EventTrigger Class

Definition

Namespace:

Microsoft.Maui.Controls

Assembly:

Microsoft.Maui.Controls.dll

Class that represents a triggering event and a list of TriggerAction objects that will be invoked when the event is raised.

public ref class EventTrigger sealed : Microsoft::Maui::Controls::TriggerBase

[Microsoft.Maui.Controls.ContentProperty("Actions")]
public sealed class EventTrigger : Microsoft.Maui.Controls.TriggerBase

[<Microsoft.Maui.Controls.ContentProperty("Actions")>]
type EventTrigger = class
    inherit TriggerBase

Public NotInheritable Class EventTrigger
Inherits TriggerBase

Inheritance

Object

BindableObject

TriggerBase

EventTrigger

Attributes

ContentPropertyAttribute

Remarks

The example below shows how developers can use an event trigger to respond to events and update the value of a control property.

With the ColorTriggerAction class below defined in the TriggerDemo namespace:

public class ColorTriggerAction : TriggerAction<Entry>
{
  protected override void Invoke(Entry sender)
  {
      Color[] color ={ Color.Red,
                       Color.Orange,
                       Color.Yellow,
                       Color.Green,
                       Color.Blue,
                       Color.Indigo,
                       Color.Violet };
      sender.TextColor = color[sender.Text.Length % color.Length];
  }
}

the developer can use the XAML below to create a page that cycles the colors of a Entry text area through the colors of the rainbow as the user enters text.

<?xml version="1.0" encoding="utf-8"?>
<ContentPage    xmlns="http://xamarin.com/schemas/2014/forms"
              xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
              xmlns:local="clr-namespace:TriggerDemo"
              x:Class="TriggerDemo.TriggerDemoPage">
<StackLayout VerticalOptions="Center">
<Label Text="Do you see colors?"
             VerticalOptions="Center"
             HorizontalOptions="Center" />
<Entry Placeholder="Type stuff here."
             VerticalOptions="Center"
             HorizontalOptions="Center"
             BackgroundColor="Black">
<Entry.Triggers>
<EventTrigger Event="TextChanged" >
<local:ColorTriggerAction />
</EventTrigger>
</Entry.Triggers>
</Entry>
</StackLayout>
</ContentPage>

Constructors

EventTrigger()

Creates a new EventTrigger instance.

Properties

Actions	Gets the list of TriggerAction objects that will be invoked when the event that is identified by the Event property is raised.
BindingContext	Gets or sets an object that contains the properties that will be targeted by the bound properties that belong to this BindableObject. This is a bindable property. (Inherited from BindableObject)
Dispatcher	Gets the dispatcher that was available when this bindable object was created, otherwise tries to find the nearest available dispatcher (probably the window's/app's). (Inherited from BindableObject)
EnterActions	Gets the list of TriggerAction objects that will be invoked when the trigger condition is met. Ignored for the EventTrigger class. (Inherited from TriggerBase)
Event	Gets or sets the name of the event that will cause the actions that are contained in the Actions to be invoked.
ExitActions	Gets the list of TriggerAction objects that will be invoked after the trigger condition is no longer met. Ignored for the EventTrigger class. (Inherited from TriggerBase)
IsSealed	Gets a value that indicates whether or not the trigger is sealed. (Inherited from TriggerBase)
TargetType	The type of object to which this TriggerBase object can be attached. (Inherited from TriggerBase)

Methods

ApplyBindings()	Applies all the current bindings to BindingContext. (Inherited from BindableObject)
ClearValue(BindableProperty)	Clears any value that is previously set for a bindable property. (Inherited from BindableObject)
ClearValue(BindablePropertyKey)	Clears any value that is previously set for a bindable property, identified by its key. (Inherited from BindableObject)
CoerceValue(BindableProperty)	Coerces the value of the specified bindable property. This is done by invoking BindableProperty.CoerceValueDelegate of the specified bindable property. (Inherited from BindableObject)
CoerceValue(BindablePropertyKey)	Coerces the value of the specified bindable property. This is done by invoking BindableProperty.CoerceValueDelegate of the specified bindable property. (Inherited from BindableObject)
GetValue(BindableProperty)	Returns the value that is contained in the given bindable property. (Inherited from BindableObject)
IsSet(BindableProperty)	Determines whether or not a bindable property exists and has a value set. (Inherited from BindableObject)
OnBindingContextChanged()	Raises the BindingContextChanged event. (Inherited from BindableObject)
OnPropertyChanged(String)	Raises the PropertyChanged event. (Inherited from BindableObject)
OnPropertyChanging(String)	Raises the PropertyChanging event. (Inherited from BindableObject)
RemoveBinding(BindableProperty)	Removes a previously set binding from a bindable property. (Inherited from BindableObject)
SetBinding(BindableProperty, BindingBase)	Assigns a binding to a bindable property. (Inherited from BindableObject)
SetValue(BindableProperty, Object)	Sets the value of the specified bindable property. (Inherited from BindableObject)
SetValue(BindablePropertyKey, Object)	Sets the value of the specified bindable property. (Inherited from BindableObject)
SetValueCore(BindableProperty, Object, SetValueFlags)	For internal use by the Microsoft.Maui.Controls platform. (Inherited from BindableObject)
UnapplyBindings()	Removes all current bindings from the current context. (Inherited from BindableObject)

Events

BindingContextChanged	Occurs when the value of the BindingContext property changes. (Inherited from BindableObject)
PropertyChanged	Occurs when a property value changes. (Inherited from BindableObject)
PropertyChanging	Occurs when a property value is changing. (Inherited from BindableObject)

Explicit Interface Implementations

IDynamicResourceHandler.SetDynamicResource(BindableProperty, String)

(Inherited from BindableObject)

Extension Methods

GetPropertyIfSet<T>(BindableObject, BindableProperty, T)
SetAppTheme<T>(BindableObject, BindableProperty, T, T)
SetAppThemeColor(BindableObject, BindableProperty, Color, Color)
SetBinding(BindableObject, BindableProperty, String, BindingMode, IValueConverter, String)	Creates and applies a binding to a property.

See also

• Setter
• PropertyCondition
• DataTrigger
• Trigger