Table of Contents

Class StyledElement

Namespace
Avalonia
Assembly
Avalonia.Base.dll

Extends an Animatable with the following features:

  • An inherited DataContext.
  • Implements IStyleable to allow styling to work on the styled element.
  • Implements ILogical to form part of a logical tree.
  • A collection of class strings for custom styling.
public class StyledElement : Animatable, INotifyPropertyChanged, IDataContextProvider, ILogical, IThemeVariantHost, IResourceHost, IResourceNode, IStyleHost, ISetLogicalParent, ISetInheritanceParent, ISupportInitialize, IStyleable, INamed
Inheritance
StyledElement
Implements
Derived
Inherited Members
Extension Methods

Constructors

StyledElement()

Initializes a new instance of the StyledElement class.

public StyledElement()

Fields

DataContextProperty

Defines the DataContext property.

public static readonly StyledProperty<object?> DataContextProperty

Field Value

StyledProperty<object>

NameProperty

Defines the Name property.

public static readonly DirectProperty<StyledElement, string?> NameProperty

Field Value

DirectProperty<StyledElement, string>

ParentProperty

Defines the Parent property.

public static readonly DirectProperty<StyledElement, StyledElement?> ParentProperty

Field Value

DirectProperty<StyledElement, StyledElement>

TemplatedParentProperty

Defines the TemplatedParent property.

public static readonly DirectProperty<StyledElement, AvaloniaObject?> TemplatedParentProperty

Field Value

DirectProperty<StyledElement, AvaloniaObject>

ThemeProperty

Defines the Theme property.

public static readonly StyledProperty<ControlTheme?> ThemeProperty

Field Value

StyledProperty<ControlTheme>

Properties

ActualThemeVariant

Gets the UI theme that is currently used by the element, which might be different than the RequestedThemeVariantProperty.

public ThemeVariant ActualThemeVariant { get; }

Property Value

ThemeVariant

If current control is contained in the ThemeVariantScope, TopLevel or Application with non-default RequestedThemeVariant, that value will be returned. Otherwise, current OS theme variant is returned.

Classes

Gets or sets the styled element's classes.

public Classes Classes { get; }

Property Value

Classes

Remarks

Classes can be used to apply user-defined styling to styled elements, or to allow styled elements that share a common purpose to be easily selected.

DataContext

Gets or sets the control's data context.

public object? DataContext { get; set; }

Property Value

object

Remarks

The data context is an inherited property that specifies the default object that will be used for data binding.

IsInitialized

Gets a value that indicates whether the element has finished initialization.

public bool IsInitialized { get; }

Property Value

bool

Remarks

For more information about when IsInitialized is set, see the Initialized event.

LogicalChildren

Gets the styled element's logical children.

protected IAvaloniaList<ILogical> LogicalChildren { get; }

Property Value

IAvaloniaList<ILogical>

Name

Gets or sets the name of the styled element.

public string? Name { get; set; }

Property Value

string

Remarks

An element's name is used to uniquely identify an element within the element's name scope. Once the element is added to a logical tree, its name cannot be changed.

Parent

Gets the styled element's logical parent.

public StyledElement? Parent { get; }

Property Value

StyledElement

PseudoClasses

Gets the Classes collection in a form that allows adding and removing pseudoclasses.

protected IPseudoClasses PseudoClasses { get; }

Property Value

IPseudoClasses

Resources

Gets or sets the styled element's resource dictionary.

public IResourceDictionary Resources { get; set; }

Property Value

IResourceDictionary

StyleKey

Gets the type by which the element is styled.

public Type StyleKey { get; }

Property Value

Type

Remarks

Usually controls are styled by their own type, but there are instances where you want an element to be styled by its base type, e.g. creating SpecialButton that derives from Button and adds extra functionality but is still styled as a regular Button. To change the style for a control class, override the StyleKeyOverride property

StyleKeyOverride

Gets the type by which the element is styled.

protected virtual Type StyleKeyOverride { get; }

Property Value

Type

Remarks

Usually controls are styled by their own type, but there are instances where you want an element to be styled by its base type, e.g. creating SpecialButton that derives from Button and adds extra functionality but is still styled as a regular Button. Override this property to change the style for a control class, returning the type that you wish the elements to be styled as.

Styles

Gets the styles for the styled element.

public Styles Styles { get; }

Property Value

Styles

Remarks

Styles for the entire application are added to the Application.Styles collection, but each styled element may in addition define its own styles which are applied to the styled element itself and its children.

TemplatedParent

Gets the styled element whose lookless template this styled element is part of.

public AvaloniaObject? TemplatedParent { get; }

Property Value

AvaloniaObject

Theme

Gets or sets the theme to be applied to the element.

public ControlTheme? Theme { get; set; }

Property Value

ControlTheme

Methods

ApplyStyling()

Applies styling to the control if the control is initialized and styling is not already applied.

public bool ApplyStyling()

Returns

bool

A value indicating whether styling is now applied to the control.

Remarks

The styling system will automatically apply styling when required, so it should not usually be necessary to call this method manually.

BeginInit() 

public virtual void BeginInit()

EndInit() 

public virtual void EndInit()

InitializeIfNeeded() 

protected void InitializeIfNeeded()

LogicalChildrenCollectionChanged(object?, NotifyCollectionChangedEventArgs) 

protected virtual void LogicalChildrenCollectionChanged(object? sender, NotifyCollectionChangedEventArgs e)

Parameters

sender object
e NotifyCollectionChangedEventArgs

OnAttachedToLogicalTree(LogicalTreeAttachmentEventArgs)

Called when the styled element is added to a rooted logical tree.

protected virtual void OnAttachedToLogicalTree(LogicalTreeAttachmentEventArgs e)

Parameters

e LogicalTreeAttachmentEventArgs

The event args.

OnDataContextBeginUpdate()

Called when the DataContext begins updating.

protected virtual void OnDataContextBeginUpdate()

OnDataContextChanged(EventArgs)

Called when the DataContext property changes.

protected virtual void OnDataContextChanged(EventArgs e)

Parameters

e EventArgs

The event args.

OnDataContextEndUpdate()

Called when the DataContext finishes updating.

protected virtual void OnDataContextEndUpdate()

OnDetachedFromLogicalTree(LogicalTreeAttachmentEventArgs)

Called when the styled element is removed from a rooted logical tree.

protected virtual void OnDetachedFromLogicalTree(LogicalTreeAttachmentEventArgs e)

Parameters

e LogicalTreeAttachmentEventArgs

The event args.

OnInitialized()

Called when the control finishes initialization.

protected virtual void OnInitialized()

OnPropertyChanged(AvaloniaPropertyChangedEventArgs)

Called when a avalonia property changes on the object.

protected override void OnPropertyChanged(AvaloniaPropertyChangedEventArgs change)

Parameters

change AvaloniaPropertyChangedEventArgs

The property change details.

TryGetResource(object, ThemeVariant?, out object?)

Tries to find a resource within the object.

public bool TryGetResource(object key, ThemeVariant? theme, out object? value)

Parameters

key object

The resource key.

theme ThemeVariant

Theme used to select theme dictionary.

value object

When this method returns, contains the value associated with the specified key, if the key is found; otherwise, null.

Returns

bool

True if the resource if found, otherwise false.

Events

ActualThemeVariantChanged

Raised when the theme variant is changed on the element or an ancestor of the element.

public event EventHandler? ActualThemeVariantChanged

Event Type

EventHandler

AttachedToLogicalTree

Raised when the styled element is attached to a rooted logical tree.

public event EventHandler<LogicalTreeAttachmentEventArgs>? AttachedToLogicalTree

Event Type

EventHandler<LogicalTreeAttachmentEventArgs>

DataContextChanged

Occurs when the DataContext property changes.

public event EventHandler? DataContextChanged

Event Type

EventHandler

Remarks

This event will be raised when the DataContext property has changed and all subscribers to that change have been notified.

DetachedFromLogicalTree

Raised when the styled element is detached from a rooted logical tree.

public event EventHandler<LogicalTreeAttachmentEventArgs>? DetachedFromLogicalTree

Event Type

EventHandler<LogicalTreeAttachmentEventArgs>

Initialized

Occurs when the styled element has finished initialization.

public event EventHandler? Initialized

Event Type

EventHandler

Remarks

The Initialized event indicates that all property values on the styled element have been set. When loading the styled element from markup, it occurs when EndInit() is called and the styled element is attached to a rooted logical tree. When the styled element is created by code and ISupportInitialize is not used, it is called when the styled element is attached to the visual tree.

ResourcesChanged

Occurs when a resource in this styled element or a parent styled element has changed.

public event EventHandler<ResourcesChangedEventArgs>? ResourcesChanged

Event Type

EventHandler<ResourcesChangedEventArgs>