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This chapter is from the book

This chapter is from the book

The Evolution of WPF

Oddly enough, WPF 4 is the fourth major release of WPF. It’s odd because the first release had the version number 3.0! The first release in November 2006 was called WPF 3.0 because it shipped as part of the .NET Framework 3.0. The second release—WPF 3.5—came almost exactly a year later (one day shy, in fact). The third release, once again, came almost a year later (in August 2008). This release was a part of Service Pack 1 (SP1) for .NET 3.5, but this was no ordinary service pack as far as WPF was concerned—it contained many new features and improvements.

In addition to these major releases, Microsoft introduced a “WPF Toolkit” in August 2008 at http://wpf.codeplex.com that, along with miscellaneous tools and samples, gets updated several times a year. The WPF Toolkit has been used as a way to ship features more quickly and in an experimental form (often with full source code). Features introduced in the WPF Toolkit often “graduate” to get included in a future release of WPF, based on customer feedback about their desirability and readiness.

When the first version of WPF was released, tool support was almost nonexistent. The following months brought primitive WPF extensions for Visual Studio 2005 and the first public preview release of Expression Blend. Now, Visual Studio 2010 not only has first-class support for WPF development but has been substantially rewritten to be a WPF application itself! Expression Blend, an application built 100% with WPF, has also gained a lot of functionality for designing and prototyping great user interfaces. And in the past several years, numerous WPF-based applications have been released from companies such as Autodesk, SAP, Disney, Blockbuster, Roxio, AMD, Hewlett Packard, Lenovo, and many more. Microsoft itself, of course, has a long list of software built with WPF (Visual Studio, Expression, Test and Lab Manager, Deep Zoom Composer, Songsmith, Surface, Semblio, Robotics Studio, LifeCam, Amalga, Games for Windows LIVE Marketplace, Office Communicator Attendant, Active Directory Administrative Center, Dynamics NAV, Pivot, PowerShell ISE, and many more).

Let’s take a closer look at how WPF has changed over time.

Enhancements in WPF 3.5 and WPF 3.5 SP1

The following notable changes were made to WPF in versions 3.5 and 3.5 SP1:

  • Interactive 3D—The worlds of 2D and 3D were woven together even more seamlessly with the UIElement3D base class, which gives 3D elements input, focus, and events; the odd-sounding Viewport2DVisual3D class, which can place any interactive 2D controls inside a 3D scene; and more. See Chapter 16, “3D Graphics.”

  • First-class interoperability with DirectX—Previously, WPF applications could only interoperate with DirectX via the lowest common denominator of Win32. Now, WPF has functionality for interacting directly with Direct3D surfaces with the D3DImage class rather than being forced to interact with its host HWND. One benefit from this is the ability to place WPF content on top of DirectX content and vice versa. See Chapter 19.

  • Better data binding—WPF gained support for XLINQ binding, better validation and debugging, and output string formatting in XAML that reduces the need for custom procedural code. See Chapter 13, “Data Binding.”

  • Better special effects—The first version of WPF shipped with a handful of bitmap effects (blur, drop shadow, outer glow, emboss, and bevel) but with a warning to not use them because their performance was so poor! This has changed, with a new set of hardware-accelerated effects and a whole new architecture that allows you to plug in your own custom hardware-accelerated effects via pixel shaders. See Chapter 15, “2D Graphics.”

  • High-performance custom drawing—WPF didn’t previously have a good answer for custom drawings that involve thousands of points or shapes, as even the lowest-level drawing primitives have too much overhead to make such things perform well. The WriteableBitmap class was enhanced so you can now specify dirty regions when drawing on it rather than getting a whole new bitmap every frame! Because WriteableBitmap only lets you set pixels, it is a very primitive form of “drawing,” however.

  • Text improvements—There’s now better performance, better international support (improved input method editor [IME] support and improved Indic script support), and enhancements to TextBox and RichTextBox. See Chapter 11, “Images, Text, and Other Controls.”

  • Enhancements to partial-trust applications—More functionality became available in the partial-trust sandbox for .NET applications, such as the ability to use Windows Communication Foundation (WCF) for web service calls (via basicHttpBinding) and the ability to read and write HTTP cookies. Also, support for XAML Browser Applications (XBAPs)—the primary mechanism for running partial-trust WPF applications—was extended to the Firefox web browser instead of just Internet Explorer (In WPF, however, the add-on that enables this is no longer installed by default.)

  • Improved deployment for applications and the .NET Framework—This arrived in many forms: a smaller and faster .NET Framework installation process thanks to the beginnings of a .NET Framework “client profile” that excludes server-only .NET pieces such as ASP.NET; a new “bootstrapper” component that handles all .NET Framework dependencies, installations, and upgrades for you as well as enabling setups with custom branding; and a variety of new ClickOnce features.

  • Improved performance—WPF and the underlying common language runtime implemented several changes that significantly boosted the performance of WPF applications without any code changes needed. For example, the load time (especially first-time load) has been dramatically improved, animations (especially slow ones) are much smoother, data binding is faster in a number of scenarios, and layered windows (described in Chapter 8) are now hardware accelerated. Other performance improvements were made that you must opt into due to compatibility constraints, such as improved virtualization and deferred scrolling in items controls, described in Chapter 10, “Items Controls.”

Enhancements in WPF 4

WPF 4 brings the following changes, on top of the changes from previous versions:

  • Multi-touch support—When running on computers that support multi-touch and run Windows 7 or later, WPF elements can get a variety of input events, from low-level data, to easy-to-consume manipulations (such as rotation and scaling), to high-level—including custom—gestures. The built-in WPF controls have also been updated to be multi-touch aware. The WPF team leveraged the work previously done by the Microsoft Surface team (whose software is built on WPF). As a result, multi-touch in WPF 4 is compatible with version 2 of the Surface SDK, which is great news for anyone considering developing for both Windows and Surface. See Chapter 6, “Input Events: Keyboard, Mouse, Stylus, and Multi-Touch.”

  • First-class support for other Windows 7 features—Multi-touch is a cool new feature of Windows 7, but there are plenty of others that don’t require special hardware—so many more users will appreciate their inclusion. WPF provides the best way to integrate with new taskbar features such as Jump Lists and icon overlays, integrate with the latest common dialogs, and more. See Chapter 8.

  • New controls—WPF 4 includes controls such as DataGrid, Calendar, and DatePicker, which originally debuted in the WPF Toolkit. See Chapter 11.

  • Easing animation functions—Eleven new animation classes such as BounceEase, ElasticEase, and SineEase enable sophisticated animations with custom rates of acceleration and deceleration to be performed completely declaratively. These “easing functions” and their infrastructure were first introduced in Silverlight 3 before being adopted by WPF 4.

  • Enhanced styling with Visual State Manager—The Visual State Manager, originally introduced in Silverlight 2, provides a new way to organize visuals and their interactivity into “visual states” and “state transitions.” This feature makes it easier for designers to work with controls in tools such as Expression Blend, but importantly also makes it easier to share templates between WPF and Silverlight.

  • Improved layout on pixel boundaries—WPF straddles the line between being automatically DPI independent (which requires ignoring physical pixel boundaries) and having visual elements that look crisp (which, especially for small elements, requires being aligned on pixel boundaries). From the beginning, WPF has supported a property called SnapsToDevicePixels that forces “pixel snapping” on elements. But using SnapsToDevicePixels can be complex and doesn’t help in some scenarios. Silverlight went back to the drawing board and created a property called UseLayoutRounding that works more naturally. WPF 4 now has this property. Just set it to true on a root element, and the positions of that element plus all of children will be rounded up or down to lie on pixel boundaries. The result is user interfaces that can scale and can easily be crisp!

  • Non-blurry text—WPF’s emphasis on DPI independence and a scalable user interface has been an issue for small text—the kind of text that occurs a lot in traditional user interfaces on 96-DPI screens. This has frustrated numerous users and developers. In fact, I’ve always claimed that I can spot a user interface created with WPF simply by looking at the blurriness of its text. WPF 4 has finally addressed this with an alternative way to render text that can make it look as crisp as GDI-based text yet with almost all the benefits that WPF brings. Visual Studio 2010, for example, uses this rendering mode for its text documents. Because there are some limitations to the new rendering approach, you must opt into it. See Chapter 11.

  • More deployment improvements—The .NET Framework client profile can run side-by-side with the full .NET Framework, and it can be used in just about every scenario relevant for WPF applications. In fact, .NET 4.0 projects in Visual Studio 2010 target the smaller client profile by default.

  • More performance improvements—In order to make vector graphics perform as well as possible, WPF can cache rendered results as bitmaps and reuse them. For advanced scenarios, you can control this behavior with the new CacheMode property. See Chapter 15. The heavy usage of WPF in Visual Studio 2010 drove a lot of miscellaneous performance improvements into WPF 4 across the board, but all WPF applications get to enjoy these improvements.

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