/opencv-android-setup

Origin

How to use this repository

  1. Download and Install Android Studio

  2. Install NDK, CMake and LLDB

  3. Clone this repository.

  4. Install OpenCV Android release :

    • Download OpenCV Android release or download latest available Android release on OpenCV website.
    • Unzip downloaded file and put OpenCV-android-sdk directory on a path of your choice.

  5. Link your Android Studio project to the OpenCV Android SDK you just downloaded :

    • [MacOS|Ubuntu] Open gradle.properties file and edit following line with your own OpenCV Android SDK directory path :

    • [MacOS|Ubuntu]

      opencvsdk=/Users/Example/Downloads/OpenCV-android-sdk

    • [Window]

      opencvsdk=C\:\\Users\\HELLO\\Downloads\\opencv-4.5.4-android-sdk\\OpenCV-android-sdk

  6. Sync Gradle and run the application on your Android Device!

Create a new Android project with Native OpenCV support

Here are the steps to follow to create a new Android Studio project with native OpenCV support :

  1. Download and Install Android Studio

  2. Install NDK, CMake and LLDB

  3. Create a new Native Android Studio project :

    • Select File -> New -> New Project... from the main menu.
    • Click Phone and Tablet tab, select Native C++ and click next.
    • Choose an Application Name, select your favorite language (Kotlin or Java), choose Minimum API level (28 here) and select next.
    • Choose Toolchain default as C++ standard and click Finish.

  4. Install OpenCV Android release :

  5. Add OpenCV Android SDK as a module into your project :

    • Open setting.gradle file and append these two lines.

      include ':opencv'
project(':opencv').projectDir = new File(opencvsdk + '/sdk')

    • Open gradle.properties file and append following line. Do not forget to use correct OpenCV Android SDK path for your machine.

    • [MacOS|Ubuntu]

      opencvsdk=/Users/Example/Downloads/OpenCV-android-sdk

    • [Window]

      opencvsdk=C\:\\Users\\HELLO\\Downloads\\opencv-4.5.4-android-sdk\\OpenCV-android-sdk

    • Open build.gradle file and add implementation project(path: ':opencv') to dependencies section :

      dependencies {
    ...
    implementation project(path: ':opencv')
}

    • Click on File -> Sync Project with Gradle Files.

  6. Add following config to app build.gradle file :

    • In android -> defaultConfig -> externalNativeBuild -> cmake section, put these three lines :

      cppFlags "-frtti -fexceptions"
abiFilters 'x86', 'x86_64', 'armeabi-v7a', 'arm64-v8a'
arguments "-DOpenCV_DIR=" + opencvsdk + "/sdk/native"

  7. Add following config to CMakeLists.txt file :

    • Before add_library instruction, add three following lines :

      include_directories(${OpenCV_DIR}/jni/include)
add_library( lib_opencv SHARED IMPORTED )
set_target_properties(lib_opencv PROPERTIES IMPORTED_LOCATION ${OpenCV_DIR}/libs/${ANDROID_ABI}/libopencv_java4.so)

    • In target_link_libraries instruction arguments, add following line :

      lib_opencv

  8. Add following permissions to your AndroidManifest.xml file :

    <uses-permission android:name="android.permission.CAMERA"/>
<uses-feature android:name="android.hardware.camera"/>
<uses-feature android:name="android.hardware.camera.autofocus"/>
<uses-feature android:name="android.hardware.camera.front"/>
<uses-feature android:name="android.hardware.camera.front.autofocus"/>

  9. Create your MainActivity :

    • Copy paste MainActivity file.

  10. Create your activity_main.xml :

    • Copy paste activity_main.xml file.

  11. Add native code in native-lib.cpp :

    • You can copy paste native-lib.cpp file. Do not forget to adapt the method name : Java_com_example_nativeopencvtemplate_MainActivity_adaptiveThresholdFromJNI should be replaced with Java_<main-activity-package-name-with-underscores>_MainActivity_adaptiveThresholdFromJNI.

  12. Sync Gradle and run the application on your Android Device!