Routed events allow events to invoke handlers on multiple listeners in an element tree. Routed events are backed by the RoutedEvent class and processed by the WPF event system. Events can route from element to root (bubbling), only at the source element (direct), or from root to element (tunneling). Attached events allow handlers to be attached to child elements. Event triggers and setters in styles allow sharing handlers across multiple elements. Commands specify actions and use a command source to invoke a command target through a command binding. Custom commands implement the ICommand interface. Triggers in styles, templates, and templates apply setters or animations when property values or events change.

2.  User actions
 moves the mouse, clicks a button, presses a key,
or draws with a pen,…
 WPF provides
 events, commands, and triggers

4.  Functional definition: A routed event is a type
of event that can invoke handlers on multiple
listeners in an element tree, rather than just
on the object that raised the event.
 Implementation definition: A routed event is a
CLR event that is backed by an instance of
the RoutedEvent class and is processed by
theWPF event system.

5.  The event route for this Click event is:
Button-->StackPanel-->Border-->...

6.  Control composition and encapsulation
 Singular handler attachment points
 Attach handler one time for multiple elements
 Class handling
 Permit a static handler that is defined by the class
 Referencing an event without reflection
 Event identification that does not require static or
run-time reflection

7.  Bubbling: routes from element to root
 Direct: only source element invoke handlers
 Tunneling: routes from root to element

8.  Attached event allows you to attach an event
handler to some child element rather than to
the parent that actually defines the event
 Attached event enable elements to handle
events that are declared in a different
element
 Attached events are routed events that
support a hookup in XAML on elements other
than the type on which the event is declared

9.  Event Button.Click is attached for Grid element

10. Routed Events

11.  EventSetters
 Represented by the <EventSetter> tag that pre-
declared in Styles
 Sharing handler for multiple elements by Styles
 EventTriggers
 Represented by the <EventTrigger> tag that pre-
declared in Styles
 Specify an event and activate when that event is
raised
 Have an Actions collection

15.  Commands specify what can application do?
 Command is an action the application
performs at the user’s request
 Single handler for a command can enables for
multiple elements
 Command allows multiple and disparate
sources to invoke the same command logic
 Command example:
 Copy: Ctrl+C, EditCopy, Copy Button,...

16.  The command is the action to be executed.
 The command source is the object which
invokes the command.
 The command target is the object that the
command is being executed on.
 The command binding is the object which
maps the command logic to the command.

17.  A command object identifies a particular
command (such as copy or paste)
 Commands are created by implementing the
ICommand interface

18. Class Command types
ApplicationCommands Commands common to almost all applications. Includes
clipboard commands, undo and
redo, and document-level operations (open, close, print,
etc.).
ComponentCommands Operations for moving through information, such as scroll
up and down, move to end, and
text selection.
EditingCommands Text editing commands such as bold, italic, center, and
justify.
MediaCommands Media-playing operations such as transport (play, pause,
etc.), volume control, and track
selection.
NavigationCommands Browser-like navigation commands such as Back, Forward,
and Refresh.

19.  A command source is the object which
invokes the command (such as MenuItem,
Button,…)
 Command sources generally implement the
ICommandSource interface

20.  A CommandBinding associates a command
with the event handlers that implement the
command
<Window.CommandBindings>
<CommandBinding Command="ApplicationCommands.Open"
Executed="OpenCmdExecuted"
CanExecute="OpenCmdCanExecute"/>
</Window.CommandBindings>

21.  The command target is the element on which
the command is executed
 The command source can explicitly set the
command target
 If the command target is not defined, the
element with keyboard focus will be used as
the command target
 invoke a command on multiple targets without
having to keep track of the command target

23.  Implement the ICommand interface
 Create a RoutedCommand
 Create a RoutedUICommand.

24. Custom RoutedCommand

26.  Style, ControlTemplate, and DataTemplate
all have a Triggers property that can contain a
set of triggers.
 A trigger sets properties or starts actions
such as animation when a property value
changes or when an event is raised

27.  Used to apply setter elements to control by
conditions of dependency properties
<StyleTargetType="{x:Type Button}">
<Setter Property="Button.Background"Value="AliceBlue" />
<Style.Triggers>
<Trigger Property="IsMouseOver"Value="True">
<Setter Property="Button.Opacity"Value="1"></Setter>
<Setter Property="Button.Background"Value="Green"></Setter>
</Trigger>
</Style.Triggers>
</Style>

28. MultipleTriggers
Multiconditions

29.  Used to apply setter elements to control by
conditions of CLR properties (data binding)
 Also have multiple and multicondition
<StyleTargetType="{x:Type ListBoxItem}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=Role}"Value="Admin">
<Setter Property="Foreground"Value="Red" />
</DataTrigger>
</Style.Triggers>
</Style>

30.  Used to raising an animation to control by
watch for events
<EventTrigger RoutedEvent="UIElement.MouseEnter" SourceName="MyText">
<BeginStoryboard>
<Storyboard>
<BooleanAnimationUsingKeyFrames
Storyboard.TargetName="Popup"
Storyboard.TargetProperty="(Popup.IsOpen)">
<DiscreteBooleanKeyFrame KeyTime="00:00:00"Value="True"/>
</BooleanAnimationUsingKeyFrames>
</Storyboard>
</BeginStoryboard>
</EventTrigger>

31. Triggers