Android Studio and Gradle dependency integration

Question

I'm following this tutorial but with Android Studio. I have done the following steps:

Creating a new project in Android Studio

Adding the OpenCV-2.4.5-sdk/sdk/java as a module

Right clicked on my main module->Change Module settings-> added the above opencv module as a dependency

For my MainActivity I used the following code (stripped down from one of the samples):

package com.example.test;

import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewListener;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.Mat;

public class MainActivity extends Activity implements CvCameraViewListener {
    private CameraBridgeViewBase mOpenCvCameraView;

    private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
        @Override
        public void onManagerConnected(int status) {
            switch (status) {
                case LoaderCallbackInterface.SUCCESS:
                {
                    Log.i("Yay", "OpenCV loaded successfully");
                    mOpenCvCameraView.enableView();
                } break;
                default:
                {
                    super.onManagerConnected(status);
                } break;
            }
        }
    };

    @Override
    public void onResume()
    {
        super.onResume();
        OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_5, this, mLoaderCallback);
    }

    @Override
    public void onCameraViewStarted(int width, int height) {

    }

    @Override
    public void onCameraViewStopped() {

    }

    @Override
    public Mat onCameraFrame(Mat inputFrame) {
        return null;
    }
}

Android Studio's text editor could identify the packages I have imported (like org.opencv.android) but when I compiled I got these errors:

Gradle: error: package org.opencv.android does not exist
Gradle: error: package org.opencv.android does not exist
Gradle: error: package org.opencv.android.CameraBridgeViewBase does not exist

Does anyone know why this happens?

Answer 1

I was having a similar issue with my Android Studio on OS X. I write the code, and Android Studio would see the .jar's I was referencing, and had declared dependencies on, but when it came time for Gradle to build the project, no go.

I opened up the 'build.gradle' file, and had to manually add dependencies. For example, here is my complete file:

buildscript {
    repositories {
        maven { url 'http://repo1.maven.org/maven2' }
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.4'
    }
}
apply plugin: 'android'

dependencies {
    compile files('libs/android-support-v4.jar')
    compile files('libs/gson-2.2.4.jar')
    compile files('libs/jsoup-1.7.2.jar')
}

android {
    compileSdkVersion 17
    buildToolsVersion "17.0.0"

    defaultConfig {
        minSdkVersion 8
        targetSdkVersion 16
    }
}

As you can guess, the lines I added are the ones referencing Gson and Jsoup.

Answer 2

Inspired by this answer, these are the steps I did:

• Put the OpenCV 2.4.5 jar file (in my case, 'opencv-library-2.4.5.jar') into the libs folder of your project
• Right click it and select Add as library
• Type this in the dependencies part of build.gradle file: compile files('libs/opencv-library-2.4.5.jar')
• Do a clean build. It can be done inside the android studio, but I also ran the gradlew.bat included inside the project folder

Now, the project should be built and run just fine.

Note: In later versions of OpenCV (e.g 2.4.7), the library can be found in ...\build\java.

Answer 3

I ran into a similar problem.

In my case, it was Android Studio failed to add the Gradle dependency for me. I had to add it myself in my project's gradle file:

compile project(":openCVLibrary2410")

It solved the problem. I hope this helps.