Mobile Web Development and Maps

by Jyrki Pulliainen on 2011-07-28

Lately I've been working on Helsinki Festival mobile site (in Finnish). The main idea of the site is to provide mobile information for users, including location and maps of the venues. While implementing the venue locations and other, yet upcoming, features, I've run in to a series of problems of which some should be shared to the wild.

Supporting wide range of devices

Due to heterogeneity of attendees the site should support a wide range of devices. At Taiste we sport a few test devices: iPhone 4, HTC Desire with original firmware and another one rooted with Cyanogenmod and two Nokia devices, the flagship N8 and an older E75. Pretty decent coverage of mobile platforms in circulation in Finland.

I'm not going to discuss about rendering woes and missing <meta name="viewport"> support here, even though they are challenges that just need to be handled when building a site like this. The problem I want to focus on is the functionality of maps and navigation on a mobile web site.

Displaying a map

I started with a dual-mode map: A static image, courtesy of Google, for devices without proper JavaScript support and a fancy embedded Google Map for devices with JavaScript support. However, this turned out to be a bit problematic.

First caveat: scrolling. On touch screen phones the scrolling of venue pages, which have embedded map, was misleading; if user started scrolling (i.e. placed her finger) on the map, she would end up scrolling the map instead of the site. By scrolling the map user would also lose sight of the marker, placed on the map. On Google Maps API this is fairly easy to disable just by passing draggable: false to options of the constructor of a Map object.

Second caveat: The marker. On the embedded map we drew a nice yellow marker. However, the Nokia N8 failed to display this marker. According to my debugging sessions the problem resides somewhere in the Google's Map Marker API, though I can't say for sure. The phone does not report any JavaScript errors, so it must be rendering the Marker to a wrong place or underneath the map element (if it renders it at all). Even with furious debugging applied, the marker could not be seen on the map.

Now the second problem was a bit harder to solve: there didn't seem to be any way we could solve it. The N8 sports a Symbian browser 7.2, which is equipped with Webkit version 525, the same version Chrome 1.0, iPhone 2.2 and Android 1.0 had in 2008, except that somehow it's crappier than those. Luckily, the new Symbian Anna upgrade should bring Browser 7.3, which has a newer webkit and it even includes viewport meta-tag support!

To overcome these two problems I wrote a custom template tag that just outputs an img tag that has an URL to a 240x240 map picture (240 is the smallest horizontal resolution we support) showing the location. The img tag is then later on accompanied with a small JavaScript that transforms the src attribute to point to a wider map picture. JavaScript is needed to sniff the width of the containing div element by using element.clientWidth. Oh, and while doing this I also discovered that Google Maps API limits the image width to 640 pixels. Damn.

Not only the static image overcame these both problems but it also renders a neater marker, with drop shadows and all!

Providing links to the internal navigator application

To ease the finding of a venue site provides a link to an internal map application. Or more specific: tries to provide one. We started with linking directly to Google Maps with proper longitudes and latitudes in the URL. This works mostly fine: on iPhone and on Android it, in almost every case, opens up the native Google Maps application. Almost.

HTC woes

During last firmware update HTC rolled out a new version of their customized Android Browser (which they call "Internet"). This updated Internet contains a small, but pretty annoying bug: it seems to break URL handling so that the Google Maps links are now opened in browser by default and there's no way to change this default. I haven't explored if it does the same with other URLs. My hypothesis is that this could be related to their own navigation software, Route 66, which is shipped with newer HTC Android devices. It could possibly open by default the Google Maps links in this application. However, the app is not available for Desire. Apparently I'm not alone with this. Funny thing is that if I type maps.google.com in the Google Search app (not the website), it asks me politely if I want to open Maps or Browser. So HTC has definitely broke something while modifying the browser.

Needless to say, the link works fine on the Cyanogenmod Desire, as it sports nearly vanilla Android browser by Google. The bad thing here is that there's no other way to send a link that suggests the phone to open Maps application with correct coordinates.

N8 woes and yays

The Nokia Browser documentation developer.nokia.com does not say a thing about opening Ovi Maps from a website. After some excessive googling I found a forum post that mentioned briefly about an undocumented services URI scheme. By calling that URI scheme with a properly formatted URL, in this case services://C2A?C2Aid=2305&Version=1.0&2305=Landmark(lat=XXX&long=YYY), it opens up the Ovi Maps application with a marker at the latitude and longitude specified. You can even supply a name with additional name parameter given to the Landmark "constructor"!

...and the issues with Series 60

Even though Nokia E75 has the same generation browser as N8, it does not support services URI scheme, at least not in the same format. I also failed to find any documentation or experience about opening Ovi Maps application from a link, so the built-in navigation is a no-go with E75. With S60, we're stuck with mobile Google Maps URL and the experience is not optimal. You could even craft a URL that gives you directions, but that would require knowing your current location and E75s browser does not support Geolocation API, so that's a no-go too.


If it would be satsifying for us to serve only iPhone/iOS and Android devices (sans current incarnation of HTC Desire, possibly other HTC Android devices too) the mapping would be easy: Either display a JavaScript map (pretty usable on those devices) or use static image provided by El Goog with a properly formatted link to maps.google.com.

However, if you need to support other OSs, it might require tremendous amounts of googling around the interwebs. I don't even have a clue how Bada or WP7 works, but luckily they both are a small minority in the browser market. I also couldn't find anything for Series 40, so the Nokia seems to keep consistent line of undocumenting through the product line.

My suggestion to mobile phone manufacturers would be a single page of documentation describing the supported URI schemes of the built-in applications to tell the developer what's possible and what's not. With examples, of course.

P.S. At the moment of writing this, we yet haven't launched the new maps and map links in to the wild, but we're in the process of doing so.

If you want to comment this blog post, just send mail to my firstname + blog @ thisdomain.tld. If the question is a proper one, it might get answered. Good ones might even end up on the site.

Tags: mobile web maps geolocation integration