fidzu : Android

Bose launched a successor to their well received noise cancelling QuietComfort 35 (QC35) headphones yesterday with Google Assistant integration, dubbed the QC35 II. They work via Bluetooth with both Android (Marshmallow and above) and iOS, and feature a dedicated Google Assistant button on the left ear cup. Voice activated commands can now play music, messages, news and of course […]

Come comment on this article: Bose QC35 II Headphones Launch with Google Assistant

22 Sep 2017 9:06pm GMT

According to sources that spoke to Reuters today, "T-Mobile US Inc is close to agreeing (on) tentative terms on a deal to merge with Sprint Corp." A merger of the two wireless carriers has been an on-again, off-again deal for several years with the two never quite able to get the time and business environment […]

Come comment on this article: Breakthrough in T-Mobile, Sprint deal as companies are close to agreement

22 Sep 2017 6:26pm GMT

Earlier this summer Motorola announced an addition to their G series of devices, the Moto G5S Plus. The new device was described as a "special edition" of the Moto G5 Plus, but in reality is an upgrade to the former device. That should make it a smartphone worthy of consideration by mid-tier buyers as we […]

Come comment on this article: Motorola now taking pre-orders for Moto G5S Plus with discount for early adopters

22 Sep 2017 5:30pm GMT

When Google launched the Moto X4 Android One device on Project Fi earlier this week, one of their selling points was the potential for Nexus device owners to trade-in their old phone for a credit against their new purchase. The ability to trade-in a phone as part of a device purchase is expanding to now be […]

Come comment on this article: Trade-in program through Google Store going live

22 Sep 2017 4:11pm GMT

VPNs are incredibly important, and for the right price, you can get a reliable one like VPNTunnel to keep yourself anonymous while browsing the web. We've got a deal on a lifetime subscription VPNTunnel that will cover up to 10 of your devices. VPNTunnel offers unlimited bandwidth and doesn't log your activities, which are both great […]

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22 Sep 2017 4:00pm GMT

For many people, Facebook has become a prime point of contact for their time spent online. That is not stopping the company from continuing to explore ways to keep users on the site even more and trying to find ways to entice new users to get on-board. For example, they have launched a dedicated section […]

Come comment on this article: Facebook testing new Explore Feed tab on Android

21 Sep 2017 4:32pm GMT

Looking for a new set of headphones to get you through your morning commute, block out your coworkers, or just jam out at home? We got our hands on the iFrogz Impulse Duo Bluetooth headphones which offer powerful sound in a sleek package that clips right to your shirt, belt, or bag. Are they worth […]

Come comment on this article: iFrogz Impulse Duo Bluetooth headset review

21 Sep 2017 4:03pm GMT

Computer maintenance can be a real pain, but the good news is there is plenty of software that can take the frustration out of it. Our Power PC Systems Optimization bundle includes a few programs that will get your PC running better than ever. The first program is IOBit's Driver Booster Pro 4 that will […]

Come comment on this article: [TA Deals] Fine tune your PC with this Systems Optimization Bundle on the cheap

21 Sep 2017 4:00pm GMT

NVIDIA has announced a new slimmed down SHIELD TV bundle that's aimed at someone who wants all of the advanced tricks that the box has to offer but doesn't really care about the gaming aspect. This bundle includes the SHIELD TV and a remote, but ditches the controller to shave a bit off the price […]

Come comment on this article: NVIDIA announces a new remote-only SHIELD TV bundle, already up for preorder

21 Sep 2017 3:25pm GMT

Rumors have been swirling around about an HTC acquisition by Google, and it kinda sorta almost happened. The two companies have announced a whopping $1.1 billion cooperation agreement that's not quite a full buyout, but should still help both companies long term. Right now, Google is going to acquire some of HTC's employees, many of […]

Come comment on this article: Google makes a major investment in HTC in exchange for employees and IP portfolio

21 Sep 2017 2:18am GMT

Throughout 2017 we have been monitoring several initiatives the Google has been working on to expand their U.S. smartphone offerings outside of their own Pixel devices. Two of the moves we have been watching involve the addition of non-Google devices to the Project Fi catalog and the launch of Android One in the U.S. Those […]

Come comment on this article: Android One comes to U.S. on the Moto X4 through Project Fi

20 Sep 2017 7:31pm GMT

If you need a new set of wireless earbuds to exercise in, we've got you covered. You can grab the TREBLAB XR500 Wireless Sports Earbuds at a hefty discount right now, offering a durable set of Bluetooth headphones with sweat resistance, a 9-hour battery life, and noise cancellation. Enjoy crisp treble & deep bass free of […]

Come comment on this article: [TA Deals] Save 79% on the TREBLAB XR500 Wireless Sports Earbuds

20 Sep 2017 4:00pm GMT

Invites are out for Google's Pixel event on October 4th, and thanks to a massive leak from Droid Life, just about everything has leaked. That might remove the surprise element from the show, but it doesn't diminish how exciting the new products are. Starting with the third generation Chromebook Pixel, now called the Google Pixelbook, we're […]

Come comment on this article: Google's entire October 4th launch event lineup has already leaked

20 Sep 2017 3:22pm GMT

At one time Nokia was the force to be reckoned with in the cell phone market. After missing the smartphone juggernaut, Nokia has floated along with different owners and tested the smartphone market with both Windows and Android powered devices. Since being purchased by HMD Global though, it seems the company is going full-on with […]

Come comment on this article: Nokia 9 renders and info leaks for latest HMD Global flagship

20 Sep 2017 2:30pm GMT

In just under a month from now, on October 16th, the Huawei Mate 10 will be officially announced by the Chinese manufacturer. We still do not know exactly how many variants of the device will be hitting the smartphone market, but we do know that at least one of them will come with the AI-infused […]

Come comment on this article: New image of Huawei Mate 10 shows up

20 Sep 2017 1:04pm GMT

Posted by Neto Marin, Developer Advocate

In June we announced the developer preview for a new Google Play Billing Library. Today, we are pleased to announce the official release of the Play Billing Library 1.0. This library simplifies the development process for Google Play Billing, allowing you to focus your efforts on your app.

Thank you for your valuable feedback and suggestions that helped us reach the 1.0 release. Watch the video below for a quick overview of the library's features.

Before you start

With Play Billing, you can receive payments from users around the world via a payment system they trust and you can take advantage of features and reports in the Play Console to manage and earn more revenue.

If you have never implemented in-app billing in your apps, or you want to know what you can offer using Play Billing Library, read the In-app Billing Overview to familiarize yourself with concepts and terminology that make it easier for you to implement In-app Billing using the Play Billing Library.

Getting started

Play Billing Library is available through Maven repository, and adding Play Billing Library to your project is simple as adding the following dependency into your app's build.gradle file:

dependencies {
    ...
    compile 'com.android.billingclient:billing:1.0'
}

The Play Billing Library 1.0 automatically adds the com.android.vending.BILLING permission to your APK. This means you no longer need to manually include it in your application module's manifest.

BillingClient and PurchasesUpdatedListener

These classes are the most important pieces when integrating the library into your Android app. The BillingClient is the bridge between your app and Google Play. You will use it for listing available products, starting the billing flow for in-app products or subscriptions (i.e. opening the payment interface), getting user purchases, and creating or modifying subscriptions.

When creating your BillingClient instance, you'll need to set a PurchasesUpdatedListener. This allows your app to receive updates from the In-app Billing API, including transaction results after the billing flow, as well as purchases completed outside of your app, e.g. user redeemed a Promo Code or bought a product on another device.

The following code demonstrates how you could override the onPurchasesUpdated() method of your PurchasesUpdatedListener:

@Override
void onPurchasesUpdated(@BillingResponse int responseCode,
        List<Purchase> purchases) {
    if (responseCode == BillingResponse.OK
            && purchases != null) {
        for (Purchase purchase : purchases) {
            handlePurchase(purchase);
        }
    } else if (responseCode == BillingResponse.USER_CANCELED) {
        // Handle an error caused by a user canceling the purchase flow.
    } else {
        // Handle any other error codes.
    }
}

You can implement the PurchasesUpdatedListener in your Activity or in any other class you want, according to your app's architecture. And here's the code for creating the BillingClient instance, and setting the PurchasesUpdatedListener:

mBillingClient = BillingClient.newBuilder(mContext)
                              .setListener(mPurchasesUpdatedListener)
                              .build();

Listing and selling products

To sell products in your app, first, you need to add them using the Play Console. For more details about how to add in-app products see the page Administering In-app Billing.

Attention: If this is a brand new app, before adding the products you must publish it to the alpha or beta distribution channel. For more information, see Draft Apps are No Longer Supported.

To get a list of product details with prices for current user, call querySkuDetailsAsync(). You must also specify a listener which implements the SkuDetailsResponseListener interface. You can then override the onSkuDetailsResponse() method which notifies the listener when the query finishes, as illustrated by the following sample code:

List<String> skuList = new ArrayList<> ();
skuList.add("premiumUpgrade");
skuList.add("gas");
SkuDetailsParams.Builder params = SkuDetailsParams.newBuilder();
params.setSkusList(skuList).setType(SkuType.INAPP);
mBillingClient.querySkuDetailsAsync(params.build(),
    new SkuDetailsResponseListener() {
        @Override
        public void onSkuDetailsResponse(SkuDetailsResult result) {
            // Process the result.
        }
    })

After the user chooses a product to buy, you'll need to start the billing flow and handle the transaction result. To start a purchase request from your app, call the launchBillingFlow() method on the Play Billing Library client. You must call the launchBillingFlow() method (and all the other methods from BillingClient) from the UI thread.

The launchBillingFlow() method needs BillingFlowParams object that contains relevant data for completing the purchase, such as the product ID of the item to purchase and the product type (in this case, SkuType.INAPP). To get an instance of BillingFlowParams, construct it with newBuilder() method:

BillingFlowParams.Builder builder = BillingFlowParams
                                       .newBuilder()
                                       .setSku(skuId).setType(SkuType.INAPP);
int responseCode = mBillingClient.launchBillingFlow(builder.build());

As we mentioned earlier, the transaction result will be sent to the onPurchasesUpdated() method. For details how to process the data received on onPurchasesUpdated() and how to handle a purchase, check the section Purchase an item in our training guide.

Consuming products

By default, all in-app products are managed. It means that Google Play tracks the product ownership and doesn't allow to buy multiple times. To be able to buy a product again, you must consume the product before it becomes available again.

It's common to implement consumption for in-app products which users may want to purchase multiple times, such as in-game currency or equipment. You typically don't want to implement consumption for in-app products that user purchases once and provide a permanent effect, such as a premium upgrade.

To consume a product, call the consumeAsync() method on the Play Billing Library client and pass in the purchaseToken String value returned when you made the purchase. The consumption result is returned via onConsumeResponse() method of the ConsumeResponseListener interface, that you must override to handle the consumption result.

The following example illustrates consuming a product using the associated purchaseToken:

ConsumeResponseListener listener = new ConsumeResponseListener() {
    @Override
    public void onConsumeResponse(@BillingResponse int responseCode, 
                                  String outToken) {
        if (responseCode == BillingResponse.OK) {
            // Handle the success of the consume operation.
            // For example, increase the number of player's coins,
            // that provide temporary benefits
        }
    }
};
mBillingClient.consumeAsync(purchaseToken, listener);

Sample updated: Trivial Drive V2

With a new library comes a refreshed sample! To help you to understand how to implement in-app billing in your app using the new Play Billing Library, we've rewritten the Trivial Drive sample from the ground up.

Since we released Trivial Drive back in 2013, many new features, devices, and platforms have been added to the Android ecosystem. To reflect this evolution, the Trivial Drive v2 sample now runs on Android TV and Android Wear.

What's next?

Before integrating within your app, you can try the Play Billing Library with the codelab published during Google I/O 2017: Buy and Subscribe: Monetize your app on Google Play.

In this codelab, you will start with a simplified version of Trivial Drive V2 that lets users to "drive" and then you will add in-app billing to it. You'll learn how to integrate purchases and subscriptions as well as the best practices for developing reliable apps that handle purchases.

Get more info on the Play Billing Library and the official reference for classes and methods documentation on the Android Developers website. For a step-by-step guide to implementing the Play Billing Library in your project, visit the library's training class.

We still want your feedback

If you have issues or questions, file a bug report on the Google Issue Tracker, and for issues and suggestions on the sample (like a bug or a new feature), contact us on the Trivial Drive issues page.

For technical questions on implementation, library usage, and best practices, you can use the tags google-play and play-billing-library on StackOverflow or visit the communities on our Google+ page.

19 Sep 2017 4:21pm GMT

Posted by Dave Smith, Developer Advocate for IoT

Android Things lets you build professional, mass-market products on a trusted platform, without previous knowledge of embedded system design. With Android Things you get a turnkey hardware solution and an easy-to-use software development platform based on Android Studio and the Android SDK -- making it easy to build designs that scale to production. Android Things is currently in developer preview and we'd love to see what you can build with our latest release.

Today we are announcing a contest with Hackster and NXP for developers to showcase their use of Android Things with other Google developer platforms. Project ideas should be added to Google's Hackster.io Community by including Android Things as a software component, then registered through the contest page.

Idea Submissions

Submit your project ideas starting today. Ideas submitted by September 29, 2017 are eligible to receive one of 120 Pico Pi i.MX6UL Kits to use in the final design. During this phase, projects do not need to be complete; we just want to see your amazing ideas! We are looking for concepts in the following categories:

• Smart Home
• Robotics
• Smart City
• Industrial IoT / Manufacturing
• Retail
• Entertainment

Project Submissions

Final projects must be submitted by Oct 31, 2017. Your project does not need to be one of the chosen recipients of a Pico kit to be eligible for the grand prize. Winners will receive support from Avnet, Dragon Innovation and Kickstarter to take their ideas from prototype to production. See the contest page for more details.

We are eager to see the projects that you come up with. More importantly, we're excited to see how your work can inspire other developers to create something great with Android Things. To learn more about the benefits of Android Things, watch the recording from the Bootstrapping IoT Products with Android Things webinar. You can also join Google's IoT Developers Community on Google+, a great resource to get updates, ask questions, and discuss ideas.

15 Sep 2017 5:00pm GMT

Posted by William Luh, Software Engineer

Google Play Protect, which includes the Verify Apps security feature, helps keep users safe from harmful apps. Google Play Protect is available on all Android devices with Google Play installed and provides users with peace of mind and insights into the state of their device security.

App developers can get similar security insights into the installed apps landscape on user devices from the SafetyNet Verify Apps API. This new suite of APIs lets developers determine whether a user's device is protected by Google Play Protect, encourage users not already using Google Play Protect to enable it, and identify any known potentially harmful apps (PHAs) that are installed on the device.

These APIs are especially useful for developers of apps that may be impacted by installed PHAs on the same device as their app. Determining that Google Play Protect is enabled with isVerifyAppsEnabled() gives developers additional assurance that a device is more likely to be clean. If a device doesn't have Google Play Protect enabled, developers can request that the user enable Google Play Protect with enableVerifyApps(). With Google Play Protect enabled, developers can use the listHarmfulApps() method to determine whether there are any potentially harmful apps installed on a user's device. This easy-to-use suite of features does not require API keys and requesting quota.

Enterprise-focused apps in particular may benefit from using the Verify Apps API. Enterprise apps are designed to safeguard a company's data from the outside world. These apps often implement strict enforcements, such as ensuring the mobile device is approved by the enterprise and requiring a strong password for lockscreens. If any of the criteria are not satisfied, the enterprise may revoke credentials and remove sensitive data from the device. Having a mechanism to enforce Google Play Protect and scan for PHAs is another tool to help enterprise app developers keep enterprise data and devices safe.

For better protection, developers should use the attestation API along with the new Verify Apps API. Use the attestation API first to establish that the device has not been modified from a known state. Once the Android system can be trusted, the results from the Verify Apps API can be trusted. Existing attestation API users may find additional benefits in using the Verify Apps API as it may be able to detect on-device PHAs. In general, using multiple signals for anti-abuse detection is encouraged.

To learn how to use this API in your app, check out the developer docs.

14 Sep 2017 7:55pm GMT

Posted by Daraiha Greene, CS Education in Media Program Manager, Multicultural Strategy, and Kate Brennan and Mathilde Cohen Solal, Google Play

Today, we are thrilled to announce Infinite Deviation: Games. Infinite Deviation is aninitiative created by Google Computer Science (CS) in Media and Ideas United in order to tackle issues of representation by bringing creativity and computer science together in unexpected ways -- ensuring that representations of computer scientists are inclusive of women, people of color, the LGBTQIA+ community, people with disabilities, and other underrepresented groups. Last year, Infinite Deviation produced a series of narrative short films to dispel stereotypes in computer science and is excited to collaborate with Google Play to bring the Infinite Deviation program to gaming.

Currently only 23% of people in the gaming industry identify as women and only 3% of game developers are African-American. From ensuring women are represented in video games to giving young girls the chance to create their own games, Google Play is committed to bringing new, diverse voices to gaming. The program gives game designers from all backgrounds the chance to pitch an original mobile game concept and have it developed, published, and promoted in partnership with Google Play. Applicants can submit their mobile game concepts until October 9.

The top three ideas will be chosen by a panel of industry experts and designers will receive the resources and support they need to bring their games to life on Google Play. Games will be judged on creativity and innovation, as well as their ability to tell original stories that resonate with underrepresented audiences.

Participants must have less than two years of professional game design experience in order to be eligible. For more information on the program, including how to apply, you can visit InfiniteDeviation.com.

By promoting original games that resonate with underrepresented audiences, we hope the program creates more favorable perceptions of computer science, bust biases, and nurture acceptance through an activity many enjoy.

13 Sep 2017 4:21pm GMT

Posted by Adriana Puchianu, Google Play Developer Marketing

There are increasing growth opportunities for indie game developers, but being one can still feel daunting in today's crowded gaming industry. We've been working hard to help indie developers find an audience and to recognize them for their creativity and innovation. We launched the Indie Corner as a destination for exciting new games along with longstanding indie masterpieces. Since launch, more than 380 games have been featured. Earlier this year, we launched Android Excellence which showcases apps and games that deliver incredible user experiences on Android, while providing another opportunity to be discovered on Google Play.

We've also held several indie games contests across the globe, giving indies the chance to showcase their games and find new audiences. In April, we selected the winner of the second Indie Games Festival in South Korea and we recently announced the top 20 finalists of this year's San Francisco event. Come and see the finalists in person on September 23rd, it's free to attend and open to the public. Soon we'll be bringing back the second Indie Games Contest in Europe too.

Watch François Alliot, the developer of Reigns, an indie game showcased in Android Excellence and the winner of last year's Indie Games Contest in Europe, share how he built a successful games business in the video below.

And, finally, check out our recent Q&A with Spry Fox, makers of the popular game Alphabear, to learn more about what it's like to be an indie game developer.

08 Sep 2017 8:16pm GMT

APP_STL := c++_shared

-DANDROID_STL=c++_shared

externalNativeBuild {
    cmake {
        arguments "-DANDROID_STL=c++_shared"
    }
}

07 Sep 2017 9:07pm GMT

Posted by Cheryl Lindo Jones, Mobile App Solutions Consultant, Google Play

As more Chromebooks are enabled with Google Play, now is a great time to optimize your Android app for Chromebooks to reach a larger audience. The changes made to optimize for large screens will benefit mobile devices that are able to project to desktop monitors, like the Samsung Galaxy S8. The current list of Chromebooks that can access the Play Store continues to grow.

There are several differences to consider when optimizing your Android app or game for Chromebooks:

• Larger screen sizes and higher resolutions
• Multi-window and resizable-window support
• Different hardware input methods: keyboard, trackpad, mouse, stylus
• Convertible Chromebooks enabling use in laptop and tablet modes

Chromebook users can change screen resolutions, switch between various input methods, and convert from laptop to tablet mode at any time, so Android apps and games should handle all of these situations gracefully.

Discoverability on Google Play

If Android apps or games require hardware not available in a Chromebook (like cellular capability or GPS), those titles will not show up on Google Play for Chromebook users, similar to Play on Android tablets. Developers should maximize discoverability on Google Play by doing the following:

Set requested permissions and uses-features in the manifest to ensure compatibility with Chromebooks. Not all Chromebooks will have touchscreens, GPS, or rear-facing cameras which are typical for smartphones. Update the manifest so that sensors and hardware not commonly found on Chromebooks are not required. Example:

<uses-feature android:name="android.hardware.touchscreen"
    android:required="false" />

Additionally, to educate Chromebook users on any Chrome OS-specific features that have been implemented, for example supporting additional input methods like keyboard, trackpad, and stylus, or supporting large, high-resolution screens with a responsive layout, developers should update the app description on Google Play. It would also be useful to provide screenshots showcasing how well the app or game works on the larger screen, or how the title works on a Chromebook specifically.

Optimizing functionality

While most apps and games already work fairly well on Chromebooks without any changes, it is still a good idea to explore how to provide an optimized, consistent experience for Chromebook users.

Large screens and resizable windows

Chromebook users will be more inclined to multitask, opening multiple apps and/or games at once, taking advantage of the screen size, and operating in a manner consistent with a desktop or laptop form factor. Unlike on Android phones, they can also change the screen resolution to fit more onto the screen, or enlarge the fonts, UI, and graphics, if needed. Multi-window support and fully resizable window support are key for this usage. Graphics, fonts, layout, and touch targets should be adjusted accordingly as the screen resolution and orientation changes.

It is also important to note that just because an app or game window is not in focus, it does not mean that it is not visible. For example, if a video app is open in an inactive window, it should continue to play content "in the background" because it could still be visible along side another app window. To fully support multi-window usage in this case, pause video in onStop(), and resume in onStart().

Targeting Android N (API level 24 and higher) will signal to the Chrome OS window manager that compatibility restrictions should not be used. This allows for more flexibility and control on the developer's part for supporting window resizing.

The system will handle window management best if Android N is targeted, but for pre-N API support, windows can be toggled between either a default size selected at app launch, or a full-screen mode with either the window bar visible, or with window UI hidden in immersive full-screen mode.

When handling different windowing modes, it is important to know that the window area for an app or game will be offset by the presence or absence of the window control bar. The app should not assume that the activity will always be at (0,0) in the window. Adjust the layout and touch targets accordingly. It is somewhat common to see apps or games become unresponsive after a window resize or orientation change because it did not gracefully handle the presence of the window control bar, or the higher resolution settings of a Chromebook screen.

Orientation support

Because of the laptop form-factor, Chromebook users expect landscape to be the default orientation for apps on Chromebooks. However, Android apps often assume that portrait is the default orientation to support, due to the typical way users interact with their smartphones. To offer flexibility to users, it is highly recommended to support both portrait and landscape orientations. Some Chromebooks are convertible, so users can change between laptop and tablet modes at will, switching between portrait and landscape orientation, according to what feels comfortable for a given use case.

Most importantly, if possible, do not require a restart if the orientation or window size changes. If a user is in the process of filling out a form, creating or editing some content, or in the middle of a level in a game and loses progress because of an window change -- intentional or not -- it would be a poor user experience.

Developers can monitor window configuration changes using onConfigurationChanged() and dynamically handle those changes by adding this line to the activity's manifest:

android:configChanges="screenSize|smallestScreenSize|orientation|screenLayout".

If it is absolutely necessary to require a restart upon changes to the window, at least restore state by using the onSaveInstanceState() method so that work or state is not lost.

Additionally, it is important to be consistent with the app's orientation as the user is navigating through activities. Currently, the system forces Android apps to follow the orientation of the root activity to help maintain consistency. However, this may result in a situation where, perhaps an app starts out in landscape orientation, and a login screen normally laid out for portrait orientation pops up, and now does not look optimized due to an unresponsive layout. Also, it is still possible to have a case where a springboard activity starts out in an orientation that is different from the primary orientation of the app. Please keep these possible scenarios in mind when designing the layout for activities.

Finally, developers should be aware of the differences in handling cameras and orientation on Chromebooks. Obviously, Android phones have front-facing and rear-facing cameras that are situated at the top of a portrait-oriented screen. The front-facing cameras on Chromebooks are situated at the top of a landscape-oriented screen. Many Chromebooks do not have rear-facing cameras. If an app requires a camera, it would be best to use android.hardware.camera.any to access the front-facing camera, if a rear-facing one is not available. Again, developers should target Android N and, if possible allow the app to be resizable so that the system can take care of properly orienting the camera previews.

Supporting multiple input methods

Chromebook users are used to interacting with webpages and apps using a keyboard and trackpad. Effectively supporting these two input methods for an Android app means:

• Supporting hotkeys for commands that a desktop app user may be familiar with
• Using arrow and tab keys and a trackpad to navigate an activity
• Allowing hover and opening context menus
• Supporting other trackpad gestures to enhance productivity in desktop/laptop mode

Something as simple as hitting return to send text in a messaging app, or allowing a user to navigate fields by hitting the tab key will make an app feel more efficient and cohesive on a Chromebook.

While there is a compatibility mode for Chrome OS to emulate touchscreen scrolling and other touch events, it would be best to optimize an Android app by declaring

<uses-feature
    android:name="android.hardware.type.pc"
    android:required="false" />

in the manifest to disable compatibility mode in order to further define custom support for keyboard and trackpad.

Similarly, the system can guess at giving focus to the right views when navigating via the tab or arrow keys on a keyboard. But for best performance, specify how keyboard navigation should be handled in the activity manifest using the android:nextFocusForward attribute for tab navigation, and android:nextFocusUp, android:nextFocusDown, android:nextFocusLeft, android:nextFocusRight attributes for arrow key navigation.

On a related note, some Chromebooks do not have touchscreens, therefore well-optimized Android apps on Chrome should not assume the user can perform typical swipe and multi-touch tap gestures to navigate through an app or game. If primary functionality cannot be performed using only a keyboard or trackpad, the user experience will be severely impacted on non-touchscreen Chromebooks. Try to "translate" existing touchscreen tap and swipe gestures into something that can be easily done on a trackpad or using the keyboard.

Newer Chromebooks are gaining stylus support, allowing for richer interactions for sketchbook and note-taking apps, photo editors, games, and more. Developers are encouraged to use available APIs to support pressure-sensitivity, tilt, and eraser inputs. To enable users to comfortably rest their hands on the screen while writing, drawing, or playing games with the stylus, support palm rejection. The system will attempt to ignore input from a user's resting palm, but in case such erroneous touch events are registered, Android apps should gracefully handle ACTION_CANCEL events to erase the erroneous inputs.

By supporting all of these additional input methods, users will be able to take full advantage of the laptop mode for Chromebooks to work more efficiently, or to be more creative.

Learn more

While a lot was covered in this article, we have additional resources for you to learn more about optimizing their apps and games for Chromebooks. Read our Medium post with tips to get your app running great on Chromebooks and watch our session at Google I/O 2017, Android Apps for Chromebooks and Large Screen Devices. There is also training material on the Android developers website for building apps for Chrome OS. If you have any questions, reach out to the Android developer community and post with the hashtag #AndroidAppsOnChromeOS.

07 Sep 2017 4:14pm GMT

Posted by Kobi Glick, Product Manager, Google Play

Every app on Android is signed with a key. This key is used to ensure the app's integrity by checking that updates are signed with the same signature. In the past, the burden of securely holding the signing key has always been with the developer. We're now offering an app signing service on Google Play that can help you if you lose or compromise your key.

Until recently, losing your key would make it impossible to update your app with a new version. A compromised key would be a serious issue too: a third-party could maliciously replace an authentic app or corrupt it. Unfortunately in such cases, the only solution was to publish a new app, with a new package name and key, and ask all of your users to install it.

App signing in the Play Console allows us to offer help in such circumstances. For existing apps, it requires transferring your app signing key to Google Play. For new apps, we can generate your app signing key. Once enrolled in app signing, you sign your APK with an upload key, which we use to authenticate your identity. We'll then strip that signature and re-sign your app with the app signing key.

The app signing key is now securely managed by Google Play meaning that you are only responsible for managing your upload key. If your upload key is compromised or lost, our developer operations team can assist by verifying your identity and resetting your upload key. We'll still re-sign with the same app signing key, allowing the app to update as usual.

Rest assured, your key will be fully protected by Google's robust cloud security infrastructure and will benefit from the ongoing investment we're making to our security systems. In the future, we plan to offer developers who sign with Google Play automatic optimizations to enhance their app distribution. Stay tuned for more news in this area!

Learn more about how app signing works in the help center or watch the session about app signing from Google I/O 2017. Get started on securing your app in the release management section of the Play Console.

06 Sep 2017 9:12pm GMT

Posted by Alan Ni, Associate Product Manager, Gboard

Messaging is getting more and more expressive -- today you can say I love you with an emoji, a gif, or a sticker. Millions of users share expressive content every day on Android devices using Gboard as their default keyboard. We want to push expression even further by allowing developers to create their own stickers for Gboard. Some of our early partners include Bitmoji, Disney, and even our own Allo team. Once published, your stickers could be seen and shared by millions of users around the world.

Using the Firebase App Indexing API, you'll be able index any sticker assets you create, publish your app to the Play Store, and get featured in the Gboard Sticker collection. Once a user downloads your sticker pack from the Play store, they'll be able to send those stickers directly from their keyboard in any Android app that supports image insertion!

Getting Started with Stickers

To kick things off, you'll need to add the Firebase App Indexing library. Visit the Firebase Getting Started Guide for details. Once you've set up Firebase App Indexing, read through our sticker guide to learn how to index those stickers. Next, create your sticker assets!

You should build and index stickers on first run after update or install to minimize the lag between a user installing the app and seeing the stickers in Gboard. Our sample app should give an idea of the end-to-end flow.

Making your Stickers Searchable

Users often look for stickers via searching on keywords. That means you'll want to add appropriate keywords to allow users to find your stickers and you can use the put method to add keywords. In the code snippet below, you'll see that a Snoopy sticker is tagged with the keywords: "bye", "snoopy", "see ya", and "good bye".

new Indexable.Builder("Sticker")
   .setName("Bye")
   // add url for sticker asset 
   .setImage("http://www.snoopysticker.com?id=1234")
   // see: Support links to your app content section
   .setUrl("http://sticker/canonical/image/bye")
   // Set the accessibility label for the sticker.
   .setDescription("A sticker for Bye")
   // Add search keywords.
   .put("keywords", "bye", "snoopy", "see ya", "good bye")
   .put("isPartOf",
        new Indexable.Builder("StickerPack")
          .setName("Snoopy Pack")
          .build())
   .build())};

For larger sticker packs, you'll want to make sure you've tagged stickers with keywords so that they're easier for users to find. We've come up with a list of common English phrases/keywords you can use to tag your stickers. But don't forget to internationalize your stickers -- to do this you'll want to first detect the device language and then index keywords that correspond to that language.

Get Featured in the Sticker Collection

Finally, share your stickers with the world! To be featured in our Sticker Collection on the Play Store, fill out this form. But first, make sure to thoroughly test the sticker pack using the latest build of Gboard, If your app has high-quality stickers and is working well with Gboard, we'll add it to our sticker collection; this is the best way to get it seen by millions of Gboard users!

We're really excited to see what sticker packs you're able to build.

01 Sep 2017 8:21pm GMT

Posted by Adriana Puchianu

Based in Berlin, Zalando is Europe's leading online fashion platform. With more than 70% of its traffic now coming from mobile, the company has invested a lot in improving the quality of its app to provide a good user experience. Investing in bridging the online and the offline worlds, as well as providing a seamless cross-platform experience, has had positive results on their user engagement and revenue. Using features like A/B testing, the pre-launch report and the new release dashboard from the Google Play Console, Zalando saw a 6% increase in installs and a 15% increase in the users' lifetime value.

Watch Rushil Dave, Senior Product Specialist and Meritxell Rivera, Android Developer discuss how the company has improved user experience and key revenue and engagement metrics by investing in app quality for their Zalando app.

01 Sep 2017 4:21pm GMT

Posted by Hoi Lam, Lead Developer Advocate, Android Wear

Android Wear 2.0 represents the the latest evolution of the Android Wear platform. It introduced the concept of standalone apps that can connect to the network directly and work independently of a smartphone. This is critical to providing apps not only to our Android users, but also iOS users - which is increasingly important as we continue to expand our diverse ecosystem of watches and users. In addition, Wear 2.0 brought multi-APK support to Wear apps, which reduces the APK size of your phone apps, and makes it possible for iOS users to experience your Wear apps.

Today, we are announcing that multi-APKs will also work for Android Wear 1.0 watches, so you can now reach all of your users without needing to bundle your Wear app within your phone app's APK. Additionally, the Google Play Store policy will change to promote the use of multi-APKs and standalone apps. This covers all types of apps that are designed to run on the watch, including watch faces, complication data providers as well as launchable apps.

Policy change

The policy change will be effective from the 18th of January, 2018. At this time, the following apps will lose the "Enhanced for Android Wear" badge in the Google Play Store and will not be eligible to be listed in the top charts in the Play Store for Android Wear:

• Mobile apps that support Wear notification enhancements but do not have a separate Wear app.
• Wear apps that are bundled with mobile apps instead of using multi-APK.

Since multi-APK is now supported by devices running Wear 1.0 and 2.0, developers embedding their Wear app APKs in phone APKs should unbundle their Wear APK and upload it to the Play Store as a multi-APK. This will allow them to continue to qualify for the "Enhanced for Android Wear" badge as well as be eligible to appear in the Android Wear top charts. The two APKs can continue to share the same package name.

In addition to providing top app charts, we periodically put together curated featured collections. To be eligible for selection for these collections, developers will need to make their Wear apps function independently from the phone, as a standalone app. These apps will need to work on watches that are paired with both iOS and Android phones.

What are standalone apps?

Standalone apps are Wear apps that do not require a phone app to run. The app either does not require network access or can access the network directly without the phone app - something that is supported by Android Wear 2.0.

To mark your app as standalone, put the following meta-data tag in the AndroidManifest.xml:

<application>
...
  <meta-data
    android:name="com.google.android.wearable.standalone"
    android:value="true" />
...
</application>

In some rare cases, the user experience may be enhanced by the syncing of data between the phone and watch. For example, a cycling app can use the watch to display the current pace, and measure the user's heart rate, while displaying a map on the phone. In this scenario, we recommend that developers ensure that their Wear apps function without a phone and treat the phone experience as optional as far as the Wear apps are concerned. In these cases, a Wear app is still considered standalone and should be marked as such in its AndroidManifest.xml file.

Wear what you want

From the beginning, Android Wear has been about wear what you want -- the styles, watches, and apps you want to wear. This latest policy change lets you highlight your Android Wear apps, giving users even more choice about what apps they want on their watches.

31 Aug 2017 5:09pm GMT

Posted by Sami Tolvanen, Senior Software Engineer, Android Security

The hardening of Android's userspace has increasingly made the underlying Linux kernel a more attractive target to attackers. As a result, more than a third of Android security bugs were found in the kernel last year. In Android 8.0 (Oreo), significant effort has gone into hardening the kernel to reduce the number and impact of security bugs.

Android Nougat worked to protect the kernel by isolating it from userspace processes with the addition of SELinux ioctl filtering and requiring seccomp-bpf support, which allows apps to filter access to available system calls when processing untrusted input. Android 8.0 focuses on kernel self-protection with four security-hardening features backported from upstream Linux to all Android kernels supported in devices that first ship with this release.

Hardened usercopy

Usercopy functions are used by the kernel to transfer data from user space to kernel space memory and back again. Since 2014, missing or invalid bounds checking has caused about 45% of Android's kernel vulnerabilities. Hardened usercopy adds bounds checking to usercopy functions, which helps developers spot misuse and fix bugs in their code. Also, if obscure driver bugs slip through, hardening these functions prevents the exploitation of such bugs.

This feature was introduced in the upstream kernel version 4.8, and we have backported it to Android kernels 3.18 and above.

int buggy_driver_function(void __user *src, size_t size)
{
    /* potential size_t overflow (don't do this) */
    u8 *buf = kmalloc(size * N, GPF_KERNEL);
    …
    /* results in buf smaller than size, and a heap overflow */
    if (copy_from_user(buf, src, size))
    return -EFAULT;

    /* never reached with CONFIG_HARDENED_USERCOPY=y */
}

An example of a security issue that hardened usercopy prevents.

Privileged Access Never (PAN) emulation

While hardened usercopy functions help find and mitigate security issues, they can only help if developers actually use them. Currently, all kernel code, including drivers, can access user space memory directly, which can lead to various security issues.

To mitigate this, CPU vendors have introduced features such as Supervisor Mode Access Prevention (SMAP) in x86 and Privileged Access Never (PAN) in ARM v8.1. These features prevent the kernel from accessing user space directly and ensure developers go through usercopy functions. Unfortunately, these hardware features are not yet widely available in devices that most Android users have today.

Upstream Linux introduced software emulation for PAN in kernel version 4.3 for ARM and 4.10 in ARM64. We have backported both features to Android kernels starting from 3.18.

Together with hardened usercopy, PAN emulation has helped find and fix bugs in four kernel drivers in Pixel devices.

int buggy_driver_copy_data(struct mydata *src, void __user *ptr)
{
    /* failure to keep track of user space pointers */
    struct mydata *dst = (struct mydata *)ptr;
    …
    /* read/write from/to an arbitrary user space memory location */
    dst->field = … ;    /* use copy_(from|to)_user instead! */
    …
    /* never reached with PAN (emulation) or SMAP */
}

An example of a security issue that PAN emulation mitigates.

Kernel Address Space Layout Randomization (KASLR)

Android has included support for Address Space Layout Randomization (ASLR) for years. Randomizing memory layout makes code reuse attacks probabilistic and therefore more difficult for an attacker to exploit, especially remotely. Android 8.0 brings this feature to the kernel. While Linux has supported KASLR on x86 since version 3.14, KASLR for ARM64 has only been available upstream since Linux 4.6. Android 8.0 makes KASLR available in Android kernels 4.4 and newer.

KASLR helps mitigate kernel vulnerabilities by randomizing the location where kernel code is loaded on each boot. On ARM64, for example, it adds 13-25 bits of entropy depending on the memory configuration of the device, which makes code reuse attacks more difficult.

Post-init read-only memory

The final hardening feature extends existing memory protections in the kernel by creating a memory region that's marked read-only after the kernel has been initialized. This makes it possible for developers to improve protection on data that needs to be writable during initialization, but shouldn't be modified after that. Having less writable memory reduces the internal attack surface of the kernel, making exploitation harder.

Post-init read-only memory was introduced in upstream kernel version 4.6 and we have backported it to Android kernels 3.18 and newer. While we have applied these protections to some data structures in the core kernel, this feature is extremely useful for developers working on kernel drivers.

Conclusion

Android Oreo includes mitigations for the most common source of security bugs in the kernel. This is especially relevant because 85% of kernel security bugs in Android have been in vendor drivers that tend to get much less scrutiny. These updates make it easier for driver developers to discover common bugs during development, stopping them before they can reach end user devices.

30 Aug 2017 8:00pm GMT

Posted by Dave Burke, VP, Android Engineering

With more than two billion active devices, Android is the largest mobile platform in the world. And for the past nine years, we've worked to create a rich set of tools, frameworks and APIs that deliver developers' creations to people everywhere. Today, we're releasing a preview of a new software development kit (SDK) called ARCore. It brings augmented reality capabilities to existing and future Android phones. Developers can start experimenting with it right now.

We've been developing the fundamental technologies that power mobile AR over the last three years with Tango, and ARCore is built on that work. But, it works without any additional hardware, which means it can scale across the Android ecosystem. ARCore will run on millions of devices, starting today with the Pixel and Samsung's S8, running 7.0 Nougat and above. We're targeting 100 million devices at the end of the preview. We're working with manufacturers like Samsung, Huawei, LG, ASUS and others to make this possible with a consistent bar for quality and high performance.

ARCore works with Java/OpenGL, Unity and Unreal and focuses on three things:

• Motion tracking: Using the phone's camera to observe feature points in the room and IMU sensor data, ARCore determines both the position and orientation (pose) of the phone as it moves. Virtual objects remain accurately placed.
• Environmental understanding: It's common for AR objects to be placed on a floor or a table. ARCore can detect horizontal surfaces using the same feature points it uses for motion tracking.
• Light estimation: ARCore observes the ambient light in the environment and makes it possible for developers to light virtual objects in ways that match their surroundings, making their appearance even more realistic.

Alongside ARCore, we've been investing in apps and services which will further support developers in creating great AR experiences. We built Blocks and Tilt Brush to make it easy for anyone to quickly create great 3D content for use in AR apps. As we mentioned at I/O, we're also working on Visual Positioning Service (VPS), a service which will enable world scale AR experiences well beyond a tabletop. And we think the Web will be a critical component of the future of AR, so we're also releasing prototype browsers for web developers so they can start experimenting with AR, too. These custom browsers allow developers to create AR-enhanced websites and run them on both Android/ARCore and iOS/ARKit.

ARCore is our next step in bringing AR to everyone, and we'll have more to share later this year. Let us know what you think through GitHub, and check out our new AR Experiments showcase where you can find some fun examples of what's possible. Show us what you build on social media with #ARCore; we'll be resharing some of our favorites.

29 Aug 2017 3:00pm GMT

Posted by Kacey Fahey, Developer Marketing, Google Play

With so many great mobile games launching this year, we saw a huge amount of interest from indie developers to showcase their art at the Google Play Indie Games Festival in San Francisco next month. While it was a tough selection process, we're excited to announce the 20 finalists, as well as our esteemed judging panel. Fans will be able to play the new and un-released indie games in a fun festival atmosphere where they can also meet the creators themselves. To attend and learn more about the event, register now for free at g.co/play/sfindiegamesfest2017.

So how did we choose the 20 finalists? We powered up our phones, put our game-faces on, and looked for games that not only met the festival requirements, but also stood out with their overall design, fun, and quality. These are the 20 finalists who will be joining us at the festival to demo their games.

Meet the finalists

In addition to playing these games and meeting the developers who made them, fans will have a chance to vote for their favorites throughout the festival. The Top 10 will then move on to present a short pitch in pursuit of going home as one of the three overall festival winners. The winners will be chosen by this year's panel of judges representing a diverse lineup of gaming expertise.

• Alex the Gamerette, YouTube Creator
• Lina Chen, Co-founder & CEO of Nix Hydra
• Emily Greer, CEO of Kongregate
• Jamil Moledina, Games Strategic Lead, Google
• Dean Takahashi, Lead Writer for GamesBeat
• Sarah Thomson, BD Lead, Indie Games, Google Play

Emceeing this year's event is J.D. Witherspoon, aka runJDrun. No stranger to gaming, YouTuber/actor/comedian, J.D. plays a wide array of games and frequently uploads gaming, vlog, and comedy content to his channels.

If you want to try out these games and celebrate the indie community, learn more about the event and register at g.co/play/sfindiegamesfest2017.

28 Aug 2017 5:09pm GMT

Posted by Steven Tepper, App Quality Consultant, Google Play

Wear 2.0 launched back in February with added support for new hardware features in addition to adopting new Material Design themes,guidelines, and a simpler vertical UI pattern. It also introduces a complications API, making it easier for apps to provide data to watch faces, and watch faces to incorporate external data. The final big update was that, apps targeting Wear 2.0 now have the ability to operate in a standalone mode, without needing a connection to a companion app on the phone.

There are a few design considerations in relation to navigation, notifications, the complications API, and the standalone functionality to help you better optimize for Wear 2.0 devices:

Navigation

1. Use the WearableDrawerLayout navigation drawer for simple and infrequent navigation: Simple navigation includes tasks such as accessing app settings, switching users or logging out. You can implement this on Wear 2.0 to switch between different views or sections of the app via a swipe down from the top of the screen, or an action drawer can be set up for context-specific actions when swiping up from the bottom of the screen.
2. Present a navigation drawer as a single-page drawer to enable users to navigate views quickly: A navigation drawer can be presented as either a multi-page or single-page drawer. The single-page layout is useful for when the user is expected to navigate quickly between 7 or less views of the app. Remember that if the app is using a single-page drawer, the iconography should be clear and understandable as there will not be any sort of text labeling in this layout. If there are more than 7 views to navigate to or the views are not easily represented by icons, you should instead use the multi-page drawer layout.
   
3. Use multiple app launchers if your app has two or three discrete functions: For example, if your app supportsboth activity tracking-with various options, actions, and views-and historical analysis and management of tracked activities, you can use multiple app launchers to handle these tasks. Alternatively, if your app has a simple home screen, these features could be placed in line, at the bottom of the screen.
4. Use peeking at the top of the action drawer to provide quick access to the primary action: If there is no primary action associated with the view, override the default behavior and force an overflow button to peek instead, exposing all actions at the bottom of a view, when tapped.

Ensure that for devices using Wear 2.0, your app takes advantage of these new UI patterns to provide a consistent user experience. Check out more training resources for Wear Navigation and Actions and the Material Design specifications for Navigation and Action Drawers.

Notifications

Wear 2.0 uses a simpler vertical navigation pattern, removing the horizontal swiping gesture to present actions for a notification. Notification actions are now presented as a single primary action (if applicable) at the bottom of a notification. If there is no primary action, expanding the notification will present options in a single, vertically scrollable view.

Notifications will work without needing many changes on both 1.x and 2.0 devices, but appear quite different:

When creating apps for Wear 2.0 devices, improve the user experience with notifications by applying the following best practices:

1. Support expandable notifications: Use BigTextStyle so that users can see more content on their watch.
2. Use the collapsed view of the notification (if applicable): Add the primary action for your notification to the collapsed view of the notification using setContentIntent(), where appropriate.
3. For messaging apps, use the MessagingStyle: Provide a rich chat app-like experience in the expanded notification using this style.
4. Update user directions which are specific to Wear 1.0: Remove any text guiding users to act on a card by swiping horizontally (the Wear 1.x pattern).
5. Enhancing notifications to use inline actions: This allows users to do things without needing tap to see the expanded notification details. Actions for messaging notifications can use several different input methods including Smart Reply presets, voice, and keyboard input. Take advantage of these features to provide added functionality and delight users.

To learn more about adding wearable features to notifications.

Complications

The complications API in Wear 2.0 makes it much easier for watch face developers and third-party data providers to surface important information users want, at a glance. Watch faces that support the API can be configured to use any of the data providers that have been installed on the watch while maintaining complete control over their appearance. Apps supporting the complication API allow the app's data to be accessible on any watch faces that support complications. These complications can be displayed in a variety of forms (short text, icon, ranged value, long text, small image, and large image) depending on what the data provider has configured and how much space has been allocated on the watch face.

To ensure that complications fit the overall design of the watch face and properly handle their data type, when adding complication support we recommend watch face makers should:

1. Use the TextRenderer class found in the Wear 2.0 SDK: This allows the text within complications to be adjusted to their bounds by shrinking the text, dynamically supporting line breaks or ellipsizing strings when they exceed the bounds of a text-based complication.
2. Use the ComplicationDrawable class to set the background color, shape, border, and font options for the complications: This gives complete control of how the complication is rendered to the watch face.
3. Design the watch face to provide a way for users to configure or adjust complications on the watch face through a settings menu: To learn how to construct these settings see the watch face sample on GitHub.
4. Use the data provider test suite app to feed dummy data to the watch face complications: This will enable you to verify that all of the complications render properly and have fonts formatted for their bounds.
5. As a complication data provider, expose relevant data by using the ComplicationProviderService: Simply define and configure what types of ComplicationData the app can provide for complications.

Standalone functionality on Wear devices

1. Make sure your app is able to handle itself if there is no companion app installed when using the android.hardware.type.watch hardware feature flag: Using this feature enables your app to become searchable and installable directly on Wear devices without needing to install a companion phone app, so ensure your app can handle itself to avoid a confusing or broken user experience.
2. Ensure your wearable app doesn't rely on the phone app for sign-in/authentication or primary functionality: When requiring complicated input for authentication (for example, password entry) your wearable app can point to the companion phone, but should rely on web UI for account/password entry rather than an app.
3. Where a companion app must be present on a phone to support your app in some other way, the app should use the CapabilityApi: This should be used to properly direct users to the Play Store listing on their companion device to install the missing app. Otherwise, the app should function on its own, using the Wear built-in Wi-Fi, GPS, or other connectivity functions.
   
4. Include wording about any companion app requirements or briefly mention how your Wear app should function within the Play Store listing description: This will help set expectations and guide users to install the correct apps for the best possible experience.
5. Incorporate the com.google.android.wearable.standalone flag in the manifest if your Wearable app can function without any phone companion interaction: This flag indicates that the wearable app can be installed and will fully function when not paired to an Android or iOS companion phone.

Though a lot was covered here, there are additional resources you can use to ensure that your apps or games are optimized and use the latest patterns and functionality on Wear. Be sure to review the quality guidelines and check out the developer training documentation to learn more best practices for wearable app development and wearable app design in order to build quality apps for Wear.

25 Aug 2017 4:50pm GMT

Posted by Takeshi Hagikura, Developer Programs Engineer

Since announcing ConstraintLayout at Google I/O last year, we've continued to improve the layout's stability and layout editor support. We've also added new features specific to ConstraintLayout that help you build various type of layouts, such as introducing chains and setting size as a ratio. In addition to these features, there is a notable performance benefit by using ConstraintLayout. In this post, we'll walk through how you can benefit from these performance improvements.

How Android draws views?

To better understand the performance of ConstraintLayout, let's take a step back and see how Android draws views.

When a user brings an Android view into focus, the Android framework directs the view to draw itself. This drawing process comprises 3 phases:

1. Measure

   The system completes a top-down traversal of the view tree to determine how large each ViewGroup and View element should be. When a ViewGroup is measured, it also measures its children.

2. Layout

   Another top-down traversal occurs, with each ViewGroup determining the positions of its children using the sizes determined in the measure phase.

3. Draw

   The system performs yet another top-down traversal. For each object in the view tree, a Canvas object is created to send a list of drawing commands to the GPU. These commands include the ViewGroup and View objects' sizes and positions, which the system determined during the previous 2 phases.

Each phase within the drawing process requires a top-down traversal of the view tree. Therefore, the more views you embed within each other (or nest) into the view hierarchy, the more time and computation power it takes for the device to draw the views. By keeping a flat hierarchy in your Android app layouts, you can create a fast and responsive user interface for your app.

The expense of a traditional layout hierarchy

With that explanation in mind, let's create a traditional layout hierarchy that uses LinearLayout and RelativeLayout objects.

Let's say we want to build a layout like the image above. If you build it with traditional layouts, the XML file contains an element hierarchy similar to the following (for this example, we've omitted the attributes):

<RelativeLayout>
  <ImageView />
  <ImageView />
  <RelativeLayout>
    <TextView />
    <LinearLayout>
      <TextView />
      <RelativeLayout>
        <EditText />
      </RelativeLayout>
    </LinearLayout>
    <LinearLayout>
      <TextView />
      <RelativeLayout>
        <EditText />
      </RelativeLayout>
    </LinearLayout>
    <TextView />
  </RelativeLayout>
  <LinearLayout >
    <Button />
    <Button />
  </LinearLayout>
</RelativeLayout>

Although there's usually room for improvement in this type of view hierarchy, you'll almost certainly still need to create a hierarchy with some nested views.

As discussed before, nested hierarchies can adversely affect performance. Let's take a look at how the nested views actually affect the UI performance using Android Studio's Systrace tool. We called the measure and layout phases for each ViewGroup (ConstraintLayout and RelativeLayout) programmatically and triggered Systrace while the measure and layout calls are executing. The following command generates an overview file that contains key events, such as expensive measure/layout passes, that occur during a 20-second interval:

python $ANDROID_HOME/platform-tools/systrace/systrace.py --time=20 -o ~/trace.html gfx view res

For more details about how you can use Systrace, see the Analyzing UI Performance with Systrace guide.

Systrace automatically highlights the (numerous) performance problems with this layout, as well as suggestions for fixing them. By clicking the "Alerts" tab, you will find that drawing this view hierarchy requires 80 expensive passes through the measure and layout phases!

Triggering that many expensive measure and layout phases is far from ideal; such a large amount of drawing activity could result in skipped frames that users notice. We can conclude that the layout has poor performance due to the nested hierarchy as well as the characteristic of RelativeLayout, which measures each of its children twice.

You can check the entire code on how we performed these measurements in our GitHub repository.

The benefits of a ConstraintLayout object

If you create the same layout using ConstraintLayout, the XML file contains an element hierarchy similar to the following (attributes again omitted):

<android.support.constraint.ConstraintLayout>
  <ImageView />
  <ImageView />
  <TextView />
  <EditText />
  <TextView />
  <TextView />
  <EditText />
  <Button />
  <Button />
  <TextView />
</android.support.constraint.ConstraintLayout>

As this example shows, the layout now has a completely flat hierarchy. This is because ConstraintLayout allows you to build complex layouts without having to nest View and ViewGroup elements.

For example, let's look at the TextView and EditText in the middle of the layout:

<LinearLayout
    android:id="@+id/camera_area"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal"
    android:layout_below="@id/title" >

    <TextView
        android:text="@string/camera"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:id="@+id/cameraLabel"
        android:labelFor="@+id/cameraType"
        android:layout_marginStart="16dp" />

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <EditText
            android:id="@+id/cameraType"
            android:ems="10"
            android:inputType="textPersonName"
            android:text="@string/camera_value"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_centerVertical="true"
            android:layout_marginTop="8dp"
            android:layout_marginStart="8dp"
            android:layout_marginEnd="8dp" />
    </RelativeLayout>
</LinearLayout>

By using ConstraintLayout instead, you can achieve the same effect just by adding a constraint from the baseline of the TextView to the baseline of the EditText without creating another ViewGroup:

<TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      app:layout_constraintLeft_creator="1"
      app:layout_constraintBaseline_creator="1"
      app:layout_constraintLeft_toLeftOf="@+id/activity_main_done"
      app:layout_constraintBaseline_toBaselineOf="@+id/cameraType" />

When running the Systrace tool for the version of our layout that uses ConstraintLayout, you see far fewer expensive measure/layout passes during the same 20-second interval. This improvement in performance makes sense, now that we're keeping the view hierarchy flat!

On a related note, we built the ConstraintLayout variant of our layout using just the layout editor instead of editing the XML by hand. To achieve the same visual effect using RelativeLayout, we probably would have needed to edit the XML by hand.

Measuring the performance difference

We analyzed how long every measure and layout pass took for two type of layouts, ConstraintLayout and RelativeLayout, by using OnFrameMetricsAvailableListener, which was introduced in Android 7.0 (API level 24). This class allows you to collect frame-by-frame timing information about your app's UI rendering.

By calling the following code, you can start recording per-frame UI actions:

window.addOnFrameMetricsAvailableListener(
        frameMetricsAvailableListener, frameMetricsHandler);

After timing information becomes available, the app triggers the frameMetricsAvailableListener() callback. We are interested in the measure/layout performance, so we call FrameMetrics.LAYOUT_MEASURE_DURATION when retrieving the actual frame duration.

Window.OnFrameMetricsAvailableListener {
        _, frameMetrics, _ ->
        val frameMetricsCopy = FrameMetrics(frameMetrics);
        // Layout measure duration in nanoseconds
        val layoutMeasureDurationNs = 
                frameMetricsCopy.getMetric(FrameMetrics.LAYOUT_MEASURE_DURATION);

To learn more about the other types of duration information that FrameMetrics can receive, see the FrameMetrics API reference.

Measurement results: ConstraintLayout is faster

Our performance comparison shows that ConstraintLayout performs about 40% better in the measure/layout phase than RelativeLayout:

As these results show, ConstraintLayout is likely to be more performant than traditional layouts. Moreover, ConstraintLayout has other features that help you build complex and performant layouts, as discussed in the benefits of a ConstraintLayout object section. For details, see the Build a Responsive UI with ConstraintLayout guide. We recommend that you use ConstraintLayout when designing your app's layouts. In almost all cases when you would have previously need a deeply-nested layout, ConstraintLayout should be your go-to layout for optimal performance and ease of use.

Appendix: Measurement environment

All the measurements above were performed in the following environment.

What's next

Check out the developer guide, the API reference documentation, and the article on Medium to fully understand what ConstraintLayout can provide for you. And once again, thank you to all who submitted feedback and issues over the months since our alpha release of ConstraintLayout. We're truly grateful that we were able to release the production-ready 1.0 version of ConstraintLayout earlier this year. As we continue to improve ConstraintLayout, please continue to send us feedback using the Android issue tracker.

24 Aug 2017 5:00pm GMT

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