Google mandates Holo theme on all Android 4.0 devices


Google (NASDAQ:GOOG) is making the inclusion of its unmodified Holo theme family a compatibility requirement for all devices running Android 4.0 and forward, a move designed to ensure a more consistent user interface and application development environment.


The theme Holo.Light.DarkActionBar is available in API level 14 and above.

"If the device has Android Market it will have the Holo themes as they were originally designed," Google Android Framework engineer Adam Powell writes on the Android Developers Blog. "This standardization goes for all of the public Holo widget styles as well. The Widget.Holo styles will be stable from device to device, safe for use as parent styles for incremental customizations within your app."

According to Powell, Holo's inclusion guarantees that developers building new and forthcoming Android applications running 4.0 (a.k.a. Ice Cream Sandwich) and up can rest assured that the app's look and feel will remain consistent on devices with a custom skin. "For developers new system themes mean more design targets for their apps," Powell explains. "Using system themes means developers can take advantage of a user's existing expectations and it can save a lot of production time, but only if an app designer can reliably predict the results. Before Android 4.0 the variance in system themes from device to device could make it difficult to design an app with a single predictable look and feel."

Powell stresses that Google has "no desire" to restrict manufacturers from designing their own themed experience across Android-powered devices. "In Android 4.0's API (level 14) we've added a new public theme family to complement the Holo family introduced in Android 3.0: DeviceDefault," he writes. "DeviceDefault themes are aliases for the device's native look and feel. The DeviceDefault theme family and widget style family offer ways for developers to target the device's native theme with all customizations intact. Formally separating these theme families will also make future merges easier for manufacturers updating to a new platform version, helping more devices update more quickly."

Android 4.0 delivers the tablet-optimized innovations introduced in Google's Android 3.0 Honeycomb update to all devices in an effort to reduce platform fragmentation. Google first confirmed Ice Cream Sandwich's forthcoming launch during its annual I/O developer conference in May, promising that moving forward, the same version of Android will run across all devices, regardless of screen size.

Android devices make up 46.9 percent of all smartphones across the United States, up 3.1 percentage points since August 2011, according to a recent comScore report. Late last year, Google senior vice president of mobile Andy Rubin announced the company now activates more than 700,000 new Android-powered devices each day.

For more:
- read this Android Developers Blog entry

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