[Gwt-openlayers-devl] About changes to JSObject, Options and ElementHelper

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

Hi all,

I have made some changes to core utility classes in GWT-OL that may be
perceived as invasive and I changed XxxParams in the layer subpackage to
XxxOptions. To my mind this will make GWT-OL more powerful and more
consistent. First a list of changes  and below some explanation:

JSObject - added getters/setters for properties
JSObjectHelper - implements getters/setters for JSObject
ElementHelper - stripped of methods that do stuff on JSObject instead of
Elements (a child of JSObject)
Options - reduced to a JSObjectWrapper, wrapping an empty javascript object
OptionsImp, OptionsBase, OptionsBaseImpl - deleted as they are no longer
relevant
XxxParams (in Layer package) - renamed to XxxOptions

For refactoring code based on GWT-OL before these changes mean:

-change imports of XxxParams to XxxOptions (the objects did not change
otherwise)
-any code that uses setAttribute methods exposed by Options should change to
setAttribute(...) to getJSObject().setProperty(...)

Please let me know if other code broke for you. This could be if anyone was
using methods in ElementHelper that were not used in the API at all (mainly
for doing stuff with Arrays, for which JSObjectArray and children seem more
appropriate).

The methods for working with JSObject were previously in ElementHelper and
to my mind they did not belong there. An Element is a very specific kind of
Javascript object that represents a DOM element. There is a lot of
functionality for working with the DOM in GWT, especially if we upgrade to
GWT 1.5. In GWT 1.4 there's already com.google.gwt.user.client.DOM,
com.google.gwt.user.client.Element and in GWT 1.5 almost all the functions
that can be called on Element in javascript can be called on it directly
from GWT (if not all).

Somehow, GWT 1.5 added all kinds of methods for direct manipulation of
Element objects, but not for direct manipulation of JavaScriptObject
objects. This is why JSObject now has methods to do this. The benefit is
that all objects in GWT-OL are, or should be JSObjectWrapper objects and
therefore have a public getJSObject method, to get at the underlying
javascript object. This way the GWT-OL API can stay clean, but it is still
possible to get at the bare javascript objects if users want to do this and
get and set properties on the underlying javascript objects. This is
desirable given the nature of GWT wrapper libraries.

The rationale for renaming XxxParams to XxxOptions is to make clear that
they are Options objects (Params is not object in GWT-OL), and to be more
consistent with terminology used in OpenLayers documentation, see this link:

http://docs.openlayers.org/library/syntax.html

Greetings,
Edwin