The Beautiful Design Winter 2013 Collection on Google Play

Posted by Marco Paglia, Android Design Team

While beauty’s in the eye of the beholder, designing apps for a platform also requires an attention to platform norms to ensure a great user experience. The Android Design site is an excellent resource for designers and developers alike to get familiar with Android’s visual, interaction, and written language. Many developers have taken advantage of the tools and techniques provided on the site, and every now and then we like to showcase a few notable apps that go above and beyond the guidelines.

This summer, we published the first Beautiful Design collection on Google Play. Today, we're refreshing the collection with a new set of apps just in time for the holiday season.

As a reminder, the goal of this collection is to highlight beautiful apps with masterfully crafted design details such as beautiful presentation of photos, crisp and meaningful layout and typography, and delightful yet intuitive gestures and transitions.

The newly updated Beautiful Design Winter 2013 collection includes:

Timely (by Bitspin), a clock app that takes animation to a whole new level. Screen transitions are liquid smooth and using the app feels more like playing with real objects than fussing around with knobs and buttons. If you’ve ever wondered if setting an alarm could be fun, Timely unequivocally answers “yes”.

Circa, a news reader that’s fast, elegant and full of beautiful design details throughout. Sophisticated typography and banner image effects, coupled with an innovative and "snappy" interaction, makes reading an article feel fast and very, very fun.

Etsy, an app that helps you explore a world of wonderful hand-crafted goods with thoughtfully designed screen transitions, beautifully arranged layouts, and subtle flourishes like a blur effect that lets you focus on the task at hand. This wonderfully detailed app is an absolute joy to use.

Airbnb, The Whole Pantry, Runtastic Heart Rate Pro, Tumblr, Umano, Yahoo! Weather… each with delightful design details.

Grand St. and Pinterest, veterans of the collection from this summer.

If you’re an Android developer, make sure to play with some of these apps to get a sense for the types of design details that can separate good apps from great ones. And remember to review the Android Design guidelines and the Android Design in Action video series for more ideas on how to design your next beautiful Android app.

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Changes to the SecretKeyFactory API in Android 4.4

Posted by Trevor Johns, Android Developer Relations team

In order to encrypt data, you need two things: some data to encrypt and an encryption key. The encryption key is typically a 128- or 256-bit integer. However, most people would rather use a short passphrase instead of a remembering a 78-digit number, so Android provides a way to generate an encryption key from ASCII text inside of javax.crypto.SecretKeyFactory.

Beginning with Android 4.4 KitKat, we’ve made a subtle change to the behavior of SecretKeyFactory. This change may break some applications that use symmetric encryption and meet all of the following conditions:

1. Use SecretKeyFactory to generate symmetric keys, and


2. Use PBKDF2WithHmacSHA1 as their key generation algorithm for SecretKeyFactory, and


3. Allow Unicode input for passphrases

Specifically, PBKDF2WithHmacSHA1 only looks at the lower 8 bits of Java characters in passphrases on devices running Android 4.3 or below. Beginning with Android 4.4, we have changed this implementation to use all available bits in Unicode characters, in compliance with recommendations in PCKS #5.

Users using only ASCII characters in passphrases will see no difference. However, passphrases using higher-order Unicode characters will result in a different key being generated on devices running Android 4.4 and later.

For backward compatibility, we have added a new key generation algorithm which preserves the old behavior: PBKDF2WithHmacSHA1And8bit. Applications that need to preserve compatibility with older platform versions (pre API 19) and meet the conditions above can make use of this code:

import android.os.Build;
 
SecretKeyFactory factory;
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
   // Use compatibility key factory -- only uses lower 8-bits of passphrase chars
   factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1And8bit");
} else {
   // Traditional key factory. Will use lower 8-bits of passphrase chars on
   // older Android versions (API level 18 and lower) and all available bits
   // on KitKat and newer (API level 19 and higher).
   factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
}

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New Tools to Take Your Games to the Next Level

In this mobile world, games aren't just for the hardcore MMOG fan anymore, they're for everyone; in fact, three out of four people with an Android phone or tablet play games. If you're a game developer, Google has a host of tools available for you to help take your game to the next level, including Google Play game services, which let's you leverage Google's strength in mobile and cloud services so you can focus on building compelling game experiences for your users. Today, we're adding more tools to your gaming toolbox, like the open sourcing of a 2D physics library, as well as new features to the Google Play game services offering, like a plug-in for Unity.

LiquidFun, a rigid-body physics library with fluid simulation

First, we are announcing the open-source release of LiquidFun, a new C++ 2D physics library that makes it easier for developers to add realistic physics to their games.

Based on Box2D, LiquidFun features particle-based fluid simulation. Game developers can use it for new game mechanics and add realistic physics to game play. Designers can use the library to create beautiful fluid interactive experiences.

The video clip below shows a circular body falling into a viscous fluid using LiquidFun.

The LiquidFun library is written in C++, so any platform that has a C++ compiler can benefit from it. To help with this, we have provided a method to build the LiquidFun library, example applications, and unit tests for Android, Linux, OSX and Windows.

We’re looking forward to seeing what you’ll do with LiquidFun and we want to hear from you about how we can make this even better! Download the latest release from our LiquidFun project page on GitHub and join our discussion list!

Google Play Games plug-in for Unity

If you are a game developer using Unity, the cross-platform game engine from Unity Technologies, you can now more easily integrate game services using a new Google Play Games plug-in for Unity. This initial version of the plug-in supports sign-in, achievements, leaderboards and cloud save on Android and iOS. You can download the plug-in from the Play Games project page on GitHub, along with documentation and sample code.

New categories for games in Google Play

New game categories are coming to the Play Store in February 2014, such as Simulation, Role Playing, and Educational! Developers can now use the Google Play Developer Console to choose a new category for their apps if the Application Type is “Games”. The New Category field in the Store Listing will set the future category for your game. This will not change the category of your game on Google Play until the new categories go live in February 2014.

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