Progress Reporting and Cancellation

The following example demonstrates how to output the save progress of a large Excel file to the console, using the GemBox.Spreadsheet library.

View on GitHub 
using GemBox.Spreadsheet;
using System;

class Program
{
    static void Main()
    {
        // If using the Professional version, put your serial key below.
        SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY");

        Console.WriteLine("Creating file");

        // Create large workbook.
        var workbook = new ExcelFile();
        var worksheet = workbook.Worksheets.Add("sheet");
        for (int i = 0; i < 1000000; i++)
            worksheet.Cells[i, 0].Value = i;

        // Create save options.
        var saveOptions = new XlsxSaveOptions();
        saveOptions.ProgressChanged += (eventSender, args) =>
        {
            Console.WriteLine($"Progress changed - {args.ProgressPercentage}%");
        };

        // Save file.
        workbook.Save("file.xlsx", saveOptions);
    }
}

Imports GemBox.Spreadsheet
Imports System

Module Program

    Sub Main()

        ' If using the Professional version, put your serial key below.
        SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY")

        Console.WriteLine("Creating file")

        ' Create large workbook.
        Dim workbook = New ExcelFile()
        Dim worksheet = workbook.Worksheets.Add("sheet")
        For i As Integer = 0 To 1000000
            worksheet.Cells(i, 0).Value = i
        Next

        ' Create save options.
        Dim saveOptions = New XlsxSaveOptions()
        AddHandler saveOptions.ProgressChanged,
            Sub(eventSender, args)
                Console.WriteLine($"Progress changed - {args.ProgressPercentage}%")
            End Sub

        ' Save file.
        workbook.Save("file.xlsx", saveOptions)

    End Sub

End Module
The progress reported with GemBox.Spreadsheet
Screenshot of the progress reported with GemBox.Spreadsheet

GemBox.Spreadsheet supports tracking the progress of long-running operations, with the option to cancel them. Currently, the supported operations are loading XLSX files and saving XLSX, PDF, and image files by handling the XlsxLoadOptions.ProgressChanged, XlsxSaveOptions.ProgressChanged, PdfSaveOptions.ProgressChanged, and ImageSaveOptions.ProgressChanged events.

Progress reporting in WPF

The ProgressChanged event is triggered on the thread that initiates the operation so if the operation is launched on the UI thread of a WPF application, the thread gets blocked and any changes resulting from the event will not be displayed.

To address this issue, you can use Tasks to execute the load operation on a separate thread and SynchronizationContext to modify the progress bar on the UI thread. The following example illustrates how this can be done.

View on GitHub 
<Window x:Class="MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Progress reporting in WPF" Height="150" Width="300">
    <Grid>
        <ProgressBar HorizontalAlignment="Left" Height="32" Margin="27,73,0,0" VerticalAlignment="Top" Width="200" Name="progressBar"/>
        <Button x:Name="button" Content="Load" HorizontalAlignment="Left" Margin="27,19,0,0" VerticalAlignment="Top" Width="236" Height="36" Click="loadButton_Click"/>
        <Label x:Name="percentageLabel" Content="" HorizontalAlignment="Left" Margin="239,77,0,0" VerticalAlignment="Top" RenderTransformOrigin="0.867,0.59"/>
    </Grid>
</Window>
using GemBox.Spreadsheet;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;

public partial class MainWindow : Window
{
    public MainWindow()
    {
        // If using the Professional version, put your serial key below.
        SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY");
        InitializeComponent();
    }

    private async void loadButton_Click(object sender, RoutedEventArgs e)
    {
        // Capture the current context on the UI thread.
        var context = SynchronizationContext.Current;

        // Create load options.
        var loadOptions = new XlsxLoadOptions();
        loadOptions.ProgressChanged += (eventSender, args) =>
        {
            var percentage = args.ProgressPercentage;
            // Invoke on the UI thread.
            context.Post(progressPercentage =>
            {
                // Update UI.
                this.progressBar.Value = (int)progressPercentage;
                this.percentageLabel.Content = progressPercentage.ToString() + "%";
            }, percentage);
        };

        this.percentageLabel.Content = "0%";
        // Use tasks to run the load operation in a new thread.
        var file = await Task.Run(() => ExcelFile.Load("%#LargeFile.xlsx%", loadOptions));
    }
}

Imports GemBox.Spreadsheet
Imports System.Threading
Imports System.Threading.Tasks
Imports System.Windows

Class MainWindow

    Public Sub New()
        ' If using the Professional version, put your serial key below.
        SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY")
        InitializeComponent()
    End Sub

    Private Async Sub loadButton_Click(sender As Object, e As RoutedEventArgs)
        ' Capture the current context on the UI thread.
        Dim context = SynchronizationContext.Current

        ' Create load options.
        Dim loadOptions = New XlsxLoadOptions()
        AddHandler loadOptions.ProgressChanged,
            Sub(eventSender, args)
                Dim percentage = args.ProgressPercentage
                ' Invoke on the UI thread.
                context.Post(
                    Sub(progressPercentage)
                        ' Update UI.
                        Me.progressBar.Value = CType(progressPercentage, Integer)
                        Me.percentageLabel.Content = progressPercentage.ToString() & "%"
                    End Sub, percentage)
            End Sub

        Me.percentageLabel.Content = "0%"
        ' Use tasks to run the load operation in a new thread.
        Await Task.Run(
            Sub()
                ExcelFile.Load("%#LargeFile.xlsx%", loadOptions)
            End Sub)
    End Sub

End Class
The progress reported in WPF with GemBox.Spreadsheet
Screenshot of the progress reported in WPF with GemBox.Spreadsheet

Progress reporting in Windows Forms

Similarly to WPF, to show the progress of an operation in the Windows Forms UI, it is necessary to run the process in a separate thread and report the changes on the UI thread.

The following example shows how to display the progress of a load operation in the progress bar.

View on GitHub 
using GemBox.Spreadsheet;
using System;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

public partial class MainForm : Form
{
    public MainForm()
    {
        // If using the Professional version, put your serial key below.
        SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY");
        InitializeComponent();
    }

    private async void loadButton_Click(object sender, EventArgs e)
    {
        // Capture the current context on the UI thread.
        var context = SynchronizationContext.Current;

        // Create load options.
        var loadOptions = new XlsxLoadOptions();
        loadOptions.ProgressChanged += (eventSender, args) =>
        {
            var percentage = args.ProgressPercentage;
            // Invoke on the UI thread.
            context.Post(progressPercentage =>
            {
                // Update UI.
                this.progressBar.Value = (int)progressPercentage;
                this.percentageLabel.Text = progressPercentage.ToString() + "%";
            }, percentage);
        };

        this.percentageLabel.Text = "0%";
        // Use tasks to run the load operation in a new thread.
        var file = await Task.Run(() => ExcelFile.Load("%#LargeFile.xlsx%", loadOptions));
    }
}

Imports GemBox.Spreadsheet
Imports System
Imports System.Threading
Imports System.Threading.Tasks
Imports System.Windows.Forms

Public Class MainForm

    Public Sub New()
        ' If using the Professional version, put your serial key below.
        SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY")
        InitializeComponent()
    End Sub

    Private Async Sub LoadButton_Click(sender As Object, e As EventArgs) Handles LoadButton.Click
        ' Capture the current context on the UI thread.
        Dim context = SynchronizationContext.Current

        ' Create load options.
        Dim loadOptions = New XlsxLoadOptions()
        AddHandler loadOptions.ProgressChanged,
            Sub(eventSender, args)
                Dim percentage = args.ProgressPercentage
                ' Invoke on the UI thread.
                context.Post(
                    Sub(progressPercentage)
                        ' Update UI.
                        Me.ProgressBar.Value = CType(progressPercentage, Integer)
                        Me.PercentageLabel.Text = progressPercentage.ToString() & "%"
                    End Sub, percentage)
            End Sub

        Me.PercentageLabel.Text = "0%"
        ' Use tasks to run the load operation in a new thread.
        Await Task.Run(
            Sub()
                ExcelFile.Load("%#LargeFile.xlsx%", loadOptions)
            End Sub)
    End Sub

End Class
The progress reported in Windows Forms with GemBox.Spreadsheet
Screenshot of the progress reported in Windows Forms with GemBox.Spreadsheet

Cancellation

GemBox.Spreadsheet supports canceling long-running operations when handling the ProgressChanged events, by calling the CancelOperation method.

The following example demonstrates how to cancel a save operation after a specified amount of time.

View on GitHub 
using GemBox.Spreadsheet;
using System;
using System.Diagnostics;

class Program
{
    static void Main()
    {
        // If using the Professional version, put your serial key below.
        SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY");

        // Create workbook.
        var workbook = new ExcelFile();
        var worksheet = workbook.Worksheets.Add("sheet");
        for (int i = 0; i < 1000000; i++)
            worksheet.Cells[i, 0].Value = i;

        var stopwatch = new Stopwatch();
        stopwatch.Start();

        // Create save options.
        var saveOptions = new XlsxSaveOptions();
        saveOptions.ProgressChanged += (sender, args) =>
        {
            // Cancel operation after five seconds.
            if (stopwatch.Elapsed.Seconds >= 5)
                args.CancelOperation();
        };

        try
        {
            workbook.Save("Cancellation.xlsx", saveOptions);
            Console.WriteLine("Operation fully finished");
        }
        catch (OperationCanceledException)
        {
            Console.WriteLine("Operation was cancelled");
        }
    }
}

Imports GemBox.Spreadsheet
Imports System
Imports System.Diagnostics

Module Program

    Sub Main()

        ' If using the Professional version, put your serial key below.
        SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY")

        ' Create workbook.
        Dim workbook = New ExcelFile()
        Dim worksheet = workbook.Worksheets.Add("sheet")
        For i As Integer = 0 To 1000000
            worksheet.Cells(i, 0).Value = i
        Next

        Dim stopwatch = New Stopwatch()
        stopwatch.Start()

        ' Create save options.
        Dim saveOptions = New XlsxSaveOptions()
        AddHandler saveOptions.ProgressChanged,
            Sub(eventSender, args)
                ' Cancel operation after five seconds.
                If stopwatch.Elapsed.Seconds >= 5 Then
                    args.CancelOperation()
                End If
            End Sub

        Try
            workbook.Save("Cancellation.xlsx", saveOptions)
            Console.WriteLine("Operation fully finished")
        Catch ex As OperationCanceledException
            Console.WriteLine("Operation was cancelled")
        End Try

    End Sub

End Module

Cancellation in WPF

The following example shows how to implement a 'Cancel' button in a WPF application.

View on GitHub 
<Window x:Class="MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Cancellation in WPF" Height="200" Width="350">
    <Grid>
        <Button x:Name="loadButton" Content="Start Loading" HorizontalAlignment="Left" Margin="57,31,0,0" VerticalAlignment="Top" Width="228" Height="31" Click="loadButton_Click" />
        <Button x:Name="cancelButton" Content="Cancel" HorizontalAlignment="Left" Margin="57,111,0,0" VerticalAlignment="Top" Width="228" Height="32" Click="cancelButton_Click" />
        <ProgressBar HorizontalAlignment="Left" Height="25" Margin="57,73,0,0" VerticalAlignment="Top" Width="228" Name="progressBar" />
    </Grid>
</Window>
using GemBox.Spreadsheet;
using System;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;

public partial class MainWindow : Window
{
    private volatile bool cancellationRequested;

    public MainWindow()
    {
        // If using the Professional version, put your serial key below.
        SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY");
        InitializeComponent();
    }

    private async void loadButton_Click(object sender, RoutedEventArgs e)
    {
        // Capture the current context on the UI thread.
        var context = SynchronizationContext.Current;

        var loadOptions = new XlsxLoadOptions();
        loadOptions.ProgressChanged += (eventSender, args) =>
        {
            // Show progress.
            context.Post(progressPercentage => this.progressBar.Value = (int)progressPercentage, args.ProgressPercentage);

            // Cancel if requested.
            if (this.cancellationRequested)
                args.CancelOperation();
        };

        try
        {
            var file = await Task.Run(() => ExcelFile.Load("%#LargeFile.xlsx%", loadOptions));
        }
        catch (OperationCanceledException)
        {
            // Operation cancelled.
        }
    }

    private void cancelButton_Click(object sender, RoutedEventArgs e)
    {
        this.cancellationRequested = true;
    }
}

Imports GemBox.Spreadsheet
Imports System
Imports System.Threading
Imports System.Threading.Tasks
Imports System.Windows

Class MainWindow

    Private Property cancellationRequested As Boolean

    Public Sub New()
        ' If using the Professional version, put your serial key below.
        SpreadsheetInfo.SetLicense("FREE-LIMITED-KEY")
        InitializeComponent()
    End Sub

    Private Async Sub loadButton_Click(sender As Object, e As RoutedEventArgs) Handles loadButton.Click
        ' Capture the current context on the UI thread.
        Dim context = SynchronizationContext.Current

        ' Create load options.
        Dim loadOptions = New XlsxLoadOptions()
        AddHandler loadOptions.ProgressChanged,
            Sub(eventSender, args)
                ' Show progress.
                context.Post(
                    Sub(progressPercentage)
                        Me.progressBar.Value = CType(progressPercentage, Integer)
                    End Sub, args.ProgressPercentage)

                ' Cancel if requested.
                If Me.cancellationRequested Then
                    args.CancelOperation()
                End If
            End Sub

        Try
            Dim file = Await Threading.Tasks.Task.Run(
                Function() As ExcelFile
                    Return ExcelFile.Load("%#LargeFile.xlsx%", loadOptions)
                End Function)
        Catch ex As OperationCanceledException
            ' Operation cancelled.
        End Try
    End Sub

    Private Sub cancelButton_Click(sender As Object, e As RoutedEventArgs) Handles cancelButton.Click
        Me.cancellationRequested = True
    End Sub

End Class
Cancellation in WPF with GemBox.Spreadsheet
Screenshot of cancelled operation in WPF with GemBox.Spreadsheet

See also

Create and write Excel files in C# and VB.NET

Create and write Excel files in C# and VB.NET

Right-to-Left Text in Excel files using C# and VB.NET

Right-to-Left Text in Excel files using C# and VB.NET

Next steps

GemBox.Spreadsheet is a .NET component that enables you to read, write, edit, convert, and print spreadsheet files from your .NET applications using one simple API.

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