A Window object is just what it sounds like: its a new Window
for your application. You should use it when you want to pop up an entirely new window. I don't often use more than one Window
in WPF because I prefer to put dynamic content in my main Window that changes based on user action.
A Page is a page inside your Window. It is mostly used for web-based systems like an XBAP, where you have a single browser window and different pages can be hosted in that window. It can also be used in Navigation Applications like sellmeadog said.
A UserControl is a reusable user-created control that you can add to your UI the same way you would add any other control. Usually I create a UserControl
when I want to build in some custom functionality (for example, a CalendarControl
), or when I have a large amount of related XAML code, such as a View
when using the MVVM design pattern.
When navigating between windows, you could simply create a new Window
object and show it
var NewWindow = new MyWindow();
newWindow.Show();
but like I said at the beginning of this answer, I prefer not to manage multiple windows if possible.
My preferred method of navigation is to create some dynamic content area using a ContentControl
, and populate that with a UserControl
containing whatever the current view is.
<Window x:Class="MyNamespace.MainWindow" ...>
<DockPanel>
<ContentControl x:Name="ContentArea" />
</DockPanel>
</Window>
and in your navigate event you can simply set it using
ContentArea.Content = new MyUserControl();
But if you're working with WPF, I'd highly recommend the MVVM design pattern. I have a very basic example on my blog that illustrates how you'd navigate using MVVM, using this pattern:
<Window x:Class="SimpleMVVMExample.ApplicationView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:SimpleMVVMExample"
Title="Simple MVVM Example" Height="350" Width="525">
<Window.Resources>
<DataTemplate DataType="{x:Type local:HomeViewModel}">
<local:HomeView /> <!-- This is a UserControl -->
</DataTemplate>
<DataTemplate DataType="{x:Type local:ProductsViewModel}">
<local:ProductsView /> <!-- This is a UserControl -->
</DataTemplate>
</Window.Resources>
<DockPanel>
<!-- Navigation Buttons -->
<Border DockPanel.Dock="Left" BorderBrush="Black"
BorderThickness="0,0,1,0">
<ItemsControl ItemsSource="{Binding PageViewModels}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button Content="{Binding Name}"
Command="{Binding DataContext.ChangePageCommand,
RelativeSource={RelativeSource AncestorType={x:Type Window}}}"
CommandParameter="{Binding }"
Margin="2,5"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Border>
<!-- Content Area -->
<ContentControl Content="{Binding CurrentPageViewModel}" />
</DockPanel>
</Window>
People use DataTemplates
that way when they want to dynamically switch Views depending on the ViewModel:
<Window>
<Window.Resources>
<DataTemplate DataType="{x:Type local:VM1}">
<!-- View 1 Here -->
</DataTemplate>
<DataTemplate DataType="{x:Type local:VM2}">
<!-- View 2 here -->
</DataTemplate>
</Window.Resources>
<ContentPresenter Content="{Binding}"/>
</Window>
So,
if Window.DataContext
is an instance of VM1
, then View1
will be displayed,
and if
Window.DataContext
is an instance of VM2
, then View2
will be displayed.
Granted, it makes no sense at all if only 1 View is expected, and never changed.
Best Answer
A Window has things like Title bar (including min/max/close buttons, etc) and can be used to host XAML elements, such as User Controls.
You are certainly not restricted to using one Window per Application, but some applications would choose that pattern (one window, hosting a variety of UserControls).
When you create a new WPF Application, by default your app is configured (in App.xaml) like this:
The
StartupUri
property tells the app which Window to open first (you can configure this if you wish)If you would like to logically separate your Window into pieces and do not want too much XAML in one file, you could do something like this:
where
HeaderUserControl
andMainSectionUserControl
are UserControls encapsulating the aspects of that Window, as needed.If you want to show another Window, you can, in code, call
Show
orShowDialog
on an instance of the new Window you want to show...Also - yes, a Page is part of a WPF Browser application, designed to be viewed in Internet Explorer.