Learn to Behave Extend Your XAML with Behaviors

Transcription

1 Learn to Behave Extend Your XAML with Behaviors Brian Noyes Chief Architect, IDesign Inc. Level: Intermediate About Brian Chief Architect IDesign Inc. ( Microsoft Regional Director ( Microsoft MVP Silverlight Publishing Developers Guide to Microsoft Prism 4, O Reilly & Assoc., March 2011 Developing Applications with Windows Workflow Foundation, LiveLessons training DVD, June 2007 Smart Client Deployment with ClickOnce, Addison Wesley, January 2007 Data Binding in Windows Forms 2.0, Addison Wesley, January 2006 The Silverlight Show, MSDN Magazine, MSDN Online, CoDe Magazine brian.noyes@idesign.net Blog: Speaking VSLive!, DevConnections, Microsoft TechEd,, DevTeach, INETA User Groups 1

2 Agenda Dependency Properties Defining Attached Behaviors Using Blend Behaviors Defining Blend Behaviors Other Behavior Sources Dependency Objects DependencyObject base class One up from Object in the inheritance hierarchy Provides support for DependencyProperties GetValue SetValue 2

3 Dependency Properties Add semantics to basic.net properties Numerous uses Attached Properties Default values Styles Animations Value provider hierarchy Support: Change Notifications Dependency Property Syntax Static member variable of type DependencyProperty Wrapper property Wrapper property just calls base class GetValue/SetValue methods Not called during XAML parsing Convenience for type safe access to property from code 3

4 Dependency Property Metadata Default value Shared across all instances Saves memory Property changed handler Set co-dependent properties Validation Side effects / behaviors Dependency Property Metadata 4

5 Attached Properties Special kind of Dependency Property Can be set on any DependencyObject derived element Set as if they were qualified properties on the object itself Advanced WPF/Silverlight techniques based on attached properties The Attached Property Trick Grab the reference to the object on which the property is set, use its API to cause something to happen, now or in the future Attached Property Syntax Declaration: Usage: 5

6 Behaviors Based on the attached property trick Define attached property Hook property change notification Grab reference to the object on which the property was set Subscribe to object events Dispatch event notification into handling classes ViewModel, Controller, etc. Use commands as means of dispatch Blend SDK Reusable components introduced by Blend Free download, free distribution and use Key libraries Microsoft.Expression.Interaction System.Windows.Interactivity 6

7 Using Blend Behaviors FluidMoveBehavior ChangePropertyAction ControlStoryboardAction DataStateBehavior InvokeCommandAction CallMethodAction Defining Blend Behaviors Extension of the concept of attached behaviors Requires the Blend SDK Behavior / Behavior<T> class Attached to target element through attached property collections in the SDK Interaction.Behaviors Interaction.Triggers Can expose multiple settable properties on the class to modify the behavior Better encapsulation than attached properties as behaviors More Blendable Drag and drop onto element in Blend, set properties in the designer 7

8 Blend Actions and Triggers Actions Behaviors that do something CallMethod, ChangeProperty, ControlStoryBoard, etc Triggers The things that let you invoke an action or behavior DataTrigger, PropertyChangedTrigger, TimerTrigger, EventTrigger Can write custom triggers and actions Other Behaviors Microsoft Expression Gallery ].Type=RootCategory&f[0].Value=behaviors Prism prism.codeplex.com 8

9 What About WinRT/Metro Apps? Good news: Attached behaviors work exactly as covered Bad News: No plans for Blend Behaviors in v1 OK news: You could write your own base class infrastructure Or find someone else who has Won t get the designer experience of using them in Blend though Summary Behaviors are to XAML as extension methods are to C# classes Behaviors are the ultimate compensation tool for lack of features in XAML If I could just do X in XAML. think custom behavior brian.noyes@idesign.net Blog: 9