18 December 2014

Making a performant watch face

Posted by Hoi Lam, Developer Advocate, Android Wear

What’s a better holiday gift than great performance? You’ve got a great watch face idea -- now, you want to make sure the face you’re presenting to the world is one of care and attention to detail.

At the core of the watch face's process is an onDraw method for canvas operations. This allows maximum flexibility for your design, but also comes with a few performance caveats. In this blog post, we will mainly focus on performance using the real life journey of how we optimised the Santa Tracker watch face, more than doubling the number of fps (from 18 fps to 42 fps) and making the animation sub-pixel smooth.

Starting point - 18 fps

Our Santa watch face contains a number of overlapping bitmaps that are used to achieve our final image. Here's a list of them from bottom to top:

  1. Background (static)
  2. Clouds which move to the middle
  3. Tick marks (static)
  4. Santa figure and sledge (static)
  5. Santa’s hands - hours and minutes
  6. Santa’s head (static)

The journey begins with these images...

Large images kill performance (+14 fps)

Image size is critical to performance in a Wear application, especially if the images will be scaled and rotated. Wasted pixel space (like Santa’s arm here) is a common asset mistake:

Before: 584 x 584 = 341,056 pixelsAfter: 48*226 = 10,848 (97% reduction)

It's tempting to use bitmaps from the original mock up that have the exact location of watch arms and components in absolute space. Sadly, this creates problems, like in Santa's arm here. While the arm is in the correct position, even transparent pixels increase the size of the image, which can cause performance problems due to memory fetch. You'll want to work with your design team to extract padding and rotational information from the images, and rely on the system to apply the transformations on our behalf.

Since the original image covers the entire screen, even though the bitmap is mostly transparent, the system still needs to check every pixel to see if they have been impacted. Cutting down the area results in significant gains in performance. After correcting both of the arms, the Santa watch face frame rate increased by 10 fps to 28 fps (fps up 56%). We saved another 4 fps (fps up 22%) by cropping Santa’s face and figure layer. 14 fps gained, not bad!

Combine Bitmaps (+7 fps)

Although it would be ideal to have the watch tick marks on top of our clouds, it actually does not make much difference visually as the clouds themselves are transparent. Therefore there is an opportunity to combine the background with the ticks.

+

When we combined these two views together, it meant that the watch needed to spend less time doing alpha blending operations between them, saving precious GPU time. So, consider collapsing alpha blended resources wherever we can in order to increase performance. By combining two full screen bitmaps, we were able to gain another 7 fps (fps up 39%).

Anti-alias vs FilterBitmap flags - what should you use? (+2 fps)

Android Wear watches come in all shapes and sizes. As a result, it is sometimes necessary to resize a bitmap before drawing on the screen. However, it is not always clear what options developers should select to make sure that the bitmap comes out smoothly. With canvas.drawBitmap, developers need to feed in a Paint object. There are two important options to set - they are anti-alias and FilterBitmap. Here’s our advice:

  • Anti-alias does not do anything for bitmaps. We often switch on the anti-alias option by default as developers when we are creating a Paint object. However, this option only really makes sense for vector objects. For bitmaps, this has no impact. The hand on the left below has anti-alias switched on, the one on the right has it switched off. So turn off anti-aliasing for bitmaps to gain performance back. For our watch face, we gained another 2 fps (fps up 11%) by switching this option off.
  • Switch on FilterBitmap for all bitmap objects which are on top of other objects - this option smooths the edges when drawBitmap is called. This should not be confused with the filter option on Bitmap.createScaledBitmap for resizing bitmaps. We need both to be turned on. The bitmaps below are the magnified view of Santa’s hand. The one on the left has FilterBitmap switched off and the one on the right has FilterBitmap switched on.
  • Eliminate expensive calls in the onDraw loop (+3 fps)

    onDraw is the most critical function call in watch faces. It's called for every drawable frame, and the actual painting process cannot move forward until it's finished. As such, our onDraw method should be as light and as performant as possible. Here's some common problems that developers run into that can be avoided:

    1. Do move heavy and common code to a precompute function - e.g. if we commonly grab R.array.cloudDegrees, try doing that in onCreate, and just referencing it in the onDraw loop.
    2. Don’t repeat the same image transform in onDraw - it’s common to resize bitmaps at runtime to fit the screen size but this is not available in onCreate. To avoid resizing the bitmap over and over again in onDraw, override onSurfaceChanged where width and height information are available and resize images there.
    3. Don't allocate objects in onDraw - this leads to high memory churn which will force garbage collection events to kick off, killing frame rates.
    4. Do analyze the CPU performance by using a tool such as the Android Device Monitor. It’s important that the onDraw execution time is short and occurs in a regular period.

    Following these simple rules will improve rendering performance drastically.

    In the first version, the Santa onDraw routine has a rogue line:

    int[] cloudDegrees = 
        getResources().getIntArray(R.array.cloudDegrees);

    This loads the int array on every call from resources which is expensive. By eliminating this, we gained another 3 fps (fps up 17%).

    Sub-pixel smooth animation (-2 fps)

    For those keeping count, we should be 44 fps, so why is the end product 42 fps? The reason is a limitation with canvas.drawBitmap. Although this command takes left and top positioning settings as a float, the API actually only deals with integers if it is purely translational for backwards compatibility reasons. As a result, the cloud can only move in increments of a whole pixel resulting in janky animations. In order to be sub-pixel smooth, we actually need to draw and then rotate rather than having pre-rotate clouds which moves towards Santa. This additional rotation costs us 2 fps. However, the effect is worthwhile as the animation is now sub-pixel smooth.

    Before - fast but janky and wobbly

    for (int i = 0; i < mCloudBitmaps.length; i++) {
        float r = centerX - (timeElapsed / mCloudSpeeds[i]) % centerX;
        float x = centerX + 
            -1 * (r * (float) Math.cos(Math.toRadians(cloudDegrees[i] + 90)));
        float y = centerY - 
            r * (float) Math.sin(Math.toRadians(cloudDegrees[i] + 90));
        mCloudFilterPaints[i].setAlpha((int) (r/centerX * 255));
        Bitmap cloud = mCloudBitmaps[i];
        canvas.drawBitmap(cloud,
            x - cloud.getWidth() / 2,
            y - cloud.getHeight() / 2,
            mCloudFilterPaints[i]);
    }

    After - slightly slower but sub-pixel smooth

    for (int i = 0; i < mCloudBitmaps.length; i++) {
        canvas.save();
        canvas.rotate(mCloudDegrees[i], centerX, centerY);
        float r = centerX - (timeElapsed / (mCloudSpeeds[i])) % centerX;
        mCloudFilterPaints[i].setAlpha((int) (r / centerX * 255));
        canvas.drawBitmap(mCloudBitmaps[i], centerX, centerY - r,
            mCloudFilterPaints[i]);
        canvas.restore();
    }

    Before: Integer translation values create janky, wobbly animation. After: smooth sailing!

    Quality on every wrist

    The watch face is the most prominent UI element in Android Wear. As craftspeople, it is our responsibility to make it shine. Let’s put quality on every wrist!

11 December 2014

New Code Samples for Lollipop

Posted by Trevor Johns, Developer Programs Engineer

With the launch of Android 5.0 Lollipop, we’ve added more than 20 new code samples demonstrating how to implement some of the great new features of this release. To access the code samples, you can easily import them in Android Studio 1.0 using the new Samples Wizard.

Go to File > Import Sample in order to browse the available samples, which include a description and preview for each. Once you’ve made your selection, select “Next” and a new project will be automatically created for you. Run the project on an emulator or device, and feel free to experiment with the code.

Samples Wizard in Android Studio 1.0
Newly imported sample project in Android Studio

Alternatively, you can browse through them via the Samples browser on the developer site. Each sample has an Overview description, Project page to browse app file structure, and Download link for obtaining a ZIP file of the sample. As a third option, code samples can also be accessed in the SDK Manager by downloading the SDK samples for Android 5.0 (API 21) and importing them as existing projects into your IDE.


Sample demonstrating transition animations

Material Design

When adopting material design, you can refer to our collection of sample code highlighting material elements:

For additional help, please refer to our design checklist, list of key APIs and widgets, and documentation guide.

To view some of these material design elements in action, check out the Google I/O app source code.

Platform

Lollipop brings the most extensive update to the Android platform yet. The Overview screen allows an app to surface multiple tasks as concurrent documents. You can include enhanced notifications with this sample code, which shows you how to use the lockscreen and heads-up notification APIs.

We also introduced a new Camera API to provide developers more advanced image capture and processing capabilities. These samples detail how to use the camera preview and take photos, how to record video, and implement a real-time high-dynamic range camera viewfinder.

Elsewhere, Project Volta encourages developers to make their apps more battery-efficient with new APIs and tools. The JobScheduler sample demonstrates how you can schedule background tasks to be completed later or under specific conditions.

For those interested in the enterprise device administration use case, there are sample apps on setting app restrictions and creating a managed profile.

Android Wear

For Android Wear, we have a speed tracker sample to show how to take advantage of GPS support on wearables. You can browse the rest of the Android Wear samples too, and here are some highlights that demonstrate the unique capabilities of wearables, such as data synchronization, notifications, and supporting round displays:

Android TV

Extend your app for Android TV using the Leanback library described in this training guide and sample.

To try out a game that is specifically optimized for Android TV, download Pie Noon from Google Play. It’s an open-source game developed in-house at Google that supports multiple players using Bluetooth controllers or touch controls on mobile devices.

Android Auto

For the use cases highlighted in the Introduction to Android Auto DevByte, we have two code samples. The Media Browser sample (DevByte) demonstrates how easy it is to make an audio app compatible with Android Auto by using the new Lollipop media APIs, while the Messaging sample (DevByte) demonstrates how to implement notifications that support replies using speech recognition.

Google Play services

Since we’ve discussed sample resources for the Android platform and form factors, we also want to mention that there are existing samples for Google Play services. With Google Play services, your app can take advantage of the latest Google-powered APIs such as Maps, Google Fit, Google Cast, and more. Access samples in the Google Play services SDK or visit the individual pages for each API on the developer site. For game developers, you can reference the Google Play Games services samples for how to add achievements, leaderboards, and multiplayer support to your game.

Check out a sample today to help you with your development!

Hello World, meet our new experimental toolchain, Jack and Jill

Posted by Paul Rashidi, Developer Programs Engineer

We've been working on a new toolchain for Android that’s designed to improve build times and simplify development by reducing dependencies on other tools. Today, we’re introducing you to Jack (Java Android Compiler Kit) and Jill (Jack Intermediate Library Linker), the two tools at the core of the new toolchain.

We are making an early, experimental version of Jack and Jill available for testing with non-production versions of your apps. This post describes how the toolchain works, how to configure it, and how to let us know of your feature requests and any bugs you find.

So how does it work?

When the new tool chain is enabled, Jill will translate any libraries you are referencing to a new Jack library file (.jack). This prepares them to be quickly merged with other .jack files. The Android Gradle plugin and Jack collect any .jack library files, along with your source code, and compiles them into a set of dex files. During the process, Jack also handles any requested code minification. The output is then assembled into an APK file as normal. We also include support for multiple dex files, if you have enabled that support.

How do I use it?

Jack and Jill are already available in the 21.1.1+ Build Tools for Android Studio. Complementary Gradle support is also currently available in the Android 1.0.0+ Gradle plugin. To get started, all you need to do is make sure you're using these versions of the tooling and then add a single line in your build.gradle file. Perform a build of your application to receive a newly built APK.

android {
    ...
    buildToolsRevision '21.1.1'
    defaultConfig {
      // Enable the experimental Jack build tools.
      useJack = true
    }
    ...
}
If you want to build your app with both toolchains, Product Flavors are a great way to do this. Your build.gradle file might look something like the snippet below.
android {
    ...
    productFlavors {
        dev {
            ...
        }
        experimental {
            useJack = true
        }
        prod {
            ...
        }
    }
    ...
}

How do I configure my build?

We are making the transition to Jack as smooth as possible by supporting minification (shrinking and/or obfuscation), as well as repackaging (i.e. similar to tools like jarjar), while using the same input files as you are used to. Minification is available in the Gradle plugin immediately and repackaging will follow. You should continue to use the "minifyEnabled true" directive to reduce the size of your app among all other optimizations you would normally use. There are more details on our reference page (linked below) regarding the level of support for each type of optimization. We encourage you to provide feedback there if your current configuration isn't supported.

Give us your feedback

We are attempting to make the toolchain as easy to test out as possible and we're looking for your help to fine tune it. Use the reference page to find known issues, file feature requests, and report bugs. Happy building!

10 December 2014

Watch Face API Now Available for Android Wear

Posted by Wayne Piekarski, Developer Advocate

We’re pleased to announce that the official Android Wear Watch Face API is now available for developers. Watch faces give users even more ways to express their personal style, while creating an opportunity for developers to customize the most prominent UI feature of the watches. Watch faces have been the most requested feature from users and developers alike, and we can’t wait to see what you build for them.

An Introduction to Watch Faces for Android Wear by Timothy Jordan

Design and development

To get started, first learn about Designing Watch Faces, and then check out the Creating Watch Faces training class. The WatchFace Sample available online and in the Android Studio samples manager also provides a number of different examples to help you jump right in. For a quick overview, you can also watch the Watch Faces for Android Wear DevByte video above.

Watch faces are services that run from your wearable app, so you can provide one or multiple watch faces with a single app install. You can also choose to have configuration activities on the phone or watch, for example to let a user change between 12 and 24-hour time, or to change the watch face’s background. You can use OpenGL to provide smooth graphics, and a background service to pull in useful data like weather and calendar events. Watch faces can be analog, or digital, or display the time in some new way that hasn’t been invented yet––it’s up to you.

Updates to existing devices

Over the next week, the latest release of Android Wear, based on Android 5.0 and implementing API 21, will roll out to users. All Android Wear devices will be updated to Android 5.0 via an over-the air (OTA) update. The update allows users to manage and configure watch faces in the Android Wear app on their phone, and install watch faces from Google Play. Any handheld device running Android 4.3 or later will continue to work with all Android Wear devices.

Upgrade your watch faces

Developers are incredibly resourceful and we’re impressed with the watch faces you were able to create without any documentation at all. If you’ve already built a watch face for Android Wear using an unofficial approach, you should migrate your apps to the official API. The official API ensures a consistent user experience across the platform, while giving you additional information and controls, such as letting you know when the watch enters ambient mode, allowing you to adjust the position of system UI elements, and more. Using the new API is also necessary for your app to be featured in the Watch Faces collection on Google Play.

Deployment of watch faces to Google Play

We recommend you update your apps on Google Play as soon as the Android Wear 5.0 API 21 OTA rollout is complete, which we’ll announce on the Android Wear Developers Google+ community. It’s important to wait until the OTA rollout is complete because a Watch Face requiring API 21 will not be visible on a watch running API 20. Once your user gets the OTA, then the watch face will become visible. If you want to immediately launch your updates during the OTA rollout, make sure you set minSdkVersion to 20 in your wearable app, otherwise the app will fail to install for pre-OTA users. Once the rollout is complete, please transition your existing watch faces to the new API by January 31, 2015, at which point we plan to remove support for watch faces that don't use the official API.

Android Wear apps on Google Play

Starting today, you can submit any of your apps for designation as Android Wear apps on Google Play by following the Distributing to Android Wear guidelines. If your apps follow the criteria in the Wear App Quality checklist and are accepted as Wear apps on Play, it will be easier for Android Wear users to discover them. To opt-in for Android Wear review, visit the Pricing & Distribution section of the Google Play Developer Console.

In the few short months since we’ve launched Android Wear, developers have already written thousands of apps, taking advantage of custom notifications, voice actions, and fully native Android capabilities. Thanks to you, users have infinite ways to personalize their watches, choosing from six devices, a range of watch bands, and thousands of apps. With support for custom watch faces launching today, users will have even more choices in the future. These choices are at the heart of a rich Android Wear ecosystem and as we continue to open up core features of the platform to developers, we can’t wait to see what you build next.

09 December 2014

Google Play services and DEX method limits

Posted by Laurence Moroney, Developer Advocate

A constraint for some Android apps is the total number of methods that the underlying compiled .dex file can support. It’s limited by 16 bits, or 65,536 values.

When you include third-party libraries in your application, you will have all of their methods in your .dex file. Larger APIs, such as those included in Google Play services, will then begin eating into the limit very quickly.

You can learn more about this, and ways that you can work around it with the Android Studio 1.0 build system here.

Additionally, with Google Play services version 6.5 or later, it is possible for you to include Google Play services in your application using a number of smaller client libraries, so that only Google Play services APIs you use will get compiled into your .dex file, and therefore their methods won't count towards your method limit.

Prior to version 6.5, you would typically have a line like this in your build.gradle file:

compile 'com.google.android.gms:play-services:6.5.87'

Starting with version 6.5, of Google Play services, you’ll be able to pick from a number of individual APIs, and you can see which ones have their own include files in the documentation. For example, if all you want to use is Maps, you would instead have:

compile 'com.google.android.gms:play-services-maps:6.5.87'

Note that this will transitively include the ‘base’ libraries, which are used across all APIs. You can include them independently with the following line:

compile 'com.google.android.gms:play-services-base:6.5.87'

The complete list of API names is below. More details can be found on the Android Developer site.

com.google.android.gms:play-services-base:6.5.87
com.google.android.gms:play-services-ads:6.5.87
com.google.android.gms:play-services-appindexing:6.5.87
com.google.android.gms:play-services-maps:6.5.87
com.google.android.gms:play-services-location:6.5.87
com.google.android.gms:play-services-fitness:6.5.87
com.google.android.gms:play-services-panorama:6.5.87
com.google.android.gms:play-services-drive:6.5.87
com.google.android.gms:play-services-games:6.5.87
com.google.android.gms:play-services-wallet:6.5.87
com.google.android.gms:play-services-identity:6.5.87
com.google.android.gms:play-services-cast:6.5.87
com.google.android.gms:play-services-plus:6.5.87
com.google.android.gms:play-services-appstate:6.5.87
com.google.android.gms:play-services-wearable:6.5.87
com.google.android.gms:play-services-all-wear:6.5.87

Note: At the time of writing, the correct version to use is 6.5.87. As this is a very granular number, it will get updated quite quickly, so be sure the check the latest version when you are coding. Often people will use a ‘+’ to denote versions, such as 6.5.+ to use the latest 6.5 build. However, it’s typically discouraged to use a ‘+’ as it can lead to inconsistencies.

Also, there are some changes to the names of the libraries that will impact you if you build applications for Android Wear. Previously you may have used play-services-wearable to include the entire Google Play services library for your wearable, and if you want to continue doing so, you should now use play-services-all-wear instead. You can continue to use play-services-wearable which will instead give you just the Wearable Data Layer API (see here). Should you do this, and you want to continue working with other Google Play services features, such as the Location APIs on your wearable, you would need to add play-services-location.

Over goes big and goes home with Android

Posted by Leticia Lago, Google Play team

Over has taken a simple idea, adding text and artwork to photos, and turned it into a creative tool that enables anyone to easily and intuitively add a unique twist to any image.

The Over team recently decided to bring their successful app to Android. “We love unlocking human creativity and Android offers a massive opportunity for doing just that. It was a no-brainer,” says Aaron Marshall, Founder, CEO, and Designer at Over. “Moving to Cape Town was eye-opening in many ways. It made me experience first-hand how many people outside the US use Android. We see users in emerging markets using mobile devices as their primary device, and believe there is a lot of opportunity in providing them with creative tools for mobile.”

The entire team was new to the platform, and were quickly impressed by the ease of development and the power of the distribution tools in the Developer Console on Google Play.

In this video, the Over team talk about their experiences learning and working with Android.

Over engineer Johan Nell, who arrived with Java experience but hadn’t worked with Android, says that he and fellow engineer Herko Lategan “were able to get a working prototype out in the first week.”

Android plays a big part in Over living up to its mantra of “go big, and go home”. As Aaron explains, “we don’t think you should be sacrificing your family to create wealth, or add value, or change the world. Being able to experiment and iterate quickly is crucial in helping us achieve this goal.”

To learn about starting a successful business with Android, be sure to check out these resources:

  • The Secrets to App Success on Google Play [ebook] — a detailed playbook on the best practices and tools you can use to maximize the reach, retention, and revenue of your new app.
  • Getting Started [training] — check out this comprehensive learning resource that takes you from first principles through to the most powerful Android APIs.

08 December 2014

Android Studio 1.0

By Jamal Eason, Product Manager, Android

Today we are excited to introduce Android Studio 1.0. Android Studio is the official Integrated Development Environment (IDE) from the Android team. It is built on the popular IntelliJ IDEA (Community Edition) Java IDE.

We first released a preview of Android Studio at I/O last year. We value the on-going feedback from you, thanks! We are making Android Studio 1.0 available for download as a stable release on the Android Developer site.

Download Android Studio

If you are currently developing for Android or thinking about getting started, now is the time to download Android Studio 1.0 (or upgrade if you are using an earlier version). Similar to the Chrome release channels, Android Studio will continue to receive updates on four different release channels: Stable, Beta, Dev, and Canary. Canary builds are at the bleeding edge of development, while the stable release is fully tested. With this range of release channels you can choose how quickly you want to get the latest features for Android Studio.

Android Studio features

With the release of Android Studio, you have access to a new set of features to enable your development workflow. Some of the key features of Android Studio are listed below, but make sure to check out the Android Studio page for a full feature overview.

Startup experience

  • First-run setup wizard — The getting started experience now installs the right Android SDK, sets up your development environment settings, and creates an optimized emulator for testing your app. Plus, we include a set of code templates to help you get started.
  • Sample Importing & templates — Android Studio includes wizards that enable you to start with new project templates or import Google code samples.

Code and resource editing, user interface design

  • Code Editing — Android Studio takes advantage of all the intelligent code editing capabilities of IntelliJ IDEA such as advanced code completion, refactoring, and code analysis.
  • Internationalization string editing — Manage string translations of your app in Android Studio.
  • User interface design — Edit and preview your Android Layouts across multiple screen sizes, languages, and even API versions.

Performance analysis

  • Memory monitor — View the memory usage of your app over time to help find ways to improve the performance of your app.

Unified build system

  • Android Studio uses a Gradle-based build system that provides a lot of flexibility and extensibility, as well as the ability to build from within and outside of the IDE. This unified build system decouples the build from Studio itself, meaning that Studio updates never impact the output of your build.
  • Some of the key features of the build systems are: build variant support to better handle different build types (debug vs. release), or different versions of the same app (paid vs. free), multi-apks handling through splits, multi-dex support, and dependency management for 3rd party libraries.

Instant access to Google Cloud Services

  • Android Studio even enables an easy way to add Google Cloud Backends & Endpoints to your app, as well as Google Cloud Messaging (find out more).

Time to migrate & update

If you are an Eclipse user, check out our migration steps or you can just import your projects right into Android Studio with the import wizard, shown below:

If you were using one of the early versions of Android Studio, you should also upgrade to version 1.0 since we have added a host of new features and have addressed many bugs.

We have also released version 1.0 of the Gradle plugin with a file format that is now stable. The communication between Android Studio and the Gradle plugin is now stable, so updating one will not require updating the other. Check the technical release notes for additional tips for updating your previous Android Studio projects.

Give us your feedback

We are always seeking to bring you the best Android development experience. We already have plans to add features ranging from improved testing and better support for game development, but we want to know how you work and what capabilities you'd like to have for your Android development.

Please take a moment to complete a short survey (less than 5 minutes). Your responses will help shape the next set of features offered in Android Studio.

Questions?

We develop Android Studio and the corresponding tools in open source, so you can also file bugs via the public Android bug tracker and we will do our best to address your issues or questions. If you have specific questions or need help in your migration, feel free to connect with the Android developer tools team on our Google+ community page.