Using group optional attribute to create an hierarchical layer tree

[jgrocha]

Hi devs,

I recovered these two classes that help create a layer tree, from an group attribute. I also add an example of usage, to geoext2/examples/tree/.

The only change in the existing code proposed in the PR is an additional protection (if clause) in src/GeoExt/tree/Util.js, updateLayerVisibilityByNode function, to make sure that we have a layer associated with the node before checking the layer's visibility. I think this test is necessary, since we might have nodes in the tree (not leafs) without a layer.

The two classes proposed in this PR are: GeoExt.tree.LayerTreeBuilder that extends GeoExt.tree.Panel GeoExt.tree.LayerGroupContainer that extends GeoExt.tree.LayerContainer

Comments are welcome.

[marcjansen]

I currently don't have time to look into this, sorry. I hope to find time for this next week. Others are free to revoew of course.

[chrismayer]

Hi @jgrocha, thanks a lot for your contribution! This seems to be a great addition for the tree package of GeoExt.

Besides some minor issues which I addressed directly as line comments (see above) I have some major points which should be done before we can merge this:

• When I run your example the group node 'Utilities' does not have a checkbox but when I check an underlying layer it appears. Can you have a look at that?
• Do you see the chance to add some unit tests?
• Can you please add some more API doc tags on the config properties and functions in your newly created classes, so the API-documentation will be complete?
• The customized layer icons for base layers (see example tree.html) are gone in your example
• To list your example in the API-Docs example section you need to do an entry in https://github.com/geoext/geoext2/blob/master/examples.json

[marcjansen]

Hey @jgrocha do you think you can tackle the comments of @chrismayer?