Developing Android Applications with Adobe AIR [22]
Hardware
The multitude of Android devices available today makes it difficult to evaluate them all. The subsections that follow discuss the major factors to examine. If you want to know about a specific phone, or if you would like a complete list of Android devices, visit these websites:
http://pdadb.net/
http://en.wikipedia.org/wiki/Category:Android_devices
http://phandroid.com/phones/
The Processor
The CPU, or central processing unit, executes software program instructions. Its speed on mobile devices varies from 500 MHz to 1 GHz. For comparison, the average speed of a desktop computer is around 2.5 GHz.
The instruction set must be ARMv7 or higher to run AIR for Android.
The GPU, or graphics processing unit, is a high-performance processor dedicated to performing geometric calculations on graphics. Its speed is evaluated in millions of triangles processed per second (mt/s), and it ranges on mobile devices from 7 mt/s to 28 mt/s. AIR uses OpenGL ES 2.0-based processors.
The graphics card, display type, and color depth affect display quality.
Memory and Storage
RAM on mobile devices varies from 128 MB to 768 MB, averaging at 512 MB. ROM is an important complementary memory type. On Android, if memory runs out, applications are terminated.
Different types of memory affect the GPU’s speed and capacity.
Storage includes the internal memory, expanded by the SD card.
The Camera
Camera quality is often evaluated by the megapixels it can store. The quality of the LED flash and the auto-focus option on the device is also a factor. Some devices include a front camera of lesser quality to use for video telephony.
Sensors
A built-in accelerometer is becoming standard on Android devices, but it is not yet universal. The GPS antenna and driver is used for satellite navigation. Touch technology is a combination of the screen touch overlay, the controller, and the software driver. The number of simultaneous touch points varies, although Android officially only supports two.
The Battery
Battery capability on an Android device is measured in milliamp hours (mAh), and is commercially evaluated by the number of hours of movie play capable on the device. Removable batteries can be replaced by stronger ones if needed.
The Display
Screen size on Android devices is measured as a diagonal, usually in inches.
Resolution is the number of pixels on the screen. The resolution varies between 800×480 and 854×480 on phones, and between 1,024×600 and 1,024×800 on tablets.
The PPI (pixels per inch) or DPI (dots per inch), also called pixel density, is the number of pixels on the screen in relation to the screen’s physical size. A device has a defined number of pixels it can display in a limited space. A higher pixel density is preferable on devices viewed at close range.
Table 5-1 lists the screen size, resolution, and PPI on some popular Android and Apple devices.
Table 5-1. Feature comparison of popular Android devices
Device
Screen size (inches)
Resolution
PPI
Samsung Galaxy Tab
7
1,024×600
170
iPad
9.7
1,024×768
132
iPad 2
9.7
1,024×768
136
Motorola Xoom
10.1
1,280×800
160
Nexus One
3.7
800×480
254
Droid 2
3.7
854×480
265
iPhone 4
3.5
960×640
326
Software
At the time of this writing, Android’s latest operating system is 3.0 and is called Honeycomb.
The process for upgrading the Android operating system is very different from the Apple model, which requires the device to be synced with iTunes. Android uses an “over the air approach” to push upgrades. Manufacturers slowly push upgrades to phones, sometimes over several months. Not all devices receive upgrades, so developing for established versions instead of recently released versions may guarantee you a broader audience.
If you are not sure what version is installed on your device, select Settings→About phone→Android version (on some devices, this information is available under “Software information”). Your phone system must have at least Android 2.2, called Froyo, to run AIR