[Users] layer tree configuration question

[Matt Priour]

I can tell you from a lot of trial & error, that the 'children' property of any gx_layerXXX nodetype are not evaluated. BaselayerContainer, OverlaylayerContainer, ParamLayer all use loaders to populate their child node arrays. The best you can do with either of these 3 node types is to set a 'baseParams' property which will need get applied as part of the node config for each of the child nodes created by the loader.

If you use gx_layer as the nodetype, then the childnodes do get evaluated. However, it also expects to find a layer property on the node and a matching layer in the layer store. If either of these conditions aren't met, errors will occur and your tree won't render or work correctly.

You have a few options:
1. Be highly specific for the layer nodes you want to customize. Use 'async' & 'gx_layer' node types with the specific layer & attributes you wish to represent. You can use a 'gx_layer' node type as a group layer container node, but it must also have a matching layer in the layer store (I've never tried a dummy layer here but it might also work).

2. Use the 'gx_layerparam' or 'gx_overlaylayercontainer' node to create the tree and then modify the node ui after creation. In other words, write a function to find the layer you are interested in, access the associated node, access the node's nodeUI and change properties there (such as the iconCls, etc...)

3. I have created a custom node type (gx_complexlayer) that has similar node construction logic as the 'gx_layer' node type but doesn't expect a layer property and expects it's descendant nodes (at some level) to have a layer property. This was useful to me as it can contain both gx_layer nodes and other loader based nodes as well as using a loader itself if configured to do so. I've made a ticket for this functionality but not submitted a patch yet, because I 'haven't written test or an example for this node type yet and it will fail in some corner cases. I have attached it as a patch here if you want to use it with the understanding that it is certainly incomplete.

Matt Priour
Kestrel Computer Consulting


From: Ralph Dell 
Sent: Friday, March 26, 2010 1:32 PM
To: users at geoext.org 
Subject: [Users] layer tree configuration question


Thanks to the examples and previous forum posts I almost have my layer tree looking exactly as I would like.

 

What I haven't been able to figure out is under  a layer check box, (in this case Schools), I would like to display icons and text that would correspond to  map symbology for different types of features in the given layer.  I do not get anything displayed under the check box and have been unsuccessful  in finding a solution.

 Any pointers or examples on how to accomplish that would be appreciated.

 

I am pulling my layers from a group layer similar to Tasmania ( Group Layer) in the Tree Nodes example.

 

Here is my json:

 

var treeConfig = new OpenLayers.Format.JSON().write([

  {

   nodeType: "gx_baselayercontainer",

  layer: 'Layers',

  isLeaf : false,

 loader: {

       param: "LAYERS"

  }

  },{

  text: 'School Layers',

  expanded: true,

  children: [{

   nodeType: "gx_layerparam",

   layer: 'Schools',

  param: "LAYERS",

  item: "catawba2:schools",

  text: 'Schools',

  expanded: true,

  children: [{                                                        // under the Schools check box I want to display symbols and text that correspond

     text: 'Elementary Schools',                     // to the symbology that I use on the map

    IconCls: 'cc_elem'                                        // nothing displays

    },{                                                                       // how can I add symbols and text here?

    text: 'Middle School Districts3',              // I don't even know if using children: [{}] is the correct approach.

    iconCls: 'cc_middle'

     }]

},{

nodeType: "gx_layerparam",

layer: 'Schools',

param: "LAYERS",

item: "catawba2:elementary_school_districts",

text: 'Elementary School Districts',

iconCls: 'cc_elem_line',

}]

 }], true);

 



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