The lowdown on developing apps for Android
May 9, 2011
Developers need to be educated on the structure of the operation system. They also should have a basic understanding of how assets are used and what the naming conventions should be, according to Mutual Mobile’s Android Human Interface Guidelines.
“Many mobile product managers might call out device diversity or fragmentation as the biggest challenge in developing for Android, but the truth is that these issues can largely be overcome with proper device targeting and best practices quality assurance cycles,” said Sam Gaddis, chief marketing officer of Mutual Mobile, Austin, TX.
“Really, the biggest misfires on Android happen when brands don't take full advantage of the platform,” he said. “Android has it's own nuances in design and functionality, and the data shows that users want a rich experience.
“We've found that the best way to ensure success on Android is to build or hire teams that have specific expertise in Android design and development.”
Mutual Mobile is an app development specialist. The company created the Android Human Interface Guidelines in hopes that developers and designers will use it as a resource to understand the platform's inherent intricacies and innovate in Android design.
Multiple screen resolutions, sizes
One of the biggest reasons for distress when developing for Android is the fact that there are various devices that run the operating system.
Different devices mean differences in screen sizes and resolutions. That means that something that may look grand on one device, may come out grainy and blurry on another.
Android suggests four general solutions for both resolution and screen size.
There are four different screen sizes: small (2-3 inches), normal (3-5 inches), large (4-7 inches) and extra large for tablets (7-10 inches).
Additionally, Android breaks resolutions up into: ldpi (100-120 dpi), mdpi (120-160 dpi), hdpi (160-240 dpi) and xhdpi (240-320 dpi).
When deciding on which Android devices to target, developers should take into account what their buttons look like, the gradients they are using, complexity of icons and the backgrounds for the app.
Mutual Mobile suggests creating the app design in multiple sizes to ensure it works on as many Android phones as possible.
“Scale is the reason most brands choose to build for Android, but the big opportunity in Android over the next few quarters will be realized as payment options become more streamlined,” Mr. Gaddis said.
“On Android, we're currently only seeing a fraction of the transaction volume that's happening on iOS, but that's sure to shift as payment becomes easier through carrier-billing, NFC, and Google's own payment system,” he said.
“Further, the Android App Market is expected to surpass the Apple App Store in size this summer, so there's no doubt that the platform has already reached critical mass – in fact, activations have surpassed 350,000 each day.”
Because Android is open source, it is flexible about user interface, according to Mutual Mobile.
The tab bar on Android can be top or bottom aligned. Mutual Mobile suggests placing it at the top because the menu bar comes from the bottom and could obscure the tab bar.
The options menu, which stores activities, is customizable in terms of the skin and width, based on the screen.
A context menu is the Android equivalent to the right click on a PC. Touching and holding brings a menu up regarding all the different actions that pertain to the selected activity.
This menu is customizable based on the purpose of the app.
Mutual Mobile’s guide also covers dialog boxes, dim and hide and list views.
Icons vs. buttons
With Android, icons and buttons need to be treated as separate and different assets.
Mutual Mobile gives best practices in its design guide for creating custom elements and correct custom bounding boxes.
In terms of icons, Android provides guidelines for icon creation on its developer Web site.
But remember, it is necessary to develop a set of icons for each of the screen densities.
The launcher icon, which is tapped on to open an application, has its own standards and styles.
When it comes to these icons, Android has a lot of rules. Launchers should be modern, clean and contemporary.
Menu icons, tab icons and status bar icons have different specifications, based on screen size and resolution. Mutual Mobile spells all of this out in detail in the design guidelines.
One of the most unique aspects of Android development is the widget, a mini application extension that runs on the home screen of the device.
It displays the application’s most relevant information at a quick glance. Users pick the widgets they want to display on their home screens.
According to Mutual Mobile, the widget has three main pieces – a bounding box, a frame and the widget’s graphical controls and other elements.
The widget has one function. The potential for different widget uses is immense, as they allow the app to multitask in clear sight without being activated.
Mutual Mobile says that smaller is better when it comes to widgets.
Draw9patch and gestures
Because of all the various devices, screen sizes and resolutions for Android, some assets need to be draw9patched. This means selecting certain portions of an image that will be allowed to stretch and expand, leaving the rest of the image intact.
Draw9patched assets should be created if they are solid colored, such as a button or tab, or if they have transparency, such as an icon, per Mutual Mobile.
Complex images that have multiple effects or rich gradient should never be draw9patched.
When it comes to gestures there are two different classes: motion events and gestures.
Motion events are the actual touch event on the screen. It works by tracking X and Y coordinates on the screen. An example is the drag and drop feature.
Gestures, according to Mutual Mobile, define the series of motion events that create a solid movement. So within the drag and drop feature, the gesture would be the movement of the object being dragged and dropped.
Just because any action could be a gesture does not mean it should be, according to Mutual Mobile.
Gingerbread and Honeycomb
Gingerbread watches apps that drain the battery too much and forces the operating system to shut them down.
Additionally, Gingerbread devices have a task manager tool that reports what resources are consumed by which apps. This way, the user can force stop applications.
Gingerbread has an updated interface in terms of simplified color, a new keyboard and improved cut and paste. It also has new gadgetry.
The operating system supports NFC, new sensors, Internet calling and new development tools for high-end video games.
The design guidelines spell-out developmental opportunities with Gingerbread.
Mutual Mobile believes that Honeycomb is a game-changer for Android.
It’s optimized UI, holographic themes, multitasking capabilities and redesigned widget structure means big things for user experience.
The Mutual Mobile design guide dissects Honeycomb.
Android is its own culture with its own complexities and functionality perks, Mutual Mobile says in its design guide.
Porting an app directly from iPhone to Android will not work.
There are just way too many differences and things that work great on the iPhone will not necessarily translate well onto Android.
Many of the differences are programmer-centric, however, asset management and user flows must be given a completely different treatment to do the device justice, per Mutual Mobile.
“The big question is not whether or not a brand should be on Android, but rather how they approach Android product strategy,” Mr. Gaddis said.
“Given that transaction volumes through the platform are still relatively low, it generally makes sense to orient Android apps more toward brand building as opposed to more transactionally-oriented iOS apps,” he said.
“The revenue will catch up though, so it's critical that brands start developing Android capabilities now in order to be ready to execute future product iterations well.”
Click here to view Mutual Mobile’s Android Human Interface Guidelines
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