Package ej.mwt.event

Class PointerEventDispatcher

  • public class PointerEventDispatcher
extends EventDispatcher
    Dispatches the pointer events received on a desktop to its children.

    Pointer events are grouped in sessions. A session starts when the pointer is pressed, and ends when the pointer is released.

    Each event of the session is sent to the leaf widget that was under the pointer during the press event (see Desktop.getWidgetAt(int, int)), then sent to all its parent hierarchy. Events are sent only to enabled widgets (see Widget.isEnabled()).

    Once a widget has consumed an event, it will be the only one to receive the next events during the session. All the other widgets (ancestors or offsprings) receive an EXITED event.

    When the pointer exits the bounds of a widget in the hierarchy, this widget receives an EXITED event and won't receive any event from the session except if it has consumed an event.

    • Constructor Detail

      • PointerEventDispatcher

        public PointerEventDispatcher​(Desktop desktop)
        Creates a desktop event dispatcher.
        Parameters:
        desktop - the desktop to dispatch in.

    • Method Detail

      • initialize

        public void initialize()
        Description copied from class: EventDispatcher
        Initializes this event dispatcher.

        For example, this method can be used to create an event generator.

        Overrides:
        initialize in class EventDispatcher

      • getPressedHierarchyLeaf

        @Nullable
public Widget getPressedHierarchyLeaf()
        Returns the leaf widget of the hierarchy which is subscribed to the ongoing pointer session.

        When a pointer session is started, all the enabled widgets under the pointer become subscribed to this session.

        The reference to this widget is initialized when the pointer is pressed ; it is updated when the pointer is dragged outside of the bounds of the widget or when a pointer event is consumed ; and it is reset when the pointer is released or when the pointer is dragged outside of the bounds of each subscribed widgets.

        Returns:
        the leaf widget of the subscribed hierarchy, or null if there is none.

      • getConsumerWidget

        @Nullable
public Widget getConsumerWidget()
        Returns the widget which has consumed the ongoing pointer session.

        When a pointer event is been consumed during a pointer session, it becomes the only widget to be subscribed to this session.

        The reference to this widget is initialized when a pointer event is consumed ; and it is reset when the pointer is released or when the pointer is dragged outside of the bounds of the widget.

        Returns:
        the consumer widget, or null if there is none.

      • getEventGenerator

        @Nullable
protected DesktopEventGenerator getEventGenerator()
        Gets the event generator of this dispatcher.
        Returns:
        the event generator of this dispatcher.

      • dispatchEvent

        public boolean dispatchEvent​(int event)
        Description copied from class: EventDispatcher
        Dispatches an event.
        Specified by:
        dispatchEvent in class EventDispatcher
        Parameters:
        event - the event to dispatch.
        Returns:
        true if the event dispatcher has dealt with the event, false otherwise.

      • isExited

        public static boolean isExited​(int event)
        Returns whether or not the given event is an exited event.
        Parameters:
        event - the event to check.
        Returns:
        true if the given event is an exited event, false otherwise.