Apress - Pro WPF With VB 2008 Windows Presentation Foundation With Dot NET 3.5

Introduction

When .NET first appeared, it introduced a small avalanche of new technologies. There was a whole new way to write web applications (ASP.NET), a whole new way to connect to databases (ADO.NET), new typesafe languages (C# and VB .NET), and a managed runtime (the CLR). Not least among these new technologies was Windows Forms, a library of classes for building Windows applications.

Although Windows Forms is a mature and full-featured toolkit, it’s hardwired to essential bits of Windows plumbing that haven’t changed much in the past ten years. Most significantly, Windows Forms relies on the Windows API to create the visual appearance of standard user interface elements such as buttons, text boxes, check boxes, and so on. As a result, these ingredients are essentially uncustomizable.

For example, if you want to create a stylish glow button you need to create a custom control and paint every aspect of the button (in all its different states) using a lower-level drawing model. Even worse, ordinary windows are carved up into distinct regions, with each control getting its own piece of real estate. As a result, there’s no good way for the painting in one control (for example, the glow effect behind a button) to spread into the area owned by another control. And don’t even think about introducing animated effects such as spinning text, shimmering buttons, shrinking windows, or live previews because you’ll have to paint every detail by hand.

The Windows Presentation Foundation (WPF) changes all this by introducing a new model with entirely different plumbing. Although WPF includes the standard controls you’re familiar with, it draws every text, border, and background fill itself. As a result, WPF can provide much more powerful features that let you alter the way any piece of screen content is rendered. Using these features, you can restyle common controls such as buttons, often without writing any code. Similarly, you can use transformation objects to rotate, stretch, scale, and skew anything in your user interface, and you can even use WPF’s baked-in animation system to do it right before the user’s eyes. And because the WPF engine renders the content for a window as part of a single operation, it can handle unlimited layers of overlapping controls, even if these controls are irregularly shaped and partially transparent.