// labs

Recently we've been using some of our own tools in other projects and found some room for improvement on the KML Loader we developed. In particular we wanted a simple class that could handle all the processing from the loader, adding the resulting overlays to the google map. Also we needed it to load in some of the styles, such as colours and line types.

So we've expanded our KmlLoader class and provided a few additional utility classes.
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Lately we have been playing around a fair bit with some google flash maps and have been amazed by the power and simplicity of the API. We used it heavily in the ABC Black Saturday site using custom markers with images and even a scrolling grid.

We were faced with another challenge of being able to mark out areas (districts) within Victoria that represented the most affected regions. These regions were sometimes complex and we needed to be able to update them simply and quickly as the need arose. The regions weren't to be displayed directly but used for two major items. Firstly to focus the map on a particular region, by moving the view to the region contained by these districts, and secondly, to assign events/markers to a district by calculating if they were contained within the bounds of the district lines.

The solution ended up being ridiculously simple. We created a shared map on google maps, with shapes defining the districts. We then could export from this online map to kml by grabbing the view in Google Earth link and changing the output parameter from nl to kml. This gave us the map of the districts in a nice kml format.

Once we had the map in kml we needed to load in the objects and create overlays for google maps. Surprisingly there wasn't a simple "load kml" function in google maps, but there are some nice kml parsing utilities in the google map extras library. So we created a kml loader class that loads the kml file, extracts the objects and creates overlays for placement on a google map. Hopefully it can be helpful to others, check it out from the following:

svn co http://svn.distriqt.com/public/trunk/gmaps


Usage:

Firstly create the loader and start the load of your kml file. You'll need to add a listener to the COMPLETE event to process the code on completion.

import com.distriqt.gmaps.kml.utils.*;
 
var kmlLoader:KmlLoader = new KmlLoader();
kmlLoader.addEventListener( Event.COMPLETE, kmlLoader_completeHandler );
kmlLoader.load(  "your-kml-file-location.kml" );

Once the loading is complete you'll have to re-curse through the object list in the loader, adding the objects to your map. Note the "map" variable in the below should be your google map instance.

function kmlLoader_completeHandler( _event:Event ):void
{
	for each (var _object:KmlDisplayObject in KmlLoader(_event.currentTarget).objects)
		addObject( _object );
}
function addObject( _object:KmlDisplayObject ):void
{
	// It may just be a container with child elements
	//    so check if there is an overlay
	if (_object.overlay != null)
	{
		// Here you can add the kml object to your map
		map.addOverlay( _object.overlay );
	}
	// Add the children
	for each (var _child:KmlDisplayObject in _object.children)
		addObject( _child );
}

Let us know if you find it useful.