[Android 1.3] [Gradle 2.5] Build with native third party shared libraries

[Stéphane Saffré]

Hello,

I am struggling to build a simple native library depending on another native third-party shared library (turbojpeg). This native library is basically a wrapper of turbojpeg library.

I have followed the documentation I have found here:

http://tools.android.com/tech-docs/android-ndk-preview

http://tools.android.com/tech-docs/new-build-system/gradle-experimental

However I am unable to make Android Studio find the third-party library. Here is the project setup

Project build.gradle:

// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript {
    repositories {
       jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle-experimental:0.2.0'
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

app module build.gradle:

apply plugin: 'com.android.model.application'
model {
    android {
        compileSdkVersion = 21
        buildToolsVersion = "22.0.1"

        defaultConfig.with {
            applicationId = "com.stephane.turbojpegplugin"
            minSdkVersion.apiLevel = 19
            targetSdkVersion.apiLevel = 19
        }
    }
    /*
     * native build settings
     */
    android.ndk {
        moduleName = "TurboJpegPlugin"
        stl = "stlport_static"
        ldLibs = [ "turbojpeg" ]
        /*
         * Other ndk flags configurable here are
         * cppFlags += "-fno-rtti"
         * cppFlags += "-fno-exceptions"
         * ldLibs    = ["android", "log"]
         * stl       = "system"
         */
    }
    android.buildTypes {
        release {
            minifyEnabled = false
            proguardFiles += file('proguard-rules.txt')
        }
    }
    android.productFlavors {
        // for detailed abiFilter descriptions, refer to "Supported ABIs" @
        // https://developer.android.com/ndk/guides/abis.html#sa
        create("arm7") {
            ndk.abiFilters += "armeabi-v7a"
        }
    }
}

Gradle builds sucessfully with these files however at project build here is the output:

Information:Gradle tasks [clean, :app:compileArm7DebugSources, :app:compileArm7DebugAndroidTestSources]

:app:clean

:app:copyArmeabi-v7aDebugTurboJpegPluginSharedLibraryGdbServer

:app:createArmeabi-v7aDebugTurboJpegPluginSharedLibraryGdbsetup

:app:compileArmeabi-v7aDebugTurboJpegPluginSharedLibraryTurboJpegPluginMainCpp

:app:linkArmeabi-v7aDebugTurboJpegPluginSharedLibrary

D:\Dev\android-ndk-r10e\toolchains\arm-linux-androideabi-4.9\prebuilt\windows-x86_64\arm-linux-androideabi\bin\ld.exe

Error:error: cannot find -lturbojpeg

D:\Dev\projects\android\TurboJpegPlugin\app\src\main\jni\TurboJpegPlugin.cpp

Error:(9) undefined reference to 'tjInitDecompress'

Error:(10) undefined reference to 'tjDecompressHeader2'

Error:(13) undefined reference to 'tjDecompress2'

Error:(14) undefined reference to 'tjDestroy'

Error:error: ld returned 1 exit status

Error:Execution failed for task ':app:linkArmeabi-v7aDebugTurboJpegPluginSharedLibrary'.

> A build operation failed.

     Linker failed while linking libTurboJpegPlugin.so.

 See the complete log at: file:///D:/Dev/projects/android/TurboJpegPlugin/app/build/tmp/linkArmeabi-v7aDebugTurboJpegPluginSharedLibrary/output.txt

Information:BUILD FAILED

Information:Total time: 0.763 secs

Information:7 errors

Information:0 warnings

Information:See complete output in console

The turbojpeg library is in the jniLibs folder like this:

Following older articles/documentation, the jniLibs folder is where the native shared libraries should be put to Android Studio automatically find them but it seems it not the case anymore. Did I miss something?

Any help would be greatly appreciated.

Thanks!

[Stéphane Saffré]

Eventually, I managed to link to the libraries giving explicitely the path the the third-party library this way:

android.productFlavors {
    // for detailed abiFilter descriptions, refer to "Supported ABIs" @
    // https://developer.android.com/ndk/guides/abis.html#sa
    create("arm7") {
        ndk.abiFilters += "armeabi-v7a"

        ndk.ldFlags += "-Lsrc/main/jniLibs/armeabi-v7a"
    }
}

Is it the expected behaviour with the experimental 0.2.0 build plugin ?

[Ignas Brašiškis]

Same problem here, I am strugling to link third party so's.

In Gradle 2.4 normal way to build against native so's was simple:
In build sets add jniLibs in sourceset –

sourceSets {
        main {
            jniLibs.srcDirs = ['jniLibs']
        }
    } 

As I understand sourceSets here are replaced by android.sources directive. I tried this:

android.sources {
    main {
        java{
            source{
                srcDir 'src'
            }
        }
        jniLibs{
            source{
                srcDir 'jniLibs'
            }
        }
    }
}

Gradle runs well however it still does not link: in runtime I get link error. Any ideas how to solve it?

[Xavier Ducrohet]

This is not yet supported by the plugin.

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Xavier Ducrohet
Android SDK Tech Lead
Google Inc.
http://developer.android.com | http://tools.android.com

Please do not send me questions directly. Thanks!

[Stéphane Saffré]

Ok, thanks for the information.

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Stéphane SAFFRÉ

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