miercuri, 9 iunie 2010

[WPF][5][3]Application object

[5][3]Application object

  • It is an interface between your application and the system
  • It is accessible from within all WPF .NET projects and provides an interface between your application and the system
  • It is the entry point of a WPF application
    • Threads in a WPF application must run in a singlethreaded apartment (STA)
    • Main must be marked with an STAThread attribute.
  • In the WPF sense, an application is a singleton object that provides services for UI components and UI programmers in the creation and execution of a WPF program.
  • It works the same for both WPF XBAP and WPF Window Applications
  • Application defines a Run method that keeps the application alive and dispatches messages appropriately

  • [STAThread]
    public static void Main()
    Application app = new Application();
    MainWindow window = new MainWindow();

  • Application also defines a StartupUri property that provides an alternate means of showing the application’s first Window.

    public static void Main()
    Application app = new Application();
    Application.Current.StartupUri = new Uri("MainWindow.xaml", UriKind.Relative);

  • It offers the possibility to hook into events and override virtual methods for your application
  • It acts similar to how the global.asax file manages contextual session and application information for ASP.NET applications
    • Activated event /OnActivated virtual method: A window activated by the system
    • Deactivated/Deactivated : A window deactivated by the system
    • SessionEnding/OnSessionEnding: Raised when a user session ends or the operating, system terminates (i.e., logoff or shutdown)
      • ReasonSessionEnding enumeration
    • Exit/OnExit: Raised after all windows are destroyed
    • Startup/OnStartup: Occurs prior to any windows being created or navigations being performed
  • The Application object is defined by the MyApp.xaml file and its corresponding code-behind file.
  • System.Windows.Application.Current
    • the instance of application
    • it is available once it is created
  • The use of the Application object to share variables across pages is fundamental to its purpose
    • Application.Current.Properties["MyName"] = "George Lache";
  • Application defines a readonly Windows collection to give you access to all open Windows.
  • MainWindow property
    • A WPF application’s main window is the top-level window that is set in the MainWindow property of the Application object.
    • This property is set by default when the first instance of the Window class is created and the Application.Current property is set
      • This setting can be overrided
  • Application.Current.Windows
    • The Application object’s Windows property get a list of each top-level Window
  • ShutdownMode property
    • OnLastWindowClose = 0 - it is the default one
    • OnMainWindowClose = 1
    • OnExplicitShutdown = 2
      • an application can also be shut down manually by calling the Application object’s Shutdown method
      • Application.Current.Shutdown()
  • How can I create a single-instance application using WPF?

bool mutexIsNew;
using (System.Threading.Mutex m = new System.Threading.Mutex(true, uniqueName, out mutexIsNew))
if (mutexIsNew)
// This is the first instance. Run the application.
// There is already an instance running. Exit!

  • A typical WPF application has a single UI thread and a render thread.
    • The render thread is an implementation detail that is never directly exposed to developers. It runs in the background and handles low-level tasks such as composition
    • DispatcherObject defines a Dispatcher property (of type Dispatcher) containing several overloads of Invoke (a synchronous call) and BeginInvoke (an asynchronous call).


  • it can be used to manage user and application settings between application sessions
  • supports data change notifications
  • we can bind to settings data just like any other data

  • <Window ... >
    <TextBlock ...
    Text="{Binding Path=LastView,
    Source={x:Static local:Properties.Settings.Default}}" />

Niciun comentariu:

Trimiteți un comentariu