Game Performance: Data-Oriented Programming

Posted by Shanee Nishry, Game Developer Advocate

To improve game performance, we’d like to highlight a programming paradigm that will help you maximize your CPU potential, make your game more efficient, and code smarter.

Before we get into detail of data-oriented programming, let’s explain the problems it solves and common pitfalls for programmers.

Memory

The first thing a programmer must understand is that memory is slow and the way you code affects how efficiently it is utilized. Inefficient memory layout and order of operations forces the CPU idle waiting for memory so it can proceed doing work.

The easiest way to demonstrate is by using an example. Take this simple code for instance:

char data[1000000]; // One Million bytes
unsigned int sum = 0;

for ( int i = 0; i < 1000000; ++i )
{
  sum += data[ i ];
}

An array of one million bytes is declared and iterated on one byte at a time. Now let's change things a little to illustrate the underlying hardware. Changes marked in bold:

char data[16000000]; // Sixteen Million bytes
unsigned int sum = 0;

for ( int i = 0; i < 16000000; i += 16 )
{
  sum += data[ i ];
}

The array is changed to contain sixteen million bytes and we iterate over one million of them, skipping 16 at a time.

A quick look suggests there shouldn’t be any effect on performance as the code is translated to the same number of instructions and runs the same number of times, however that is not the case. Here is the difference graph. Note that this is on a logarithmic scale–if the scale were linear, the performance difference would be too large to display on any reasonably-sized graph!


Graph in logarithmic scale

The simple change making the loop skip 16 bytes at a time makes the program run 5 times slower!

The average difference in performance is 5x and is consistent when iterating 1,000 bytes up to a million bytes, sometimes increasing up to 7x. This is a serious change in performance.

Note: The benchmark was run on multiple hardware configurations including a desktop with Intel 5930K 3.50GHz CPU, a Macbook Pro Retina laptop with 2.6 GHz Intel i7 CPU and Android Nexus 5 and Nexus 6 devices. The results were pretty consistent.

If you wish to replicate the test, you might have to ensure the memory is out of the cache before running the loop because some compilers will cache the array on declaration. Read below to understand more on how it works.

Explanation

What happens in the example is quite simply explained when you understand how the CPU accesses data. The CPU can’t access data in RAM; the data must be copied to the cache, a smaller but extremely fast memory line which resides near the CPU chip.

When the program starts, the CPU is set to run an instruction on part of the array but that data is still not in the cache, therefore causing a cache miss and forcing the CPU to wait for the data to be copied into the cache.

For simplicity sake, assume a cache size of 16 bytes for the L1 cache line, this means 16 bytes will be copied starting from the requested address for the instruction.

In the first code example, the program next tries to operate on the following byte, which is already copied into the cache following the initial cache miss, therefore continuing smoothly. This is also true for the next 14 bytes. After 16 bytes, since the first cache miss the loop, will encounter another cache miss and the CPU will again wait for data to operate on, copying the next 16 bytes into the cache.

In the second code sample, the loop skips 16 bytes at a time but hardware continues to operate the same. The cache copies the 16 subsequent bytes each time it encounters a cache miss which means the loop will trigger a cache miss with each iteration and cause the CPU to wait idle for data each time!

Note: Modern hardware implements cache prefetch algorithms to prevent incurring a cache miss per frame, but even with prefetching, more bandwidth is used and performance is lower in our example test.

In reality the cache lines tend to be larger than 16 bytes, the program would run much slower if it were to wait for data at every iteration. A Krait-400 found in the Nexus 5 has a L0 data cache of 4 KB with 64 Bytes per line.

If you are wondering why cache lines are so small, the main reason is that making fast memory is expensive.

Data-Oriented Design

The way to solve such performance issues is by designing your data to fit into the cache and have the program to operate on the entire data continuously.

This can be done by organizing your game objects inside Structures of Arrays (SoA) instead of Arrays of Structures (AoS) and pre-allocating enough memory to contain the expected data.

For example, a simple physics object in an AoS layout might look like this:

struct PhysicsObject
{
  Vec3 mPosition;
  Vec3 mVelocity;

  float mMass;
  float mDrag;
  Vec3 mCenterOfMass;

  Vec3 mRotation;
  Vec3 mAngularVelocity;

  float mAngularDrag;
};

This is a common way way to present an object in C++.

On the other hand, using SoA layout looks more like this:

class PhysicsSystem
{
private:
  size_t mNumObjects;
  std::vector< Vec3 > mPositions;
  std::vector< Vec3 > mVelocities;
  std::vector< float > mMasses;
  std::vector< float > mDrags;

  // ...
};

Let’s compare how a simple function to update object positions by their velocity would operate.

For the AoS layout, a function would look like this:

void UpdatePositions( PhysicsObject* objects, const size_t num_objects, const float delta_time )
{
  for ( int i = 0; i < num_objects; ++i )
  {
    objects[i].mPosition += objects[i].mVelocity * delta_time;
  }
}

The PhysicsObject is loaded into the cache but only the first 2 variables are used. Being 12 bytes each amounts to 24 bytes of the cache line being utilised per iteration and causing a cache miss with every object on a 64 bytes cache line of a Nexus 5.

Now let’s look at the SoA way. This is our iteration code:

void PhysicsSystem::SimulateObjects( const float delta_time )
{
  for ( int i = 0; i < mNumObjects; ++i )
  {
    mPositions[ i ] += mVelocities[i] * delta_time;
  }
}

With this code, we immediately cause 2 cache misses, but we are then able to run smoothly for about 5.3 iterations before causing the next 2 cache misses resulting in a significant performance increase!

The way data is sent to the hardware matters. Be aware of data-oriented design and look for places it will perform better than object-oriented code.

We have barely scratched the surface. There is still more to data-oriented programming than structuring your objects. For example, the cache is used for storing instructions and function memory so optimizing your functions and local variables affects cache misses and hits. We also did not mention the L2 cache and how data-oriented design makes your application easier to multithread.

Make sure to profile your code to find out where you might want to implement data-oriented design. You can use different profilers for different architecture, including the NVIDIA Tegra System Profiler, ARM Streamline Performance Analyzer, Intel and PowerVR PVRMonitor.

If you want to learn more on how to optimize for your cache, read on cache prefetching for various CPU architectures.

America explained to non-Americans

America explained to non-Americans

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How To Setup Enhanced Ecommerce Impressions Using Scroll Tracking

A version of this post originally appeared on Google Analytics Certified Partner InfoTrust’s site.
by Nate Denlinger, Web Developer at GACP InfoTrust, LLC

One of our specialities here at InfoTrust is helping ecommerce businesses leverage their web analytics to make better data-driven marketing decisions. This typically starts with installing Google’s Universal Analytics web analytics software and utilizing all of the functionality that is offered with Enhanced Ecommerce tracking capabilities.
Enhanced Ecommerce provides you with a complete picture of what customers on your site are seeing, interacting with and purchasing.
One of the ways you track what your customers are seeing is with product impressions (whenever a user sees an image or description of your products on your website).
Normally, you track what products users see or impressions by simply adding an array of product objects to the DataLayer. These represent the products seen on the page, meaning when any page loads with product images/descriptions, data is sent to Google Analytics that a user saw those specific products. This works well.
However, there is a major issue with this method.  Sometimes you are sending impressions for products that the user never actually sees. This can happen when your page scrolls vertically and some products are off the page or “below the fold”.
For example, lets take a look at a page on Etsy.com:
Sample page on Etsy.com (click for full size)
Here are the results for the search term “Linens”. Currently, you can see sixteen products listed in the search results.  However, in the normal method of sending product impressions, a product impression would be sent for every product on the page.
So, in reality this is what we are telling Google Analytics that the user is seeing (every single product on the page):
Sample page of Etsy.com (click for full-size)

Obviously, no one’s screen looks like this, but by sending all products as an impression, we are effectively saying that our customer saw all 63 products. What happens if the user never scrolls past the 16 products shown in the first screenshot?
We are greatly skewing the impressions for the products on the bottom of the page, because often times, users are not scrolling the entire length of the page (and therefore not seeing the additional products).
This could cause you to make incorrect assumptions about how well a product is selling based off of position.
The solution: Scroll-based impression tracking!
Here is how it works at a high level:
  1. Instead of automatically adding all product impressions to the DataLayer, we add it to another variable just for temporary storage. Meaning, we do not send all the products loaded on a page directly to Google Analytics, but rather just identify the products that loaded on the page.
  2. When the page loads, we actually see what products are visible on the page (ones “above the fold” or where the user can actually see them) and add only those products to the DataLayer for product impressions. Now we don’t send any other product impressions unless they are actually visible to the user.
  3. Once the user starts to scroll, we start capturing all the products that haven’t been seen before. We continue to capture these products until the user stops scrolling for a certain amount of time.
  4. We then batch all of those products together and send them to the DataLayer as product impressions. 
  5. If the user starts to scroll again, we start checking again. However, we never send the same product twice on the same page. If they scroll to the bottom then back up, we don’t send the first products twice.
Using our example on the “Linen” search results, right away we would send product impressions for the first 16 products. Then, let’s say the user scrolled halfway down the page and stopped. We would then send product impressions for products 18 through 40. The user then scrolls to the bottom of the page so we would send product impressions for 41 through 63. Finally the user scrolls back to the top of the page before clicking on the first product. No more impressions would be sent as impressions for all products have already been sent.
The result: Product impressions are only sent as users actually navigate through the pages and can see the products. This is a much more accurate form of product impression tracking since it reflects actual user navigation. 
Next steps: for the technical how-to guide + code samples, please see this post on the InfoTrust site.

An update on Eclipse Android Developer Tools

Posted by Jamal Eason, Product Manager, Android

Over the past few years, our team has focused on improving the development experience for building Android apps with Android Studio. Since the launch of Android Studio, we have been impressed with the excitement and positive feedback. As the official Android IDE, Android Studio gives you access to a powerful and comprehensive suite of tools to evolve your app across Android platforms, whether it’s on the phone, wrist, car or TV.

To that end and to focus all of our efforts on making Android Studio better and faster, we are ending development and official support for the Android Developer Tools (ADT) in Eclipse at the end of the year. This specifically includes the Eclipse ADT plugin and Android Ant build system.

Time to Migrate

If you have not had the chance to migrate your projects to Android Studio, now is the time. To get started, download Android Studio. For many developers, migration is as simple as importing your existing Eclipse ADT projects in Android Studio with File → New→ Import Project as shown below:

For more details on the migration process, check out the migration guide. Also, to learn more about Android Studio and the underlying build system, check out this overview page.

Next Steps

Over the next few months, we are migrating the rest of the standalone performance tools (e.g. DDMS, Trace Viewer) and building in additional support for the Android NDK into Android Studio.

We are focused on Android Studio so that our team can deliver a great experience on a unified development environment. Android tools inside Eclipse will continue to live on in the open source community via the Eclipse Foundation. Check out the latest Eclipse Andmore project if you are interested in contributing or learning more.

For those of you that are new to Android Studio, we are excited for you to integrate Android Studio into your development workflow. Also, if you want to contribute to Android Studio, you can also check out the project source code. To follow all the updates on Android Studio, join our Google+ community.

Remarketing Lists for Search Ads, Powered by Google Analytics

Today we’re excited to announce you can use audiences (previously remarketing lists) created in Google Analytics to reach your customers on Google Search, with no tagging changes required. 
Remarketing Lists for Search Ads (RLSA) allows you to tailor your search ads and based on your visitors’ past activity on your website. Now you can leverage more than 200 Google Analytics dimensions and metrics to create and activate your audiences for remarketing, then use those audiences to reach and re-engage your customers with a consistent message across both Google Search and Display.
TransUnion cuts CPA in half with RLSA
In order to find more customers while reducing waste in their search campaigns, TransUnion, a leading financial services provider, used the audience creation capabilities in Google Analytics to spend more efficiently on Google Search.
TransUnion started by creating two audiences. The first was for new customers―those who had visited the site and started, but not completed a credit application. The other included customers who had already converted. Splitting the audience between new and existing customers allowed TransUnion to bid higher on Google search ads for new customers and spend less on converted customers.
The new RLSA capabilities in Google Analytics yielded impressive conversion rates and cost efficiencies for TransUnion’s search campaigns. RLSA visitors had a lower bounce rate and viewed twice as many pages per session compared with regular visitors. 
By using more tailored text with their remarketing lists, TransUnion increased their conversion rate by 65% and average transaction value by 58%. Meanwhile, CPCs for existing customers dropped 50%, resulting in a roughly 50% drop in their cost per transaction. Read the full case study here
How to get started
Getting started with RLSA is easier than ever before thanks to Instant Activation. Within the Admin tab, simply click Property, then Tracking Info, and finally Data Collection. Ensure that Remarketing is set to ‘ON.’


Once you’ve enabled this setting, all your eligible audiences will begin to populate for RLSA.

Building Audiences
If you’d like to create new audiences, there are three ways to get started. 
First, you can create a new audience using the Audience builder in the remarketing section of the Admin tab. Make sure you select the relevant AdWords account to share your audience with for remarketing.

Admin Remarketing.png

If you have an existing segment you’d like to turn into an audience, simply click on the segment options and select “Build Audience” right from within reporting. This option will take you directly to the audience builder as above.  

Segment Remarketing.png
Finally, you can get started quickly and easily by importing audiences from the Google Analytics Solutions Gallery.
Activating audiences in AdWords
Once you have shared an audience with AdWords, it will appear instantly in your AdWords Shared Library and will show eligible users in the column List size (Google search).  Keep in mind that an audience must accumulate a minimum of 1,000 users before you can use it for remarketing on Google Search. To get started, follow the instructions in the AdWords Help Center


Support for RLSA with Google Analytics is part of an ongoing investment to provide powerful ways to activate your customer insights in Google Analytics, along with recent features like Cohort Analysis, Lifetime Value Analysis, and Active User Reporting. Stay tuned for more announcements!
Happy Analyzing,
Lan Huang, Technical Lead, Google Analytics,
Xiaorui Gan, Technical Lead, Google Search Ads

Android Developer Story: Shifty Jelly drives double-digit growth with material design and expansion to the car and wearables

Posted by Lily Sheringham, Google Play team

Pocket Casts is a leading podcasting app on Google Play built by Australian-based mobile development company Shifty Jelly. The company recently achieved $1 million in sales for the first time, reaching more than 500K users.

According to the co-founder Russell Ivanovic, the adoption of material design played a significant role in driving user engagement for Pocket Casts by streamlining the user experience. Moreover, users are now able to access the app beyond the smartphone — in the car with Android Auto, on a watch with Android Wear or on the TV with Google Cast. The rapid innovation of Android features helped Pocket Casts increase sales by 30 percent.

We chatted with co-founders and Android developers Russell and Philip Simpson to learn more about how they are growing their business with Android.

Here are some of the features Pocket Casts used:

  • Material Design: Learn more about material design and how it helps you create beautiful, engaging apps.
  • Android Wear: Extend your app to Android Wear devices with enhanced notifications or a standalone wearable app.
  • Android Auto: Extend your app to an interface that’s optimized for driving with Android Auto.
  • Google Cast: let your users cast your app’s content to Google Cast devices like Chromecast, Android TV, and speakers with Google Cast built-in.

And check out the Pocket Casts app on Google Play!

Learn to optimize your tag implementation with Google Tag Manager Fundamentals

We’re excited to announce that our next Analytics Academy course, Google Tag Manager Fundamentals, is now open for participation. Whether you’re a marketer, analyst, or developer, this course will teach you how Google Tag Manager can simplify the tag implementation and management process.

You’ll join instructor Krista Seiden to explore topics through the lens of a fictional online retailer, The Great Outdoors and their Travel Adventures website. Using practical examples, she’ll show you how to use tools like Google Analytics and Google AdWords tags to improve your data collection process and advertising strategies.

By participating in the course, you’ll explore:

  • the core concepts and principles of tag management using Google Tag Manager
  • how to create website tags and manage firing triggers
  • how to enhance your Google Analytics implementation
  • the importance of using the Data Layer to collect valuable data for analysis
  • how to configure other marketing tags, like AdWords Conversion Tracking and Dynamic Remarketing

We’re looking forward to your participation in this course!

Sign up for Google Tag Manager Fundamentals and start learning today.

Happy tagging!

Post By: Lizzie Pace & The Google Analytics Education Team

Fitness Apps on Android Wear

Posted by Joshua Gordon, Developer Advocate

Go for a run, improve your game, and explore the great outdoors with Android Wear! Developers are creating a diverse array of fitness apps that provide everything from pace and heart rate while running, to golf tips on your favorite course, to trail maps for hiking. Let’s take a look features of the open and flexible Wear platform they use to create great user experiences.

Always-on stats

If your app supports always-on, you’ll never have to touch or twist your watch to activate the display. Running and want to see your pace? Glance at your wrist and it’s there! Runtastic, Endomondo, and MapMyRun use always-on to keep your stats visible, even in ambient mode. When it’s time for golf, I use Golfshot. Likewise, Golfshot uses always-on to continuously show yardage to the hole, so I never have to drop my club. Check out the doc, DevByte, and code sample to learn more.

Runtastic automatically transitions to ambient mode to conserve battery. There, it reduces the frequency at which stats are updated to about once per 10 seconds.


Maps, routes, and markers

It’s encouraging to see how much ground I’ve covered when I go for a run or ride! Using the Maps API, you can show users their route, position, and place markers on the map they can tap to see more info you provide. All of this functionality is available to you using the same Maps API you’ve already worked with on Android. Check out the doc, DevByte, code sample, and blog post to learn more.

Endomondo tracks your route while your run. You can pan and zoom the map.

Google Fit

Google Fit is an open platform designed to make it easier to write fitness apps. It provides APIs to help with many common tasks. For example, you can use the Recording API to estimate how many steps the user has taken and how many calories they’ve burned. You can make that data to your app via the History API, and even access it over the web via REST, without having to write your own backend. Now, Google Fit can store data from a wide variety of exercises, from running to weightlifting. Check out the DevByte and code samples to learn more.

Bluetooth Low Energy: pair with your watch

With the latest release of Android Wear, developers can now pair BLE devices directly with the Wearable. This is a great opportunity for all fitness apps — and especially for running — where carrying both a phone and the Wearable can be problematic. Imagine if your users could pair their heart rate straps or bicycle cadence sensors directly to their Wear device, and leave their phones at home. BLE is now supported by all Wear devices, and is supported by Google Fit. To learn more about it, check out this guide and DevByte.

Pack light with onboard GPS

When I’m running, carrying both a phone and a wearable can be a bit much. If you’re using an Android Wear device that supports onboard GPS, you can leave your phone at home! Since not all Wear devices have an onboard GPS sensor, you can use the FusedLocationProviderApi to seamlessly retrieve GPS coordinates from the phone if not available on the wearable. Check out this handy guide for more about detecting location on Wear.

RunKeeper supports onboard GPS if it’s available on your Wearable.


Sync data transparently

When I’m back home and ready for more details on my activity, I can see them by opening the app on my phone. My favorite fitness apps transparently sync data between my Wearable and phone. To learn more about syncing data between devices, watch this DevByte on the DataLayer API.

Next Steps

Android Wear gives you the tools and training you need to create exceptional fitness apps. To get started on yours, visit developer.android.com/wear and join the discussion at g.co/androidweardev.

What I mean when I say ‘definitely.’

What I mean when I say 'definitely.'

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Growing Android TV engagement with search and recommendations

Posted by Maru Ahues, Media Developer Advocate

When it comes to TV, content is king. But to enjoy great content, you first need to find it. We created Android TV with that in mind: a truly smart TV should deliver interesting content to users. Today, EPIX® joins a growing list of apps that use the Android TV platform to make it easy to enjoy movies, TV shows, sports highlights, music videos and more.

Making TV Apps Searchable

Think of your favorite movie. Now try to locate it in one of your streaming apps. If you have a few apps to choose from, it might take some hunting before you can watch that movie. With Android TV, we want to make it easier to be entertained. Finding ‘Teenage Mutant Ninja Turtles’ should be as easy as picking up the remote, saying ‘Teenage Mutant Ninja Turtles’ and letting the TV find it.

Searching for ‘Teenage Mutant Ninja Turtles’ shows results from Google Play and EPIX

You can drive users directly to content within your app by making it searchable from the Android TV search interface. Join app developers like EPIX, Sky News, YouTube, and Hulu Plus who are already making content discovery a breeze.

Recommending TV Content

When users want suggestions for content, the recommendations row on Android TV helps them quickly access relevant content right from the home screen. Recommendations are based on the user’s recent and frequent usage behaviors, as well as content preferences.

Recommendations from installed apps, like EPIX, appear in the Android TV home screen

Android TV allows developers to create recommendations for movies, TV shows, music and other types of content. Your app can provide recommendations to users to help get your content noticed. As an example, EPIX shows hollywood movies. NBA Game Time serves up basketball highlights. Washington Post offers video summaries of world events, and YouTube suggests videos based on your subscriptions and viewing history.

With less than one year since the consumer launch of Android TV, we’re already building upon a simpler, smarter and more personalized TV experience, and we can’t wait to see what you create.

More Material Design with Topeka for Android

Posted by Ben Weiss, Developer Programs Engineer

Material design is a new system for visual, interaction and motion design. We originally launched the Topeka web app as an Open Source example of material design on the web.

Today, we’re publishing a new material design example: The Android version of Topeka. It demonstrates that the same branding and material design principles can be used to create a consistent experience across platforms.

Grab the code today on GitHub.

The juicy bits

While the project demonstrates a lot of different aspects of material design, let’s take a quick look at some of the most interesting bits.

Transitions

Topeka for Android features several possibilities for transition implementation. For starters the Transitions API within ActivityOptions provides an easy, yet effective way to make great transitions between Activities.

To achieve this, we register the shared string in a resources file like this:

<resources>
    <string name="transition_avatar">AvatarTransition</string>
</resources>

Then we use it within the source’s and target’s view as transitionName

<ImageView
    android:id="@+id/avatar"
    android:layout_width="@dimen/avatar_size"
    android:layout_height="@dimen/avatar_size"
    android:layout_marginEnd="@dimen/keyline_16"
    android:transitionName="@string/transition_avatar"/>

And then make the actual transition happen within SignInFragment.

private void performSignInWithTransition(View v) {
    Activity activity = getActivity();
    ActivityOptions activityOptions = ActivityOptions
            .makeSceneTransitionAnimation(activity, v,
                    activity.getString(R.string.transition_avatar));
    CategorySelectionActivity.start(activity, mPlayer, activityOptions);
    activity.finishAfterTransition();
}

For multiple transition participants with ActivityOptions you can take a look at the CategorySelectionFragment.

Animations

When it comes to more complex animations you can orchestrate your own animations as we did for scoring.

To get this right it is important to make sure all elements are carefully choreographed.
The AbsQuizView class performs a handful of carefully crafted animations when a question has been answered:

The animation starts with a color change for the floating action button, depending on the provided answer. After this has finished, the button shrinks out of view with a scale animation. The view holding the question itself also moves offscreen. We scale this view to a small green square before sliding it up behind the app bar. During the scaling the foreground of the view changes color to match the color of the fab that just disappeared. This establishes continuity across the various quiz question states.

All this takes place in less than a second’s time. We introduced a number of minor pauses (start delays) to keep the animation from being too overwhelming, while ensuring it’s still fast.

The code responsible for this exists within AbsQuizView’s performScoreAnimation method.

FAB placement

The recently announced Floating Action Buttons are great for executing promoted actions. In the case of Topeka, we use it to submit an answer. The FAB also straddles two surfaces with variable heights; like this:

To achieve this we query the height of the top view (R.id.question_view) and then set padding on the FloatingActionButton once the view hierarchy has been laid out:

private void addFloatingActionButton() {
    final int fabSize = getResources().getDimensionPixelSize(R.dimen.fab_size);
    int bottomOfQuestionView = findViewById(R.id.question_view).getBottom();
    final LayoutParams fabLayoutParams = new LayoutParams(fabSize, fabSize,
            Gravity.END | Gravity.TOP);
    final int fabPadding = getResources().getDimensionPixelSize(R.dimen.padding_fab);
    final int halfAFab = fabSize / 2;
    fabLayoutParams.setMargins(0, // left
        bottomOfQuestionView - halfAFab, //top
        0, // right
        fabPadding); // bottom
    addView(mSubmitAnswer, fabLayoutParams);
}

To make sure that this only happens after the initial layout, we use an OnLayoutChangeListener in the AbsQuizView’s constructor:

addOnLayoutChangeListener(new OnLayoutChangeListener() {
    @Override
    public void onLayoutChange(View v, int l, int t, int r, int b,
            int oldLeft, int oldTop, int oldRight, int oldBottom) {
        removeOnLayoutChangeListener(this);
        addFloatingActionButton();
    }
});

Round OutlineProvider

Creating circular masks on API 21 onward is now really simple. Just extend the ViewOutlineProvider class and override the getOutline() method like this:

@Override
public final void getOutline(View view, Outline outline) {
    final int size = view.getResources().
        getDimensionPixelSize(R.id.view_size);
    outline.setOval(0, 0, size, size);
}

and setClipToOutline(true) on the target view in order to get the right shadow shape.

Check out more details within the outlineprovider package within Topeka for Android.

Vector Drawables

We use vector drawables to display icons in several places throughout the app. You might be aware of our collection of Material Design Icons on GitHub which contains about 750 icons for you to use. The best thing for Android developers: As of Lollipop you can use these VectorDrawables within your apps so they will look crisp no matter what density the device’s screen. For example, the back arrow ic_arrow_back from the icons repository has been adapted to Android’s vector drawable format.

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="24dp"
    android:height="24dp"
    android:viewportWidth="48"
    android:viewportHeight="48">
    <path
        android:pathData="M40 22H15.66l11.17-11.17L24 8 8 24l16 16 2.83-2.83L15.66 26H40v-4z"
        android:fillColor="?android:attr/textColorPrimary" />
</vector>

The vector drawable only has to be stored once within the res/drawable folder. This means less disk space is being used for drawable assets.

Property Animations

Did you know that you can easily animate any property of a View beyond the standard transformations offered by the ViewPropertyAnimator class (and it’s handy View#animate syntax)? For example in AbsQuizView we define a property for animating the view’s foreground color.

// Property for animating the foreground
public static final Property FOREGROUND_COLOR =
        new IntProperty("foregroundColor") {

            @Override
            public void setValue(FrameLayout layout, int value) {
                if (layout.getForeground() instanceof ColorDrawable) {
                    ((ColorDrawable) layout.getForeground()).setColor(value);
                } else {
                    layout.setForeground(new ColorDrawable(value));
                }
            }

            @Override
            public Integer get(FrameLayout layout) {
                return ((ColorDrawable) layout.getForeground()).getColor();
            }
        };

This can later be used to animate changes to said foreground color from one value to another like this:

final ObjectAnimator foregroundAnimator = ObjectAnimator
        .ofArgb(this, FOREGROUND_COLOR, Color.WHITE, backgroundColor);

This is not particularly new, as it has been added with API 12, but still can come in quite handy when you want to animate color changes in an easy fashion.

Tests

In addition to exemplifying material design components, Topeka for Android also features a set of unit and instrumentation tests that utilize the new testing APIs, namely “Gradle Unit Test Support” and the “Android Testing Support Library.” The implemented tests make the app resilient against changes to the data model. This catches breakages early, gives you more confidence in your code and allows for easy refactoring. Take a look at the androidTest and test folders for more details on how these tests are implemented within Topeka. For a deeper dive into Testing on Android, start reading about the Testing Tools.

What’s next?

With Topeka for Android, you can see how material design lets you create a more consistent experience across Android and the web. The project also highlights some of the best material design features of the Android 5.0 SDK and the new Android Design Library.

While the project currently only supports API 21+, there’s already a feature request open to support earlier versions, using tools like AppCompat and the new Android Design Support Library.

Have a look at the project and let us know in the project issue tracker if you’d like to contribute, or on Google+ or Twitter if you have questions.

Updates to Unity, C++, and iOS tools for Play game services

Posted by Benjamin Frenkel, Product Manager

To further support all you game developers, we’ve updated our popular developer tools to give you a consistent set of game services across platforms for a better, more stable experience, with a particular focus on improvements to the Play game services Unity plugin. In addition, we added support for the Nearby Connections API, launched earlier this year at GDC, to our C++ SDK and Unity plugin.

Let’s take a look a closer look!

Unity plugin feature parity and stability improvements

We’ve added full support for Events and Quests in the Unity plugin. If you’re a Unity developer, you can now incorporate Quests into your games and take full advantage of Player Analytics natively within the Unity IDE.

We’ve also listened to feedback from our community of Unity plugin users and made stability improvements to Play game services Multiplayer, Saved Games, and to sign-in. You’ll now have a much better experience integrating with these Play game services, with fewer crashes and glitches.

C++ SDK and Unity support for the Nearby Connections API

We have added support for the Nearby Connections API to our C++ SDK and Unity plugin. You can now easily build awesome second screen and local multiplayer experiences, like this Beach Bugging Racing example, with the development tools you are most comfortable with.

Easier and more stable iOS builds with CocoaPods

We’ve also made major improvements to our Play game services CocoaPods, which simplify dependency management and building App Store packages from Xcode. The CocoaPods will improve building for iOS with the Play game services iOS and C++ SDKs, and the Unity plugin. We also improved the stability of multiplayer on iOS, eliminating many of the issues around accepting match invitations.

Finally, we improved our support for iOS 8, making it easier to set up multiplayer push notifications, and fixing UI compatibility issues.

Quick links to get you started

Play game services developer page: https://developers.google.com/games/services/
Case studies: http://developer.android.com/distribute/stories/games.html

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Joseph Sikorski made a documentary about the Tesla Tower at Wardenclyffe

Joseph Sikorski made a documentary about the Tesla Tower at Wardenclyffe

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Android Developer Story: Trello Increases engagement with material design

Posted by Laura Della Torre, Google Play team

Trello is a visual collaboration tool that gives teams a shared perspective on projects. It’s built around the concept of a traditional office whiteboard. Simplicity and flexibility are core to the product, so the Trello team recently redesigned their Android app using the material design guidelines to double down on that effort.

According to Fyza Hashim, Designer at Trello, material design had an immediate impact on streamlining app-design and -development at the company. She added that, “Because the guidelines are so thorough and well thought out, you don’t have to go back and forth with developers.”

Sharing is a key component of Trello, so material design helped continue the same cohesive design and intuitive experience on both web and mobile. This makes sharing even easier. As a result, Trello has also seen double digit growth in user engagement with more and more sessions added per week.

Watch the video where we caught up with Michael Pryor, CEO; Hamid Palo, Mobile Lead; and Fyza at the Trello offices in New York to learn more.

Material design — learn more about material design and how it helps you create beautiful, engaging apps.

Android Developer Story: Trello Increases engagement with material design

Posted by Laura Della Torre, Google Play team

Trello is a visual collaboration tool that gives teams a shared perspective on projects. It’s built around the concept of a traditional office whiteboard. Simplicity and flexibility are core to the product, so the Trello team recently redesigned their Android app using the material design guidelines to double down on that effort.

According to Fyza Hashim, Designer at Trello, material design had an immediate impact on streamlining app-design and -development at the company. She added that, “Because the guidelines are so thorough and well thought out, you don’t have to go back and forth with developers.”

Sharing is a key component of Trello, so material design helped continue the same cohesive design and intuitive experience on both web and mobile. This makes sharing even easier. As a result, Trello has also seen double digit growth in user engagement with more and more sessions added per week.

Watch the video where we caught up with Michael Pryor, CEO; Hamid Palo, Mobile Lead; and Fyza at the Trello offices in New York to learn more.

Material design — learn more about material design and how it helps you create beautiful, engaging apps.

Tyrannosaurus Standup

Tyrannosaurus Standup

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8 things I learned from wearing an Apple Watch for a couple of weeks

8 things I learned from wearing an Apple Watch for a couple of weeks

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BT Increases Sales Volume and Efficiency Using DoubleClick Bid Manager With Google Analytics Premium

Cross-posted on the DoubleClick Advertiser Blog
Modern marketers live in a world that’s dominated by data. Advancements in programmatic buying enable marketers to leverage data and analytics to connect precisely, in real time. Advertisers who are smart about organizing, segmenting, and acting on this data are realizing the benefits of more personalized marketing. BT, a leading telecommunications firm in the UK, did just that and saw fantastic results.  

BT wanted to increase the relevance of their remarketing campaigns by creating more precise audience lists. With the help of their media agency Maxus, BT found that using Google Analytics Premium with DoubleClick Bid Manager offered the ideal solution. 
Google Analytics Premium gave BT the ability to create granular audience segments based on site behavior metrics such as recency, frequency, referral source, and stage of cart abandonment. Once these audience lists were created, the native integration between Google Analytics Premium and DoubleClick Bid Manager meant they could be shared with the platform to make more precise media buys in just a few clicks.

Using Google Analytics Premium with DoubleClick Bid Manager put Maxus and BT in the driver’s seat of their media campaigns. They not only gleaned full transparency with a single customer view and de-duplicated metrics across all channels, but also saw better measurement through unified reporting, and the ability to optimize based on the results.




”Our goals were to build up ‘best practices’ of programmatic display remarketing techniques with a focus on driving post-click sales,” says Alison Thorburn, Head of Digital DR Media at BT. “The DoubleClick suite of products enabled us to do this quickly and efficiently as audience data can be easily organized and utilized.” 

The new analytics-driven approach produced a 69% increase in post-click sales and an 87% reduction in post-click cost per acquisition compared to the previous year’s remarketing activity. It also compared favorably to the remarketing activity that ran simultaneously outside of DoubleClick Bid Manager; post-click sales were 30% higher and post-click cost per acquisition was 42% lower. BT has now consolidated its display remarketing through DoubleClick BidManager.
Read the full case study here.
Posted by-
Kelley Sternhagen, Product Marketing, Google Analytics

Kelly Cox, Product Marketing, DoubleClick

Introducing new Android training programs with Udacity

Posted by Peter Lubbers, Senior Program Manager, Google Developer Training

We know how important it is for you to efficiently develop the skills to build better Android apps and be successful in your jobs. To meet your training needs, we’ve partnered with Udacity to create Android training courses, ranging from beginner to more advanced content.

Last week at Google I/O we announced the Android Nanodegree, an education credential that is designed for busy people to learn new skills and advance their careers in a short amount of time from anywhere at any time. The nanodegree ties together our Android courses, and provides you with a certificate that may help you be a more marketable Android developer.

Training courses

All training courses are developed and taught by expert Google instructors from the Developer Platform team. In addition to updating our popular Developing Android Apps course and releasing Advanced Android App Development, we now have courses for everyone from beginning programmers to advanced developers who want to configure their Gradle build settings. And then there’s all the fun stuff in between—designing great-looking, high performance apps, making your apps run on watches, TVs, and in cars, and using Google services like Maps, Ads, Analytics, and Fit.

Each course is available individually, without charge, at udacity.com/google. Our instructors are waiting for you:

Android Nanodegree

You can also enroll in the new Android Nanodegree for a monthly subscription fee, which gives you access to coaches who will review your code, provide guidance on your project, answer questions about the class, and help keep you on track when you need it.

More importantly, you will learn by doing, focusing only on where you need to grow. Since the Nanodegree is based on your skills and the projects in your portfolio, you do not need to complete the courses that address the skills you already have. You can focus on writing the code and building the projects that meet the requirements for the Nanodegree credential.
We’ll also be inviting 50 Android Nanodegree graduates to Google’s headquarters in Mountain View, California, for a three day intensive Android Career Summit in November. Participants will have the opportunity to experience Google’s company culture and attend workshops focused on developing their personal career paths. Participants will then leverage the skills learned from Udacity’s Android Nanodegree during a two-day hackathon.

To help you learn more about this program and and courses within it, Google and Udacity are partnering up for an “Ask the Experts” live streamed series. In the first episode on Wednesday, June 3rd at 2pm PDT, Join Sebastian Thrun, Peter Lubbers and Jocelyn Becker who will be answering your questions on the Nanodegree. RSVP here and ask and vote for questions here.

Android training in Arabic

We also believe that everyone has the right to learn how to develop Android apps. Today, there is a great need for developers in countries outside of the United States as software powers every industry from food and transportation to healthcare and retail. As a first step in getting the Android Nanodegree localized and targeted for individual countries, we have worked with the Government of Egypt and Udacity to create end-to-end translations of our top Android courses into Arabic (including fully dubbed video). Google will offer 2,000 scholarships to students to get a certificate for completing the Arabic version of the Android Fundamentals course. Google will also host job fairs and sessions for students with local employers and the Egyptian Government. For more information, see www.udacity.com/egypt.

Complete Android course catalog

Here are the currently-planned courses in the Android Nanodegree:

So get learning now at udacity.com/android

Android Design Support Library

Posted by Ian Lake, Developer Advocate

Android 5.0 Lollipop was one of the most significant Android releases ever, in no small part due to the introduction of material design, a new design language that refreshed the entire Android experience. Our detailed spec is a great place to start to adopt material design, but we understand that it can be a challenge for developers, particularly ones concerned with backward compatibility. With a little help from the new Android Design Support Library, we’re bringing a number of important material design components to all developers and to all Android 2.1 or higher devices. You’ll find a navigation drawer view, floating labels for editing text, a floating action button, snackbar, tabs, and a motion and scroll framework to tie them together.

Navigation View

The navigation drawer can be an important focal point for identity and navigation within your app and consistency in the design here can make a considerable difference in how easy your app is to navigate, particularly for first time users. NavigationView makes this easier by providing the framework you need for the navigation drawer as well as the ability to inflate your navigation items through a menu resource.

You use NavigationView as DrawerLayout’s drawer content view with a layout such as:

<android.support.v4.widget.DrawerLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true">

    <!-- your content layout -->

    <android.support.design.widget.NavigationView
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_gravity="start"
            app:headerLayout="@layout/drawer_header"
            app:menu="@menu/drawer"/>
</android.support.v4.widget.DrawerLayout>

You’ll note two attributes for NavigationView: app:headerLayout controls the (optional) layout used for the header. app:menu is the menu resource inflated for the navigation items (which can also be updated at runtime). NavigationView takes care of the scrim protection of the status bar for you, ensuring that your NavigationView interacts with the status bar appropriately on API21+ devices.

The simplest drawer menus will be a collection of checkable menu items:

<group android:checkableBehavior="single">
    <item
        android:id="@+id/navigation_item_1"
        android:checked="true"
        android:icon="@drawable/ic_android"
        android:title="@string/navigation_item_1"/>
    <item
        android:id="@+id/navigation_item_2"
        android:icon="@drawable/ic_android"
        android:title="@string/navigation_item_2"/>
</group>

The checked item will appear highlighted in the navigation drawer, ensuring the user knows which navigation item is currently selected.

You can also use subheaders in your menu to separate groups of items:

<item
    android:id="@+id/navigation_subheader"
    android:title="@string/navigation_subheader">
    <menu>
        <item
            android:id="@+id/navigation_sub_item_1"
            android:icon="@drawable/ic_android"
            android:title="@string/navigation_sub_item_1"/>
        <item
            android:id="@+id/navigation_sub_item_2"
            android:icon="@drawable/ic_android"
            android:title="@string/navigation_sub_item_2"/>
    </menu>
</item>

You’ll get callbacks on selected items by setting a OnNavigationItemSelectedListener using setNavigationItemSelectedListener(). This provides you with the MenuItem that was clicked, allowing you to handle selection events, changed the checked status, load new content, programmatically close the drawer, or any other actions you may want.

Floating labels for editing text

Even the humble EditText has room to improve in material design. While an EditText alone will hide the hint text after the first character is typed, you can now wrap it in a TextInputLayout, causing the hint text to become a floating label above the EditText, ensuring that users never lose context in what they are entering.

In addition to showing hints, you can also display an error message below the EditText by calling setError().

Floating Action Button

A floating action button is a round button denoting a primary action on your interface. The Design library’s FloatingActionButton gives you a single consistent implementation, by default colored using the colorAccent from your theme.

In addition to the normal size floating action button, it also supports the mini size (fabSize="mini") when visual continuity with other elements is critical. As FloatingActionButton extends ImageView, you’ll use android:src or any of the methods such as setImageDrawable() to control the icon shown within the FloatingActionButton.

Snackbar

Providing lightweight, quick feedback about an operation is a perfect opportunity to use a snackbar. Snackbars are shown on the bottom of the screen and contain text with an optional single action. They automatically time out after the given time length by animating off the screen. In addition, users can swipe them away before the timeout.

By including the ability to interact with the Snackbar through swiping it away or actions, these are considerably more powerful than toasts, another lightweight feedback mechanism. However, you’ll find the API very familiar:

Snackbar
  .make(parentLayout, R.string.snackbar_text, Snackbar.LENGTH_LONG)
  .setAction(R.string.snackbar_action, myOnClickListener)
  .show(); // Don’t forget to show!

You’ll note the use of a View as the first parameter to make() - Snackbar will attempt to find an appropriate parent of the Snackbar’s view to ensure that it is anchored to the bottom.

Tabs

Switching between different views in your app via tabs is not a new concept to material design and they are equally at home as a top level navigation pattern or for organizing different groupings of content within your app (say, different genres of music).

The Design library’s TabLayout implements both fixed tabs, where the view’s width is divided equally between all of the tabs, as well as scrollable tabs, where the tabs are not a uniform size and can scroll horizontally. Tabs can be added programmatically:

TabLayout tabLayout = ...;
tabLayout.addTab(tabLayout.newTab().setText("Tab 1"));

However, if you are using a ViewPager for horizontal paging between tabs, you can create tabs directly from your PagerAdapter’s getPageTitle() and then connect the two together using setupWithViewPager(). This ensures that tab selection events update the ViewPager and page changes update the selected tab.

CoordinatorLayout, motion, and scrolling

Distinctive visuals are only one part of material design: motion is also an important part of making a great material designed app. While there are a lot of parts of motion in material design including touch ripples and meaningful transitions, the Design library introduces CoordinatorLayout, a layout which provides an additional level of control over touch events between child views, something which many of the components in the Design library take advantage of.

CoordinatorLayout and floating action buttons

A great example of this is when you add a FloatingActionButton as a child of your CoordinatorLayout and then pass that CoordinatorLayout to your Snackbar.make() call – instead of the snackbar displaying over the floating action button, the FloatingActionButton takes advantage of additional callbacks provided by CoordinatorLayout to automatically move upward as the snackbar animates in and returns to its position when the snackbar animates out on Android 3.0 and higher devices – no extra code required.

CoordinatorLayout also provides an layout_anchor attribute which, along with layout_anchorGravity, can be used to place floating views, such as the FloatingActionButton, relative to other views.

CoordinatorLayout and the app bar

The other main use case for the CoordinatorLayout concerns the app bar (formerly action bar) and scrolling techniques. You may already be using a Toolbar in your layout, allowing you to more easily customize the look and integration of that iconic part of an app with the rest of your layout. The Design library takes this to the next level: using an AppBarLayout allows your Toolbar and other views (such as tabs provided by TabLayout) to react to scroll events in a sibling view marked with a ScrollingViewBehavior. Therefore you can create a layout such as:

 <android.support.design.widget.CoordinatorLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
     
     <! -- Your Scrollable View -->
    <android.support.v7.widget.RecyclerView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_behavior="@string/appbar_scrolling_view_behavior" />

    <android.support.design.widget.AppBarLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
   <android.support.v7.widget.Toolbar
                  ...
                  app:layout_scrollFlags="scroll|enterAlways">

        <android.support.design.widget.TabLayout
                  ...
                  app:layout_scrollFlags="scroll|enterAlways">
     </android.support.design.widget.AppBarLayout>
</android.support.design.widget.CoordinatorLayout>

Now, as the user scrolls the RecyclerView, the AppBarLayout can respond to those events by using the children’s scroll flags to control how they enter (scroll on screen) and exit (scroll off screen). Flags include:

  • scroll: this flag should be set for all views that want to scroll off the screen – for views that do not use this flag, they’ll remain pinned to the top of the screen
  • enterAlways: this flag ensures that any downward scroll will cause this view to become visible, enabling the ‘quick return’ pattern
  • enterAlwaysCollapsed: When your view has declared a minHeight and you use this flag, your View will only enter at its minimum height (i.e., ‘collapsed’), only re-expanding to its full height when the scrolling view has reached it’s top.
  • exitUntilCollapsed: this flag causes the view to scroll off until it is ‘collapsed’ (its minHeight) before exiting

One note: all views using the scroll flag must be declared before views that do not use the flag. This ensures that all views exit from the top, leaving the fixed elements behind.

Collapsing Toolbars

Adding a Toolbar directly to an AppBarLayout gives you access to the enterAlwaysCollapsed and exitUntilCollapsed scroll flags, but not the detailed control on how different elements react to collapsing. For that, you can use CollapsingToolbarLayout:

<android.support.design.widget.AppBarLayout
        android:layout_height="192dp"
        android:layout_width="match_parent">
    <android.support.design.widget.CollapsingToolbarLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:layout_scrollFlags="scroll|exitUntilCollapsed">
        <android.support.v7.widget.Toolbar
                android:layout_height="?attr/actionBarSize"
                android:layout_width="match_parent"
                app:layout_collapseMode="pin"/>
        </android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>

This setup uses CollapsingToolbarLayout’s app:layout_collapseMode="pin" to ensure that the Toolbar itself remains pinned to the top of the screen while the view collapses. Even better, when you use CollapsingToolbarLayout and Toolbar together, the title will automatically appear larger when the layout is fully visible, then transition to its default size as it is collapsed. Note that in those cases, you should call setTitle() on the CollapsingToolbarLayout, rather than on the Toolbar itself.

In addition to pinning a view, you can use app:layout_collapseMode="parallax" (and optionally app:layout_collapseParallaxMultiplier="0.7" to set the parallax multiplier) to implement parallax scrolling (say of a sibling ImageView within the CollapsingToolbarLayout). This use case pairs nicely with the app:contentScrim="?attr/colorPrimary" attribute for CollapsingToolbarLayout, adding a full bleed scrim when the view is collapsed.

CoordinatorLayout and custom views

One thing that is important to note is that CoordinatorLayout doesn’t have any innate understanding of a FloatingActionButton or AppBarLayout work – it just provides an additional API in the form of a Coordinator.Behavior, which allows child views to better control touch events and gestures as well as declare dependencies between each other and receive callbacks via onDependentViewChanged().

Views can declare a default Behavior by using the CoordinatorLayout.DefaultBehavior(YourView.Behavior.class) annotation,or set it in your layout files by with the app:layout_behavior="com.example.app.YourView$Behavior" attribute. This framework makes it possible for any view to integrate with CoordinatorLayout.

Available now!

The Design library is available now, so make sure to update the Android Support Repository in the SDK Manager. You can then start using the Design library with a single new dependency:

 compile 'com.android.support:design:22.2.0'

Note that as the Design library depends on the Support v4 and AppCompat Support Libraries, those will be included automatically when you add the Design library dependency. We also took care that these new widgets are usable in the Android Studio Layout Editor’s Design view (find them under CustomView), giving you an easier way to preview some of these new components.

The Design library, AppCompat, and all of the Android Support Library are important tools in providing the building blocks needed to build a modern, great looking Android app without building everything from scratch.