Running zipalign with zopfli recompression after building APK from command line to make it smaller

Question

As mentioned in Google Developers' article, it is now possible to recompress APK files using zopfli by running zipalign -z. In my case, a 200 KB reduction is observed on a 5.1 MB APK file.

Normally I build the APK using a custom shell script, by running gradle assembleRelease.

I want to run zipalign -z <the final apk> after the above command. However, zipalign is located in the build-tools/<build tools version> directory, which I can't locate it except by pulling out the <build tools version> from the build.gradle file and constructing the path manually.

Is it possible to run zipalign using the gradle command that automatically run the zipalign on the correct build-tools directory without me having to reconstuct the path?

For example a command such as gradle runBuildTools zipalign -z $FINAL_APK $FINAL_APK.out

Canteen

NOTE: Google no longer recommends Zopfli compression for APKs: "Update: Previously this article contained a section on recompressing files in your APK using a stronger compression algorithm called Zopfli. This feature is now being removed from our build tools as of Android Studio 2.2 and is no longer recommended, as it might interfere with future plans for making Play Store incremental updates even smaller." – Dithyramb

Answer 1

The article that you linked to has been updated with the gradle task to add the zopfli compression to the end of the assembleRelease task.

//add zopfli to variants with release build type
android.applicationVariants.all { variant ->
  if (variant.buildType.name == 'release') {
    variant.outputs.each { output ->
        output.assemble.doLast {
            println "Zopflifying... it might take a while"
            exec {
                commandLine output.zipAlign.zipAlignExe,'-f','-z', '4', output.outputFile.absolutePath , output.outputFile.absolutePath.replaceAll('\\.apk$', '-zopfli.apk')
            }
        }
    }
  }
}

Nicotinism

Thanks!! That is exactly what I needed. – Drongo

For future readers, it's not recommended to use Zopfli compression anymore. Please check the article that is linked in the answer for more information. – Linseed