Apps By Carl Parker. Warning The instructions in this guide are intended for use with all Android devices running Android 4. The information in this guide is provided for instructional and educational purposes only.
There is no guarantee that these instructions will work under your specific and unique circumstances. Use these instructions at your own risk.
We shall not hold any responsibility or liability for whatever happens to you or your device arising from your use of the info in this guide. Read and understand the whole guide first before actually performing the instructions. Requirements Any Android device running Android 4. For backup tips, check our guides on how to sync your data to the cloud and how to create local backups of your mobile data.
Easier text input - an improved algorithm for tap-typing recognition makes text input easier. Bluetooth Smart support a. Restricted profiles - put your tablet into a mode with limited access to apps and content. Setup wizard simplification - getting started on Android is easier thanks to the ability to correct previous input, and because of streamlined user agreements.
Faster user switching - switching users from the lock screen is now faster. Explore these carousel items. Use the previous and next buttons, as well as the keyboard arrows, to change the displayed item. An even sweeter Jelly Bean Jelly Bean 4. Apps with permission to access and change Wi-Fi can configure authentication credentials for a variety of EAP and Phase 2 authentication methods. This protects the operating system against potential security vulnerabilities. The KeyChain API now provides a method that allows applications to confirm that system-wide keys are bound to a hardware root of trust for the device.
This provides a place to create or store private keys that cannot be exported off the device, even in the event of a root or kernel compromise. Using the APIs, apps can create or store private keys that cannot be seen or used by other apps , and can be added to the keystore without any user interaction. The keystore provider provides the same security benefits that the KeyChain API provides for system-wide credentials, such as binding credentials to a device.
Private keys in the keystore cannot be exported off the device. This reduces root attack surface and likelihood of potential security vulnerabilities. Systrace uses a new command syntax and lets you collect more types of profiling data. You can now collect trace data from hardware modules , kernel functions , Dalvik VM including garbage collection, resources loading , and more. There's minimal impact on the performance of your app, so timings reported give you an accurate view of what your app is doing.
You can visualize app-specific events in a timeline in the Systrace output file and analyze the events in the context of other kernel and user space trace data.
Together with existing Systrace tags, custom app sections can give you new ways to understand the performance and behavior of your apps. On-screen GPU profiling in Android 4. You can choose to display profiling data as on-screen bar or line graphs , with colors indicating time spent creating drawing commands blue , issuing the commands orange , and waiting for the commands to complete yellow. The system updates the on-screen graphs continuously, displaying a graph for each visible Activity, including the navigation bar and notification bar.
If you see operations that cross the green line, you can analyze them further using Systrace and other tools. On devices running Android 4. This new policy helps you catch and fix such cases. Improvements in the hardware-accelerated 2D renderer make common animations such as scrolling and swiping smoother and faster.
In particular, drawing is optimized for layers, clipping and certain shapes rounded rects, circles and ovals. A variety of WebView rendering optimizations make scrolling of web pages smoother and free from jitter and lags. It automatically takes advantage of GPU computation resources whenever possible, dramatically improving performance for graphics and image processing. Any app using Renderscript on a supported device can benefit immediately from this GPU integration without recompiling.
All screen sizes now feature the status bar on top, with pull-down access to notifications and a new Quick Settings menu. The familiar system bar appears on the bottom, with buttons easily accessible from either hand. The Application Tray is also available on all screen sizes. Now several users can share a single Android tablet , with each user having convenient access to a dedicated user space. Users can switch to their spaces with a single touch from the lock screen.
On a multiuser device, Android gives each user a separate environment, including user-specific emulated SD card storage. Users also have their own homescreens, widgets, accounts, settings, files, and apps, and the system keeps these separate. All users share core system services, but the system ensures that each user's applications and data remain isolated. In effect, each of the multiple users has their own Android device. Users can install and uninstall apps at any time in their own environments.
To save storage space, Google Play downloads an APK only if it's not already installed by another user on the device. If the app is already installed, Google Play records the new user's installation in the usual way but doesn't download another copy of the app. Multiple users can run the same copy of an APK because the system creates a new instance for each user, including a user-specific data directory. For developers, multi-user support is transparent — your apps do not need to do anything special to run normally in a multi-user environment and there are no changes you need to make in your existing or published APKs.
The system manages your app in each user space just as it does in a single-user environment. You can extend app widgets to run on the lock screen, for instant access to your content. In Android 4. Users can add as many as five lock screen widgets, choosing from widgets provided by installed apps. The lock screen displays each widget in its own panel, letting users swipe left and right to view different panels and their widgets. Like all app widgets, lock screen widgets can display any kind of content and they can accept direct user interaction.
They can be entirely self-contained, such as a widget that offers controls to play music, or they can let users jump straight to an Activity in your app, after unlocking along the way as needed. For developers, lock screen widgets offer a great new way to engage users. You can take advantage of this new capability by building a new app widget or by extending an existing home screen widget.
If your app already includes home screen widgets, you can extend them to the lock screen with minimal change. To give users an optimal experience, you can update the widget to use the full lock screen area when available and resize when needed on smaller screens. You can also add features to your widgets that might be especially useful or convenient on the lock screen. In this mode, the system launches a daydream — a remote content service provided by an installed app — as the device screensaver.
A user can enable Daydream from the Settings app and then choose the daydream to display. Daydreams combine the best capabilities of live wallpapers and home screen widgets, but they are more powerful. They let you offer the any kind of content in a completely new context, with user interactions such as flipping through photos, playing audio or video, or jumping straight into your app with a single touch.
Because daydreams can start automatically when a device is charging or docked, they also give your app a great way to support new types of user experiences, such as leanback or exhibition mode, demo or kiosk mode, and "attract mode" — all without requiring special hardware. Daydream lets you create powerful interactive screensavers that display any kind of content. They can play video and audio and they can even accept direct user interaction.
You can provide multiple daydreams in your app and you can offer distinct content and display settings for each. Apps can build on this to deliver new kinds of interaction and entertainment experiences to users. Apps interact with displays through a new display manager system service. Your app can enumerate the displays and check the capabilities of each, including size, density, display name, ID, support for secure video, and more. Your app can also receive callbacks when displays are added or removed or when their capabilities change, to better manage your content on external displays.
Your app just gives the display to use, a theme for the window, and any unique content to show. The Presentation handles inflating resources and rendering your content according to the characteristics of the targeted display. You can take full control of two or more independent displays using Presentation.
A Presentation gives your app full control over the remote display window and its content and lets you manage it based on user input events such as key presses, gestures, motion events, and more. You can use all of the normal tools to create a UI and render content in the Presentation, from building an arbitrary view hierarchy to using SurfaceView or SurfaceTexture to draw directly into the window for streamed content or camera previews.
When multiple external displays are available, you can create as many Presentations as you need, with each one showing unique content on a specific display. For this, the system can help your app choose the best display to use. Alternatively, you can use the media router service, extended in Android 4. Your app can display content by default in the main Activity until a preferred Presentation display is attached, at which time it can automatically switch to Presentation content on the preferred display.
For apps that handle protected or encrypted content, the display API now reports the secure video capabilities of attached displays. Your app query a display to find out if it offers a secure video output or provides protected graphics buffers and then choose the appropriate content stream or decoding to make the content viewable. For additional security on SurfaceView objects, your app can set a secure flag to indicate that the contents should never appear in screenshots or on a non-secure display output, even when mirrored.
When a wireless display is connected, users can stream any type of content to the big screen, including photos, games, maps, and more. Apps can take advantage of wireless displays in the same way as they do other external displays and no extra work is needed.
The system manages the network connection and streams your Presentation or other app content to the wireless display as needed. Developers can now mirror their layouts for RTL languages. With native RTL support, you can deliver the same great app experience to all of your users, whether their language uses a script that reads right-to-left or one that reads left-to-right.
When the user switches the system language to a right-to-left script, the system now provides automatic mirroring of app UI layouts and all view widgets, in addition to bidi mirroring of text elements for both reading and character input.
Your app can take advantage of RTL layout mirroring in your app with minimal effort. The system then handles the mirroring and display of your UI as appropriate.
For precise control over your app UI, Android 4. You can even create custom versions of layout, drawables, and other resources for display when a right-to-left script is in use. For more control over your UI components and to make them more modular, Android 4.
For any Fragment, a new Fragment manager lets you insert other Fragments as child nodes in the View hierarchy. You can use nested Fragments in a variety of ways, but they are especially useful for implementing dynamic and reusable UI components inside of a UI component that is itself dynamic and reusable. For example, if you use ViewPager to create fragments that swipe left and right, you can now insert fragments into each Fragment of the view pager.
To let you take advantage of nested Fragments more broadly in your app, this capability is added to the latest version of the Android Support Library. The system now helps accessibility services distinguish between touch exploration and accessibility gestures while in touch-exploration mode. When a user touches the screen, the system notifies the service that a generic touch interaction has started. It then tracks the speed of the touch interaction and determines whether it is a touch exploration slow or accessibility gesture fast and notifies the service.
When the touch interaction ends, the system notifies the service. The system provides a new global accessibility option that lets an accessibility service open the Quick Settings menu based on an action by the user. Also added in Android 4. To give accessibility services insight into the meaning of Views for accessibility purposes, the framework provides new APIs for associating a View as the label for another View. The label for each View is available to accessibility services through AccessibilityNodeInfo.
On supported devices, apps can use a new HDR camera scene mode to capture an image using high dynamic range imaging techniques. Additionally, the framework now provides an API to let apps check whether the camera shutter sound can be disabled. Apps can then let the user disable the sound or choose an alternative sound in place of the standard shutter sound, which is recommended.
Filterscript is a subset of Renderscript that is focused on optimized image processing across a broad range of device chipsets. Filterscript is ideal for hardware-accelerating simple image-processing and computation operations such as those that might be written for OpenGL ES fragment shaders. Because it places a relaxed set of constraints on hardware, your operations are optimized and accelerated on more types of device chipsets.
Any app targeting API level 17 or higher can make use of Filterscript. Intrinsics are available for blends, blur, color matrix, 3x3 and 5x5 convolve, per-channel lookup table, and converting an Android YUV buffer to RGB.
You can now create groups of Renderscript scripts and execute them all with a single call as though they were part of a single script. This allows Renderscript to optimize execution of the scripts in ways that it could not do if the scripts were executed individually.
Renderscript image-processing benchmarks run on different Android platform versions Android 4. If you have a directed acyclic graph of Renderscript operations to run, you can use a builder class to create a script group defining the operations. At execution time, Renderscript optimizes the run order and the connections between these operations for best performance. When you use Renderscript for computation operations, you apps benefit from ongoing performance and optimization improvements in the Renderscript engine itself, without any impact on your app code or any need for recompilation.
As optimization improves, your operations execute faster and on more chipsets, without any work on your part.
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