There is great article describing how to create KML files using PHP4 and PHP5.

One thing to note (that I have read in other place):

When a call is made from the client (Google Earth) to the server, the server must (1) return a response code of HTTP 200 and (2) set the response’s content type to text/plain or application/vnd.google-earth.kml+xml.

At this point there are still two things missing in GoogleMaps jigsaw:

• how to change the draggable icon image, so it still shows the ‘cloud info’
• how to create a box with checkboxes to switch off and on the overlayed KML data layers

After a while it seams like the first issue has been solved by itself… I’ve added G_DEFAULT_ICON to my GIcon definition and it started to work
icon = new GIcon(G_DEFAULT_ICON);

Reply on the second issue I’ve managed to find here:
http://gmaps-samples.googlecode.com/svn/trunk/ggeoxml/ggeoxml_loader.html

Haven’t tested it yet, but looks fairly simple to implement.

BTW, had a while working with Info Boxes (you know, those white Clouds) and there is quite a lot you can do with them, to get the ball-park idea have a look here.

Ah, and this tutorial is fantastic! Number of articles and examples huge… I would even say overwhelming. ALthough, to be honest Google Maps Documentation seams to be all you may need during the way. At least it did well to me.

KML is a file format used to display geographic data in an Earth browser such as Google Earth, Google Maps, and Google Maps for mobile. KML uses a tag-based structure with nested elements and attributes and is based on the XML standard. All tags are case-sensitive and must be appear exactly as they are listed in the KML Reference. The Reference indicates which tags are optional. Within a given element, tags must appear in the order shown in the Reference.

Using KML you can position on the map following “objects”: placemarks, descriptions, ground overlays, paths, and polygons.

Smaple KML document:

<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2">
<Document>
<Placemark>
<name>CDATA example</name>
<description>
<![CDATA[
<h1>CDATA Tags are useful!</h1>
<p><font color="red">Text is <i>more readable</i> and
<b>easier to write</b> when you can avoid using entity
references.</font></p>
]]>
</description>
<Point>
<coordinates>102.595626,14.996729</coordinates>
</Point>
</Placemark>
</Document>
</kml>


But going back to business… Geocoding using JavaScript is piece of piss… geocoder.getLatLng() is doing all for you.
So I was able to create a simple address lookup, which sets the marker on the map… easy! My only worry now is, when I want to make this marker dragabble, it seams like I can’t have the custom icon… I mean I can, but then the ‘cloud info’ is not appearing. There definitely has to be a way of solving this. Give me some time.

I have learnt about KML and RSS goecoding… or rather map overlaying – and this will have huge impact on what I’m going to develop. Let me draft you the idea of using KML to overlay markers on the map (as I understand this up to know). Say you are dealing with many locations, which number constantly grows – users adding new locations. My initial way of thisking was “easy, just get the lat/lng of each location, store them in db and load on the map when necesary” – and this was so wrong! Maybe not wrong, as this would work, but very inefficient. Go we can tackle this a bit better? Using KML (or GeoRSS). Keep adding user-data to DB, but to display all markers on the map (can be divided into categories for easy switching on/off) create dynamically updated on each INSERT KML file (this is simple XML really). When the map is requested there are no DB queries, no time taken by PHP to parse them, nothing at all… just simple file loading! Isn’t that beautiful?
Also, if my understanding is correct, you can even compress KML file using ZIP format and it becomes KMZ which can also be loaded into GoogleMap.

KML (KMZ) and GeoRSS (which sounds like same thing done in a different format to me) is my current learning direction, so stay tuned.

http://mapki.com/wiki/Main_Page – especially its huge tutorials sections

http://koti.mbnet.fi/ojalesa/exam/index.html – handful of GoogleMaps examples

No magic up to this point. Although there is few things worth remembering:

• use onunload="GUnload()" inside your body tag
• page encoding should be utf-8, to use something different add eg. ‘oe=iso-8859-2′ to the api path (this is not recommended!)
• map.setCenter() must be set before any other operation on the map
• getBounds() you can get the dimentions of the current viewport
• getZoom() you can get current zoom (0-20)
• GMap2.disableDragging() method disables the ability to click and drag the map to a new location.

You can use map.setMapType(G_SATELLITE_MAP); to set one of those types of maps:

• G_NORMAL_MAP displays the default road map view
• G_SATELLITE_MAP displays Google Earth satellite images
• G_HYBRID_MAP displays a mixture of normal and satellite views
• G_DEFAULT_MAP_TYPES contains an array of the above three types, useful for iterative processing.
• G_PHYSICAL_MAP displays a physical map based on terrain information.

Using map.addControl(new GLargeMapControl()); you can show numerous different controls to allow user interaction with the map

• GLargeMapControl3D – a large pan/zoom control as now used on Google Maps. Appears in the top left corner of the map by default.
• GLargeMapControl – a simpler large pan/zoom control. Appears in the top left corner of the map by default.
• GSmallMapControl – a smaller pan/zoom control. Appears in the top left corner of the map by default.
• GSmallZoomControl3D – a small zoom control (with no panning controls) as now used on Google Maps.
• GSmallZoomControl – a small zoom control (no panning controls) used in the small map blowup windows used to display driving directions steps on Google Maps.
• GScaleControl – a map scale
• GMapTypeControl – buttons that let the user toggle between map types (such as Map and Satellite)
• GHierarchicalMapTypeControl – a selection of nested buttons and menu items for placing many map type selectors.
• GOverviewMapControl – a collapsible overview map in the corner of the screen

Other than that, only from Google Maps API, I have learnt today what Events, Controls and Layers (and other Overlays) are. To be honest, it’s good to know this stuff, but this doesn’t move me any further with satisfying my GoogleMaps needs. But I am good hope… tomorrow Google Maps Services, which means loads of fun with Geocoding.

This is just a kind-of-notepad for me to put down my notes about learning Google Maps API. I thought it may be of some use to anyone else, hence the idea of using WordPress.

As I’m starting tomorrow… here are just few quick links I got when Google GoogleMaps API:

http://code.google.com/intl/pl/apis/maps/documentation/

http://web4you.com.pl/

http://econym.org.uk/gmap/

Hopefully this enables me to crack on tomorrow…