Question

I have found this : How to show a loading graphic/animation when wpf data binding is taking place

But don’t understand how to apply it for my work.

I have My MainWindow. It call all my user controls in it.

On a user control, I have a DataGrid. after press “Go” button, the datagrid load data from MySQL. It take a long time to do and I want to show a dialog window with “Please Wait” during the loading of the datagrig.

I have found the link below but don’t understant how to call it correctly.

Do I need to put this “loader” in a new class file like “Loader.cs” andthe button call it ? Ok but how to close it when datagrid is finished ?

I’m lost… Well if an other solution exist and simply to use…

Thanks by advance

EDIT TEST 1 :

Tried an simple test with slider to get a time to wait and a button.

using System;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;

namespace TEST_LoadingPage
{
/// <summary>
/// Logique d'interaction pour MainWindow.xaml
/// </summary>
public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void btnTester_Click(object sender, RoutedEventArgs e)
    {
        Window waitWindow = new Window { Height = 100, Width = 200, WindowStartupLocation = WindowStartupLocation.CenterScreen, WindowStyle = WindowStyle.None };
        waitWindow.Content = new TextBlock { Text = "Veuillez patienter...", FontSize = 30, HorizontalAlignment = HorizontalAlignment.Center, VerticalAlignment = VerticalAlignment.Center };

        BackgroundWorker worker = new BackgroundWorker();
        worker.DoWork += delegate
        {
            Dispatcher.BeginInvoke(new Action(delegate { waitWindow.ShowDialog(); }));
            lbReussite.Visibility = Loop.Pause(slider.Value);
            Dispatcher.BeginInvoke(new Action(delegate() { waitWindow.Close(); }));
        };
        worker.RunWorkerAsync();
    }
}

public class Loop
{
    public static System.Windows.Visibility Pause(double duree)
    {
        try
        {
            DateTime begin = new DateTime();
            DateTime end = new DateTime();
            int i = 0;
            begin = DateTime.Now;
            end = DateTime.Now.AddSeconds(duree);

            while (DateTime.Now <= end)
                i++;

            return System.Windows.Visibility.Visible;
        }
        catch (Exception)
        {
            return System.Windows.Visibility.Hidden;
        }
    }
}
}

but don’t work with error :

The calling thread can not access this object because a different thread owns it

I know its a courant error but I don’t see “DispatcherTimer” or else that I’ve seen before in precedent project… So I’ll try the second code tomorrow BUT. I don’t understand where i put my method 🙁

EDIT 2

I tried with your code… I’m too stupide maybe.

I’ve write the class in a Loader.cs and in my MainWiondow (its a test)

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void btnTester_Click(object sender, RoutedEventArgs e)
    {
        Loader<List<Donnees>> loader = new Loader<List<Donnees>>(GenerateList((int)slider.Value);
        loader.JobFinished += new Loader<Donnees>.OnJobFinished(loader_JobFinished);
        loader.Load();

    }

    private List<Donnees> GenerateList(int number)
    {
        List<Donnees> list = new List<Donnees>();
        for (int i = 1; i <= number; i++)
        {
            Donnees data = new Donnees();
            data.Id = i;
            data.Name = "Ligne " + i;
            list.Add(data);
        }
        return list;
    }

    void loader_JobFinished(object sender, List<Donnees> result)
    {
        result = GenerateList((int)slider.Value);
        dgDataGrid.ItemsSource = result;
    }

}

public class Donnees
{
    #region Properties

    private int id;
    public int Id
    {
        get { return id; }
        set { id = value; }
    }

    private string name;
    public string Name
    {
        get { return name; }
        set { name = value; }
    }

    #endregion

    public Donnees()
    {
        id = -1;
        name = "";
    }
}

Answer 1

You put the following code in a method in the code-behind of your DataGrid-UserControl which gets called in your button-click-eventhandler:

Window waitWindow = new Window { Height = 100, Width = 200, WindowStartupLocation = WindowStartupLocation.CenterScreen, WindowStyle = WindowStyle.None };
waitWindow.Content = new TextBlock { Text = "Please Wait", FontSize = 30, FontWeight = FontWeights.Bold, HorizontalAlignment = HorizontalAlignment.Center, VerticalAlignment = VerticalAlignment.Center };

Now you can decide…

…if you want to create a DataLoader-class, which loads the data and fires an DataLoaded event when completed, than add:

BackgroundWorker worker = new BackgroundWorker();
worker.DoWork += delegate
{
    Dispatcher.BeginInvoke(new Action(delegate { waitWindow.ShowDialog(); }));
    DataLoader dataLoader = new DataLoader();
    dataLoader.DataLoaded += delegate
    {
        Dispatcher.BeginInvoke(new Action(delegate() { waitWindow.Close(); }));
    };

    dataLoader.LoadData();
};

worker.RunWorkerAsync();

… or if you just copy your data-loading-code into this method and add:

BackgroundWorker worker = new BackgroundWorker();
worker.DoWork += delegate
{
    Dispatcher.BeginInvoke(new Action(delegate { waitWindow.ShowDialog(); }));
    //do dataloading here
    Dispatcher.BeginInvoke(new Action(delegate() { waitWindow.Close(); }));
};
worker.RunWorkerAsync();

EDIT: I wrote a class, which should do what you want without much code in the code-behind:

public class Loader<TFuncResult,TFirstArgType>:FrameworkElement
{
    private Func<TFirstArgType,TFuncResult> _execute;
    public TFuncResult Result { get; private set; }

    public delegate void OnJobFinished(object sender, TFuncResult result);
    public event OnJobFinished JobFinished;

    public Loader(Func<TFirstArgType,TFuncResult> execute)
    {
        if (execute == null)
            throw new ArgumentNullException("execute");

        _execute = execute;
    }

    private Window GetWaitWindow()
    {
        Window waitWindow = new Window { Height = 100, Width = 200, WindowStartupLocation = WindowStartupLocation.CenterScreen, WindowStyle = WindowStyle.None };
        waitWindow.Content = new TextBlock { Text = "Please Wait", FontSize = 30, FontWeight = FontWeights.Bold, HorizontalAlignment = HorizontalAlignment.Center, VerticalAlignment = VerticalAlignment.Center };

        return waitWindow;
    }

    public void Load(TFirstArgType firstarg, Window waitWindow = null)
    {
        if (waitWindow == null)
        {
            waitWindow = GetWaitWindow();
        }
        BackgroundWorker worker = new BackgroundWorker();
        worker.DoWork += delegate
        {
            Dispatcher.BeginInvoke(new Action(delegate { waitWindow.ShowDialog(); }));
            Result = _execute(firstarg);
            Dispatcher.BeginInvoke(new Action(delegate() { waitWindow.Close(); }));
        };
        worker.RunWorkerCompleted += delegate
        {
            worker.Dispose();
            if (JobFinished != null)
            {
                JobFinished(this, Result);
            }
        };
        worker.RunWorkerAsync();
    }
}

EDIT 2: How to use it:

Lets say your GenerateList() returns Data of Type List<Donnees> and the arguments Type is of Type int (works with all Types):

Place this where you want to load the Data (e.g. in your Window_Loaded-Event):

Loader<List<Donnees>, int> loader = new Loader<List<Donnees>, int>(GenerateList);
loader.JobFinished += new Loader<List<Donnees>, int>.OnJobFinished(loader_JobFinished);
loader.Load((int)slider.Value);

Now call this EventHandler in the Code-Behind:

void loader_JobFinished(object sender, List<Donnees> result)
{
    YourDataGrid.DataSource = result
}