Re: [Gwt-openlayers-devl] [Gwt-openlayers-users] Wrapping OpenLayers.Util.X ?

[Edwin C. <com...@gm...>]

Hi Andrew,

The Util class does indeed contain some handy functions that would be
nice to wrap. The Util class should never be instantiated and should
only have static methods in my opinion so both a Util and UtilImpl are
not strictly necessary, but having both may give more flexibility and
clarity than only a Util with static JSNI methods in it.

If we mirror OL then Util is in the
org.gwtopenmaps.client.openlayers.* namespace and not in
org.gwtopenmaps.client.openlayers.util.*

Example of usage:

Util.extend(x:JSObjectWrapper, y:JSObjectWrapper)

in Util:

public static JSObjectWrapper extend(JSObjectWrapper destination,
JSObjectWrapper source){
  JSObject obj = UtilImpl.extend(destination.getJSObject(),
source.getJSObject());
  return destination.setJSObject(obj);
}

In UtilImpl

public static JSObject extend(JSObject destination, JSObject source)/*-{
  return $wnd.OpenLayers.Util.extend(destination, source);
}-*/;

The example you give is immediately an example for which plain JSNI
seems the most appropriate, because you need to create a function that
can be pretty broad. You could off course do sth similar as in
setFormatOutput of MousePositionOptions, but plain JSNI is more
straightfoward:

public static void onImageLoadErrorDisplayNone()/*-{
   $wnd.Openlayers.Util.onImageLoadError = function()
{this.style.display ="none";}
}-*/;

Such a function could off course be added as a convenience to GWT-OL
on the Util object.

Greetings,
Edwin

On 17 February 2010 07:18, Andrew Hughes <ahh...@gm...> wrote:
> Hi Guys,
> There is a (handy) OpenLayer's class that doesn't appear to be wrapped
> 'OpenLayers/Util.js': http://trac.openlayers.org/browser/tags/openlayers/release-2.8/lib/OpenLayers/Util.js
> I'd like to wrapping this with: org.gwtopenmaps.openlayers.client.Util.java
> and org.gwtopenmaps.openlayers.client.UtilImp.java
> There's a slight naming overlap with
> the org.gwtopenmaps.openlayers.client.util package. But is a minor issue.
> Anyone like to chip in on this one? Trac ticket e.t.c. I need this so I can
> fix those annoying pink tiles for missing map images.
> Like this.. OpenLayers.Util.onImageLoadError = function() {
> this.style.display="none";}
> This appears to be a singleton (same for us) and I'm not sure if this should
> 'extends OpenLayersObjectWrapper'. Some advice would be great.
> Cheers :)
> --AH
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