Activity Indicator in GWT MAP

What I would like to have is an activity indicator, which is displa开发者_如何学运维yed after my app is up and running, but while GWT is making AJAX calls.

For example have a look at following site : http://www.foodtrucksmap.com/#

Any ideas on how to achieve it?

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You can use an activity indicator from here, they are animated gifs so you can display one like this:

<g:Image ui:field="activityImage"/>

MyResources resources = GWT.create(MyResources.class);
this.activityImage.setResource(resources.activityImage());

and in your resources interface you would set the image:

public interface MyResources extends ClientBundle{
    // use the actual path to your image
    @Source("../resources/images/activityImage.gif")
    ImageResource activityImage();
}

When you make your async calls:

loadingImage.setVisible(true);

and in the callback:

loadingImage.setVisible(false);

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I had to deal with the same kind of stuff few days back. The way I did was, created an Icon and Overlayed on the map.

Icon icon = Icon.newInstance("loading.gif"); // load you gif as icon
MarkerOptions options = MarkerOptions.newInstance();
options.setIcon(icon);
Marker indicator = new Marker(point, options); 

So before the Async call and after you map is up, just add the icon to the map using

map.addOverlay(indicator);

and after the Async call remove the overlay using

map.removeOverlay(indicator);

I am not sure how correct this approach is, but this is what I did and it worked.