CODEWITHSUNDEEP
javaeventsgwt
Stephen Cagle
Stephen Cagle

Reputation: 14554

Stop a event from bubbling in GWT

I have the following snippet of code, changeTextArea is a TextArea object.

changeTextArea.addKeyboardListener(new KeyboardListenerAdapter()
  public void onKeyPress( Widget sender, char keyCode, int modifier){
    //do something
    //I WISH TO STOP THE EVENT THAT MAPS TO THIS KEYPRESS FROM BUBBLING ANY FURTHER
  }
}

How would I stop the Event that is causing this method to be called from bubbling up from changeTextArea into the Panels/Widgets/Composites/Whatever that contain changeTextArea. Put succinctly, how do I stop it from bubbling any further. Any help would be appreciated (especially code samples).

Upvotes: 5

Views: 11199

Answers (4)

guillermo
guillermo

Reputation: 1

you could reach it when possible by doing event.doit = false

Upvotes: 0

Sean
Sean

Reputation: 21

You can call the sender's cancelKey() event. Here's an example that will only allow numbers to be inputted, all other keys get rejected.

private class RowColChangeHandler implements KeyPressHandler {

    public void onKeyPress(KeyPressEvent event) {
        char keyCode = event.getCharCode();
        if(keyCode <48 || keyCode >57)
        {
            ((TextArea)event.getSource()).cancelKey();
        }
    }
}

Upvotes: 2

jgindin
jgindin

Reputation: 948

You can definitely use the Event's cancelBubble() and preventDefault() methods from within any code that has access to the Event. There's no need to have an event preview...

Upvotes: 4

rustyshelf
rustyshelf

Reputation: 45121

As far as I know you can't do it via a keyboard listener, but it is possible by adding an event preview using the DOM class:

DOM.addEventPreview(EventPreview preview)

Then when you get the event:

onEventPreview(Event event)

You should return false, to say you want to cancel the event. The Event object also supports this method:

public final void cancelBubble(boolean cancel)

Cancels bubbling for the given event. This will stop the event from being propagated to parent elements.

You can find more details here: http://google-web-toolkit.googlecode.com/svn/javadoc/1.5/index.html?overview-summary.html

Upvotes: 6

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