Transcript Unit Testing in .NET

Overview of WPF
Ivan Krivyakov
Senior Managing Consultant
SunGard Consulting Services
E-mail:
[email protected]
[email protected]
http://www.ikriv.com/demo/wpf/
Overview of WPF
What Is This Presentation About
 WPF for an experienced developer
 What makes WPF different?
 Things to explore
 Definitely not a tutorial
Overview of WPF
Why Is WPF Important?
 It’s 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
Overview of WPF
A Contrived Mixture Formula
WPF =
XAML
+ Data Binding
+ Styles
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
Overview of WPF
XAML
Describing UI artifacts:
<DockPanel LastChildFill="True">
<StackPanel Orientation="Vertical" DockPanel.Dock="Top">
<TextBlock Margin="2">Count:</TextBlock>
<TextBox Margin="5" Text="{Binding Count}" />
<TextBlock Margin="2">Results:</TextBlock>
</StackPanel>
<ListBox Margin="5" ItemsSource="{Binding Results}" />
</DockPanel>
Describing custom data classes:
<my:NumericViewModel Count="5">
<my:NumericViewModel.Sequence>
<my:SquareRoots />
</my:NumericViewModel.Sequence>
</my:NumericViewModel>
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
Overview of WPF
XAML
 ImageButtonDemo sample
Overview of WPF
Data Binding
<TextBlock Text=“{Binding
Names.Count}” />
<ListBox ItemsSource=“{Binding
Names}” />
 By default binds to the DataContext
object of the UI element
 Can bind to properties of other UI
elements, static instances, etc.
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
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(StateProperty); }
set { this.SetValue(StateProperty, value); }
}
public static readonly DependencyProperty StateProperty =
DependencyProperty.Register(
"State",
typeof(Boolean),
typeof(MyStateControl),
new PropertyMetadata(false));
}
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:
<DockPanel>
<TextBlock DockPanel.Dock=“Top” />
</DockPanel>
 “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#
Overview of WPF
Data Change Notification
 Binding mechanism must know
when things change
 Dependency properties are set via
WPF-controlled methods
GetValue, SetValue
Overview of WPF
Data Change Notification
For regular properties must implement
interface INotifyPropertyChanged
{
event … PropertyChanged;
}
class MyClass : INotifyPropertyChanged
{
string _data;
string Data
{
get { return _data; }
set { if (value == _data) return;
_data = value;
PropertyChanged(…”Data”…);
}
}
}
Overview of WPF
Data Binding
 Binding source: regular property or
dependency property
 Binding target: dependency property
 Animation target: dependency property
Overview of WPF
Data Binding
 NumericFunctions Sample
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
Overview of WPF
Data Templates
 NumericFunctions sample revisited
using data template
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
Overview of WPF
Styles and Control Templates
 ClockControl demo
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
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
Overview of WPF
MVVM vs MVP
Model
View
Model
View
WPF
Binding
Mechanism
ViewModel
Presenter
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
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
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
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
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/enus/magazine/dd419663.asp