TriggerBase TriggerBase TriggerBase TriggerBase Class

Definition

Represents the base class for specifying a conditional value within a Style object.

public ref class TriggerBase abstract : System::Windows::DependencyObject
[System.Windows.Localizability(System.Windows.LocalizationCategory.None, Readability=System.Windows.Readability.Unreadable)]
public abstract class TriggerBase : System.Windows.DependencyObject
type TriggerBase = class
    inherit DependencyObject
Public MustInherit Class TriggerBase
Inherits DependencyObject
Inheritance
Derived
Attributes

Examples

There are several different types of triggers: Trigger, MultiTrigger, EventTrigger, DataTrigger, and MultiDataTrigger.

The Trigger class is the simplest type of triggers. A Trigger object allows you to apply changes based on the value of a property. For example, the following example shows a named Style available to Button controls. The Style defines a Trigger element that changes the Foreground property of a button when the IsPressed property is true.

<Style x:Key="Triggers" TargetType="Button">
    <Style.Triggers>
    <Trigger Property="IsPressed" Value="true">
        <Setter Property = "Foreground" Value="Green"/>
    </Trigger>
    </Style.Triggers>
</Style>

If you need to apply changes based on the state of multiple properties, you can use the MultiTrigger. For an example, see the MultiTrigger page.

The EventTrigger class allows you to apply changes when an event occurs. The following example contains two EventTrigger objects, one of which occurs when the mouse enters the element and the other occurs when the mouse leaves the element.

<Style TargetType="Rectangle">
  <Setter Property="Width" Value="50" />
  <Setter Property="Height" Value="50" />
  <Setter Property="Margin" Value="20" />
  <Setter Property="HorizontalAlignment" Value="Left" />
  <Style.Triggers>
    <EventTrigger RoutedEvent="MouseEnter">
        <BeginStoryboard>
            <Storyboard>
              <DoubleAnimation To="300" Duration="0:0:1.5" 
                AccelerationRatio="0.10" DecelerationRatio="0.25" 
                Storyboard.TargetProperty="(Canvas.Width)" />
            </Storyboard>
        </BeginStoryboard>
    </EventTrigger>
    <EventTrigger RoutedEvent="MouseLeave">
        <BeginStoryboard>
            <Storyboard>
              <DoubleAnimation Duration="0:0:1.5" 
                AccelerationRatio="0.10" DecelerationRatio="0.25" 
                Storyboard.TargetProperty="(Canvas.Width)" />
            </Storyboard>
        </BeginStoryboard>
    </EventTrigger>
  </Style.Triggers>
</Style>

These are also the DataTrigger and the MultiDataTrigger classes. These are similar to Trigger and MultiTrigger except that they are for data-bound properties.

Remarks

The WPF styling and templating model allows you to specify triggers within your Style, ControlTemplate, and DataTemplate. Essentially, TriggerBase is the base class for objects that allow you to apply changes when certain conditions (such as when a certain property value becomes true, or when an event occurs) are satisfied.

Properties

DependencyObjectType DependencyObjectType DependencyObjectType DependencyObjectType

Gets the DependencyObjectType that wraps the CLR type of this instance.

(Inherited from DependencyObject)
Dispatcher Dispatcher Dispatcher Dispatcher

Gets the Dispatcher this DispatcherObject is associated with.

(Inherited from DispatcherObject)
EnterActions EnterActions EnterActions EnterActions

Gets a collection of TriggerAction objects to apply when the trigger object becomes active. This property does not apply to the EventTrigger class.

ExitActions ExitActions ExitActions ExitActions

Gets a collection of TriggerAction objects to apply when the trigger object becomes inactive. This property does not apply to the EventTrigger class.

IsSealed IsSealed IsSealed IsSealed

Gets a value that indicates whether this instance is currently sealed (read-only).

(Inherited from DependencyObject)

Methods

CheckAccess() CheckAccess() CheckAccess() CheckAccess()

Determines whether the calling thread has access to this DispatcherObject.

(Inherited from DispatcherObject)
ClearValue(DependencyProperty) ClearValue(DependencyProperty) ClearValue(DependencyProperty) ClearValue(DependencyProperty)

Clears the local value of a property. The property to be cleared is specified by a DependencyProperty identifier.

(Inherited from DependencyObject)
ClearValue(DependencyPropertyKey) ClearValue(DependencyPropertyKey) ClearValue(DependencyPropertyKey) ClearValue(DependencyPropertyKey)

Clears the local value of a read-only property. The property to be cleared is specified by a DependencyPropertyKey.

(Inherited from DependencyObject)
CoerceValue(DependencyProperty) CoerceValue(DependencyProperty) CoerceValue(DependencyProperty) CoerceValue(DependencyProperty)

Coerces the value of the specified dependency property. This is accomplished by invoking any CoerceValueCallback function specified in property metadata for the dependency property as it exists on the calling DependencyObject.

(Inherited from DependencyObject)
Equals(Object) Equals(Object) Equals(Object) Equals(Object)

Determines whether a provided DependencyObject is equivalent to the current DependencyObject.

(Inherited from DependencyObject)
GetHashCode() GetHashCode() GetHashCode() GetHashCode()

Gets a hash code for this DependencyObject.

(Inherited from DependencyObject)
GetLocalValueEnumerator() GetLocalValueEnumerator() GetLocalValueEnumerator() GetLocalValueEnumerator()

Creates a specialized enumerator for determining which dependency properties have locally set values on this DependencyObject.

(Inherited from DependencyObject)
GetType() GetType() GetType() GetType()

Gets the Type of the current instance.

(Inherited from Object)
GetValue(DependencyProperty) GetValue(DependencyProperty) GetValue(DependencyProperty) GetValue(DependencyProperty)

Returns the current effective value of a dependency property on this instance of a DependencyObject.

(Inherited from DependencyObject)
InvalidateProperty(DependencyProperty) InvalidateProperty(DependencyProperty) InvalidateProperty(DependencyProperty) InvalidateProperty(DependencyProperty)

Re-evaluates the effective value for the specified dependency property

(Inherited from DependencyObject)
MemberwiseClone() MemberwiseClone() MemberwiseClone() MemberwiseClone()

Creates a shallow copy of the current Object.

(Inherited from Object)
OnPropertyChanged(DependencyPropertyChangedEventArgs) OnPropertyChanged(DependencyPropertyChangedEventArgs) OnPropertyChanged(DependencyPropertyChangedEventArgs) OnPropertyChanged(DependencyPropertyChangedEventArgs)

Invoked whenever the effective value of any dependency property on this DependencyObject has been updated. The specific dependency property that changed is reported in the event data.

(Inherited from DependencyObject)
ReadLocalValue(DependencyProperty) ReadLocalValue(DependencyProperty) ReadLocalValue(DependencyProperty) ReadLocalValue(DependencyProperty)

Returns the local value of a dependency property, if it exists.

(Inherited from DependencyObject)
SetCurrentValue(DependencyProperty, Object) SetCurrentValue(DependencyProperty, Object) SetCurrentValue(DependencyProperty, Object) SetCurrentValue(DependencyProperty, Object)

Sets the value of a dependency property without changing its value source.

(Inherited from DependencyObject)
SetValue(DependencyProperty, Object) SetValue(DependencyProperty, Object) SetValue(DependencyProperty, Object) SetValue(DependencyProperty, Object)

Sets the local value of a dependency property, specified by its dependency property identifier.

(Inherited from DependencyObject)
SetValue(DependencyPropertyKey, Object) SetValue(DependencyPropertyKey, Object) SetValue(DependencyPropertyKey, Object) SetValue(DependencyPropertyKey, Object)

Sets the local value of a read-only dependency property, specified by the DependencyPropertyKey identifier of the dependency property.

(Inherited from DependencyObject)
ShouldSerializeProperty(DependencyProperty) ShouldSerializeProperty(DependencyProperty) ShouldSerializeProperty(DependencyProperty) ShouldSerializeProperty(DependencyProperty)

Returns a value that indicates whether serialization processes should serialize the value for the provided dependency property.

(Inherited from DependencyObject)
ToString() ToString() ToString() ToString()

Returns a string that represents the current object.

(Inherited from Object)
VerifyAccess() VerifyAccess() VerifyAccess() VerifyAccess()

Enforces that the calling thread has access to this DispatcherObject.

(Inherited from DispatcherObject)

Applies to

See Also