Overview of WPF

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Overview of WPF

• Ivan Krivyakov
• Senior Managing Consultant
• SunGard Consulting Services
• E-mail
• Ivan.Krivyakov_at_SunGard.com
• ivan_at_ikriv.com
• http//www.ikriv.com/demo/wpf/

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Overview of WPF

• What Is This Presentation About
• WPF for an experienced developer
• What makes WPF different?
• Things to explore
• Definitely not a tutorial

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Overview of WPF

• Why Is WPF Important?
• Its a major technology from a big market player
• It is gaining ground in replacing Windows Forms
• Many clients start including WPF knowledge as a
  requirement for hire
• Officially released in Nov 2006 and still popular
  definitely not a hype bubble

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Overview of WPF

• A Contrived Mixture Formula
• WPF
• XAML
• Data Binding
• Styles

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Overview of WPF

• XAML
• XML-based object definition language
• Defines objects and their properties
• Similar to the language of Spring.Net
• Primarily used to describe UI artifacts
• Can describe almost any .NET type
• Limited support of generics

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Overview of WPF

• XAML
• Describing UI artifacts
• ltDockPanel LastChildFill"True"gt
• ltStackPanel Orientation"Vertical"
  DockPanel.Dock"Top"gt
• ltTextBlock Margin"2"gtCountlt/TextBloc
  kgt
• ltTextBox Margin"5" Text"Binding
  Count" /gt
• ltTextBlock Margin"2"gtResultslt/TextBl
  ockgt
• lt/StackPanelgt
• ltListBox Margin"5" ItemsSource"Binding
  Results" /gt
• lt/DockPanelgt
• Describing custom data classes
• ltmyNumericViewModel Count"5"gt
• ltmyNumericViewModel.Sequencegt
• ltmySquareRoots /gt
• lt/myNumericViewModel.Sequencegt

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Overview of WPF

• XAML
• Many controls accept arbitrary content
• E.g. a button may contain any combination of
  other controls, such as text, images, and even
  text boxes, etc.
• Thus no need for special image button or Image
  property on a button class

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Overview of WPF

• XAML
• ImageButtonDemo sample

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Overview of WPF

• Data Binding
• ltTextBlock TextBinding Names.Count /gt
• ltListBox ItemsSourceBinding Names /gt
• By default binds to the DataContext object of the
  UI element
• Can bind to properties of other UI elements,
  static instances, etc.

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Overview of WPF

• Dependency Properties
• CLR properties get, set
• WPF dependency properties get, set, default
  value, change notification, validation,
  animation, etc.
• Dependency properties are set via reflection-like
  API
• WPF DependencyObject class has a map from
  property descriptors to property values
• Most WPF classes derive (directly or indirectly)
  from DependencyObject

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Overview of WPF

• Dependency Properties
• The Dependency property API is somewhat bulky
• public class MyStateControl ButtonBase
• public MyStateControl() base()
• public Boolean State
• get return (Boolean)this.GetValue(StatePrope
  rty)
• set this.SetValue(StateProperty, value)
• public static readonly DependencyProperty
  StateProperty
• DependencyProperty.Register(
• "State",
• typeof(Boolean),
• typeof(MyStateControl),
• new PropertyMetadata(false))

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Overview of WPF

• Dependency Properties
• GetValue(), SetValue() can accept properties
  owned by other classes. These called attached
  properties
• In XAML attached properties look like so
• ltDockPanelgt
• ltTextBlock DockPanel.DockTop /gt
• lt/DockPanelgt
• Dock property is owned by the DockPanel class,
  but it is set on a TextBlock instance. This is
  somewhat similar to extension methods in C

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Overview of WPF

• Data Change Notification
• Binding mechanism must know when things change
• Dependency properties are set via WPF-controlled
  methods GetValue, SetValue

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Overview of WPF

• Data Change Notification
• For regular properties must implement
• interface INotifyPropertyChanged event
  PropertyChangedclass MyClass
  INotifyPropertyChanged
• string _data
• string Data
• get return _data
• set if (value _data) return
• _data value
• PropertyChanged(Data)

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Overview of WPF

• Data Binding
• Binding source regular property or dependency
  property
• Binding target dependency property
• Animation target dependency property

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Overview of WPF

• Data Binding
• NumericFunctions Sample

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Overview of WPF

• Data Templates
• Data templates replace owner draw items in item
  controls like list boxes
• Rule of thumb avoid assembling text for UI in
  code. Use data templates instead

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Overview of WPF

• Data Templates
• NumericFunctions sample revisited using data
  template

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Overview of WPF

• Styles and Control Templates
• Lookless controls behavior is separated from
  appearance
• Behavior control class, appearance control
  style
• Clock control may have Time property, and can
  track current time
• Styles can define colors, fonts, and even
  completely overhaul the appearance of the control

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Overview of WPF

• Styles and Control Templates
• ClockControl demo

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Overview of WPF

• WPF Binaries
• Main shipped with .NET 3.0 and later
• WPF toolkit additional controls such as data
  grid, date picker control
• Prism composite application guidance for WPF

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Overview of WPF

• Expression Blend
• Writing XAML by hand, especially grid layouts,
  may be overwhelming
• Visual Studio has limited editing capabilities
• Expression Blend is a separate application for
  editing XAML documents
• Pros and Cons

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Overview of WPF

• MVVM vs MVP

Model
View
Presenter
Model
WPF Binding Mechanism
View
ViewModel
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Overview of WPF

• MVVM vs MVP
• MVVM is a WPF version of MVP
• View is pure XAML
• ViewModel has data to display
• ViewModel may be more detailed/redundant than
  business objects
• ViewModel does not have a reference to the view

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Overview of WPF

• MVVM vs MVP
• All communication to the view is done via
  bindings
• Bindings take on most of the work of the
  presenter
• ViewModel is mostly about presentation data. If
  there is no complex business logic, model is not
  necessary

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Overview of WPF

• MVVM and Commands
• Out of the box WPF does not fully support MVVM
• Exchanging data is easy, dealing with commands,
  focus, etc. is more difficult. Not having
  reference to the view causes problems
• Default mechanism of routed commands is not
  compatible with MVVM, since commands are
  delivered to the view

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Overview of WPF

• Summary
• WPF is very flexible, it has almost mathematical
  beauty
• New approach to UI programming binding, attached
  properties, MVVM
• A learning curve
• Fair number of gotchas and bugs
• Performance is a frequent concern
• Demand for WPF is on the rise

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Overview of WPF

• References
• Book Programming WPF by Chris Sells
• WPF toolkit et al. http//wpf.codeplex.com/
• Prism http//compositewpf.codeplex.com/
• MVVM
• http//msdn.microsoft.com/en-us/magazine/dd419663
  .asp