Google I/O, MKBHD and how I missed a selfie with Sundar Pichai

Google I/O is the company’s annual developer conference where they showcase new products they’ve been working on over the past one year. The “I/O” traditionally stands for Input/Output, and in here it also stands for Innovation in the Open. The event features highly technical sessions and talks to give developers a first hand experience and the technical know-how to start developing for their new products. Google I/O brings together developers from across the globe. It’s a great way to meet the developer community. This year’s I/O was hosted in Google’s own backyard at the Shoreline Amphitheatre in Mountain View, California with over a staggering 7000 attendees!

Check out the highlights of this year


 

APPLIED CS WITH ANDROID

Google I/O is mostly invite-based, the number of tickets open to the public is really limited and these tickets are sold via lottery system. They can cost around 900$ or 300$ for students. Google issues the rest of the tickets through its various communities and programs. I am part of Google’s program called Applied CS with Android. It’s a course designed for university CS students where they practically apply concepts of Computer Science using Android as a platform. This course is delivered by a student facilitator within the college and I was chosen as the student facilitator for mine. Read here to know more about this program.

both

Through the program, they had 2 tickets to offer across the facilitators in India, me and a senior, Muthu Ramakrishnan (on the right) from SRM university got selected through an application process. He’s the boss that tried to bring Netflix into India using YIFY torrents, read about him here. I will be referring to him as “the boss” from now 😀
 

INTERNATIONAL DATE LINE

It was my first visit to the United States and the first noob moment struck when I received my flight tickets, it said the departure was at 4 am on 15th May and the arrival was at 2 pm on the same day, but the total journey took around 24 hrs.

khtm4

and the boss didn’t give it out so easily 😀

dateLine

Well of course, the date line! Travelling towards the East, when you cross the international date line, you would gain a day.

dateLineRoute

The San Francisco timezone in particular is 12 hrs and 30 mins behind India. So yeah, essentially we would be travelling back in time just like the boss said 😀
 

BADGE-PICKUP

It was badge-pickup day, the keynote seating was to be pre-assigned on a first come, first serve basis. The badge pick-up began at 7 am, but we were not going to miss out Sundar Pichai’s keynote from the back, so me and the boss got up early by 5. We took an Uber to Shoreline Amphitheatre and reached there by 5:30 only to find people had been standing there from 4:30! Slowly the queue started to build up, by 6 the queue was stretching across 2 blocks. At 7, the gates opened and we were finally in.

IMG-20160517-WA0015

We received our badges and some swag, this included a T-shirt, a sipper, a pair of sun glasses and a Google cardboard.

IMG_20160703_133441

It was time for some photographs in front of the Google logo. Google had their logo put up in almost all their buildings and signs but most of these were the old ones.

google-logo-2

The boss insisted that we click a picture in front of the new one. So we both grabbed a G-bike (G-bikes are these colorful girly bikes you find lying all around the Google campus) and started wandering around the Google campus in search for the new one.

gbike

We finally came across the updated logo at 1098 Alta Avenue.

newlogo
 

KEY-NOTE

Snapchat-794565494586146779

We arrived leisurely the next day because we had guaranteed spots in the front or so we believed. When we got there, there was a huge crowd of people, almost all of the 7000 attendees waiting in line to grab the best seat possible.

IMG-20160518-WA0002

We met up with some fellow developers from India who came through the Google-Developer-Group program, we were all standing in line together.

IMG-20160518-WA0004

Also waiting in line was Marques Brownlee, the dope tech-reviewer popularly known as MKBHD. I rushed through the crowd to meet him. I was grinning the whole time like a little girl, I couldn’t help it, I was starstruck and he said “Take it easy” 😀

IMG_20160518_090053

The keynote gates opened and we managed to grab a good seat. The atmosphere was electric with all the nerds in one place 😀

IMG-20160518-WA0011

Sundar Pichai came to the stage, the Indian inside me glistening with pride as the whole crowd cheered for him!

sundar

He began talking about the advancement in the field of Artificial Intelligence, Machine learning and how they are helping power Google’s various apps. For example, Google Photos is unlike any other photo gallery app, it will identify key-aspects from your pictures like people, animals, objects, places etc. from which you can retrieve appropriate image results when you search for queries like “cat”,”beach” which would find images containing cats and photos taken on the beach from your albums.

Watch the full keynote here. Here are some of my favorite announcements from the key-note.
 

GOOGLE HOME

googleHome

Similar to Amazon’s Echo, Google has released a new voice-assistant called Google Home. With the form factor of a speaker, it houses a mic and connects to all chromecast devices and even nest devices. It comes with all the goodness of Google built right into it, synced across anything and everything, you can use it for search, playing music, booking movie tickets, home-automation and what not! Talking to an assistant, you would expect it to remember conversations and they’ve done just that. If you ask the assistant “Who is Chuck Norris”, followed by “When was he born ?”, speech assistants like Siri would fail. But with the improved Google Now in the assistant, it remembers the “he” refers to Chuck Norris and gives his birthday!

Chuck-Norris-Approves-Meme-10
 

ALLO

Google brings a new messenger app called “allo” (not hello).  It is in all aspects similar to WhatsApp, except for the fact that it has an AI built into it. Anyone who has used the Hike Messenger would be familiar with a bot called Natasha, it served as a bot you can have a conversation with, get details about movies, weather etc. But Allo takes it to a whole new level, it’s listening to your conversations all the time. Let’s say you are talking about going for dinner at an Italian place and BAM! Allo brings up a list of Italian restaurants nearby, right into your chat screen.

allo1

So you get the idea, you no longer have to go outside the app and Google for something, it’s all accessible from within. Allo also gives you smart replies (intelligent replies based on the context), that means you no longer have to type.

allo2

Interestingly, it also lets you beef up the text and smileys so you can convey more emotions.

smiley

Overall it’s an app designed to ease out your chatting experience. But what about privacy ? Would you let an A.I listen in on all your conversations ?  Here‘s what the infamous Edward Snowden has to say.
 

DUO

Duo is a new mobile-only video chatting app that competes with Apple’s facetime. The only feature that makes duo stand out is the knock-knock feature, when somebody calls, you can already see through their camera before you even choose to pick-up the call.

duo
 

DAYDREAM

Virtual Reality is now built right into Android with the last version Nougat. You can simply switch into VR mode, wear your cardboard and immerse into a new UI built just for VR. They’ve also released designs for a new bluetooth remote which would act as the controller for the VR mode, like a tiny Wiimote.

remote

The name “Daydream” was already taken in Android, the screensavers were originally called Daydream. This got me pretty confused during the key-note. Since the original Daydream was never a high-profile feature, they decided to rename it back to plain old “screensaver”.
 

INSTANT APPS

This was one of my favorite announcements in the I/O. Instant apps lets you instantly run an app without installing it! This means you can try out an app before you install it. But isn’t that the same as installing an app and then uninstalling it? Nope, when you run an instant app you are not downloading the whole app, rather just a part of the app to demonstrate a feature, that’s why it launches instantly. That’s not all, you can use just a part of the app when you require it. Let’s say you wanna buy a pair of pants, the website offers you an instant app rather than the whole e-commerce app. You purchase the pair of pants, finish the transaction and you’re done with the app. You can later choose to install it or remove it. This is really helpful when you want to use services that you don’t often rely on.
 

WEAR 2.0

androidweartwooh-100661858-primary.idge

With Android Wear 2.0, you no longer need to carry your phone to use your smartwatch. Apps can now run separately on the watch. You can even type back replies using a tiny keyboard in the watch, though you can still sync it your phone and use the phone keyboard instead to input fields ( but that beats the whole purpose of a smartwatch doesn’t it o.O )
 

DEVELOPER SESSIONS

queue

After the keynote, the developer sessions were underway. Google did not think this through. They setup domes everywhere to host the sessions, but these could fit only a few people. I could not go to the first session I had planned to go to because it got full. When people started realizing this, they prioritized their sessions, skipped some to camp out in front of the next one to guarantee a seat. The lines started growing really long, the ones at the back not knowing when the capacity was full. So they introduced a ticketing system, everyone who got the ticket was guaranteed a spot, the rest had to move on! So I strictly prioritized for the Project Tango sessions.

All the sessions are available on YouTube
 

PROJECT TANGO

Part of Google’s ATAP (Advanced Technology and Projects) division, project Tango is a new technology that gives your phone and tablet, the ability to understand their position relative to the world around them, i.e the sense of space. In layman’s terms, if you move from point A to point B, the Tango device is capable of retracing it’s path back to point A. This technology allows the device to precisely measure the dimensions of objects and understand planes when you point your camera at something, allowing the device to render 3D objects in real time giving you augmented reality.

Read more about project Tango here

Check out this demonstration to truly understand what Tango is capable of! This was my favorite demonstration in Google I/O, I was spellbound, so was the whole crowd sitting there.

On one hand you have the immersive experience of VR and on the other the capability to render the world you see the way you want, combine these two and you no longer need to live in actual reality 😀
 

SELFIE WITH SUNDAR PICHAI

In the evening, they had concerts inside the amphitheatre. I forgot to wear my jacket, it was quite chilly to the point where it became unbearable. So me and the boss got off from our seats to get me a hoodie from the store. Near the exit, we saw people crowding, amidst them was the CEO of Google, Sundar Pichai. Again I was starstruck! I didn’t know how to react but the boss jumped through the crowd and managed to click a quick selfie and we later discovered that I almost ended up in it too (right between them) 😀

IMG_20160518_202222-2
 

MEET-UP

IMG_20160520_202736

After Google I/O we met up with Sebastian and Aida, they are heading the Applied CS with Android and other developer relation programs at Google. Riya who was part of the pilot program for Applied CS also joined us. They took us around the Google campus. We even played volleyball inside, it was super fun!

Google I/O was an incredible experience, the kind of people you meet here and the exposure that you get is beyond comprehension. You get to meet the experts one-on-one and ask your burning questions, you get expert advice and suggestions to improve your products and best of all, you get to meet awesome people like you and make new friends! Now I realize why they call it “Innovation in the Open”. I thank Google for having me, hope to be back next year 🙂

How to setup Google Play Game Services in LibGDX using Android Studio

Hands down, one of the most nerve wracking API integration I’ve ever done! Mostly due to the jargon-filled Google documentation and the lack of  libGDX-specific tutorials. Hopefully, this post would give you more clarity to implement the same.

1) Create a new Game Service

Head over to your dashboard and select Game services

Note: You don’t need to have your game added under All applications in order to test Play Services.

Click on Add new game. Choose I don’t use any Google APIs in my game yet tab and Fill out your game name and category.

  • Game details: Make sure to fill in all mandatory fields like description, graphic assets etc.
  • Linked apps: Choose Android, fill in the package name ( This package name should match with the one in your AndroidManifest file ) To properly authorize your app, follow my guide
  • Events: This is not mandatory, leave it for now.
  • Achievements: It is mandatory that you have at least 5 achievements in your game. If you don’t plan on having them just leave them unimplemented in your game but make sure to fill these up and obtain the tick mark.
  • Leaderboards: You can add as many leaderboards as you want depending upon your game.
  • Testing: Make sure you have filled in all the necessary fields and the game service is ready to be tested. Add testers: Only the users you specify will be able to use the game service when it is unpublished, make sure to add an account other than your dev account as the dev account may not work sometimes.
  • Publishing: It’s better to publish it with the whole game when it’s ready. You can still test all the features with the test accounts.

 

2) Install Play Services packages

Untitled-9

Open up SDK Manager in Android Studio, ( Click the button next to the AVD manager in the top toolbar ) click Launch Standalone SDK Manager

Scroll down to the Extras section and make sure these 2 packages are installed and updated to the latest :

  • Google Play services
  • Google Repository

 

3) Add BaseGameUtils Library

Didn’t we just add the Play services packages, what is this for?

This repository contains a lot of sample projects including libraries, each one implementing a different play service. So that means they’ve written all the code  for you! You don’t have to talk to the API and handle all those lousy exceptions, you just have to add it as a library module for your project and call the necessary methods. Good job Google 😀

Here’s the repository, Clone it or Download it as ZIP.

Extract it inside your project folder. Inside the extracted folder, open the  BasicSamples folder and you’d find all the sample projects. These are only for reference, you essentially need the libraries folder.

Open Android Studio, goto File > New > Import Module

Point the Source directory to BasicSamples\libraries\BaseGameUtils

 

4) Add dependencies

Now that we’ve added all the necessary packages and libraries, we need to explicitly tell our build system ( Gradle ) to compile them. In the project tree on the left, under Gradle Scripts,

Open the build.grade(Project: <Project name>) file, add these 2 lines

project(":android") {
    ...
    dependencies {
        ...
        compile 'com.google.android.gms:play-services-games:8.4.0'
        // 8.4 is the latest as of now, keep it updated
        compile project(':BaseGameUtils')
        ...
    }
    ...
}

If you are using other play-services APIs, add them in the dependencies list. But if the number of method references in your app exceeds the 65K limit, your app may fail to compile, in that case you need to enable multidex support.

Open the build.gradle(Module: android) file, add these 2 lines

android {
    defaultConfig {
        ...
        multiDexEnabled true
        ...
    }
}

dependencies {
  ...
  compile 'com.android.support:multidex:1.0.0'
  ...
}

Let Gradle sync the project.

 

5) Update Android Manifest

We’ve linked our project with the play services api, but our game still doesn’t know which game service to connect to and obviously the game would have to access the google play game servers over the internet. For that, in the Android Manifest file, we need to pass in the details of our game service and obtain permission to access the internet.

Go back to your dashboard. Open up Game services > Leaderboards and click on Get resources. This will pop-up a window with XML content, copy  it. Inside your android Project, go to res > values and create a new Values XML File, name it ids and paste the contents inside it. It’ll look something like this.

<?xml version="1.0" encoding="utf-8"?>
<resources>
  <string name="app_id">767948611622</string>
  <string name="achievement_dum_dum">CgkIpsC36qwWEAIQAw</string>
  <string name="leaderboard_highest">CgkIpsC36qwWEAIQAA</string>
</resources>

Open up AndroidManifest.xml and add these 4 lines

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android">
    ...
    <application>
        ...
        <meta-data android:name="com.google.android.gms.games.APP_ID" android:value="@string/app_id" />
        <meta-data android:name="com.google.android.gms.version" android:value="@integer/google_play_services_version" />
    </application>
    ...
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
</manifest>

 

6) Implementation

Now that everything is set up, we are ready to implement play services. Since all our game classes are inside the libGDX core project, we can’t directly call these methods because these are Android methods. So we create an interface inside our core project and implement this interface inside the Android Project. Makes sense ?

So inside the core Project, create a new interface and call it PlayServices. In this example we will implementing these basic play game services.

public interface PlayServices
{
    public void signIn();
    public void signOut();
    public void rateGame();
    public void unlockAchievement();
    public void submitScore(int highScore);
    public void showAchievement()
    public void showScore();
    public boolean isSignedIn();
}

Inside the android Project, open up the default Activity, in my case it is called AndroidLauncher.java

Declare these 2 members inside the class

private GameHelper gameHelper;
private final static int requestCode = 1;

Inside the onCreate() method, initialize these members

gameHelper = new GameHelper(this, GameHelper.CLIENT_GAMES);
gameHelper.enableDebugLog(false);

GameHelper.GameHelperListener gameHelperListener = new GameHelper.GameHelperListener()
{
    @Override
    public void onSignInFailed(){ }

    @Override
    public void onSignInSucceeded(){ }
};

gameHelper.setup(gameHelperListener);

Now we want play services to start automatically when the game begins and stop when the game exits, also we need to handle exceptions when the user fails to sign in. This is where the BaseGameUtil libraries come in, it takes care of all this, we just have to override our Activity methods and pass it on to them.

 @Override
    protected void onStart()
    {
        super.onStart();
        gameHelper.onStart(this);
    }

    @Override
    protected void onStop()
    {
        super.onStop();
        gameHelper.onStop();
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        super.onActivityResult(requestCode, resultCode, data);
        gameHelper.onActivityResult(requestCode, resultCode, data);
    }

Now, let’s implement the interface we created.

public class AndroidLauncher extends AndroidApplication implements PlayServices

Define the implemented methods like this.

    @Override
    public void signIn()
    {
        try
        {
            runOnUiThread(new Runnable()
            {
                @Override
                public void run()
                {
                    gameHelper.beginUserInitiatedSignIn();
                }
            });
        }
        catch (Exception e)
        {
             Gdx.app.log("MainActivity", "Log in failed: " + e.getMessage() + ".");
        }
    }

    @Override
    public void signOut()
    {
        try
        {
            runOnUiThread(new Runnable()
            {
                @Override
                public void run()
                {
                    gameHelper.signOut();
                }
            });
        }
        catch (Exception e)
        {
            Gdx.app.log("MainActivity", "Log out failed: " + e.getMessage() + ".");
        }
    }

    @Override
    public void rateGame()
    {
        String str = "Your PlayStore Link";
        startActivity(new Intent(Intent.ACTION_VIEW, Uri.parse(str)));
    }

    @Override
    public void unlockAchievement()
    {
        Games.Achievements.unlock(gameHelper.getApiClient(),
         getString(R.string.achievement_dum_dum));
    }

    @Override
    public void submitScore(int highScore)
    {
        if (isSignedIn() == true)
        {
            Games.Leaderboards.submitScore(gameHelper.getApiClient(),
             getString(R.string.leaderboard_highest), highScore);
        }
    }

    @Override
    public void showAchievement()
    {
        if (isSignedIn() == true)
        {
            startActivityForResult(Games.Achievements.getAchievementsIntent(gameHelper.getApiClient(),
             getString(R.string.achievement_dum_dum)), requestCode);
        }
        else
        {
            signIn()
        }
    }

    @Override
    public void showScore()
    {
        if (isSignedIn() == true)
        {
            startActivityForResult(Games.Leaderboards.getLeaderboardIntent(gameHelper.getApiClient(),
             getString(R.string.leaderboard_highest)), requestCode);
        }
        else
        {
            signIn()
        }
    }

    @Override
    public boolean isSignedIn()
    {
        return gameHelper.isSignedIn();
    }

But how can the core Project reference these methods ? For that we need to pass an object of this activity to the core Project class. Here MainGame is my core Project class, I’m passing an object of AndroidLauncher which is my default Activity.

initialize(new MainGame(this), config);

Now inside the MainGame class, we create a constructor to pass this reference to the interface PlayServices

public static PlayServices playServices;

public MainGame(PlayServices playServices)
{
    this.playServices = playServices;
}

My MainGame class has minimal functionality, it only sets the MainMenu screen, and I want to be able to call the PlayServices functions from the MainMenu screen. To do that, pass the object of MainGame when you set the screen.

setScreen(new MainMenu(this));

In the MainMenu class, create an object of MainGame and use a constructor to pass this reference

public static MainGame game;

public MainMenuScreen(MainGame game)
{
    this.game = game;
}

Now using this object you can call any of the PlayServices interface methods like this.

game.playServices.signIn();
game.playServices.signOut();
game.playServices.rateGame();
game.playServices.unlockAchievement();
game.playServices.submitScore(score);
game.playServices.showScore();
game.playServices.showAchievement();
game.playServices.isSignedIn();

 

If you have any doubts, leave them in the comments section below.

How to obtain SHA1 Signing certificate fingerprint from Android Studio

Untitled-8

I’m pretty sure that looking at this pop-up for the first time would be intimidating. This is a simple method to extract the SHA1 fingerprint right from Android Studio without using keytool. If you have no idea what I’m talking about, read along and understand the whole process.

Steps to obtain the SHA1 fingerprint is at the end of this post.

 

What is a signing certificate ?

268751

Android requires that all apps be digitally signed with a certificate before they can be installed. Think of it like labeling your app as your own. You make a label with your name and stick it on your app, this ensures you are the rightful developer of the app. Only with the same signing certificate you can roll out future updates for your app, and for that reason you should never lose this certificate.

To further protect your app, this certificate is coupled with a digital key so that it remains reasonably unhackable.

 

What is a key store ?

The key store is basically a file containing all your cryptographic keys. All your certificates and corresponding keys are saved in this file encrypted.

There are 2 types of keystores

  1. Debug key store : This key store is generated by the Android SDK so that you don’t have to sign the app each time you deploy it for testing.
  2. Release key store : However you cannot use the debug key store when you want to publish the app. You have to generate your own release keystore and sign your app with a release key to publish your app.

 

How to create a release key  ?

Open up Android Studio. Goto Build > Generate Signed APK

First let’s create a new key store. Click on Create new

Untitled-5

A new dialogue box pops-up.

Untitled-6

Key store path: Make sure you give a secure location. You do not want to lose it. I repeat, you do not want to lose it!

Key store Password: This password is for the key store file, remember you can use the same keystore for storing all your keys for your various app(s). So this is like a master password.

Key Alias: Name this as <your app name>+’Key’ or something. This is specific to this signing key for this app. ( This is the equivalent of a  key in a hashtable )

Key Password: This password is specific to this signing key for this app. You can very well use the same password used for the keystore.

Validity: Give it say, 100 years!

Certificate: You are required to fill in at least one entry in this.

Click OK and proceed with the build.

Untitled-7

Make sure you choose the Build Type as release and click Finish

 

Deploy in release mode

Untitled-9

The release key signed APK is generated, but this does not deploy it on the device/emulator like it normally would. To do that, Goto File > Project Structure

In the left, under Modules, choose android

Untitled-10

Choose the Signing tab, click on the green + button and fill in the details, which you gave when you created the release key. The default configuration name is config. Let it be.

Go to Build Types, Choose release

Untitled-14

In the Signing Config option, choose config. Click on OK.

To use the release signing key when deploying the app, click on the tiny square found at the bottom left of Android Studio and choose Build Variants

Untitled-13

In the Build Variants sidebar, choose release. From now on, whenever you deploy the app, the signed version  with your release key is pushed on to the device/emulator.

But when you deploy it for the first time, you will encounter this error.

Untitled-18

This is because of the conflicting signatures for the same package. Click on OK and the release build will be pushed.

 

What is a SHA1 fingerprint ?

SHA1 stands for Secure Hash Algorithm One. A one-way cryptographic function that can be used to act as a ‘signature’ for a sequence of bytes. It is very unlikely that 2 different byte sequences would produce the same value (though not impossible). So instead of shipping the app with the entire key store and uploading a copy of it to the playstore, we use this cryptographic signature to easily validate the authenticity. Read more about SHA1 here.

 

Obtain the SHA1 fingerprint

Important : Run your app in release mode once before proceeding.

Click on Gradle ( or SBT ) found on the top right of Android Studio. First time you open it, it’ll be blank, click on the refresh button and it’ll list the name of your project ( My project name is Segments ).

Untitled-15

Expand the tree like this and double click on Signing Report

Untitled-16

Voila! you find the SHA1 fingerprint of both the release key and the debug key.

Untitled-17

You can even use the debug key SHA1 for testing Google API services. Just make sure that the app accessing this API is signed with the same key as that provided to authorize the app.

 

An unexpected error occurred. Please try again later. (480000x)

You might get this error when you submit the SHA1 fingerprint, this happens when you use the same fingerprint+package combination as a new linked app. Go to your developer console and delete any duplicates projects that you may find. Deletion takes 7 days though.

 

JNI ( Java Native Interface ) for C/C++ with examples

When writing applications in Java, there are times when Java alone fails to meet the needs of an application. You might want to use a feature not present in the standard Java class library or you might just want to use an existing library written in some other language. That’s where JNI comes in.

I found that most of the online documentation on JNI seems pretty scattered and obsolete. Therefore the scope of this post is to show you how to implement JNI with simple examples for :

  • Writing a HelloWorld in C and calling it from Java
  • Passing Integers and Strings from C to Java
  • Passing object Arrays from C to Java

The same can be implemented with C++ too. Note the modification mentioned in step 4 below.

Clone all the examples from Git

 

HelloWorld from C

1. Write the Java code

//HelloWorld.java

public class HelloWorld 
{
  native void cfunction();//Declaring the native function
                            
  static
  {
     System.loadLibrary("forhelloworld");//Linking the native library
  }                                      //which we will be creating.

  public static void main(String args[]) 
  {
     HelloWorld obj = new HelloWorld();
     obj.cfunction();//Calling the native function
  }
}

2. Compile the Java code and generate the class file


javac HelloWorld.java

3. Generate a Header file from the class file


javah HelloWorld

This will generate a file HelloWorld.h which contains :

//HelloWorld.h

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class HelloWorld */

#ifndef _Included_HelloWorld
#define _Included_HelloWorld
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     HelloWorld
 * Method:    cfunction
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_HelloWorld_cfunction
  (JNIEnv *, jobject);

#ifdef __cplusplus
}
#endif
#endif

3. Obtain the JNI function signature from the header file

  1. These 2 lines make up the function header :
JNIEXPORT void JNICALL Java_HelloWorld_cfunction
(JNIEnv *, jobject);

Even if we declare native functions with no arguments, the JNI function signature still holds 2 arguments, they are:

  • JNIEnv * : A pointer referencing all the JNI functions
  • jobject     : An equivalent of this pointer

4. Write the native code using the function signature

  • Add the header file jni.h
  • Instead of the main() function, use the function signature obtained from the previous step.
  • Add argument variables for JNIEnv (env) and Jobject (jobj).
  • IMPORTANT :: If the native code is in C++, please note the only modification to be made is that the JNI functions should be called as env->func_name() instead of (*env)->func_name(). That is because C uses structures while C++ uses classes.
//HelloWorld.c
 
#include <jni.h>
#include <stdio.h>
 
JNIEXPORT void JNICALL Java_HelloWorld_cfunction
(JNIEnv *env, jobject jobj)
{
   printf("\n > C says HelloWorld !\n");
}

5. Generate the library file from the native code

gcc -o libforhelloworld.so -shared -fPIC -I (PATH TO jni.h header) HelloWorld.c -lc 
  •     libforhelloworld.so is the name of the native library you are going to create, it should be named as “lib”+(the library name used in the load library statement within the java code)
  •     -fPIC is some sort optimization for loading the machine code into the RAM, gcc requested this flag to be set. Might not be required for all systems.

If you don’t specify the path correctly you will encounter this error :

HelloWorld.c:1:17: fatal error: jni.h: No such file or directory
 #include <jni.h>
                 ^
compilation terminated.

It is usually present inside

/usr/lib/jvm/default-java/include

or

/usr/lib/jvm/java-1.7.0-openjdk-amd64/include

depending upon the version of Java you have installed in your system.

6. Place the library file in the standard /usr/lib folder

If the previous command executed successfully, it would have generated a file libforhelloworld.so . Conventionally this library file need not be placed anywhere else, it needs to reside in the current working directory.

But for that to work you need to have set the JAVA_PATH variables correctly, in most cases they won’t be set correctly. An easy hack to this would be to just place it inside /usr/lib

sudo cp libforhelloworld.so /usr/lib

If you don’t place the library file, you would encounter this error :

Exception in thread "main" java.lang.UnsatisfiedLinkError: no forhelloworld in java.library.path
        at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1886)
        at java.lang.Runtime.loadLibrary0(Runtime.java:849)
        at java.lang.System.loadLibrary(System.java:1088)
        at HelloWorld.<clinit>(HelloWorld.java:9)

7. Execute the Java application

java HelloWorld

If you’ve followed all the steps correctly, C would greet the world 😀

 > C says HelloWorld !

 

PASS INTEGERS FROM C TO JAVA

Example : Write a Java program to find the factorial of a number. Pass the number as an argument from Java to a native function in C which returns the factorial as an integer.

Java code

//factorial.java
 
import java.util.Scanner;
 
public class factorial
{
  native int fact(int num);
 
  static
  {
        System.loadLibrary("forfact");
  }
 
  public static void main(String args[])
  {
        Scanner inp = new Scanner(System.in);
 
        System.out.println(" > Enter number :: ");
        int num = inp.nextInt();
 
        factorial obj = new factorial();
 
        System.out.println(" > The factorial of "+num+" is "+obj.fact(num));
  }
}                                                                                                         

C code

//factorial.c
 
#include <jni.h>
#include <stdio.h>
 
JNIEXPORT jint JNICALL Java_factorial_fact
(JNIEnv *env, jobject jobj, jint num)
{
  jint result=1;
 
  while(num)
  {
        result*=num;
        num--;
  }
 
return result;
}

 

PASS STRINGS FROM C TO JAVA

Example : Write a Java program to reverse a given string. Pass the given string as an argument from Java to a native function in C which returns the reversed string.

Java code

//reverse.java
 
import java.util.Scanner;
 
public class reverse
{
  native String reversefunc(String word);
 
  static
  {
        System.loadLibrary("forreverse");
  }
 
  public static void main(String args[])
  {
        Scanner inp = new Scanner(System.in);
 
        System.out.println(" > Enter a string :: ");
        String word = inp.nextLine();
 
        reverse obj = new reverse();
 
        System.out.println(" > The reversed string is :: "+obj.reversefunc(word));
  }
}

C code

//reverse.c
 
#include <jni.h>
#include <stdio.h>
 
JNIEXPORT jstring JNICALL Java_reverse_reversefunc
(JNIEnv *env,jobject jobj,jstring original)
{
  const char *org;
  char *rev;
 
  org = (*env)->GetStringUTFChars(env,original,NULL);
 
  int i;
  int size = (*env)->GetStringUTFLength(env,original);
   
  for(i=0;i<size;i++)
        rev[i]=org[size-i-1];
 
  rev[size]='\0';
 
return (*env)->NewStringUTF(env,rev);
}

 

PASS INTEGER ARRAYS FROM C TO JAVA

Example : Write a program that generates the first n Fibonacci numbers. Pass ‘n’ as an argument from Java to a native function in C that returns the Fibonacci numbers as an integer array.

Java code

//fibonacci.java
 
import java.util.Scanner;
 
public class fibonacci
{
  native int[] returnfibo(int n);
 
  static
  {
        System.loadLibrary("fibonacci");
  }
 
  public static void main(String args[])
  {
        Scanner inp = new Scanner(System.in);
 
        System.out.println(" > Enter n :: ");
        int n = inp.nextInt();
 
        fibonacci obj = new fibonacci();
        int[] Fibo = obj.returnfibo(n);
 
        System.out.println(" > The first "+n+" fibonacci numbers are :: ");
 
        for(int i=0;i<n;i++)
          System.out.print(Fibo[i]+",");
  }
}

C code

//fibonacci.c
 
#include <jni.h>
#include <stdio.h>
 
JNIEXPORT jintArray JNICALL Java_fibonacci_returnfibo
(JNIEnv *env,jobject jobj,jint n)
{
  jintArray fiboarray  = (*env)->NewIntArray(env,n);
 
  int first=0;
  int second=1;
  int next;
  int i;
  int fibo[n];
 
  for(i=0;i<n;i++)
  {
        if(i<=1)
          next = i;
        else
        {
          next = first + second;
          first = second;
          second = next;
        }
 
        fibo[i] = next;
  }
 
  (*env)->SetIntArrayRegion(env,fiboarray,0,n,fibo);
 
return fiboarray;
}

 

PASS STRING ARRAYS FROM C TO JAVA

Example : Write a Java program that displays the days of the week, which are passed from a native function in C.

Java code

//daysofweek.java
 
public class daysofweek
{
  native String[] returndays();
 
   static
   {
      System.loadLibrary("daysofweek");
   }
 
   static public void main(String args[])
   {
 
      daysofweek obj = new daysofweek();
      String[] days = obj.returndays();
 
      System.out.println(" > The days of the week are :: ");
      for(String name: days)
        System.out.println(name);
   }
}

C code

//daysofweek.c
 
#include <jni.h>
#include <stdio.h>
 
JNIEXPORT jobjectArray JNICALL Java_daysofweek_returndays(JNIEnv *env, jobject jobj)
{
 
  char *days[]={"Sunday",
                "Monday",
                "Tuesday",
                "Wednesday",
                "Thursday",
                "Friday",
                "Saturday"};
 
  jstring str;
  jobjectArray day = 0;
  jsize len = 7;
  int i;
 
  day = (*env)->NewObjectArray(env,len,(*env)->FindClass(env,"java/lang/String"),0);
   
  for(i=0;i<7;i++)
  {
    str = (*env)->NewStringUTF(env,days[i]);
    (*env)->SetObjectArrayElement(env,day,i,str);
  }
   
return day;
}

As you can see, the C code is returning an array of char pointers (C strings), while the Java code is expecting an array of Java Strings. But you don’t have to worry about that, the good old implicit conversion comes to the rescue 🙂

DALVIK vs A.R.T ( Android Run Time )

Android [4.4] KitKat users would have noticed the new option to choose the default run-time environment in Android (Dalvik or ART). Dalvik has been the run-time environment in Android since the very beginning. Although ART was added as an experimental feature in Kitkat, it has now replaced Dalvik from Android [5.0] Lollipop.

Image1

WHAT IS RUN-TIME ?

When a software program is executed, it is in a run-time state. During this state, the program sends instructions to the computer’s processor to access the system resources. To do this, we have a run-time environment that executes software instructions when a program is running. These instructions translate the software code into machine code (byte code) that the computer is capable of understanding. In simpler terms, it means that all Android application files (APKs) are basically un-compiled instructions.

WHY ANDROID USES A VIRTUAL MACHINE ?

Android uses a virtual machine as its run-time environment to compile and run its applications. Unlike our Virtual Box, this virtual machine does not emulate the entire computer! Using a virtual machine ensures that the application execution is isolated from the core operating system, so even if the application contains some malicious code, it cannot directly affect the system. This provides stability and reliability for the operating system. This also provides more compatibility, since different processors use different instruction sets and architectures, compilation on the device ensures compatibility with the specific device.

HOW DALVIK WORKS ? WHY IT GOT REPLACED ?

Dalvik uses a JIT (Just-In-Time) compiler for its process virtual machine. Applications need a lot of resources to run. Taking up a lot of resource can slow down the system. But with JIT, the resources are fetched just when they are needed meaning the application gets compiled when they are launched and are loaded into RAM. But compiling the entire code when we launch an application takes a lot of time which translates into what we call lag. But the entire code is not compiled on every application-launch, rather the part of the code that is needed to run the application is compiled every time and gets stored in cache called as the dalvik-cache so it can be reused and this cache gets optimized with every compilation overtime and creates something like a tree of dependencies on every device.

Boss Android users would know that they have to wipe dalvik-cache  before they install a new ROM in their Android, that is because this tree of dependency now has to reconstructed for the new system in the ROM.

But if the compiled application that is loaded into RAM is manually killed, the whole process of compilation has to be done again. Over time, the dalvik-cache gets bigger and does not get cleaned and this takes up a lot of storage, which slows down the device.

HOW A.R.T SOLVES THIS ?

A.R.T uses AOT (Ahead-Of-Time) compiler. When an application is installed, the A.O.T compiler translates the entire code into machine code via compilation. So this means the application doesn’t need to compiled again and again. This makes the process of launching and using the application faster and smoother because the pre-compiled code (machine code) just needs to be executed and all the resources are readily available. Reducing the number of compilations also improves the battery life of the device. But compiling the entire code means installing the application will take more time and storage as well.

DOES IT REALLY MAKE A DIFFERENCE ?

Although on paper, A.R.T smokes Dalvik, it doesn’t make a huge difference as you would expect. Apps do launch faster and the performance is a tad better in A.R.T.

ART-performance-comparison-e1404425718598

Here’s a a slide shown on one of the I/O keynotes.

A.R.T may use the “Ahead-Of-Time” method of compilation, but I personally don’t think it is ahead of it’s time! Yes, it does make more sense, it might be the next right step towards a better Android. But it still uses a virtual machine and running applications through a VM would never be faster than running applications in native code!

This article featured in the June issue of the Open Source For You magazine.                View here

How to create BOSS boot animations for Android

Boot animation is the first thing you stare at when you power ON your Android device, so what’s a BOSS Android without a BOSS boot animation ? 😀

Here’s an example of what I created.

This is a tutorial on how to create boot animations from scratch using Adobe AfterEffects.

You could also use any of these alternative methods and proceed to Step 2.

  • Convert a video into boot animation [ here ]
  • Convert a GIF into boot animation [ here ]
  • Use a static image as boot animation

 

STEP 1 : CREATE YOUR BOOTANIMATION

Figure out the screen resolution of your Android. Create a new composition in AfterEffects with that specific resolution. Set the required duration for the animation.

1

Create your animation. Here’s a basic guide to animating in AfterEffects.

2

Here’s the interesting part, the boot animation is not stored in Android as a video file, rather it is saved frame by frame as image files.

Rendering the composition :

  • Set the Output Module format as PNG Sequence 
  • Output To a new folder with the naming sequence as [#####].png

3
 

STEP 2 : PACKAGING THE BOOT ANIMATION

After rendering the composition, the output folder will contain the animation stripped down to each frame as PNG images. Rename the output folder to folder1. If you want a part of the animation to loop, put those frames into another folder named folder2. Now place the folder(s) into another folder named bootanimation. i.e :


bootanimation
 ├───folder1 ( Main animation )
 └───folder2 ( Part that must loop )

 
To package the boot animation. Download this tool ( Windows binary ). MAC / UNIX users may use WINE.

Open the Boot Animation Creator. Choose the folder bootanimation.

4

Set the properties. Select the first line and click on edit.11

Now choose the appropriate resolution and framerate as set in the AfterEffects composition. 8

Click on Add loop and choose folder1.

6

If the number of loops is set to 0, that part will keep looping.

7

Click on next and save exactly as bootanimation.zip. Preview the animation using this tool. You could also create a shutdown animation, follow the same steps and save exactly as shutdownanimation.zip. But mind you, shutdown animations wouldn’t last as long as boot animations, so make it short.
 

STEP 3 : INSTALLING THE BOOT ANIMATION

There are 3 ways to install the boot animation

  1. Using a root file explorer ( ROOT )
  2. Using ADB ( WITHOUT ROOT )
  3. Flashing a new ROM with the boot animation ( RECOVERY )

I recommend not to use 3rd party apps to install boot animations!
 

USING ROOT FILE EXPLORER

I recommend using ES file explorer. Press menu and set Root Explorer ON

Screenshot_2015-08-02-10-22-29

Place the bootanimation.zip in your phone storage, copy and replace it with the file in /system/media

Screenshot_2015-08-02-10-23-18

Long press the new bootanimation.zip and select properties.

Screenshot_2015-08-02-10-23-41

Tap on Change next to Permissions and set it like this

Screenshot_2015-08-02-10-23-47

You’re done ! Reboot the device to view the new boot animation.
 

USING ADB

Navigate to your adb binary folder and place the bootanimation.zip file there. Hold shift and right-click, open command window here. ( Here’s a noob guide to setting up basic adb )

Type the command :


adb push bootanimation.zip /data/local
adb reboot

 

FLASHING A NEW ROM WITH THE BOOT ANIMATION

Open up your ROM ZIP file and replace the bootanimation.zip file present in System > Media and flash the new ROM.
 
 
Leave a comment if you have any doubts. No matter how noob the question is, I’ll be glad to help 🙂

How to root Lava Iris X8

The other day I bought a new LAVA Iris X8 specifically for Android development and guess what, I rooted the device on the first day 😀

Here’s my rooted X8.

Untitled6
This is the most safest and noob-friendly method to root your X8. Yes, I have tested this method on my own device and I did not soft-brick it in the process. Screenshot_2015-04-01-21-44-32 > Will I receive the official Lollipop update ( as promised by LAVA ) even after I root my X8 ?                                                                                                                                       Yes, you will receive the update, but you’d probably lose root access after you install the update. But don’t worry, I will post a rooting tutorial right after the update is released.

> Will I void my phone’s warranty if I root my device ?                                                          Well, of course you will void your warranty 😀

DISCLAIMER :: I have tested this rooting method on my device, but I will not be responsible if you mess something up :/

Here we go,

STEP 1 : ENABLE USB-DEBUGGING IN YOUR PHONE

Goto Settings > About phone and keep tapping Build number until a toast message pops-up saying ” You are now a developer  ” Now, go back to Settings and you will find a new entry Developer options, inside it check USB debugging option. Untitled-3

STEP 2 : INSTALL ADB DRIVERS IN YOUR COMPUTER

I recommend using XP / Vista / 7 for this, because it is cumbersome to setup the drivers in Windows 8 / 8.1 and in most cases, the drivers would not get installed properly. Download the Driver package here This contains all the VCOM,USB and ADB drivers ( all that you need ), most of which are common to all Mediatek ( Your phone’s processor ) devices. After you download the rar file, extract it. Now goto Device Manager

  •  Right-click on My Computer > Properties > Device Manager

Under Other devices or Ports, you will find an entry of your device with the exclamation symbol like this.

  •  Right-click > Update Driver software

04-devmgr Choose the Browse option and locate the extracted folder, Windows will automatically identify the driver and install it. 05-browse

STEP 3 : INSTALL KINGO ROOT IN YOUR COMPUTER ( Download here )
Step 4 : CONNECT THE PHONE TO THE COMPUTER VIA USB AND ROOT

Make sure the computer has an active internet connection. Open the Kingo root application, it will automatically recognize the device and starts installing the necessary dependency drivers. Now click on ROOT, it will automatically start downloading the necessary root files and does everything for you. It takes a couple of minutes, the phone might do some reboots in the process, don’t panic ! On completion, it’ll say “Root succeeded” and you will find a new Kingo root icon in the app drawer.

Step 5 : INSTALL SUPERSU ( IF KINGO ROOT FAILS TO INSTALL IT )

Although Kingo root succeeded, it failed to install SuperSU in my X8. If you can’t find SuperSU in your app-drawer, follow this step. Download SuperSU from the playstore. Screenshot_2015-04-01-22-02-17 SuperSU prompts you to install it. Choose Normal mode, phone reboots after the installation is complete Untitled-5 After rebooting, SuperSU still won’t show up in the app drawer because it conflicts with the SuperSU package Kingo root tried to install, so you need to remove it.

  • Goto Settings > Apps > SuperSU > Uninstall updates

Screenshot_2015-04-01-21-46-44 Then reboot your device and you’re done. The next time an app requires root privileges, SuperSU will prompt your permission.

CUSTOM RECOVERY

Thanks to the folks at XDA, we finally have a custom recovery !

Download here ( Carliv Touch v3.3 )

You can flash the recovery by using either of these two :

  • Mobileuncle MTK tools ( without PC )
  • SP Flashtool

Mobileuncle MTK tools

  1. Place the recovery.img file in the root of your SD card.
  2. Download Mobileuncle MTK tools here
  3. Place the recovery.img file in the root of your SD card
  4. Open the application, grant root permissions
  5. Go into Recovery update, it will automatically find the recovery.img file
  6. Tap on it and choose OK for the prompt
  7. It will install the recovery and reboot into recovery

SP Flashtool

  1. Download the application here ( Windows )
  2. Just extract the ZIP file.
  3. Download Scatter-text file for the X8 here
  4. Open Flashtool.exe from the extracted folder, load the scatter-text file
  5. Choose the recovery.img file and click on Download
  6. Power-off the phone and connect the phone to the PC
  7. Wait for the magic ring to appear !
  8. Doesn’t make sense ? Follow this noob guide

To boot into recovery

  • Hold volume up + volume down + power button at OFF state
  • Use Mobileuncle MTK tools application and tap Reboot into Recovery
  • Use adb command  $ adb reboot recovery
CUSTOMIZE X8 LIKE A BOSS

Right now, there’s isn’t much development happening for the X8. I am currently working on porting a CWM recovery for this device. After a custom recovery has been ported, custom ROMs would soon be available, hopefully ! Until then, all you can do is customize the stock ROM with the Xposed Framework. Xposed framework allows you to customize the UI, system apps and provides awesome functionalities through modules that you never thought were necessary! Read here if you are interested to know how it works.

The best thing about Xposed is, it does all this without actually modifying the APKs, meaning that if you uninstall the framework, you will remove all the customizations you made. Make sure you uninstall Xposed Installer before you install the official Lollipop update from LAVA. Download Xposed here Open Xposed and tap on Install/Update in Framework ( provide root access ). Don’t panic after seeing this warning message, I’ve tested the installation on my device.

Untitled-4

The phone will reboot after the installation is complete. Xposed installer does not add any functionality by itself, you need to install modules for that. Head over to Download in Xposed Installer and choose the modules of your choice and make sure you download the Kitkat [KK] version of each module.

To use a module, enable it in Xposed Installer and reboot your device. Since we don’t have a custom recovery setup as of now ( which I am working on ). We cannot recover from soft-bricks ( Boot-loops ), so don’t install modules that may potentially soft-brick your device ! If none of the modules work, read this post

Xposed modules I’m using on my X8

  • Xui mod                          >   Awesome List animations
  • Greenify                          >   Epic battery saver
  • GravityBox                      >   UI customization
  • Tinted Status Bar            >   Change status bar color based on the app
  • Screen-off Animation      >   Well, duh !
CHANGE FONT

Download iFont from the playstore, ( provide root access ) it has a plethora of fonts lined up. Before you set a font, Goto Settings and choose the Change font mode as System mode(need ROOT) Untitled-6   Here’s a list of my Top 10 Root apps for Android, an article that featured in the 2015 February issue of the Open Source For You magazine. View here

STOCK ROM ( KITKAT 4.4.2 ) IS NOW AVAILABLE

Mirror 1 | Mirror 2

Leave a comment if you have any doubts, I’ll be glad to help 🙂