How to copy files in C# with a customizable progress indicator and or progress bar

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Introduction

After reading about lots of ways to copy files with a progress indicator in C# and finding them all to be a little... long winded, I decided to write this article to help my fellow coders. It's a simple way to copy files and folders with a customizable progress bar/indicator.

Background

The class uses the Windows Kernal32 CopyFileEx function to do the copying of files. This being said, it does use one pointer, and so needs to be compiled with the /unsafe parameter (or simply tick the 'allow unsafe code' option in the project's properties)

You can create your own way to display the progress of the copy. To do this, simply implement the ICopyFileDiag interface and pass your class to the copy method.

//The interface for the Dialog the CopyFiles class uses.
public interface ICopyFilesDiag
{
    //needed to sync the CopyClass update events with the dialog thread
    System.ComponentModel.ISynchronizeInvoke SynchronizationObject { get; set; }

    //This event should fire when you want to cancel the copy
    event CopyFiles.DEL_cancelCopy EN_cancelCopy;

    //This is how the CopyClass will send your dialog information about
    //the transfer
    void update(Int32 totalFiles, Int32 copiedFiles, Int64 totalBytes, 
                Int64 copiedBytes, String currentFilename);
    void Show();
    void Hide();
}

Using the code

The guts of the code is in the CopyFiles class; however, once this is referenced in your application, it's simply a case of specifying a list of files for a directory to copy and the location to copy it to.

You then choose to do the copy asynchronously or synchronously:

private void But_CopyFiles_Click(object sender, EventArgs e)
{

    //This the list of random files we want 
    //to copy into a single new directory
    List<String> TempFiles = new List<String>();
    TempFiles.Add("C:\\Copy Test Folder\\test.txt");
    TempFiles.Add("C:\\Copy Test Folder\\Bob.txt");
    TempFiles.Add("C:\\Copy Test Folder\\Test4\\Bob.Trev.txt");
    TempFiles.Add("C:\\Copy Test Folder\\Test4\\test.txt");
    TempFiles.Add("C:\\Copy Test Folder\\Test3\\Bob.Trev.txt");
    TempFiles.Add("C:\\Copy Test Folder\\Test3\\test.txt");
    TempFiles.Add("C:\\Copy Test Folder\\Test3\\B.o.b.Trev..txt");
    TempFiles.Add("C:\\Copy Test Folder\\Test2\\Bob.Trev.txt");
    TempFiles.Add("C:\\Copy Test Folder\\Test2\\test.txt");
    TempFiles.Add("C:\\Copy Test Folder\\Test1\\test.txt");
    TempFiles.Add("C:\\Copy Test Folder\\Test1\\B.o.b.Trev..txt");
    TempFiles.Add("C:\\Copy Test Folder\\Test1\\Bob.Trev.txt");

    //I would recommend you put at least one large file in this folder
    //to see the progress bar in action.
    CopyFiles.CopyFiles Temp = new CopyFiles.CopyFiles(TempFiles, "C:\\Test");
    
    //Uncomment the next line to copy the file tree.
    //CopyFiles.CopyFiles Temp = 
    // new CopyFiles.CopyFiles("C:\\Copy Test Folder", "C:\\Test");

    //Create the default Copy Files Dialog window from our Copy Files assembly
    //and sync it with our main/current thread
    CopyFiles.DIA_CopyFiles TempDiag = new CopyFiles.DIA_CopyFiles();
    TempDiag.SynchronizationObject = this;

    //Copy the files anysncrinsuly
    Temp.CopyAsync(TempDiag);

    //Uncomment this line to do a synchronous copy.
    ///Temp.Copy();

}

This is an example of how the ICopyFileDiag can be implemented:

public partial class DIA_CopyFiles : Form, ICopyFilesDiag
{
    // Properties
    public System.ComponentModel.ISynchronizeInvoke 
           SynchronizationObject { get; set; }
    // Constructors
    public DIA_CopyFiles()
    {
        InitializeComponent();
    }
    // Methods
    public void update(Int32 totalFiles, Int32 copiedFiles, 
           Int64 totalBytes, Int64 copiedBytes, String currentFilename)
    {
        Prog_TotalFiles.Maximum = totalFiles;
        Prog_TotalFiles.Value = copiedFiles;
        Prog_CurrentFile.Maximum = 100;
        if (totalBytes != 0)
        {
            Prog_CurrentFile.Value = Convert.ToInt32((100f / 
                  (totalBytes / 1024f)) * (copiedBytes / 1024f));
        }
        Lab_TotalFiles.Text = "Total files (" + copiedFiles + 
                  "/" + totalFiles + ")";
        Lab_CurrentFile.Text = currentFilename;
    }
    private void But_Cancel_Click(object sender, EventArgs e)
    {
        RaiseCancel();
    }
    private void DIA_CopyFiles_Closed(object sender, System.EventArgs e)
    {
        RaiseCancel();
    }
    private void RaiseCancel()
    {
        if (EN_cancelCopy != null)
        {
            EN_cancelCopy();
        }
    }
    //Events
    public event CopyFiles.DEL_cancelCopy EN_cancelCopy;
}