy operation
var operationHeavy = manager.CreateOperation(5);

// Report progress on both
operationLight.Report(0.8); // 80%
operationHeavy.Report(0.4); // 40%

// Print total progress
Console.WriteLine(manager.Progress); // 0.46667 (~47%)

Pre-creating operations

Often you may need to pre-create operations in cases where the number of operations is known ahead of time and you want ProgressManager to account for them when calculating aggregated progress.

var manager = new ProgressManager();

// Create 2 operations
var operations = manager.CreateOperations(2);

// Perform first operation (from 0% to 50%)
using (var operation = operations[0])

// Perform second operation (from 50% to 100%)
using (var operation = operations[1])

Integrating with other code

The standard guideline for reporting progress in .NET is to use an instance of System.IProgress<T>.

Since Gress represents progress as double, the ProgressOperation class also implements IProgress<double>. If you have existing code or 3rd-party libraries that report progress using IProgress<double> then you can simply use ProgressOperation as the corresponding parameter.

Here's an example that uses YoutubeExplode and Gress to download a YouTube video and report progress.

var youtubeClient = new YoutubeClient();
var progressManager = new ProgressManager();

using (var operation = progressManager.CreateOperation())
    // Get stream info
    var streamInfoSet = await youtubeClient.GetVideoMediaStreamInfosAsync("9bZkp7q19f0")
    var streamInfo = streamInfoSet.Muxed.WithHighestVideoQuality();

    // Download stream (operation here is passed as IProgress<double>)
    await youtubeClient.DownloadMediaStreamAsync(streamInfo, "ouput.bin", operation);

Integrating with XAML

Both ProgressManager and ProgressOperation implement INotifyPropertyChanged so corresponding bound properties will be automatically refreshed every time progress changes.

The following is a rough example of how ProgressManager can be used in WPF.

public class MainViewModel
    public IProgressManager ProgressManager { get; } = new ProgressManager();
    public ICommand ExecuteOperationCommand { get; }

    public MainViewModel()
        ExecuteOperationCommand = new RelayCommand(ExecuteOperation);

    public async void ExecuteOperation()
        using (var operation = ProgressManager.CreateOperation())
            for (var i = 0; i < 100; i++)
                await Task.Delay(200); // simulate time-consuming task
                operation.Report((i+1)/100); // report progress
    d:DataContext="{d:DesignInstance Type=MainViewModel}">
        <!-- Button that starts a new operation -->
        <Button Margin="32" Content="Execute" Command="{Binding ExecuteOperationCommand}" />

        <!-- Progress bar that shows total progress -->
        <ProgressBar Margin="32" Height="10" Minimum="0" Maximum="1" Value="{Binding ProgressManager.Progress, Mode=OneWay}" />

Libraries used