Package com.vaadin.flow.component.internal

Class ComponentSizeObserver

java.lang.Object

com.vaadin.flow.component.internal.ComponentSizeObserver

All Implemented Interfaces:

Serializable

public class ComponentSizeObserver
extends Object
implements Serializable

Per-UI shared ResizeObserver manager that tracks component sizes using a single browser ResizeObserver instance.

One instance is created per UI, lazily via get(UI) when the first component's size is observed. A single browser ResizeObserver is used to track all observed elements, dispatching a custom "vaadin-component-resize" event on the UI element with aggregated size data.

For internal use only. May be renamed or removed in a future release.

See Also:

• Serialized Form

Method Summary

Modifier and Type	Method	Description
static ComponentSizeObserver	get(UI ui)	Returns the ComponentSizeObserver for the given UI, creating it lazily.
void	observe(Element element, ValueSignal<Component.Size> signal)	Starts observing the given element and updates the signal with size changes.
void	unobserve(ValueSignal<Component.Size> signal)	Stops observing the component associated with the given signal.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

get

public static ComponentSizeObserver get(UI ui)

Returns the ComponentSizeObserver for the given UI, creating it lazily.

Parameters:

ui - the UI to get the observer for

Returns:

the observer instance

observe

public void observe(Element element,
 ValueSignal<Component.Size> signal)

Starts observing the given element and updates the signal with size changes.

Parameters:

element - the element to observe

signal - the signal to update

unobserve

public void unobserve(ValueSignal<Component.Size> signal)

Stops observing the component associated with the given signal.

Parameters:

signal - the signal whose component should stop being observed