Tuesday, February 15, 2011

WPF in Visual Studio

Windows Presentation Foundation (WPF) is a .NET technology for building desktop
applications. The result of building a WPF application is an *.exe file that you can
run directly on your computer or deploy and run on any other computer that has .NET
installed. With WPF, you can add a graphical user interface (GUI), pronounced "Gooey,"
that makes it easier for users to work with your program.
This Article will show you how to lay out a screen in WPF and explain the controls, such
as Button and TextBox, that you can place on the screen. You'll also learn how to capture
events off controls, allowing you to add code that runs based on user input. Since most
applications work with data, this Articlebuilds on what you learned in C#, OOPS concepts
and shows how to bind data to controls in the GUI.
This Article will show you how to build a WPF GUI with the VS Designer, but
sometimes you must work at a lower level and manipulate the XAML, pronounced
"Zammel," that defines the GUI. XAML is an XML format that WPF and Silverlight
use to define a GUI. There are two Article in this blog that will help you get up to
speed in XAML: Article 1, "XML in Visual Studio" and Article 2, " XAML in WPF and
Silverlight." If you aren't familiar with XML, start with Article 1. However, if you have
a good grasp of basic XML syntax, go straight to Article 2. I'll try to explain WPF in
a way that any XAML you see can be understood in its context, but you might want to
review the Articles to avoid any confusion. Once you're familiar with XAML, you can
return here and start with the next section, which explains how to start a WPF project.
Starting a WPF Project
May be you know that how to create and build projects. The example explained how
to create a Console application. However, what you learned there is generally applicable
to most other application types. This section builds upon what you already know about
projects and explains what is unique to a WPF application. To get started, open the New
Project window; select WPF Application; and fill in the project name, location, and
solution name. I'm naming the examples in the chapter as MyShop to continue the idea
of customers who buy products. Figure 1 shows the new WPF application in VS, including
a Toolbox, a Designer, and a Solution Explorer. The Toolbox contains controls, which are
user interface (UI) elements, such as Button and Textbox, that you can drag and drop onto
the Designer.

There is another .NET technology, Windows Forms, for creating desktop applications.
This book doesn't discuss Windows Forms because it's an older technology. The way
forward for desktop application development is WPF, and the intention of this book is to
help guide you in a direction most beneficial to you.

The Designer allows you to lay out the UI of the application; it is divided into Design
on the top and XAML on the bottom. The Design surface allows you to visually work
with controls and layouts of those controls. The XAML editor allows you to work with
the XML representation of the controls on the design surface. The Design and XAML are
interrelated because a change in one causes a change in the other. For example, if you add
a Button to the Design, you'll see the XML representation of that Button in the XAML.
Figure 1  new WPF application project
Understanding Layout
A layout defines how you can position and size controls on a screen. WPF windows and
controls have a Content (can occasionally be called something else) property that accepts
a single control. In some cases, such as a Button control, the content can be text. However,
many situations call for the ability to lay out multiple controls. This section concentrates
on performing layout in windows, and a Window has a Content property that accepts
only one control; that one control should be a layout control, which is the subject of this
WPF includes several layout controls, including Grid, StackPanel, DockPanel,
WrapPanel, and Canvas. By default, VS will generate a window with a Grid as the layout
control. However, you are free to replace the Grid with any other layout control that suits
your needs. This section will show you how to use each of these controls.
Grid Layout
Whenever starting a new WPF project, VS adds a Grid. A Grid is a layout control that
allows you to create a set of rows and columns that hold other controls. You can add rows
and columns to a Grid through the Visual Designer by clicking in the middle of a window
in design view. Figure 2 shows a column being added to a Grid.
The thin vertical line in the middle of the window is a new border between two columns.
After clicking the window, you'll see two thick borders on the left and top of the window.
While you hover over the top border, VS draws a vertical line that moves left and right as
you run your mouse along the top border. You can do the same with the left border, adding
rows to the Grid. This is a very quick way to add rows and columns to a Grid.
Figure 2 Adding columns and rows to a Grid

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