How to Use Opencv in Using Gradle

How to use opencv in using Gradle?

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.5.+'
    }
}
apply plugin: 'android'

repositories {
    mavenCentral()
    maven {
        url 'http://maven2.javacv.googlecode.com/git/'
    }
}

dependencies {
    compile 'com.android.support:support-v4:13.0.+'
    compile 'com.googlecode.javacv:javacv:0.5'
    instrumentTestCompile 'junit:junit:4.4'
}

android {
    compileSdkVersion 14
    buildToolsVersion "17.0.0"

    defaultConfig {
        minSdkVersion 7
        targetSdkVersion 14
    }
}

This is worked for me :)

How to import OpenCV 4.5 in Android Studio

This is the complete procedure that currently works for me with OpenCV 4.5.2 on Android Studio 4.1.3.

1. In your project click on File > New > Import Module... and select the /sdk directory inside your OpenCV download. Give it a meaningful name and wait for the procedure to finish: the directory you selected should have been copied in the root of your project where the default /app directory resides;
2. open the Project Structure (for example by clicking on File > Project Structure...), then go to Dependencies (on the left), click on app and on the + icon in the Declared Dependencies tab (not the one in the Modules tab);
3. click on Module Dependency and select the checkbox for the OpenCV SDK that you imported earlier. You should now see it in the list with the other dependencies, so click on Apply and OK to exit from the Project Structure;
4. open the build.gradle file of your app module, copy the values of compileSdkVersion, minSdkVersion and targetSdkVersion, then paste them in the build.gradle file of the OpenCV module replacing the default ones so they match exactly. You can also update the sourceCompatibility and targetCompatibility fields to JavaVersion.VERSION_1_8;
5. finally, sync your project with Gradle files.

To check if it works, add this snippet to your code, for example in MainActivity:

if (OpenCVLoader.initDebug()) {
    Log.d("myTag", "OpenCV loaded")
}

OpenCV in Android Studio

The below steps for using Android OpenCV sdk in Android Studio. This is a simplified version of this(1) SO answer.

1. Download latest OpenCV sdk for Android from OpenCV.org and decompress the zip file.
2. Import OpenCV to Android Studio, From File -> New -> Import Module, choose sdk/java folder in the unzipped opencv archive.
3. Update build.gradle under imported OpenCV module to update 4 fields to match your project build.gradle a) compileSdkVersion b) buildToolsVersion c) minSdkVersion and d) targetSdkVersion.
4. Add module dependency by Application -> Module Settings, and select the Dependencies tab. Click + icon at bottom, choose Module Dependency and select the imported OpenCV module.
   
   
   • For Android Studio v1.2.2, to access to Module Settings :
     in the project view, right-click the dependent module
     -> Open Module Settings
5. Copy libs folder under sdk/native to Android Studio under app/src/main.
6. In Android Studio, rename the copied libs directory to jniLibs and we are done.

Step (6) is since Android studio expects native libs in app/src/main/jniLibs instead of older libs folder. For those new to Android OpenCV, don't miss below steps

• include static{ System.loadLibrary("opencv_java"); } (Note: for OpenCV version 3 at this step you should instead load the library opencv_java3.)
• For step(5), if you ignore any platform libs like x86, make sure your device/emulator is not on that platform.

OpenCV written is in C/C++. Java wrappers are

1. Android OpenCV SDK - OpenCV.org maintained Android Java wrapper. I suggest this one.
2. OpenCV Java - OpenCV.org maintained auto generated desktop Java wrapper.
3. JavaCV - Popular Java wrapper maintained by independent developer(s). Not Android specific. This library might get out of sync with OpenCV newer versions.

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