com.codename1.ui.util

Class EventDispatcher

java.lang.Object

com.codename1.ui.util.EventDispatcher

public class EventDispatcher
extends Object

Handles event dispatching while guaranteeing that all events would be fired properly on the EDT regardless of their source. This class handles listener registration/removal in a safe and uniform way.

To integrate this into your code you can use something like:

Constructor Summary

Constructors

Constructor and Description
EventDispatcher()

Method Summary

Modifier and Type	Method and Description
void	addListener(Object listener) Add a listener to the dispatcher that would receive the events when they occurs
void	fireActionEvent(ActionEvent ev) Fires the event safely on the EDT without risk of concurrency errors
void	fireBindTargetChange(Component source, String propertyName, Object oldValue, Object newValue) Fired when a property of the component changes to a new value
void	fireDataChangeEvent(int index, int type) Fires the event safely on the EDT without risk of concurrency errors
void	fireFocus(Component c) Fires the event safely on the EDT without risk of concurrency errors
void	fireScrollEvent(int scrollX, int scrollY, int oldscrollX, int oldscrollY) Fires the event safely on the EDT without risk of concurrency errors
void	fireSelectionEvent(int oldSelection, int newSelection) Fires the event safely on the EDT without risk of concurrency errors
void	fireStyleChangeEvent(String property, Style source) Fires the style change even to the listeners
Collection	getListenerCollection() Returns the collection of the listeners
Vector	getListenerVector() Deprecated. use getListenerCollection instead, this method will now be VERY SLOW
boolean	hasListeners() Returns true if the event dispatcher has registered listeners
boolean	isBlocking() Indicates whether this dispatcher blocks when firing events or not, normally a dispatcher uses callSeriallyAndWait() to be 100% synchronous with event delivery however this method is very slow.
void	removeListener(Object listener) Remove the listener from the dispatcher
void	setBlocking(boolean blocking) Indicates whether this dispatcher blocks when firing events or not, normally a dispatcher uses callSeriallyAndWait() to be 100% synchronous with event delivery however this method is very slow.
static void	setFireStyleEventsOnNonEDT(boolean fire) When set to true, style events will be dispatched even from non-EDT threads.

Methods inherited from class java.lang.Object

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

Constructor Detail

EventDispatcher

public EventDispatcher()

Method Detail

setFireStyleEventsOnNonEDT

public static void setFireStyleEventsOnNonEDT(boolean fire)

When set to true, style events will be dispatched even from non-EDT threads. When set to false, when in non-EDT threads, style events will not be dispatched at all (And developer has to make sure changes will be reflected by calling revalidate after all the changes) Default is false. Setting this to true results in a performance penalty, and it is better instead to simply aggregate events performed on non-EDT threads and when all are over - call revalidate on the relevant container.

Parameters:

fire - true to fire on non-EDT, false otherwise

addListener

public void addListener(Object listener)

Add a listener to the dispatcher that would receive the events when they occurs

Parameters:

listener - a dispatcher listener to add

getListenerVector

public Vector getListenerVector()

Deprecated. use getListenerCollection instead, this method will now be VERY SLOW

Returns the vector of the listeners

Returns:

the vector of listeners attached to the event dispatcher

getListenerCollection

public Collection getListenerCollection()

Returns the collection of the listeners

Returns:

the collection of listeners attached to the event dispatcher

removeListener

public void removeListener(Object listener)

Remove the listener from the dispatcher

Parameters:

listener - a dispatcher listener to remove

fireDataChangeEvent

public void fireDataChangeEvent(int index,
                                int type)

Fires the event safely on the EDT without risk of concurrency errors

Parameters:

index - the index of the event

type - the type of the event

fireBindTargetChange

public void fireBindTargetChange(Component source,
                                 String propertyName,
                                 Object oldValue,
                                 Object newValue)

Fired when a property of the component changes to a new value

Parameters:

source - the source component

propertyName - the name of the property

oldValue - the old value of the property

newValue - the new value for the property

fireStyleChangeEvent

public void fireStyleChangeEvent(String property,
                                 Style source)

Fires the style change even to the listeners

Parameters:

property - the property name for the event

source - the style firing the event

fireActionEvent

public void fireActionEvent(ActionEvent ev)

Fires the event safely on the EDT without risk of concurrency errors

Parameters:

ev - the ActionEvent to fire to the listeners

fireSelectionEvent

public void fireSelectionEvent(int oldSelection,
                               int newSelection)

Fires the event safely on the EDT without risk of concurrency errors

Parameters:

oldSelection - old selection

newSelection - new selection

fireScrollEvent

public void fireScrollEvent(int scrollX,
                            int scrollY,
                            int oldscrollX,
                            int oldscrollY)

Fires the event safely on the EDT without risk of concurrency errors

fireFocus

public void fireFocus(Component c)

Fires the event safely on the EDT without risk of concurrency errors

Parameters:

c - the Component that gets the focus event

hasListeners

public boolean hasListeners()

Returns true if the event dispatcher has registered listeners

Returns:

true if the event dispatcher has registered listeners

isBlocking

public boolean isBlocking()

Indicates whether this dispatcher blocks when firing events or not, normally a dispatcher uses callSeriallyAndWait() to be 100% synchronous with event delivery however this method is very slow. By setting blocking to false the callSerially method is used which allows much faster execution for IO heavy operations.

Returns:

the blocking state

setBlocking

public void setBlocking(boolean blocking)

Indicates whether this dispatcher blocks when firing events or not, normally a dispatcher uses callSeriallyAndWait() to be 100% synchronous with event delivery however this method is very slow. By setting blocking to false the callSerially method is used which allows much faster execution for IO heavy operations.

Parameters:

blocking - the blocking value