DataTrigger DataTrigger Class

Definition

Class that represents a condition on an arbitrary binding, along with a list of Setter objects that will be applied when the condition is met.

[Xamarin.Forms.ContentProperty("Setters")]
[Xamarin.Forms.Xaml.AcceptEmptyServiceProvider]
public sealed class DataTrigger : Xamarin.Forms.TriggerBase, Xamarin.Forms.Xaml.IValueProvider
type DataTrigger = class
    inherit TriggerBase
    interface IValueProvider
Inheritance
Attributes
Implements

Remarks

The DataTrigger class is suitable for checking values on other controls, as well as any property on the control to which it has been added. That is, its default binding context is the control to which it has been added.

The XML example below prompts the user to type in the secret, which is, "The text color is green". When the user has typed "The", the Entry text changes color to red. When the user completes the secret, the Label text turns green. The code is turned back to the default color if the user then edits the secret. This example shows how to bind to the enclosing control (Entry from Entry), and to an arbitary control (Entry from Label)


              <?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="Can you tell me the secret?" VerticalOptions="Center" HorizontalOptions="Center">
                          <Label.Triggers>
                              <DataTrigger TargetType="Label"
                                  Binding="{Binding Source={x:Reference checkEntry},
                                                    Path=Text}"
                                  Value="The text color is green">
                                  <Setter Property="TextColor" Value="Color.Green" />
                              </DataTrigger>
                          </Label.Triggers>
                      </Label>
                      <Entry Placeholder="Type the secret here." x:Name="checkEntry" VerticalOptions="Center" HorizontalOptions="Center">
                          <Entry.Triggers>
                              <DataTrigger TargetType="Entry"
                                  Binding="{Binding Text}"
                                  Value="The">
                                  <Setter Property="TextColor" Value="Red" />
                              </DataTrigger>
                          </Entry.Triggers>
                      </Entry>
                  </StackLayout>
              </ContentPage>

Constructors

DataTrigger(Type) DataTrigger(Type)

Initializes a new DataTrigger instance.

Properties

Binding Binding

Gets or sets the binding whose value will be compared to Value to determine when to invoke the setters.

BindingContext BindingContext

Gets or sets object that contains the properties that will be targeted by the bound properties that belong to this BindableObject.

(Inherited from BindableObject)
EnterActions EnterActions

Gets the list of Xamarin.Forms.TirggerAction objects that will be invoked when the trigger condition is met. Ignored for the EventTrigger class.

(Inherited from TriggerBase)
ExitActions ExitActions

Gets the list of Xamarin.Forms.TirggerAction objects that will be invoked after the trigger condition is no longer met. Ignored for the EventTrigger class.

(Inherited from TriggerBase)
IsSealed IsSealed

Gets a value that indicates whether or not the trigger is sealed.

(Inherited from TriggerBase)
Setters Setters

Gets the list of Setter objects that will be applied when the binding that is named by the Binding property becomes equal to Value.

TargetType TargetType

The type of object to which this TriggerBase object can be attached.

(Inherited from TriggerBase)
Value Value

Gets or sets the value of the binding, named by the Binding property, that will cause the setters to be applied.

Explicit Interface Implementations

IAttachedObject.AttachTo(BindableObject) IAttachedObject.AttachTo(BindableObject)

For internal use by the Xamarin.Forms platform.

(Inherited from TriggerBase)
IAttachedObject.DetachFrom(BindableObject) IAttachedObject.DetachFrom(BindableObject)

For internal use by the Xamarin.Forms platform.

(Inherited from TriggerBase)
IDynamicResourceHandler.SetDynamicResource(BindableProperty, String) IDynamicResourceHandler.SetDynamicResource(BindableProperty, String)

For internal use by the Xamarin.Forms platform.

(Inherited from BindableObject)
IValueProvider.ProvideValue(IServiceProvider) IValueProvider.ProvideValue(IServiceProvider)

For internal use by the XAML infrastructure.

Methods

ApplyBindings() ApplyBindings()

Apply the bindings to BindingContext.

(Inherited from BindableObject)
ClearValue(BindableProperty) ClearValue(BindableProperty)

Clears any value set by Xamarin.Forms.BindableObject.SetValue for property.

(Inherited from BindableObject)
ClearValue(BindablePropertyKey) ClearValue(BindablePropertyKey)

Clears any value set by Xamarin.Forms.BindableObject.SetValue for the property that is identified by propertyKey.

(Inherited from BindableObject)
GetValue(BindableProperty) GetValue(BindableProperty)

Returns the value that is contained the BindableProperty.

(Inherited from BindableObject)
GetValues(BindableProperty, BindableProperty) GetValues(BindableProperty, BindableProperty)

For internal use by the Xamarin.Forms platform.

(Inherited from BindableObject)
GetValues(BindableProperty, BindableProperty, BindableProperty) GetValues(BindableProperty, BindableProperty, BindableProperty)

For internal use by the Xamarin.Forms platform.

(Inherited from BindableObject)
IsSet(BindableProperty) IsSet(BindableProperty)

Returns true if the target property exists and has been set.

(Inherited from BindableObject)
OnBindingContextChanged() OnBindingContextChanged()

Override this method to execute an action when the BindingContext changes.

(Inherited from BindableObject)
OnPropertyChanged(String) OnPropertyChanged(String)

Call this method from a child class to notify that a change happened on a property.

(Inherited from BindableObject)
OnPropertyChanging(String) OnPropertyChanging(String)

Call this method from a child class to notify that a change is going to happen on a property.

(Inherited from BindableObject)
RemoveBinding(BindableProperty) RemoveBinding(BindableProperty)

Removes a previously set binding.

(Inherited from BindableObject)
SetBinding(BindableProperty, BindingBase) SetBinding(BindableProperty, BindingBase)

Assigns a binding to a property.

(Inherited from BindableObject)
SetValue(BindableProperty, Object) SetValue(BindableProperty, Object)

Sets the value of the specified property.

(Inherited from BindableObject)
SetValue(BindablePropertyKey, Object) SetValue(BindablePropertyKey, Object)

Sets the value of the propertyKey.

(Inherited from BindableObject)
SetValueCore(BindableProperty, Object, SetValueFlags) SetValueCore(BindableProperty, Object, SetValueFlags)

For internal use by the Xamarin.Forms platform.

(Inherited from BindableObject)
UnapplyBindings() UnapplyBindings()

Unapplies all previously set bindings.

(Inherited from BindableObject)

Events

BindingContextChanged BindingContextChanged

Raised whenever the BindingContext property changes.

(Inherited from BindableObject)
PropertyChanged PropertyChanged

Raised when a property has changed.

(Inherited from BindableObject)
PropertyChanging PropertyChanging

Raised when a property is about to change.

(Inherited from BindableObject)

Extension Methods

SetBinding(BindableObject, BindableProperty, String, BindingMode, IValueConverter, String) SetBinding(BindableObject, BindableProperty, String, BindingMode, IValueConverter, String)

Creates and applies a binding to a property.

SetBinding<TSource>(BindableObject, BindableProperty, Expression<Func<TSource,Object>>, BindingMode, IValueConverter, String) SetBinding<TSource>(BindableObject, BindableProperty, Expression<Func<TSource,Object>>, BindingMode, IValueConverter, String)

Creates and applies a binding from an expression.

GetGroup<TView,TItem>(TItem) GetGroup<TView,TItem>(TItem)

For internal use by platform renderers.

GetGroupHeaderContent<TView,TItem>(TItem) GetGroupHeaderContent<TView,TItem>(TItem)

For internal use by platform renderers.

GetIndex<TView,TItem>(TItem) GetIndex<TView,TItem>(TItem)

For internal use by platform renderers.

GetIsGroupHeader<TView,TItem>(TItem) GetIsGroupHeader<TView,TItem>(TItem)

For internal use by platform renderers.

SetIsGroupHeader<TView,TItem>(TItem, Boolean) SetIsGroupHeader<TView,TItem>(TItem, Boolean)

For internal use by platform renderers.

LoadFromXaml<TXaml>(TXaml, String) LoadFromXaml<TXaml>(TXaml, String)

Returns an initialized view by loading the specified xaml.

LoadFromXaml<TXaml>(TXaml, Type) LoadFromXaml<TXaml>(TXaml, Type)

Returns a TXaml with the properties that are defined in the application manifest for callingType.

Applies to