Develop Reference

Is APK size affected by unused packages in ReactNative?

I want to know do unused packages cause APK size to grow?
Consider I install dozens of NPM packages for my project but I never import and use them. These files obviously increase my project folder size but do they affect APK size when building APK?
The question can be answered about .ipa too.

APK Analyzer will not look for any unused dependent NPM packages because all your javascript code is bundled by metro before being included in your Android project as an index.android.bundle asset:
Metro is a JavaScript bundler. It takes in an entry file and various options, and gives you back a single JavaScript file that includes all your code and its dependencies.
So any unused dependencies must be pruned before creating the apk. Read about Tree shaking, which does exactly that:
Tree shaking is a process in which the bundler includes only the code that is actually used.
Note that only modules that have a dependency from your code will be included in the bundle.

How do I add media codecs support to Crosswalk while using the Cordova plug-in?

I'm building a PhoneGap app which needs to play AAC audio. It works well using the native WebView, but I would like to use Crosswalk on a build targeting APIs 16-20 because some CSS features in my app do not work at all on Android 4.x.
When I make a copy of the project to add Crosswalk Lite, I can see that the app works except for the <audio> element pointing to a AAC file. This is because Crosswalk does not ship with proprietary codecs by default.
The linked page says:
To build Crosswalk with these codecs, a developer must run the build
with the “must accept a EULA” switch turned on:
$ xwalk/gyp_xwalk -Dmediacodecs_EULA=1
Then build Crosswalk. The ffmpegsumo.dll or libffmpegsumo.so in
the build output directory will contain the proprietary codecs.
Refer to Crosswalk Build Instruction for more details.
However, I am adding Crosswalk using the suggested plug-in, thus I get pre-built libraries without proprietary codecs:
phonegap plugin add cordova-plugin-crosswalk-webview --variable XWALK_MODE="lite" --save
How can I integrate proprietary codecs in the Cordova Crosswalk plug-in?

I managed to understand the (convoluted) process of building everything. This answer deals with the process of compiling a custom build of the full Crosswalk (not the lite version).
Actually, I decided to finally use the standard build and replace AAC audio with MP3s, but I thought this answer could be useful for future reference.
Environment
I compiled Crosswalk in a Ubuntu 16.04 Docker container to avoid "polluting" my system and to ensure I had the right Linux version. The standard image is pretty barebones so I installed some dependencies. I also set up a shared folder to access the compiled files:
docker run -it -v /home/andrea/shared:/shared ubuntu:16.04 /bin/bash
apt update
apt install -y python git nano lsb-release sudo wget curl software-properties-common
export EDITOR=nano # life it too short to learn vi
Finally, it is necessary to add the multiverse repositories:
apt-add-repository multiverse
Note: this procedure needs a lot of space. Make sure to have at least 25GB of free space before continuing.
Requirements
Install the depot_tools as outlined in the documentation:
git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
export PATH=$PATH:/path/to/depot_tools
Initialize a working directory with:
mkdir crosswalk-checkout
cd crosswalk-checkout
export XWALK_OS_ANDROID=1
gclient config --name src/xwalk https://github.com/crosswalk-project/crosswalk.git
Then edit the config file with nano .gclient and add the following line:
target_os = ['android']
Save the file.
Fetching the source
Attempt a first sync with:
gclient sync
This command will fail but it's OK. The instructions say:
Do not worry if gyp_xwalk fails due to missing dependencies; installing them is covered in a later section, after which you can run gyp_xwalk manually again.
Adjust the install-build-deps.sh file and then run it:
sed -si "s/msttcorefonts/ttf-mscorefonts-installer/g" src/build/install-build-deps.sh
sudo ./src/build/install-build-deps-android.sh
Run gclient sync again and wait until it finishes correctly.
Building
By inspecting the files src/xwalk/build/common.gypi and src/tools/mb/mb_config.pyl, we can see that we need to add ffmpeg_branding="Chrome" in the build arguments.
To prevent an error later on, install the development package related to libnotify:
sudo apt install libnotify-dev
Move to the src directory and open the configuration:
cd src/
gn args out/Default
Ensure the content is as follows:
import("//xwalk/build/android.gni")
target_os = "android"
is_debug = false
ffmpeg_branding = "Chrome"
use_sysroot = false
The parameters use_sysroot = false prevents yet another error. When saving the file, you should see something like this:
Waiting for editor on "/home/utente/crosswalk-checkout/src/out/Default/args.gn"...
Generating files...
Done. Wrote 6060 targets from 1003 files in 2416ms
Issue cd .. and run gclient sync again.
Finally, to build the core library do:
cd src/
ninja -C out/Default xwalk_core_library
This will build the library for ARM, producing an AAR file located at:
src/out/Default/xwalk_core_library.aar
Copy this file in a safe place.
Building for x86
Get back to the args with:
gn args out/Default
Add the following line:
target_cpu = "x86"
Save the file, run gclient sync again and then repeat the ninja command. Make a copy of the new AAR file which now contains the x86 libraries.
Using the AAR files
The standard Cordova Crosswalk plug-in uses a single AAR file with libraries for both platforms. This message by Raphael Kubo da Costa suggests how to produce this single archive:
AAR files are just zip files; given the only difference between the ARM
and x86 AAR files are the different shared libraries, you can use
something like zipmerge or anything that merges zip files (or even
extract everything into some directory and then create one new zip file)
to build one final, multi-architecture AAR archive.
Finally, to use the custom built AAR file in the Cordova plug-in, see How to change the Crosswalk version used by the Cordova Crosswalk Webview plugin.

How does the apt-plugin work?

So,
We are using Dagger 2 in our Android application.
Code generated by
Dagger 2 is located in build/generated/source/apt.
In the documentation of apt-plugin it states that :"Using this plugin Android Studio will be configured to place the generated sources on the build path, preventing errors in the IDE"
If I remove apt-plugin from my build.gradle file, in a place where I use generated code I see compilation error. (Which is reasonable, generated code is not my source).
The questions are:
What does it mean that apt-plugin configures Android Studio so that it places generated code to build path ?
From what I know final dex file is generated from source folder that is specified in build.gradle, how do these generated files become the source ?
Thanks.

The apt-plguin is a gradle plugin and as such it runs with your build script.
This plugin configures apt to be run with your build and sources to be generated. It further adds the path of the generated files to your source sets, which is why the build succeeds and Android Studio recognizes the files as well.
For further information you could always have a look on the gradle documentation on Gradle Plugins.

Visual Studio 2015 Cordova exclude folder from build

I have a Cordova project in Visual Studio 2015.
I've added some node modules, which doesn't display in project (in VS), but exists on disk, when all other files in project folder were added there by default without excluding.
So now I need a way to exclude node_modules from build, 'cause there're just dev tools (autoprefixer, less, watch, etc.), in case of that generated apk file size increases, which's not applicable for me (total size ~10MB, without node_modules - only 3MB). Does it really possible to do that without physical removing that folder? Maybe I don't know about some configurations or so on?

Final solution I found was to move node_modules to parent directory and fix paths in config files.

phonegap build command resetting the asset/www source code

Whenever I execute phonegap build android/ios, my asset folder is getting reset to sample folder and source code.
Because of this , whatever the code I am copying into the asset/www it is being overwritten by sample codes of phonegap
Does anybody come across this issue.
What could be the reason.?

This is the correct behavior of cordova/phonegap project.
Under yourProjectRoot/platforms/android/assets/www there are the source copied in build phase from the yourProjectRoot/www directory, you must implement your HTML5/js code in this folder, this is the entry point for you source.
I suggest you to take a look here: Build the App before start the development.

Help of PhoneGap build command says:
Builds your application for one or more specified platforms. When no
platforms are specified, all installed platforms will be built.
The build task will first prepare and then compile your application.
If you want more control, you can individually prepare and compile
your application with the commands.
Your platform specific www folder is overwritten because prepare command is fired.
If you preparing your entire project in platform specific folder like ${PROJECT_ROOT}/platforms/android and you want to compile it than you have to run phonegap compile your_platform. It will bypass prepare and go straight to compile.