[Chameleon] Context file and Tree Legend

[Paul Spencer]

Dave,

as Tom has indicated, probably a great starting point would be the 
XMLThemeLegend widget.  In fact, you may be able to use this widget 
almost as is.  The widget uses two input files called the theme file and 
the renderer file.

The theme file associates layers into groups and then groups into 
themes, and provides styling options for them

The renderer file is used to convert the themes/groups/layers into HTML. 
  The renderer file is simply an HTML file that is included into the 
application at the point of the widget.  There is some processing done 
on the renderer file to replace specific tags with results from the 
current set of layers (as structured by the instructions contained in 
the theme file).

A carefully crafted renderer file could output sufficient javascript to 
initialize a javascript/DHTML based treemenu (for instance).  It is very 
flexible.

You may need to modify the XMLThemeLegend widget because right now it 
doesn't provide details down to the layer level (although you can fake 
it by creating one group per layer).

Importing of context documents is done by mapserver internally, 
chameleon only works with a PHP MapScript map object.  There are a 
couple of ways you could set this up to work from a database.  One would 
be to have a web service that is called that returns the XML content of 
a Context document from a database.  Another would be to write some code 
inside your application to extract the contents of the Context file from 
a database and then write a context file, then open it :)

Cheers,

Paul

Kralidis,Tom [Burlington] wrote:

> Hi,
> 
> You may be able to achieve this through the XML Theme files?  This groups
> layers together in this manner.  We had this requirement in earlier
> projects.
> 
> Recent versions of Chameleon support non-context imports.  However, keep in
> mind by that supporting context documents, you can create and use, share
> context documents from and to any application.
> 
> ..Tom
> 
> =========================
> Tom Kralidis
> Systems Scientist
> Environment Canada
> Tel: +01-905-336-4409
> http://www.ec.gc.ca/cise/
> 
> ========================= 
> 
> 
> -----Original Message-----
> From: Dave Astolfo [mailto:dastolfo1@cogeco.ca] 
> Sent: Tuesday, January 27, 2004 10:40 AM
> To: Chameleon@lists.maptools.org
> Subject: [Chameleon] Context file and Tree Legend
> 
> 
> Hi All, 
> I am somewhat new to Chameleon / MapServer. I have been challenged with
> having to create a new Legend Widget.  Here is what I am trying to do:
> 
> 
> I am  trying to create a legend that uses a tree-like structure (multi
> level).  
> LEGEND 
> Layer List 
> +  Category 1 
> -------Category 1.1 
> -------Category 1.2 
> +  Category 2 
> -------Category 2.1 
> -------Category 2.2 
> ... etc.... 
> 
> 
> The challenge is that the information needed to create the legend would be
> more than the Context file contains.  For example,  in order to know where
> to place a Layer name in the tree,
>  the context file would require additional info such as PARENT_ID.  I was
> able to get this working in the GMAP demo by some JavaScript I found. The
> challenge here is that GMAP was written 
> In PHP and JavaScript while we need to get it working in an environment
> where the Chameleon service is doing most of the legwork.   
> So my questions are: 
> 1)  Is there a way to feed Chameleon the same info that is in the Context
> file from say a XML recordset stream from a database?  If so, can someone
> point me to the code/files where Chameleon opens and reads the context.xml
> file it is passed?
> 2) Does anybody have examples of Legend Widgets that they wrote that may be
> similar to what I am trying to do? 
> 3) Can someone direct me on which way I should go if I have to create my own
> widget? Is there any code I could start with?
> 
> 
> Any help or suggestions is appreciated. 
> Thanks a bunch! 
> Dave A. 
> _______________________________________________
> Chameleon mailing list
> Chameleon@lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/chameleon
> 

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|Paul Spencer                           spencer@dmsolutions.ca    |
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|Applications & Software Development                              |
|DM Solutions Group Inc                 http://www.dmsolutions.ca/|
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