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Developing Windows Presentation Foundation Applications Introduction Microsoft® Windows® Presentation Foundation provides a new model and tools for developers to build client applicati

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Developing Windows Presentation Foundation

Applications

Introduction

Microsoft® Windows® Presentation Foundation provides a new model and tools for

developers to build client applications that combine advanced UI elements and provide

easy access to content from a variety of sources This session provides an overview of

how to create applications by using Windows Presentation Foundation

Objectives

After completing this section, you will be able to:

• Describe Windows Presentation Foundation

• Explain XAML

• Create applications by using XAML

• Create a Windows Presentation Foundation application

• Manage windows in XAML

• Navigate application pages in XAML

• Build XAML browser applications

• Create rich 2-D and 3-D content

• Use data binding in Windows Presentation Foundation

Introducing Windows Presentation Foundation

The Microsoft Windows Presentation Foundation provides the foundation for building

applications in Microsoft Windows Vista™, blending together application UI, documents,

and media content, while exploiting the full power of your computer Windows

Presentation Foundation is exposed through the Microsoft NET Framework Windows

Presentation Foundation consists of:

• A display engine that takes full advantage of modern graphics hardware

• An extensible set of managed classes that developers can use to create rich, visually

stunning applications

• Extensible Application Markup Language (XAML), which enables developers to use

an XML-based model to declaratively manipulate the object model

Windows Presentation Foundation is based on the following design principles:

• Integration of various content sources into a single model Windows Presentation

Foundation provides a single model that can be used to manipulate content from a

variety of media sources, document sources, and user interface sources and allows

seamless integration of content within a single application You can use the same

constructs for animation, data binding, and styling regardless of whether you are

targeting 2-D, 3-D, or text content

• Use of vector-based graphics The composition engine is vector-based, allowing for

scaling of all output to match the resolution of a specific machine

• Support for declarative programming The use of XAML allows applications to parse and manipulate UI logic at run time for dynamic workflow scenarios Furthermore, the XAML/code-behind model embodied in Windows Presentation Foundation allows designers and developers to work collaboratively on client application design and development

• Easy deployment Web-browser applications run from within Microsoft Internet Explorer®, either occupying the entire window or fitting in an inline frame Stand-alone applications are locally installed via ClickOnce or MSI technologies

• Document life-cycle options Windows Presentation Foundation introduces a new set

of document and print technologies

Powerful 3-D graphics hardware that is now standard in most computers is today utilized for most applications The Windows Presentation Foundation sets out to take full advantage of these capabilities as a platform for building rich, immersive, user

under-experiences

What Is XAML?

XAML (pronounced “zamel”) is a new declarative language for creating application user

interfaces It offers a wealth of new controls and elements with capabilities such as forms

development, animation, and rendering of 2-D and 3-D graphics

When a developer creates an application in Windows Presentation Foundation, most of

the code is written and implemented in XAML XAML code must be well-formed XML,

be saved in a file with the xaml extension, and have a namespace that maps to XML

namespaces

XAML provides the following benefits:

• Faster and easier application implementation Markup-based interfaces are quick to

build and are easily modifiable They require less code than traditional structured

programming

• Easier to localize Because XAML separates the user interface from the application

logic, it is easier to localize the user interface This also gives the ability for

developers to modify application logic without affecting the user interface

• Familiar development environment Developers with experience using HTML or other Web-oriented markup languages will find XAML a familiar environment for developing applications

• Third-party support XAML can be developed in many different development tools, which offers third-party developers opportunities to create applications by using a variety of visual tools

• Extensible Using object-oriented programming techniques, developers can extend XAML by creating custom controls, elements, and functionality

• No performance penalty With XAML, there is no performance penalty because XAML is an XML-based representation of the object model

Programming with XAML

XAML is the preferred way to create a UI in the Windows Presentation Foundation

programming model because it enables you to separate UI definition from logic It also

enables you to integrate code by using code-behind files that are joined to the markup

through partial class definitions For simple cases, you can also specify inline code

Every XAML tag corresponds directly to a NET Framework class whose properties are

controlled through the use of XML attributes For example, the <Button> tag corresponds

directly to the System.Windows.Controls.Button class

Each XAML file includes the following elements:

• Root element As with all well-formed XML files, XAML files must have one root

tag When creating the XAML file, use a root element such as a DockPanel or

Canvas that can support a content model so that you can add child elements or other

content to it or an element such as Window or Page that is part of the application

model

The root element contains Web links references to two of the schemas used by

XAML files These schemas are available at: http://schemas.microsoft.com/winfx/

2006/xaml/presentation and http://schemas.microsoft.com/winfx/2006/xaml These

schemas contain the definitions of graphical elements represented by WPF and often

have a corresponding object associated with them

• Properties XAML properties that are expressed as attributes enable you to add

features to object element tags Often, the properties that appear as XAML attributes

on an element are inherited from base classes For example, the Background

property is not an immediately declared property on the Button class but is instead inherited from the base Control class

• Name property Many XAML elements support a Name property This property is

particularly important because it allows you to reference a particular element from code-behind when that element was originally created from XAML markup

The following code illustrates a simple XAML file:

Demonstration 1: Writing and Building a XAML Application

In this demonstration, you will see how you can write and build a XAML application

Key Points

The key points of this demonstration are:

• Every XAML file includes some core elements

• You can use a variety of tools to create a XAML application, including XamlPad and

Microsoft Visual Studio® 2005

Creating a Windows Presentation Foundation Application

You can create a WPF application by using a code-behind file or by using inline code

Most applications consist of both XAML and code, such as Microsoft Visual Basic® or

Microsoft Visual C#®, in a code-behind file As a best practice, you should avoid or limit

the use of inline code

Using the code-behind model

When you use a code-behind model, the code for the application is contained within a

class file separate from the XAML file that displays the user interface This model is

similar to the code-behind model used with Microsoft ASP.NET The model allows a

clean separation of the XAML content from the application code The root XAML

element in an XAML file identifies where the application expects to find the code-behind

file when it compiles The root element specifies a namespace and class as its x:Class

attribute value

Using inline code

You can also embed your code within a XAML file You do this by using the x:Code

directive element, which can contain inline programming code to interact with the XAML on the same page

Demonstration 2: Developing XAML Applications in

Visual Studio 2005

In this demonstration, you will see how you can develop XAML applications in

Visual Studio 2005

Key Points

The key points of this demonstration are:

• Visual Studio 2005 provides the Design, Xaml, and Source views of a XAML

application

• You can use Visual Studio 2005 to add controls, text, and event handling to an

XAML application

Managing Windows

Windows Presentation Foundation applications typically have at least one and sometimes

several windows Windows are used for a variety of purposes, including hosting

graphical UIs, displaying graphics or text information, and handling user interaction

The Windows Presentation Foundation Application class provides basic support for

windows In particular, the Application class handles message dispatching so that you do

not need to implement a message pump or window procedure The Application object

maintains a collection of references to the windows in your application By default,

closing the last window shuts down the application

In Windows Presentation Foundation, you can represent windows by using one of these

three objects:

• Window object Supports core window functionality

• NavigationWindow object Extends the Window object to support navigation from

one XAML page to another

• Page object The Page object, which enables you to set several window properties in

markup, is typically used as the root element of the pages that make up a navigation

application Use the Page object to define pages that you need to navigate to

Windows Presentation Foundation applications have a window that is designated as the main window When you start your application, the first window that you create becomes

the main window You can get a reference to that window from the MainWindow property of the Application object Because this is a read/write property, you can change your main window by assigning another window to MainWindow

Application hosting and window management

You can compile Windows Presentation Foundation applications to run as a XAML browser application or a Windows application These two hosting scenarios impose different requirements for window use as shown in the following table

Requirement XAML Browser Application Windows Application

window Window types Implicitly uses a NavigationWindow Can use either Window or

NavigationWindow

Window properties Can specify only three properties:

Title, Height, and Width

Can specify all properties

New windows Can launch only pop-up elements,

and they must stay within the window border

Can launch additional windows and dialog boxes

Navigating Application Pages

The Windows Presentation Foundation framework provides you with a powerful and

flexible way to control the flow of your program It is particularly useful if your

navigation targets must be determined at run time from user feedback or external data or

you need to navigate a hierarchy of information Although structured navigation can be

used for stand-alone applications, it is typically used for relatively short applications that

are called by larger applications This type of program guides users through complex

procedures in which the next step in the procedure is often not determined until the user

has provided input

When users work with a multi-page application, they typically proceed through a number

of pages Each time they do so, they unload the current page and load the next page,

usually called the target page With Windows Presentation Foundation, you can use one

of several techniques to navigate from one page to the next

• Navigate to a specified URI

• Navigate to a specified page object

• Navigate forward or backward in the journal

For example, you can navigate to a new XAML page by using the following code:

private void btnGoToPage2(object sender, RoutedEventArgs args)

the target page function to the previous page function, you need to call the OnReturn

method When you call this method, the system returns you the previous page function

in the stack You do not need to know anything about the previous page function This feature allows you to call a page function from any other page in your application and easily return to that page You can also pass data in this fashion across pages