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Why WPF, and What About Silverlight?

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Adam Nathan explains how WPF 4 and Windows 7 are bringing multi-touch to the masses.
This chapter is from the book

This chapter is from the book

In This Chapter

  • A Look at the Past
  • Enter WPF
  • The Evolution of WPF
  • What About Silverlight?

In movies and on TV, the main characters are typically an exaggeration of the people you encounter in real life. They’re more attractive, they react more quickly, and they somehow always know exactly what to do. The same could be said about the software they use.

This first struck me back in 1994 when watching the movie Disclosure, starring Michael Douglas, Demi Moore, and an email program that looks nothing like Microsoft Outlook! Throughout the movie, we’re treated to various visual features of the program: a spinning three-dimensional “e,” messages that unfold when you open them and crumple when you delete them, hints of inking support, and slick animations when you print messages. (The email program isn’t even the most unrealistic software in the movie. I’ll just say “virtual reality database” and leave it at that.)

Usability issues aside, Hollywood has been telling us for a long time that software in the real world isn’t as compelling as it should be. You can probably think of several examples on your own of TV shows and movies with comically unrealistic software. But lately, real-world software has been catching up to Hollywood’s standards! You can already see it in traditional operating systems (yes, even in Windows), on the web, and in software for devices such as the iPhone, iPad, Zune, TiVo, Wii, Xbox, Windows phones, and many more. Users have increasing expectations for the experience of using software, and companies are spending a great deal of time and money on user interfaces that differentiate themselves from the competition. This isn’t limited to consumer-facing software; even business applications and internal tools can greatly benefit from a polished user interface.

With higher demands placed on user interfaces, traditional software development processes and technologies often fall short. Modern software usually needs to support rapid iteration and major user interface changes throughout the process—whether such changes are driven by professional graphic designers, developers with a knack for designing user interfaces, or a boss who wants the product to be more “shiny” and animated. For this to be successful, you need technology and tools that make it natural to separate the user interface from the rest of the implementation as much as possible and to decouple visual behavior from the underlying program logic. Developers should be able to create a fully functional “ugly” application that designers can directly retheme without requiring developers to translate their artwork. The Win32 style of programming, in which controls directly contain code to paint and repaint themselves, makes rapid user interface iteration far too difficult for most projects.

In 2006, Microsoft released a technology to help people create 21st-century software that meets these high demands: Windows Presentation Foundation (WPF). With the release of WPF 4 in 2010, the technology is better than ever at delivering amazing results for just about any kind of software. Almost a decade after Tom Cruise helped popularize the idea of multi-touch computer input in the movie Minority Report, and after successful multi-touch implementations in a variety of devices (most notably the iPhone), WPF 4 and Windows 7 are bringing multi-touch to the masses. Hollywood better start coming up with some fresh ideas!

A Look at the Past

The primary technologies behind many Windows-based user interfaces—the graphics device interface (GDI) and USER subsystems—were introduced with Windows 1.0 in 1985. That’s almost prehistoric in the world of technology! In the early 1990s, OpenGL (created by Silicon Graphics) became a popular graphics library for doing advanced two-dimensional (2D) and three-dimensional (3D) graphics on both Windows and non-Windows systems. This was leveraged by people creating computer-aided design (CAD) programs, scientific visualization programs, and games. DirectX, a Microsoft technology introduced in 1995, provided a new high-performance alternative for 2D graphics, input, communication, sound, and eventually 3D (introduced with DirectX 2 in 1996).

Over the years, many enhancements have been made to both GDI and DirectX. GDI+, introduced in the Windows XP time frame, tried to improve upon GDI by adding support for features such as alpha blending and gradient brushes. It ended up being slower than GDI due to its complexity and lack of hardware acceleration. DirectX (which, by the way, is the technology behind Xbox) continually comes out with new versions that push the limits of what can be done with computer graphics. With the introduction of .NET and managed code in 2002, developers were treated to a highly productive model for creating Windows (and web) applications. In this world, Windows Forms (built on top of GDI+) became the primary way a C#, Visual Basic, and (to a lesser degree) C++ developer started to create new user interfaces on Windows. Windows Forms has been a successful and productive technology, but it still has all the fundamental limitations of GDI+ and USER.

Starting with DirectX 9, Microsoft shipped a DirectX framework for managed code (much like it shipped libraries specifically for Visual Basic in the past), which eventually was supplanted by the XNA Framework. Although this enables C# developers to use DirectX without most of the complications of .NET/COM interoperability, these managed frameworks aren’t significantly easier to use than their unmanaged counterparts unless you’re writing a game. (The XNA Framework makes writing a game easier because it includes new libraries specifically for game development and works with compelling tools such as the XNA Framework Content Pipeline and XNA Game Studio Express.)

So although you could have developed a Windows-based email program with the 3D effects seen in Disclosure ever since the mid-1990s with non-GDI technologies (actually, probably mixing DirectX or OpenGL with GDI), such technologies are rarely used in mainstream Windows applications even more than a decade later. There are several reasons for this: The hardware required to get a decent experience hasn’t been ubiquitous until recently, it has been at least an order of magnitude harder to use alternative technologies, and GDI-based experiences have been considered “good enough.”

Graphics hardware continues to get better and cheaper and consumer expectations continue to rise, but until WPF, the difficulty of creating modern user experiences had not been addressed. Some developers would take matters into their own hands to get cooler-looking applications and controls on Windows. A simple example of this is using bitmaps for buttons instead of using the standard button control. These types of customizations can not only be expensive to develop, but they also often produce a flakier experience. Such applications often aren’t as accessible as they should be, don’t handle high dots-per-inch (DPI) settings very well, and have other visual glitches.

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