When developers from around the world gathered in San Francisco this week to worship at the altar of Android (Google’s mobile operating system), they heard speakers discuss ways applications can save battery life, how clothing can be integrated with software, and how to build better interfaces.

The conference kicked off with keynotes from American Express and Motorola, but all hands were present Tuesday for the Google keynote, given by Romain Guy and Chet Haase, both senior software engineers at Google.

Their keynote showed off a myriad of new features of Android 4.0, codenamed “Ice Cream Sandwich” (ICS). The pair said there are dozens of new APIs in Android 4.0, though existing APIs will always remain in the platform to ensure backward compatibility.

There are hundreds of changes to the interface and standard applications in ICS, said Guy and Haase. Many of these changes are refinements or fixes to previous behaviors. Others are designed to improve the overall mobile Internet experience.

One such change comes to the Android Web browser, said Guy. “There are many websites I go to on my phone, and I hate it when they give me the mobile version of the website. We have a feature where you can request a desktop version of the website. We have better tabs UI so you can see up to 16 tabs, and you can synchronize your bookmarks with Chrome if you use that on your desktop.”

For developers, there are new ways to build GUIs and new features in the underlying toolkit. Said Guy: “We now have TextureView. It’s a replacement for SurfaceView, and it addresses some of the limitations of SurfaceView. We have hardware graphics acceleration on by default; we added stylus and mouse input, also. And we now have a pluggable dictionary and spell-checker.

“The goal is to make complex layouts easier. Before, you’d have a couple layouts: one for vertical, one for horizontal, one for tablets. Instead, you can now just have a single grid layout; there’s no nesting.”
Watching Android
Elsewhere at the show, wearable computing devices and Android accessories were popular topics. On the final day, the WIMM One, a wristwatch-like device for interacting with smartphones, was launched, with devices already shipping. Keith Clanton, technical director at WIMM Labs, demonstrated the software development process for this device, which ties closely to Android’s standard APIs.

The WIMM One is not only a window into your phone, it’s also a micro app platform, he said. That means developers can add WIMM functionality to their traditional Android applications. A WIMM One wearer could check his or her wrist to see the time, check a recent e-mail, or read an SMS without having to pull out their phone.

Developing applications for a 1-inch screen is a very different problem, said Clanton. To that end, he detailed some of the best practices for UI design for such a small device.

Those UI guidelines state that developers should focus on interface gestures, like swipes and taps, and endeavor to simplify features, minimize input and reduce hierarchy. “Simplicity and consistency are critical to a successful UI on a micro device,” he said.

“We try to use the paradigms as consistently as possible so they seem familiar to the users. This is a simplified view, that’s why it’s critical to simplify everything. We all want our applications to look cool, but keep it simple. Streamline features, and if they don’t make sense or don’t work, remove them. Not only is the user wasting lots of time if they’re having to do tedious input on the device, but we’re also wearing down the battery. It’s not efficient for the user or the device to try to accomplish too much on the device. We want to augment and compliment the functionality of existing devices, not replace them. This isn’t a replacement for a phone.”
Wearing Arduino
But commercial devices weren’t the only wearable options at the show. Rachel Lyra-Hospodar  showed off numerous tools and techniques for building devices with the Arduino prototyping platform.

Arduino was chosen by Google in May as its officially supported device development platform for the Android, and Lyra-Hospodar even demonstrated one of Google’s Arduino-based Accessory Development Kits in her talk. She intimated, however, that at US$400 a pop, ADK devices are highly overpriced. She said that $25 can purchase a fairly simple entry-level Arduino board without all the Google extras, which she said amounts to a handful of components, like servomotors and LEDs.

Perhaps the most interesting aspect of Lyra-Hospodar’s talk was the fact that she is not an expert programmer. She said that she is a seamstress originally, but the wealth of existing libraries, examples and tutorials on the Web enabled her to learn about microcontrollers on her own. Specifically, she said that the Arduino IDE has a large amount of sample code included, and that she typically cobbles together her wearable electronics software from these samples.

That doesn’t mean Lyra-Hospodar’s not still encountering difficulties in her work. “Signal processing is really hard,” she said while discussing the Pants Interface, her project to create a pair of pants with a keyboard embedded in the thigh area. “You software people need to help us with that.”

After her talk, Lyra-Hospodar found numerous attendees to help her with her signal-processing problems. Her goal is to create clothing that includes a computer interface, so she can use the same interface devices on any machine, wherever she goes.
Forking Androids
Karim Yaghmour, founder and president of Opersys (an open-source software consultancy), gave a talk on Monday about the world of Android forks, mods and hacks. His focus was primarily on how he managed to build Android applications that relied on glibc rather than Google’s own Bionic C library, which is included in the Android OS. He demonstrated techniques to allow glibc and Bionic applications to run side-by-side on the same device, and he detailed the code and methods required in his slides, which are available on the AnDevCon website.

There are a lot of differences between the standard desktop or server Linux and Android Linux, said Yaghmour. One of the big differences is that Android’s file system is “non-FHS-compliant. FHS says you have to have bin, usr, etc. Android disregards FHS entirely. It doesn’t have a lib or a bin directory, which is good for us because we can put things in there and they won’t conflict with existing files. But some packages you get off the Web won’t work properly because of this.”

Yaghmour also talked about the major forks and modified distributions of Android. Chief among them is CyanogenMod, a set of third-party firmware for Android devices that enable some additional functionality, such as a DSP audio equalizer, and have support for OS UI themes.

The other two forks of the Android Open Source Platform are known as Replicant.us and MIUI, neither of which, said Yaghmour, are quite ready for prime time. Replicant offers FDroid, an open-source client and server for an app store, which he said was interesting and useful. Replicant is also an effort to replace non-open-source components of Android with free and open-source alternatives.

MIUI, which comes from China, includes a completely redone UI, which Yaghmour said was quite slick.
By the numbers
Don Kellogg, director of telecom research for Nielsen, gave a presentation that was chock full of juicy demographic information on Android users. Nielsen launched a new method of metering its users earlier this year. The company famous for its television ratings now has a phone-based application that can track the habits of its users. Those users are compensated for their volunteering, just as Nielsen families are compensated for having television-tracking devices in their homes to see what people are watching.

Kellogg detailed some of the trends he’s discovered after a year of logging data from this new metering method. He said the average smartphone user uses 38 applications in a given month. He also stated that, currently, 44% of Americans have smartphones. The graph he showed representing the rise of smartphones showed that their uptake is generally parallel to the uptake of all mobile phones. Smartphone sales, however, do rise and fall with the seasons and the launches of new phones.

“The growth of smartphones is not a hockey stick graph,” said Kellogg. “We’re going to hit the 50% penetration rate somewhere between February and March of next year. Given the Apple launch of the iPhone 4GS, it may be closer to January.”

Kellogg went on to show off a day in the life of an average smartphone user. Ninety-four percent of the time, the device is not active. Six percent of the time, it is active. Users average 1 hour, 25 minutes of use per day. For the entire day, though, only 3% is spent on phone calls.

What are those users doing during that active time? Forty percent of active use time is spent on Facebook, either on the Web or on a native Facebook app. Twenty-eight percent of that time is spent gaming. Messaging takes up 8%, and Internet usage was 12%. Beyond that, 1% of time was spent on e-mail, 7% on preloaded applications, and only 1% on third-party applications.

As for demographics, Kellogg showed that, by manufacturer, Motorola device users tended to be the most affluent and wealthy. He showed over 34% of Motorola Android owners were making more than $100,000 per year. He added that Motorola devices are popular on Verizon’s network, and that this skews those numbers higher, as a higher percentage of Verizon customers make over $100,000 per year compared to other carriers.

Perhaps the most interesting bit of information Kellogg intimated was the relative popularity of the various Android devices. He showed the HTC Evo 4G was the single most popular Android handset, both overall and within the last quarter. Over the last quarter, the Motorola Droid X came in second, and the LG Optimus S placed third.

“You need to make sure you test on the Evo,” said Kellogg. “The other thing I’d point out is there are a lot of large-format screen devices here. The Evo, the Droid X and the Samsung Charge are all large-format screens. Make sure if you’re developing Android applications, you develop for a larger screen size.”

He also showed that reviews make a big difference to users. “You cannot release an app that is not fully baked because people use reviews quite a bit,” he said. “Sixty-one percent of folks say reviews are extremely or very important. It’s OK to iterate and improve, but make sure it’s ready.”

Then came the bad news. Unfortunately, the top 10 applications in the Android app store account for 34% of all time spent with third-party applications. While these applications are successful and profitable, the commercial viability of the rest of the app store is greatly lessened.

“Eighty-four percent of all time spent is with the top 1,000 apps. Facebook is by far the largest app; it makes up about one fourth of all time spent,” said Kellogg.

The story is much the same on iOS: The top 10 applications make up 45% of the overall app usage on that platform.

Finally, Kellogg explained how applications get upgraded. Most users said they upgraded from a free version to a paid version because they wanted additional functionality. The least successful upgrade trick, however, was using a timed trial. When the time runs out on the trial version, under 25% of users upgraded.

“Don’t make your free app or your trial app too good,” he said. “You don’t want to make it expire, but you don’t want to make it good enough so people won’t buy the full version.”
Speaking clearly
With all the cultural excitement over Apple’s voice assistant, Siri, voice recognition has become a hot item for mobile developers. On Sunday night, Pioneer launched Zypr, a voice-recognition API and service aimed at giving developers a way to integrate such capabilities into their applications.

David Frerichs, CTO of Zypr, said that Siri will make voice recognition the new killer app for mobile. “From our perspective, Siri is an ad campaign that is going to drill into people’s minds that we should talk to our devices,” he said. “Siri is great on Apple devices, but what happens when you want to use a non-Apple device? Into that gap steps Zypr. We have a comprehensive conversational voice user interface system any developer can use on any platform.”
Zypr came out of Pioneer’s car audio division initially, but as the project grew, Frerichs said it became apparent that Zypr would be useful for more than just in-car usage. Thus, it was turned into a RESTful API, supplemented with a monetization path for independent developers.

Frerichs said that Zypr offers category-based APIs, specifically targeted at social networking, maps, shopping, Internet media and others. Thus, Zypr offers tailor-made API calls for each of these services, he said.