The Window class has more than 100 public properties, and some of themsuch as the Title property that identifies the windoware quite important. But by far the most important property of Window is the Content property.
You set the Content property of the window to the object you want in the window's client area.
You can set the Content property to a string, you can set it to a bitmap, you can set it to a drawing, and you can set it to a button, or a scrollbar, or any one of 50-odd controls supported by the Windows Presentation Foundation.
You can set the Content property to just about anything. But there's only one little problem:
You can only set the Content property to one object.
This restriction is apt to be a bit frustrating in the early stages of working with content. Eventually, of course, you'll see how to set the Content property to an object that can play host to multiple other objects. For now, working with a single content object will keep us busy enough.
We've seen that window content can be plain text. But the purpose of the Content property is not to display simple unformatted text. No, no, no, no, no. What the Content property really wants is something more graphical in nature, and that's an instance of any class that derives from UIElement.
UIElement is an extremely important class in the Windows Presentation Foundation. This is the class that implements keyboard, mouse, and stylus handling. The UIElement class also contains an important method named OnRender. The OnRender method is invoked to obtain the graphical representation of an object.
As far as the Content property goes, the world is divided into two groups of objects: Those that derive from UIElement and those that do not. In the latter group, the object is displayed with ToString; in the former group, it's displayed with OnRender. Classes that derive from UIElement (and their instantiated objects) are often referred to collectively as elements.
The only class that inherits directly from UIElement is FrameworkElement, and all the elements you'll encounter in the Windows Presentation Foundation derive from FrameworkElement. In theory, UIElement provides the necessary structure of user interface events and screen rendering that can support various programming frameworks. The Windows Presentation Foundation is one such framework and consists of all the classes that derive from FrameworkElement. In a practical sense, you probably won't make much of a distinction between the properties, methods, and events defined by UIElement and those defined by FrameworkElement.
One popular class that inherits from FrameworkElement is Image. Here's the class hierarchy:
Object
--DispatcherObject (abstract)
------DependencyObject
----------Visual (abstract)
------------------UIElement
----------------------FrameworkElement
----------------------------Image
The Image class lets you easily include an image in a document or an application.
We've seen that window content can be plain text. But the purpose of the Content property is not to display simple unformatted text. No, no, no, no, no. What the Content property really wants is something more graphical in nature, and that's an instance of any class that derives from UIElement.
UIElement is an extremely important class in the Windows Presentation Foundation. This is the class that implements keyboard, mouse, and stylus handling. The UIElement class also contains an important method named OnRender. The OnRender method is invoked to obtain the graphical representation of an object.
As far as the Content property goes, the world is divided into two groups of objects: Those that derive from UIElement and those that do not. In the latter group, the object is displayed with ToString; in the former group, it's displayed with OnRender. Classes that derive from UIElement (and their instantiated objects) are often referred to collectively as elements.
The only class that inherits directly from UIElement is FrameworkElement, and all the elements you'll encounter in the Windows Presentation Foundation derive from FrameworkElement. In theory, UIElement provides the necessary structure of user interface events and screen rendering that can support various programming frameworks. The Windows Presentation Foundation is one such framework and consists of all the classes that derive from FrameworkElement. In a practical sense, you probably won't make much of a distinction between the properties, methods, and events defined by UIElement and those defined by FrameworkElement.
One popular class that inherits from FrameworkElement is Image. Here's the class hierarchy:
Object
--DispatcherObject (abstract)
------DependencyObject
----------Visual (abstract)
------------------UIElement
----------------------FrameworkElement
----------------------------Image
The Image class lets you easily include an image in a document or an application.
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