Visual C#: Navigation in Applications
Excerpt by Robert Green and Ken Getz
In most client applications, users can have any number of windows open at the same time. In Outlook, you can have the Inbox, Calendar, Tasks, and Contacts open at the same time. You can have multiple messages, appointments, tasks and contacts open at the same time. You are limited solely by your tolerance for navigating amongst large numbers of windows. When you create a Windows Forms Application project in Visual Studio, the first thing you see is a form. Often this will be your startup form.
You then add any number of forms to the application. Each form is a window and it serves a purpose, whether it is data entry or reporting or a splash screen or navigation. Whether users navigate by selecting a menu item or clicking a button, the application displays a new form in a new window. Web applications take the opposite approach. Typically, you will have one window open, and that is the browser. As you navigate within a site, you load a different page in the browser and you have one page open at a time. This is not always the case, but it is true much more often than not. In a WPF application, you can choose either of these navigation paradigms. The WindowNavigationDemo sample application consists of three windows. The MainWindow.xaml file defines the application's startup window.
It contains buttons to display the other two windows, defined in Window1.xaml and Window2.xaml. Both of these windows can be open at the same time, as shown in the figure below.
Figure above, this application uses window-based navigation. When you create an application based on the WPF Application project template, Visual Studio assumes that you will use windows-based navigation. It sets the startup window to MainWindow.xaml.
If you want to use page-based navigation, and make your application look and feel more like a Web application, you need to use pages rather than windows. You should also consider using hyperlinks rather than buttons. The Page class is similar to the Window class. Each is a container and can contain a single element, such as a StackPanel, DockPanel, or Grid. A primary difference between a window and a page is that a page is designed to be navigated to. A page can be hosted in a Window, a NavigationWindow, a Frame, another page, or the browser. Because it is not a standalone container, it has a smaller set of properties than a window. The Page class contains several properties, including the following:
- Background: Determines the background for the page
- Foreground: Determines the default foreground for the page. All elements in the page will have this foreground by default.
- FontFamily and FontSize: Determine the default font family and size for the page. All elements in the page will have this font size and family by default.
- ShowsNavigationUI: Determines whether the page displays back and forward buttons.
- Title: Sets the name of the page used in the navigation history.
- WindowHeight and WindowWidth: Determine the height and widthof the window that hosts the page.
- WindowTitle: Determines the title of the window that hosts the page.
The NavigationWindow class represents a window with built-in navigation support. This class derives from the Window class and includes the ability to display content and navigate. The content can be any .NET Framework object or HTML page, but typically the content will be in a page. The NavigationWindow object supports not only navigation but the navigation history. Some of the properties of the NavigationWindow class are: BackStack and ForwardStack: Return an IEnumerable you can use to enumerate the entries in the window's back and forward navigation history.
- CanGoBack and CanGoForward: Indicate whether there is at least one entry in the back and forward navigation history.
- CurrentSource: Gets the uniform resource identifier (URI) of the content that was last navigated to.
- ShowNavigationUI: Determines whether a NavigationWindow shows its navigation buttons.
- Source: Gets or sets the uniform resource identifier (URI) of the current content, or the URI of new content that is currently being navigated to.
This post is an excerpt from the online courseware Presentation Foundation Using Visual C# 2010 course written by expert Ken Getz and Robert Green.