Android 4.1 Jelly Bean

Welcome to Android 4.1, Jelly Bean!

Android 4.1 is the fastest and smoothest version of Android yet. We’ve made improvements throughout the platform and added great new features for users and developers. This document provides a glimpse of what's new for developers.

See the Android 4.1 APIs document for a detailed look at the new developer APIs,

Find out more about the Jelly Bean features for users atwww.android.com

Faster, Smoother, More Responsive

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Android 4.1 is optimized to deliver Android's best performance and lowest touch latency, in an effortless, intuitive UI.

To ensure a consistent framerate, Android 4.1 extends vsync timing across all drawing and animation done by the Android framework. Everything runs in lockstep against a 16 millisecond vsync heartbeat — application rendering, touch events, screen composition, and display refresh — so frames don’t get ahead or behind.

Android 4.1 also adds triple buffering in the graphics pipeline, for more consistent rendering that makes everything feel smoother, from scrolling to paging and animations.

Android 4.1 reduces touch latency not only by synchronizing touch to vsync timing, but also by actually anticipatingwhere your finger will be at the time of the screen refresh. This results in a more reactive and uniform touch response. In addition, after periods of inactivity, Android applies a CPU input boost at the next touch event, to make sure there’s no latency.

Tooling can help you get the absolute best performance out of your apps. Android 4.1 is designed to work with a new tool called systrace, which collects data directly from the Linux kernel to produce an overall picture of system activities. The data is represented as a group of vertically stacked time series graphs, to help isolate rendering interruptions and other issues. The tool is available now in the Android SDK (Tools R20 or higher)

Enhanced Accessibility

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New APIs for accessibility services let you handle gestures and manage accessibility focus as the user moves through the on-screen elements and navigation buttons using accessibility gestures, accessories, and other input. The Talkback system and explore-by-touch are redesigned to use accessibility focus for easier use and offer a complete set of APIs for developers.

Accessibility services can link their own tutorials into the Accessibility settings, to help users configure and use their services.

Apps that use standard View components inherit support for the new accessibility features automatically, without any changes in their code. Apps that use custom Views can use new accessibility node APIs to indicate the parts of the View that are of interest to accessibility services.