Android fuels mobile apps on devices that range far beyond your typical small-screen smartphone, from new Chromebooks like the lightweight, high-performance Google Pixelbook Go to multi-display devices and foldable phones like the Samsung Galaxy Fold. Not to mention the more than 175M Android tablets that have the Google Play store installed.1
These large-screen devices set the stage for more engaging and visually immersive experiences, whether by creating a larger canvas for creativity or by giving users faster, more flexible ways to work. As we’ve continued to prioritize large-screen devices with OEM partners like Samsung, Asus, and Lenovo, we’ve been able to expand our reach to a huge new audience of users.
During the week of Black Friday in 2018, 1 in 3 notebooks sold in the U.S. were Chromebooks.2 Chromebook unit sales also increased 22% YoY, while the rest of the notebook category decreased -6.1%.3 And we’re not just reaching more users — we’re reaching more engaged users. In fact, in just the last year, the total amount of time spent in Android apps on Chrome OS has grown 4X.4
By making adjustments for larger screens, you can provide richer experiences across all these devices and tap into a wider audience of app users. Development teams around the world — including Adobe Lightroom, Evernote, and Gameloft, among many others — have already seen some incredible results:
With the goal of allowing users to play any video file, anywhere, on any device or screen size, the developers at VideoLAN project decided to adapt VLC — an open source, cross-platform multimedia player — for all screens. The team started by adding keyboard and mouse support before designing multiple versions of the layout to allow users to easily scale and resize the app.
Users can now enjoy the same immersive experience across a range of different devices and form factors, and VideoLAN has already received overwhelmingly positive feedback from users around the world.
War Robots — a 12-player real-time battle game developed by Pixonic — was originally designed for early-generation phones. The team enabled windowed gameplay so users could play in one window while watching their favorite streamers or upgrading their robots in another, created new tutorials and controls that appear whenever players switch between desktop and tablet mode, and added support for keyboard and mouse input.
More than 100,000 players have already played War Robots on Chrome OS since Pixonic rolled out the latest optimizations, which made War Robots’ battles even more thrilling and engaging on larger screens, and Pixonic has seen 25% longer user sessions on Chromebooks as a result.
1) Laptop and tablet mode Test your core app functions to make sure everything works smoothly without crashing as users switch between different modes.
2) Window management and layout Support multi-window mode and free-form window resizing, and be sure to design optimized layouts for both landscape and portrait orientations. Set up your app to correctly handle configuration changes to avoid crashes when people rotate their devices.
3) Keyboard and mouse input Make sure your app is fully functional without touch input, and add support for keyboards, mice, and game controllers (if applicable).
4) Hardware support If you’re using NDK, be sure to support x86 (32 and 64bit) ABIs to ensure the highest possible performance.
From the start, our goal has been to make the Chromebook a simple, secure, and speedy environment for everyone. The launch of Linux (Beta) on Chrome OS allowed Android developers to build and test apps with a Chromebook. And earlier this year at I/O, we announced that Android Studio 3.5 now fully supports Chrome OS with a simple one-click installation.
Since then, we’ve been working on a few improvements that make Chromebooks an even better place for safe and seamless Android app development. Let’s start with the biggest one:
Deploying an app directly to Chrome OS to enable full Android development In the past, you could only test your apps by deploying them to Android phones. With Chrome OS’s upcoming M80 release, you’ll be able to deploy Android apps directly to your Chromebook. That way, you can develop and test your app on the same machine, all without a connected device or needing to put your laptop in developer mode. Developers can start testing this feature in developer channel in November.
GPU acceleration for a snappier, jank-free UI (now in beta channel) We’ve enabled GPU support to reduce latency and deliver a snappier UI. That goes for developer apps such as Android Studio, Unity Editor, or Visual Studio Code. And for developers who also work on web apps, GPU acceleration means faster testing with Chrome Canary or Firefox.
Container backup and restore to easily move between devices Previously, Linux files and apps were tied entirely to the device — if you lost your device, you lost all the work inside of it. Now, Chrome OS’s container-based architecture allows you to pack up your entire workspace and export it to external storage or Drive. The backup file can be restored at any point, either on the same machine — which is helpful when jumping back to a previous state — or to move to another Chromebook.
You can now find import and export buttons in your Linux settings.
Picture-in-picture (PiP) support
If you’ve built PIP support into your Android apps, you’ll see that function work seamlessly in Chrome OS in 2020. But you can start testing this feature now by enabling PiP in Android settings → Developer options.
With millions of users on Chromebooks, tablets, foldables, and now multi-display devices, designing app experiences with larger screens in mind is crucial. Seize this opportunity to engage more users by optimizing your existing apps to work great across all screens. And the latest Linux features on Chrome OS give you the power to use a single machine to build and run Android apps. Don’t hesitate to take action to ensure your apps work seamlessly on larger screens with Linux on Chrome OS.
1. The number of tablets only accounts for devices that have the Google Play Store installed (e.g., excluding tablets in China); the actual number of tablets capable of running Android applications is much larger.
2. The NPD Group, Inc., Retail Tracking Service, U.S., Notebook Computers, Chrome OS, based on units, Nov. 18, 2018–Nov. 24, 2018 vs. Nov. 19, 2017–Nov. 25, 2017.
3. The NPD Group, Inc., U.S. Retail Tracking Service, Notebook Computers, based on units, Sept. 2018–Aug. 2019. Sales are adjusted for 5 weeks in Jan. 2018 vs. 4 weeks in Jan. 2019.
4. Google Internal Data, March 2018–March 2019.
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:
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.
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" />
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.
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().
onStop()
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.
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:
onConfigurationChanged()
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.
onSaveInstanceState()
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.
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:
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.
android:nextFocusForward
android:nextFocusUp
android:nextFocusDown
android:nextFocusLeft
android:nextFocusRight
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.
ACTION_CANCEL
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.
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.
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