Wed, 06 Jun 07
Posted in Programming, Google Maps, BarCamp, GIS at 9:39 am by moore
One of my clients is helping out with this unconference. If you’re into GIS, it seems like it’d be worth going. I certainly had fun at the last unconference I went to. I am planning to attend; hope I see you there.
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FRUGOS (Front Range Users of Geospatial Open Source) is holding its
first GeoSummit on Saturday, June 16th at Churchill Navigation–100
Arapahoe–in Boulder.
This will be a unique gathering of a variety of folks interested in
Place–geo-types, hackers, academics, artists, amateur enthusiasts,
etc. While there certainly will be representation from the GIS and open
source worlds, we encourage all who are fascinated about the
intersections of technology and engagement with the world around us to
participate.
Also, we’ll be structuring the day around the “un-conference” model (see
http://www.barcamp.org), so, for starters, you
can expect:
No Pitches
No PowerPoint
No Passivity (unless you’re a little sleepy after lunch)
Bring your laptop (we’ll have wireless), and a project or enthusiasm
you’d like to talk about with the group, get feedback, and collaborate
on fresh solutions: the agenda of the day will be structured during
the morning registration/sign-up/socializing period.
If interested–
1) RSVP by joining the Google Groups set up for this event–
http://groups.google.com/group/geosummit
2) Bring a laptop (and cellphone/GPS if your enthusiasms tilt that
way), your idea/project, and willingness to collaborate
3) Spread the word
Tentative Schedule
9:30-10:30AM Registration, refreshment, socializing
10:30-12ish Sessions
12ish-2 Lunch (there’s a grill, beverages, and hiking trails)
2-? Sessions
This promises to be a great combination of creativity, intellectual
engagement, eating and drinking, and socializing.
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Technorati Tags: barcamp, gis, unconference
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Sat, 16 Sep 06
Posted in Programming, Google Maps at 10:39 pm by moore
I recently upgraded a simple simple Google Map that I built last spring to display some of the cross country skiing around Boulder. You can see the original version here. I built this based on this XML.com article, using XMLHttpRequest to retrieve the data from the server and Gmarker.openInfoWindoXSLT() with this XSL stylesheet to present the data.
I decided to upgrade this map last week to version two. Since openInfoWindowXSLT is no longer supported on every browser, I feared that the upgrade would take significant effort, even though the map very simple. However, the upgrade ended up being easier than I thought it would be. To get started, I read the Google Upgrade Guide–this document explains just what changes were made in the API. The changes that affected my map included:
A few method name changes–centerAndZoom becomes setCenter GPoint is no longer used to indicate a latitude and longitude location on a map, and its replacement, GLatLng, reverses the order of the constructor’s arguments. Zoom levels are flipped around, with larger numbers now signifying higher resolutions The biggest effort was modifing the code not to use the XSLT process for generating infoWindows. However, this was easier than I thought it would be. I simply wrote a javascript method that mimicked what the XSL had previously done. Sure, accessing the DOM elements was a bit of a hassle that required some debugging (that’s the win of XSL–declarative DOM access), but the alternatives were either ignore browsers that don’t have built-in XSLT support (Safari) or integrate AJAXSLT, a Google sponsored project to provide cross browser XSLT support. If this were a larger project that depended on more XSLT, I probably would have done the latter.
Upgrading my (admittedly very simple map) took about 1.5 hours. Visit the new map and take a look at the code.
Technorati Tags: google maps upgrade
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Tue, 12 Sep 06
Posted in Books, Programming, Dynamic Languages, Google Maps at 8:04 pm by moore
Seven months ago, I wrote about Google Maps Gotchas. I mentioned Scott Davis’ Google Maps API Pragmatic Friday article, published by the Pragmatic Programmer folks. Well, a few things have happened since then. In April, Google released version two of their maps API (though they still haven’t set a date when version one will no longer be supported), Scott revised his article and I spent a tax deductible $8.50 to give it a read. What you’ll find below is my take on his article.
The good: first, the ordering was easy, and I received my custom PDF (complete with “Prepared Exclusively for Daniel Scott Moore” as a footer on every page) in less than 20 minutes. Scott explains in a very easy to understand fashion how to create a map. He also covers each of the API’s javascript objects and how to use them. In particular, I thought the list of events and objects that fire them (in the ‘Events’ chapter) was a good reference. Now, Google provides a class reference, but Scott’s are a bit easier to understand here’s a comparison, for the Gmarker class:
Google API:
A GMarker marks a position on the map. It implements the GOverlay interface andthus is added to the map using the GMap2.addOverlay() method.A marker object has a point, which is the geographical position where the marker is anchored on the map, and an icon. If the icon is not set in the constructor, the default icon G_DEFAULT_ICON is used.
After it is added to a map, the info window of that map can be opened through the marker. The marker object will fire mouse events and infowindow events.
Davis’ Book:
In the Core Objects section, we introduced the GLatLng. A GLatLng stores a Latitude / Longitude coordinate, but it doesn’t offer you a way to visualize it on a map. A GMarker is the way to add GLatLngs GMarker to the map for display purposes. The GMarker constructor takes a GLatLng as the only required argument.Once we have the marker, we need to tell the map to display it; map.addOverlay(myMarker) should do the trick. (Objects that you superimpose over the map are called Overlays.) You can remove the Overlays marker using map.removeOverlay(myMarker). To remove all overlays, use map.clearOverlays( ).
var myPoint = new GLatLng(38.898748, -77.037684);
var myMarker = new GMarker(myPoint);
map.addOverlay(myMarker);
Theoretically a map can support an unlimited number of markers, but anecdotal evidence suggests that performance starts to slow down significantly after a hundred or so markers. (File under, “Doc, it hurts when I do this.”)
I liked the real world examples–the fact that you could click through and see the code Scott was writing about in action on his website is a real plus. In addition, he builds a decently complex example in Chapter 7 where the user can add and delete cities. He also gives a good warning about examples that use Gmap, rather than Gmap2.
However, there were some issues. Scott’s coverage of the upgrade to version two of the API is, unfortunately, rather spotty. In his blog, the June release of that feature, and the April revision of the book). He also doesn’t cover GDownloadURL, a convenience method for XMLHttpRequest processing, or the GUnload methods. I’ll freely admit that the maps API is a moving target, and some of the omissions above may be due to that.
However, there are other problems. Though billed as a beginner book, he omits what I consider to be one of the fundamental challenges of Google Maps development–the performance obstacles large numbers of database driven markers (other than the comment mentioned above in the GMarker reference). In addition, he doesn’t cover design options, nor cross browser issues (like the transparent PNG in IE issue).
In the last chapter, he mentions good examples of mapping websites, but Scott omits references to useful websites–something that even dead tree books do. In particular, he doesn’t mention mapki.com (a wiki full of useful user provided data) nor the Google Maps group (which some users consider a primary differentiator between Google and Yahoo Maps).
One final gripe is that the 75 pages of content that I expected were really only 45–text only filled about 60% of the column width. I expect that in articles I read for free on the web, but in books that I pay for, I like a bit higher content to page ratio.
In short, this ebook is a good choice for the first time Google Maps builder. This is due to the tutorial nature of much of the book, the examples, and the explanation of typical good javascript code, such as using anonymous functions for the event handlers. It is not entirely adequate in covering version 2 of the API, possibly due to API changes, and it ignored some of the more complex aspects of the API.
If you’re looking for a folksy introduction to Google Maps api, it’s worth the $8.50 to have a coherent guide. If you’ve muddled through one google maps project, piecing together things from the API docs and various blogs, it becomes less worthwhile. But if you want some kind of discussion about complex Google Maps issues this document is not the right place to look.
Technorati Tags: Scott Davis, Google Maps, Pragmatic Fridays
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