I recently had the chance to read WPF Unleashed by Adam Nathan.

I can’t imagine a better book to learn WPF for developers with a good win32/GDI/Windows Forms background. If you are not already experienced in these fields, then you’ll certainly find this book overwhelming.

What I really enjoyed is that the author has a mature vision about WPF although we are still in the early days of this platform. What I mean by mature vision is that the book is full of non trivial tips and also contains a lot of advanced remarks that shed lights on implementation details.

WPF is still young from MS clients point of view, but for MSFT insiders, WPF is 6 or 7 years old (or even older?! btw I would like to know the history of the WPF development). I remember Don Box introducing XAML 4 years ago during the PDC 2003 KeyNote. Adam is a senior software development engineer in Microsoft’s .NET Developer Division since 1999, hence the unique vision provided in the book.

The author did also a great job at underlining the intentions behind each part of WPF. As a former technical author, I consider that explaining the intentions surrounding a technical subject as the most important part of writing. Technology is all about intentions! You won’t do anything good with an API as long as you don’t understand the intentions that motivated the engineers who developed it. In my opinion, MSDN often lacks intentions and it is its biggest flaw (although this point got a bit better in the last years).

Another good point is that the book comes with an excellent 50 pages introduction about WPF 3D done by Daniel Lehenbauer, the Lead Developer Responsible for WPF 3D. Here also, you can feel that each remark and each tip provided will be a great help once you’ll have to use WPF 3D in the real-world.

Finally, WPF Unleashed layout is colorful. It certainly makes the reading more pleasant. This particular details generated many talks.

WPF Unleashed is a great book, but WPF is a fantastic technology. I’m really looking forward using it in my own developments. Here are some rambling about some cool details that positively surprised me as a win32/GDI/Windows Forms developer:

• Most of WPF code will be XAML declarative code and not C# or VB.NET procedural code. XAML is a general-purpose declarative language based on XML. Although it is heavily used by WPF, some others framework such as Windows Workflow Fundation use XAML and you can easily use it to handle your own scenarios. XAML code doesn’t compile to IL or C# or VB.NET code but to a binary form (the BAML format). BAML has the double advantage over XML that it yields lighter documents and that BAML documents can be parsed more quickly. Concretely, most of XAML code will be automatically generated by tools. There is no doubt that this XML format will be easier to parse than the messy Windows Forms generated code. Hence, I expect that XAML editors such as the upcoming Microsoft Expression Blend will be much more reliable than the Windows Forms ones.

• Windows Forms heavily relies on the notion of .NET properties. The engineers of WPF thought that .NET properties were not enough to handle common WPF scenarios and they introduced Dependency Properties. The value of a Dependency Property depends on one or several providers for determining its value at any point of time. For example, the notion of WPF animation continuously modifies the value of a Dependency property to move or rotate an UI object. Dependency Property is the corner-stone to provide declaratively (in XAML) your own logic on value change notifications. Dependency Property is also great to handle inheritance scenario such as: the font of a panel have been changed, which control child’ font should be updated?

• WPF comes with an entire new API to draw things on the screen. The main difference with the GDI API is that WPF is a completely retained mode graphics system rather than an immediate mode graphics system as GDI. Basically, in immediate mode it is your responsibility to draw the correct pixels when a region of the screen is invalidated (hence the famous WM_PAINT and OnPaint). In retained mode you just have to describe higher-level concepts such as “place a 10x10 blue square at (0,0)”. Clearly retained mode is a simpler way to code complex UI scenarios and it also represents the magic that makes WPF a 100% vector based framework.

• WPF relies heavily on the logical tree vs. visual trees paradigms. Logical tree is the well know controls tree (a Panel contains 2 GroupBoxes that each contains two Buttons and a Textbox…). Developers will be mainly concerned by the logical tree. The visual tree is the visual representation of things that will be displayed on screen by the retained mode graphics engine. Although a ListBox is logically a single control its default visual tree representation is composed of more primitive WPF elements such as a Border, one or two scrollbars… In WPF the visual tree is decoupled from the logical tree. Thus it is easy to do crazy things such as displaying items of your ListBox on the faces of a rotating 3D polygon.

As Adam pinpoints in his introduction, WPF is the definitive technology to allow doing UI that looks like what you see in the Hollywood movies, such as slick 3D animations when you print a document or when you send a mail. 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.