Question

I want add handler or listener to button which will respond every time I press key on keyboard even It’s not focus on it. How I can do that ?

Answer 1

import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.Event.NativePreviewEvent;
import com.google.gwt.user.client.Event.NativePreviewHandler;

Event.addNativePreviewHandler(new NativePreviewHandler() {

   @Override
   public void onPreviewNativeEvent(NativePreviewEvent event) {
      if (event.getNativeEvent().getKeyCode() == KeyCodes.KEY_DELETE) { //needs an int code
         //fire an event to your button or call your method

         event.getNativeEvent().stopPropagation(); //optional
         event.getNativeEvent().preventDefault(); //optional
      }
   }
});

I was using a code like this in my onModuleLoad() method to catch the a keypress event and hide it from the browser. You can also use the

import com.google.gwt.user.client.Element;

Element as = (Element) Element.as(event.getNativeEvent().getEventTarget());
as.getTagName();

to check where it is coming from (for example tag name is “input”, “textarea”), and do your event handling based on that.