This document discusses various techniques for optimizing mobile apps for emerging markets, including: 1. Optimizing app size by using color filters to reduce assets, compressing images using formats like WebP and JPEG that can significantly reduce file sizes, and removing unused resources and content to make apps smaller. 2. Optimizing network usage by building for failure-prone networks, scaling images appropriately, using checksums to avoid re-transferring files, and transferring data in blocks. 3. Optimizing for different phone capabilities by using libraries like Facebook's Device Year Class to conditionally include features based on a device's age and power, and redesigning apps to remove features for low-end hardware.

1. OptimizingYour Apps
For Emerging Markets
#DroidconMtl

3. Emerging Markets
Drive Growth

4. Source:Mediacellsvia TheGuardian

5. Source:Mediacellsvia TheGuardian

6. 44
36
21
51
37
11
80
10
9
25
66
9
Smartphone Featurephone Multimediaphone
Brazil Russia
India China

7. 1. Optimizing App Size

8. The smaller, the better

9. ColorFilters

10. Use Color Filter
• Faster way to experimentwithcolor schemes.
• Reduce thenumber of assets, which in turn reduces
theapk size.
• Less memory used as the number of assets are
reduced.

11. Code
ImageViewredCircle=(ImageView)findViewById(R.id.circle_red_imageview);
ImageViewgreenCircle=(ImageView)findViewById(R.id.circle_green_imageview);
ImageViewblueCircle=(ImageView)findViewById(R.id.circle_blue_imageview);
// wecancreatethecolor valuesindifferent ways:
redCircle.getDrawable().setColorFilter(Color.RED,PorterDuff.Mode.MULTIPLY);
greenCircle.getDrawable().setColorFilter(0xff00ff00,PorterDuff.Mode.MULTIPLY);
blueCircle.getDrawable().setColorFilter(getResources().getColor(R.color.blue),PorterDuff.Mode.
MULTIPLY);

12. Image
Optimizations
ColorFilters

13. JPEG WEBP PNG GIF
Lossy
Lossless
Transparency
Animation
WebP

14. No Noticeable Change
PNG
24kb
WebP
10kb

15. Compatibility
• You can use thenativeWebP decoder on 4.2 and
later.
• For lower versions, use libpng to convert to PNG
format and thenuseit intheapp.

16. Other Libraries
• Use programs like OptiPNG,TruePNG and PNGCrush
to significantlyreduce the size of PNG images.
• Use mozjpeg for jpegimages.
• 5-10% size reduction
• Won’t cause any visible changesto the images.

17. Remove Unused
Content
Image
Optimizations
ColorFilters

18. Remove Unused Content
• Use Resource Shrinking.

19. Code
android{
...
buildTypes{
release{
minifyEnabledtrue
shrinkResourcestrue
proguardFilesgetDefaultProguardFile('proguard-android.txt'),'proguard-rules.pro'
}
}
}

20. Remove Unused Content
• Use Resource Shrinking.
• Use tools likeLintand ProGuard.
• Use Android-Unused-Resources jar fileif you are
stillusingEclipse.
https://code.google.com/p/android-unused-resources/

21. 2.Optimizing Network
Calls

22. Expensive DataFlaky Networks
Challenges

23. Build for Failure

24. Most efficient way to
transfer is to not transfer

25. Image Scaling

26. Appropriate Image Size
• Store multipleimagesizes on the server
• Low-res devices mightnever need a fullresolution
image
• Most timesthe smallest imagesize is sufficient.

28. ChecksumImage Scaling

29. Client A Client BServer
Checksum
ID
Send File ID
TransferFile
CS ID

30. Code
publicstaticStringgetMD5EncryptedString(StringencTarget){
MessageDigest mdEnc=null;
mdEnc=MessageDigest.getInstance("MD5");
// Encryptionalgorithm
mdEnc.update(encTarget.getBytes(),0,encTarget.length());
Stringmd5=newBigInteger(1,mdEnc.digest()).toString(16);
while(md5.length()<32){
md5="0"+md5;
}
returnmd5;
}

31. Checksum
• Avoid transfers as muchas possible.
• For filetransfers, first compute themd5 checksum
and send it to the server to checkif it already exists
on theserver.
• The cost to upload theentire file againcan be
avoided.

32. Image Scaling Checksum Transferin Blocks

33. Transfer in blocks
• Do data transfers in blocks.
• Keeptrack of the blocks thathave been transferred
and yet to be transferred.
• The block size can vary based on the type of
connection.

34. Testing for different
networks is a pain

35. Testing for different networks
• Facebook recently open-sourced AugmentedTraffic
Control(ATC).
• It is a tool to simulatenetworkconditions.
• It can simulate2G, Edge, 3G, and LTE networks.
• Has multipleprofiles for a lot of differentcountries.
http://facebook.github.io/augmented-traffic-control/

36. 3.Optimizing for Different
Phones

37. Small ScreensSlow Processing
Challenges

38. Developing for flagship
devices is easy

39. YearClass

41. Code
int year =YearClass.get(getApplicationContext());
if (year >=2013){
// Doadvancedanimation
}elseif (year >2010){
// Dosimpleanimation
}else{
// Phonetooslow,don't doanyanimations
}
https://github.com/facebook/device-year-class

42. RedesignYearClass

43. Redesign
• Remove featuresfrom low-end devices if they won’t
have the best user experience.
• This could be animations,videos or even
functionalities.
• No feature>>>Bad feature

44. @vinaygaba
Questions?