Application.Startup Event

public:
 event System::Windows::StartupEventHandler ^ Startup;

public event System.Windows.StartupEventHandler Startup;

member this.Startup : System.Windows.StartupEventHandler 

Public Custom Event Startup As StartupEventHandler 

Event Type

Examples

The following example shows how to acquire and process command-line options from a standalone application. If the /StartMinimized command-line parameter was provided, the application opens the main window in a minimized state.

<Application
 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 x:Class="SDKSample.App"
 Startup="App_Startup" />

using System.Windows;

namespace SDKSample
{
 public partial class App : Application
 {
 void App_Startup(object sender, StartupEventArgs e)
 {
 // Application is running
 // Process command line args
 bool startMinimized = false;
 for (int i = 0; i != e.Args.Length; ++i)
 {
 if (e.Args[i] == "/StartMinimized")
 {
 startMinimized = true;
 }
 }

 // Create main application window, starting minimized if specified
 MainWindow mainWindow = new MainWindow();
 if (startMinimized)
 {
 mainWindow.WindowState = WindowState.Minimized;
 }
 mainWindow.Show();
 }
 }
}

Imports System.Windows

Namespace SDKSample
 Partial Public Class App
 Inherits Application
 Private Sub App_Startup(ByVal sender As Object, ByVal e As StartupEventArgs)
 ' Application is running
 ' Process command line args
 Dim startMinimized As Boolean = False
 Dim i As Integer = 0
 Do While i <> e.Args.Length
 If e.Args(i) = "/StartMinimized" Then
 startMinimized = True
 End If
 i += 1
 Loop

 ' Create main application window, starting minimized if specified
 Dim mainWindow As New MainWindow()
 If startMinimized Then
 mainWindow.WindowState = WindowState.Minimized
 End If
 mainWindow.Show()
 End Sub
 End Class
End Namespace

XAML browser applications (XBAPs) cannot retrieve and process command-line arguments because they are launched with ClickOnce deployment (see Deploying a WPF Application (WPF)). However, they can retrieve and process query string parameters from the URLs that are used to launch them.

Remarks

A typical Windows Presentation Foundation application may perform a variety of initialization tasks when it starts up, including:

• Processing command-line parameters.

• Opening the main window.

• Initializing application-scope resources.

• Initializing application-scope properties.

You can declaratively specify the main window and application-scope resources using XAML (StartupUri and Resources, respectively). Sometimes, however, the resources or main window of your application can only be determined programmatically at run time. Additionally, application-scope properties and command-line parameters can only be used programmatically. Programmatic initialization can be performed by handling the Startup event, including the following:

• Acquire and process command-line parameters, which are available from the Args property of the StartupEventArgs class that is passed to the Startup event handler.

• Initialize application-scope resources by using the Resources property.

• Initialize application-scope properties by using the Properties property.

• Instantiate and show one (or more) windows.

If you set StartupUri using XAML, the main window that is created is not available from either the MainWindow property or the Windows property of the Application object until after the Startup event is processed. If you need access to the main window during startup, you need to manually create a new window object from your Startup event handler.

The command-line arguments that are passed to the Startup event handler are not the same as the URL query string parameters that are passed to an XAML browser application (XBAP).

See also

• OnStartup(StartupEventArgs)
• Exit