Package org.vaadin.miki.superfields.lazyload

Class ComponentObserver

java.lang.Object
com.vaadin.flow.component.Component
org.vaadin.miki.superfields.lazyload.ComponentObserver
All Implemented Interfaces:
com.vaadin.flow.component.AttachNotifier, com.vaadin.flow.component.DetachNotifier, com.vaadin.flow.component.HasElement, com.vaadin.flow.component.HasStyle, Serializable, HasId, WithIdMixin<ComponentObserver>
Direct Known Subclasses:
ObservedField.ObservedFieldElement
@JsModule("./component-observer.js") @Tag("component-observer") public class ComponentObserver extends com.vaadin.flow.component.Component implements WithIdMixin<ComponentObserver>
A component that wraps Intersection Observer on the client-side to notify server-side about visibility changes. Note: Intersection Observer API is experimental and not all browsers implement it.
Since:
2020-04-28
Author:
miki
See Also:

  • Constructor Summary

    Constructors
    Constructor
    Description
    ComponentObserver(double... visibilityRanges)
    Creates the observer using entire document as viewport.
    ComponentObserver(com.vaadin.flow.component.Component viewportRoot, String rootMargin, double... visibilityRanges)
    Creates the observer using provided document as viewport root and provided root margins.

  • Method Summary

    Modifier and Type
    Method
    Description
    com.vaadin.flow.shared.Registration
    addComponentObservationListener(ComponentObservationListener listener)
    Adds a listener that will be informed about changes in observed components.
    protected void
    fireComponentObservationEvent(ComponentObservationEvent event)
    Broadcasts the event using Component.getEventBus().
    double[]
    getVisibilityRanges()
    Returns an array with visibility ranges registered for this component.
    protected void
    initClient()
     
    boolean
    isObserving(com.vaadin.flow.component.Component component)
    Checks whether or not given Component is being observed by this object.
    void
    observe(com.vaadin.flow.component.Component... components)
    Starts observation of given components.
    protected void
    observe(String indexString, com.vaadin.flow.component.Component component)
    Observes the given component with given index.
    protected void
    onAttach(com.vaadin.flow.component.AttachEvent attachEvent)
     
    protected void
    onDetach(com.vaadin.flow.component.DetachEvent detachEvent)
     
    void
    unobserve(com.vaadin.flow.component.Component... components)
    Stops observation of given components.

    Methods inherited from class com.vaadin.flow.component.Component

    addListener, findAncestor, fireEvent, from, get, getChildren, getElement, getEventBus, getId, getListeners, getLocale, getParent, getTranslation, getTranslation, getTranslation, getTranslation, getTranslation, getTranslation, getUI, hasListener, isAttached, isTemplateMapped, isVisible, onEnabledStateChanged, removeFromParent, scrollIntoView, scrollIntoView, set, setElement, setId, setVisible

    Methods inherited from class java.lang.Object

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

    Methods inherited from interface com.vaadin.flow.component.AttachNotifier

    addAttachListener

    Methods inherited from interface com.vaadin.flow.component.DetachNotifier

    addDetachListener

    Methods inherited from interface org.vaadin.miki.markers.HasId

    getId, setId

    Methods inherited from interface com.vaadin.flow.component.HasStyle

    addClassName, addClassNames, getClassName, getClassNames, getStyle, hasClassName, removeClassName, removeClassNames, setClassName, setClassName

    Methods inherited from interface org.vaadin.miki.markers.WithIdMixin

    withId

  • Constructor Details

    • ComponentObserver

      public ComponentObserver(double... visibilityRanges)
      Creates the observer using entire document as viewport.
      Parameters:
      visibilityRanges - Ranges at which to trigger visibility change events. If not specified, [0.0, 1.0] will be used.

    • ComponentObserver

      public ComponentObserver(com.vaadin.flow.component.Component viewportRoot, String rootMargin, double... visibilityRanges)
      Creates the observer using provided document as viewport root and provided root margins.
      Parameters:
      viewportRoot - Component to use as viewport root.
      rootMargin - Root margin (CSS-like expression).
      visibilityRanges - Ranges at which to trigger visibility change events. If not specified, [0.0, 1.0] will be used.

  • Method Details

    • initClient

      protected void initClient()

    • onDetach

      protected void onDetach(com.vaadin.flow.component.DetachEvent detachEvent)
      Overrides:
      onDetach in class com.vaadin.flow.component.Component

    • onAttach

      protected void onAttach(com.vaadin.flow.component.AttachEvent attachEvent)
      Overrides:
      onAttach in class com.vaadin.flow.component.Component

    • fireComponentObservationEvent

      protected void fireComponentObservationEvent(ComponentObservationEvent event)
      Broadcasts the event using Component.getEventBus().
      Parameters:
      event - Event with relevant information about what happened.

    • observe

      protected void observe(String indexString, com.vaadin.flow.component.Component component)
      Observes the given component with given index. Will override the component currently associated with given index, if the was any.
      Parameters:
      indexString - Index string to register the component with.
      component - Component to observe.

    • observe

      public void observe(com.vaadin.flow.component.Component... components)
      Starts observation of given components. If a given component is already being observed, it will not be observed an additional time. Given component will stop being observed when it gets detached or when unobserve(Component...) method is called.
      Parameters:
      components - Components to observe.

    • unobserve

      public void unobserve(com.vaadin.flow.component.Component... components)
      Stops observation of given components. If a given component has not been registered with observe(Component...), nothing will happen.
      Parameters:
      components - Components to stop observing.

    • addComponentObservationListener

      public com.vaadin.flow.shared.Registration addComponentObservationListener(ComponentObservationListener listener)
      Adds a listener that will be informed about changes in observed components.
      Parameters:
      listener - Listener to add.
      Returns:
      Registration that can be used to stop listening.

    • isObserving

      public boolean isObserving(com.vaadin.flow.component.Component component)
      Checks whether or not given Component is being observed by this object.
      Parameters:
      component - A Component.
      Returns:
      true when the component has been added through observe(Component...) and not removed with unobserve(Component...).

    • getVisibilityRanges

      public double[] getVisibilityRanges()
      Returns an array with visibility ranges registered for this component. Modifying the resulting array has no effect on this object.
      Returns:
      A non-empty array with visibility ranges.