WPF Dialog Patterns

Creating and managing dialog windows for user interaction.

Advanced Patterns: See ADVANCED.md for MVVM dialog service, modeless dialogs, and input dialogs.

1. Dialog Types Overview

Dialog Types ├── Modal Dialogs (ShowDialog) │ ├── Custom Window dialogs │ └── MessageBox ├── Modeless Dialogs (Show) │ └── Tool windows, floating panels └── Common Dialogs ├── OpenFileDialog ├── SaveFileDialog └── FolderBrowserDialog

2. MessageBox

2.1 Basic Usage

// Simple message MessageBox.Show("Operation completed successfully.");

// With title MessageBox.Show("File saved.", "Success");

// With buttons var result = MessageBox.Show( "Do you want to save changes?", "Confirm", MessageBoxButton.YesNoCancel);

// With icon MessageBox.Show( "An error occurred.", "Error", MessageBoxButton.OK, MessageBoxImage.Error);

2.2 MessageBox Options

Buttons:

Value Buttons

OK OK

OKCancel OK, Cancel

YesNo Yes, No

YesNoCancel Yes, No, Cancel

Icons:

Value Icon

None No icon

Information Info circle

Warning Warning triangle

Error Red X

2.3 Processing Results

var result = MessageBox.Show( "Are you sure you want to delete this item?", "Confirm Delete", MessageBoxButton.YesNo, MessageBoxImage.Warning, MessageBoxResult.No); // Default button

switch (result) { case MessageBoxResult.Yes: DeleteItem(); break; case MessageBoxResult.No: // Cancelled break; }

3. Custom Modal Dialog

3.1 Dialog Window XAML

<Window x:Class="MyApp.Dialogs.SettingsDialog" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Settings" Width="400" Height="300" WindowStartupLocation="CenterOwner" ResizeMode="NoResize" ShowInTaskbar="False"> <Grid Margin="20"> <Grid.RowDefinitions> <RowDefinition Height="*"/> <RowDefinition Height="Auto"/> </Grid.RowDefinitions>

    <!-- Content -->
    <StackPanel Grid.Row="0">
        <Label Content="User Name:"/>
        <TextBox x:Name="UserNameTextBox" Margin="0,5,0,15"/>
        <CheckBox x:Name="EnableNotificationsCheckBox"
                  Content="Enable notifications"/>
    </StackPanel>

    <!-- Dialog buttons -->
    <StackPanel Grid.Row="1" Orientation="Horizontal" HorizontalAlignment="Right">
        <Button Content="OK" Width="80" Margin="0,0,10,0"
                Click="OkButton_Click" IsDefault="True"/>
        <Button Content="Cancel" Width="80"
                Click="CancelButton_Click" IsCancel="True"/>
    </StackPanel>
</Grid>

</Window>

3.2 Dialog Code-Behind

namespace MyApp.Dialogs;

using System.Windows;

public partial class SettingsDialog : Window { public string UserName { get; private set; } = string.Empty; public bool EnableNotifications { get; private set; }

public SettingsDialog()
{
    InitializeComponent();
}

private void OkButton_Click(object sender, RoutedEventArgs e)
{
    // Validate input
    if (string.IsNullOrWhiteSpace(UserNameTextBox.Text))
    {
        MessageBox.Show("Please enter a user name.", "Validation Error",
            MessageBoxButton.OK, MessageBoxImage.Warning);
        UserNameTextBox.Focus();
        return;
    }

    // Set results
    UserName = UserNameTextBox.Text;
    EnableNotifications = EnableNotificationsCheckBox.IsChecked ?? false;

    // Close with success
    DialogResult = true;
}

private void CancelButton_Click(object sender, RoutedEventArgs e)
{
    DialogResult = false;
}

}

3.3 Using the Dialog

private void OpenSettings_Click(object sender, RoutedEventArgs e) { var dialog = new SettingsDialog { Owner = this // Set owner for centering };

if (dialog.ShowDialog() == true)
{
    // User clicked OK
    _currentUserName = dialog.UserName;
    _enableNotifications = dialog.EnableNotifications;
    ApplySettings();
}

}

4. Common Dialogs

4.1 OpenFileDialog

using Microsoft.Win32;

private void OpenFile_Click(object sender, RoutedEventArgs e) { var dialog = new OpenFileDialog { Title = "Open File", Filter = "Text files (.txt)|.txt|All files (.)|.", FilterIndex = 1, InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), Multiselect = false, CheckFileExists = true };

if (dialog.ShowDialog() == true)
{
    var filePath = dialog.FileName;
    LoadFile(filePath);
}

}

// Multiple file selection private void OpenMultipleFiles_Click(object sender, RoutedEventArgs e) { var dialog = new OpenFileDialog { Multiselect = true, Filter = "Image files (.png;.jpg)|.png;.jpg" };

if (dialog.ShowDialog() == true)
{
    foreach (var file in dialog.FileNames)
    {
        ProcessFile(file);
    }
}

}

4.2 SaveFileDialog

using Microsoft.Win32;

private void SaveFile_Click(object sender, RoutedEventArgs e) { var dialog = new SaveFileDialog { Title = "Save File", Filter = "Text files (.txt)|.txt|All files (.)|.", FileName = "document.txt", DefaultExt = ".txt", AddExtension = true, OverwritePrompt = true };

if (dialog.ShowDialog() == true)
{
    var filePath = dialog.FileName;
    SaveFile(filePath);
}

}

4.3 .NET 8+ Folder Picker

// .NET 8+ includes OpenFolderDialog private void SelectFolder_Click(object sender, RoutedEventArgs e) { var dialog = new OpenFolderDialog { Title = "Select Output Folder", InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) };

if (dialog.ShowDialog() == true)
{
    var folderPath = dialog.FolderName;
    ProcessFolder(folderPath);
}

}

5. References

• Dialog Boxes Overview - Microsoft Docs

• MessageBox Class - Microsoft Docs

• OpenFileDialog Class - Microsoft Docs