MSDN Magazine - September 2008 - (Page 87)

A d vA n c e d W P F Understanding Routed Events And Commands In WPF Brian noyes One of the most daunting things about getting up to event handler for the Click event will be added to the codebehind speed on Windows® Presentation Foundation (WPF) is that there are so many new constructs to master. Even simple things like Microsoft® .NET Framework properties and events have new counterparts in WPF with added capabilities and associated complexity—specifically dependency properties and routed events. Then there is all the brand new stuff, such as animations, styling, control templates, and routed commands. There is a lot to learn. In this article I am going to focus on two very important items in the list of new WPF elements to master. These items—routed events and routed commands—are related to each other. They form the basis for communication among the various parts of your user interface—whether those parts are individual controls on one big Window class or whether they are controls and their supporting code in separate, decoupled parts of your user interface. For this article I am assuming you are already familiar with the fundamentals of WPF, such as how to construct a UI using built-in WPF controls and declaring the layout of your UI in XAML. of your Window class. This should feel no different than hooking up events in Windows Forms and ASP.NET. It is actually a little closer to the coding model for ASP.NET but more like the runtime model of Windows Forms. Specifically, in your XAML markup for the button, you end up with code like this: Click Me The XAML declaration for hooking up an event looks just like a property assignment in XAML but results in a normal event hookup on the object that specified the event handler. This hookup actually happens in a compile-time-generated partial class for your window. To see this, go to the constructor for your class, right-click This article discusses: • event routing and visual trees • command routing • Avoiding command focus problems • Going beyond routed commands Routed Events Overview When you are first getting started with WPF, you will likely use routed events without even knowing you are using them. For example, if you add a button to your window in the Visual Studio® designer and name it myButton and then double-click on it, the Click event will get hooked up in your XAML markup and an Technologies discussed: WPF code download available at: msdn.microsoft.com/magazine/cc135911 September 2008 87 http://msdn.microsoft.com/magazine/cc135911

Table of Contents Feed for the Digital Edition of MSDN Magazine - September 2008

MSDN Magazine - September 2008 Contents Toolbox CLR Inside Out Data Points Advanced Basics Office Space Cutting Edge Hierarchy ID New Features for Microsoft SQL Server 2008 Prism Data Services Advanced WPF Test Run Security Briefs Foundations { End Bracket }

MSDN Magazine - September 2008

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