env/opencv-4.8.0/cmake/android/android_gradle_projects.cmake

# https://developer.android.com/studio/releases/gradle-plugin
set(ANDROID_GRADLE_PLUGIN_VERSION "3.2.1" CACHE STRING "Android Gradle Plugin version")
message(STATUS "Android Gradle Plugin version: ${ANDROID_GRADLE_PLUGIN_VERSION}")

set(KOTLIN_PLUGIN_VERSION "1.4.10" CACHE STRING "Kotlin Plugin version")
message(STATUS "Kotlin Plugin version: ${KOTLIN_PLUGIN_VERSION}")

if(BUILD_KOTLIN_EXTENSIONS)
  set(KOTLIN_PLUGIN_DECLARATION "apply plugin: 'kotlin-android'" CACHE STRING "Kotlin Plugin version")
  set(KOTLIN_STD_LIB "implementation 'org.jetbrains.kotlin:kotlin-stdlib:${KOTLIN_PLUGIN_VERSION}'" CACHE STRING "Kotlin Standard Library dependency")
else()
  set(KOTLIN_PLUGIN_DECLARATION "" CACHE STRING "Kotlin Plugin version")
  set(KOTLIN_STD_LIB "" CACHE STRING "Kotlin Standard Library dependency")
endif()

set(GRADLE_VERSION "5.6.4" CACHE STRING "Gradle version")
message(STATUS "Gradle version: ${GRADLE_VERSION}")

set(ANDROID_COMPILE_SDK_VERSION "26" CACHE STRING "Android compileSdkVersion")
if(ANDROID_NATIVE_API_LEVEL GREATER 21)
  set(ANDROID_MIN_SDK_VERSION "${ANDROID_NATIVE_API_LEVEL}" CACHE STRING "Android minSdkVersion")
else()
  set(ANDROID_MIN_SDK_VERSION "21" CACHE STRING "Android minSdkVersion")
endif()
set(ANDROID_TARGET_SDK_VERSION "26" CACHE STRING "Android minSdkVersion")

set(ANDROID_BUILD_BASE_DIR "${OpenCV_BINARY_DIR}/opencv_android" CACHE INTERNAL "")
set(ANDROID_TMP_INSTALL_BASE_DIR "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/install/opencv_android")

set(ANDROID_INSTALL_SAMPLES_DIR "samples")

set(ANDROID_BUILD_ABI_FILTER "
reset()
include '${ANDROID_ABI}'
")

set(ANDROID_INSTALL_ABI_FILTER "
//reset()
//include 'armeabi-v7a'
//include 'arm64-v8a'
//include 'x86'
//include 'x86_64'
")
if(NOT INSTALL_CREATE_DISTRIB)
  set(ANDROID_INSTALL_ABI_FILTER "${ANDROID_BUILD_ABI_FILTER}")
endif()

# BUG: Ninja generator generates broken targets with ANDROID_ABI_FILTER name (CMake 3.11.2)
#set(__spaces "                        ")
#string(REPLACE "\n" "\n${__spaces}" ANDROID_ABI_FILTER "${__spaces}${ANDROID_BUILD_ABI_FILTER}")
#string(REPLACE REGEX "[ ]+$" "" ANDROID_ABI_FILTER "${ANDROID_ABI_FILTER}")
set(ANDROID_ABI_FILTER "${ANDROID_BUILD_ABI_FILTER}")
set(ANDROID_STRICT_BUILD_CONFIGURATION "true")
configure_file("${OpenCV_SOURCE_DIR}/samples/android/build.gradle.in" "${ANDROID_BUILD_BASE_DIR}/build.gradle" @ONLY)

set(ANDROID_ABI_FILTER "${ANDROID_INSTALL_ABI_FILTER}")
set(ANDROID_STRICT_BUILD_CONFIGURATION "false")
configure_file("${OpenCV_SOURCE_DIR}/samples/android/build.gradle.in" "${ANDROID_TMP_INSTALL_BASE_DIR}/${ANDROID_INSTALL_SAMPLES_DIR}/build.gradle" @ONLY)
install(FILES "${ANDROID_TMP_INSTALL_BASE_DIR}/${ANDROID_INSTALL_SAMPLES_DIR}/build.gradle" DESTINATION "${ANDROID_INSTALL_SAMPLES_DIR}" COMPONENT samples)

configure_file("${OpenCV_SOURCE_DIR}/platforms/android/gradle-wrapper/gradle/wrapper/gradle-wrapper.properties.in" "${ANDROID_BUILD_BASE_DIR}/gradle/wrapper/gradle-wrapper.properties" @ONLY)
install(FILES "${ANDROID_BUILD_BASE_DIR}/gradle/wrapper/gradle-wrapper.properties" DESTINATION "${ANDROID_INSTALL_SAMPLES_DIR}/gradle/wrapper" COMPONENT samples)

set(GRADLE_WRAPPER_FILES
    "gradle/wrapper/gradle-wrapper.jar"
    "gradlew.bat"
    "gradlew"
    "gradle.properties"
)
foreach(fname ${GRADLE_WRAPPER_FILES})
  get_filename_component(__dir "${fname}" DIRECTORY)
  set(__permissions "")
  set(__permissions_prefix "")
  if(fname STREQUAL "gradlew")
    set(__permissions FILE_PERMISSIONS OWNER_READ OWNER_WRITE OWNER_EXECUTE GROUP_READ GROUP_EXECUTE WORLD_READ WORLD_EXECUTE)
  endif()
  file(COPY "${OpenCV_SOURCE_DIR}/platforms/android/gradle-wrapper/${fname}" DESTINATION "${ANDROID_BUILD_BASE_DIR}/${__dir}" ${__permissions})
  string(REPLACE "FILE_PERMISSIONS" "PERMISSIONS" __permissions "${__permissions}")
  if("${__dir}" STREQUAL "")
    set(__dir ".")
  endif()
  install(FILES "${OpenCV_SOURCE_DIR}/platforms/android/gradle-wrapper/${fname}" DESTINATION "${ANDROID_INSTALL_SAMPLES_DIR}/${__dir}" COMPONENT samples ${__permissions})
endforeach()

# set build.gradle namespace
if(NOT (ANDROID_GRADLE_PLUGIN_VERSION VERSION_LESS "7.3.0"))
  ocv_update(OPENCV_ANDROID_NAMESPACE_DECLARATION "namespace 'org.opencv'")
else()
  ocv_update(OPENCV_ANDROID_NAMESPACE_DECLARATION "")
endif()

# set android gradle java version in build.gradle and set aidl config
if(NOT (ANDROID_GRADLE_PLUGIN_VERSION VERSION_LESS "8.0.0"))
  # AGP-8.0 requires a minimum JDK version of JDK17
  ocv_update(ANDROID_GRADLE_JAVA_VERSION_INIT "17")
  # Enable aidl configuration for OpenCV compile with AGP-8.0
  ocv_update(ANDROID_GRADLE_BUILD_FEATURE_AIDL "buildFeatures { aidl true }")
else()
  ocv_update(ANDROID_GRADLE_JAVA_VERSION_INIT "1_8")
  ocv_update(ANDROID_GRADLE_BUILD_FEATURE_AIDL "")
endif()

set(ANDROID_GRADLE_JAVA_VERSION "${ANDROID_GRADLE_JAVA_VERSION_INIT}" CACHE STRING "Android Gradle Java version")
message(STATUS "Android Gradle Java version: ${ANDROID_GRADLE_JAVA_VERSION}")

# force reusing of the same CMake version
if(NOT OPENCV_SKIP_ANDROID_FORCE_CMAKE)
  if(NOT DEFINED _CMAKE_INSTALL_DIR)
    get_filename_component(_CMAKE_INSTALL_DIR "${CMAKE_ROOT}" PATH)
    get_filename_component(_CMAKE_INSTALL_DIR "${_CMAKE_INSTALL_DIR}" PATH)
  endif()
  ocv_update_file("${ANDROID_BUILD_BASE_DIR}/local.properties" "cmake.dir=${_CMAKE_INSTALL_DIR}")
endif()

file(WRITE "${ANDROID_BUILD_BASE_DIR}/settings.gradle" "
include ':opencv'
")

file(WRITE "${ANDROID_TMP_INSTALL_BASE_DIR}/settings.gradle" "
rootProject.name = 'opencv_samples'

def opencvsdk='../'
//def opencvsdk='/<path to OpenCV-android-sdk>'
//println opencvsdk
include ':opencv'
project(':opencv').projectDir = new File(opencvsdk + '/sdk')
")

ocv_check_environment_variables(OPENCV_GRADLE_VERBOSE_OPTIONS)

macro(add_android_project target path)
  get_filename_component(__dir "${path}" NAME)

  set(OPENCV_ANDROID_CMAKE_EXTRA_ARGS "")
  if(DEFINED ANDROID_TOOLCHAIN)
    set(OPENCV_ANDROID_CMAKE_EXTRA_ARGS "${OPENCV_ANDROID_CMAKE_EXTRA_ARGS},\n\"-DANDROID_TOOLCHAIN=${ANDROID_TOOLCHAIN}\"")
  endif()
  if(DEFINED ANDROID_STL)
    set(OPENCV_ANDROID_CMAKE_EXTRA_ARGS "${OPENCV_ANDROID_CMAKE_EXTRA_ARGS},\n\"-DANDROID_STL=${ANDROID_STL}\"")
  endif()

  #
  # Build
  #
  set(ANDROID_SAMPLE_JNI_PATH "${path}/jni")
  set(ANDROID_SAMPLE_JAVA_PATH "${path}/src")
  set(ANDROID_SAMPLE_RES_PATH "${path}/res")
  set(ANDROID_SAMPLE_MANIFEST_PATH "${path}/gradle/AndroidManifest.xml")

  set(ANDROID_ABI_FILTER "${ANDROID_BUILD_ABI_FILTER}")
  set(ANDROID_PROJECT_JNI_PATH "../../")

  string(REPLACE ";" "', '" ANDROID_SAMPLE_JAVA_PATH "['${ANDROID_SAMPLE_JAVA_PATH}']")
  string(REPLACE ";" "', '" ANDROID_SAMPLE_RES_PATH "['${ANDROID_SAMPLE_RES_PATH}']")
  configure_file("${path}/build.gradle.in" "${ANDROID_BUILD_BASE_DIR}/${__dir}/build.gradle" @ONLY)

  file(APPEND "${ANDROID_BUILD_BASE_DIR}/settings.gradle" "
include ':${__dir}'
")

  if (BUILD_ANDROID_EXAMPLES)
    # build apk
    set(APK_FILE "${ANDROID_BUILD_BASE_DIR}/${__dir}/build/outputs/apk/release/${__dir}-${ANDROID_ABI}-release-unsigned.apk")
    ocv_update(OPENCV_GRADLE_VERBOSE_OPTIONS "-i")
    add_custom_command(
        OUTPUT "${APK_FILE}" "${OPENCV_DEPHELPER}/android_sample_${__dir}"
        COMMAND ./gradlew ${OPENCV_GRADLE_VERBOSE_OPTIONS} "${__dir}:assemble"
        COMMAND ${CMAKE_COMMAND} -E touch "${OPENCV_DEPHELPER}/android_sample_${__dir}"
        WORKING_DIRECTORY "${ANDROID_BUILD_BASE_DIR}"
        DEPENDS ${depends} opencv_java_android
        COMMENT "Building OpenCV Android sample project: ${__dir}"
    )
  else()  # install only
    # copy samples
    add_custom_command(
        OUTPUT "${OPENCV_DEPHELPER}/android_sample_${__dir}"
        COMMAND ${CMAKE_COMMAND} -E touch "${OPENCV_DEPHELPER}/android_sample_${__dir}"
        WORKING_DIRECTORY "${ANDROID_BUILD_BASE_DIR}"
        DEPENDS ${depends} opencv_java_android
        COMMENT "Copying OpenCV Android sample project: ${__dir}"
    )
  endif()

  file(REMOVE "${OPENCV_DEPHELPER}/android_sample_${__dir}")  # force rebuild after CMake run

  add_custom_target(android_sample_${__dir} ALL DEPENDS "${OPENCV_DEPHELPER}/android_sample_${__dir}" SOURCES "${ANDROID_SAMPLE_MANIFEST_PATH}")

  #
  # Install
  #
  set(ANDROID_SAMPLE_JNI_PATH "jni")
  set(ANDROID_SAMPLE_JAVA_PATH "src")
  set(ANDROID_SAMPLE_RES_PATH "res")
  set(ANDROID_SAMPLE_MANIFEST_PATH "AndroidManifest.xml")

  install(DIRECTORY "${path}/res" DESTINATION "${ANDROID_INSTALL_SAMPLES_DIR}/${__dir}" COMPONENT samples OPTIONAL)
  install(DIRECTORY "${path}/src" DESTINATION "${ANDROID_INSTALL_SAMPLES_DIR}/${__dir}" COMPONENT samples)
  install(DIRECTORY "${path}/jni" DESTINATION "${ANDROID_INSTALL_SAMPLES_DIR}/${__dir}" COMPONENT samples OPTIONAL)

  install(FILES "${path}/gradle/AndroidManifest.xml" DESTINATION "${ANDROID_INSTALL_SAMPLES_DIR}/${__dir}" COMPONENT samples)

  set(ANDROID_ABI_FILTER "${ANDROID_INSTALL_ABI_FILTER}")
  set(ANDROID_PROJECT_JNI_PATH "native/jni")

  string(REPLACE ";" "', '" ANDROID_SAMPLE_JAVA_PATH "['${ANDROID_SAMPLE_JAVA_PATH}']")
  string(REPLACE ";" "', '" ANDROID_SAMPLE_RES_PATH "['${ANDROID_SAMPLE_RES_PATH}']")
  configure_file("${path}/build.gradle.in" "${ANDROID_TMP_INSTALL_BASE_DIR}/${__dir}/build.gradle" @ONLY)
  install(FILES "${ANDROID_TMP_INSTALL_BASE_DIR}/${__dir}/build.gradle" DESTINATION "${ANDROID_INSTALL_SAMPLES_DIR}/${__dir}" COMPONENT samples)

  file(APPEND "${ANDROID_TMP_INSTALL_BASE_DIR}/settings.gradle" "
include ':${__dir}'
")

endmacro()

install(FILES "${ANDROID_TMP_INSTALL_BASE_DIR}/settings.gradle" DESTINATION "${ANDROID_INSTALL_SAMPLES_DIR}" COMPONENT samples)