Merge pull request #24473 from alexlyulkov:al/samples_with_maven

Updated Android samples for modern Android studio. Added OpenCV from Maven support. #24473

Updated samples for recent Android studio:

- added namespace field that is required in build.gradle files
- replaced _switch_ by _if-else_ because it doesn't work with constants from resources
- added missed log library dependency in face-detection/jni/CMakeLists.txt
- use local.properties to define NDK location

Added support for OpenCV from Maven. Now you can choose 3 possible sources of OpenCV lib in settings.gradle: SDK path, local Maven repository, public Maven repository. (Creating Maven repository from SDK is added here #24456 )

There are differences in project configs for SDK and Maven versions:

- different dependencies in build.gradle
- different OpenCV library names in CMakeLists.txt
- SDK version requires OpenCV_DIR definition

Requires:
- https://github.com/opencv/ci-gha-workflow/pull/124
- https://github.com/opencv-infrastructure/opencv-gha-dockerfile/pull/26

cmake/android/android_gradle_projects.cmake

@@ -1,8 +1,8 @@
 # https://developer.android.com/studio/releases/gradle-plugin
-set(ANDROID_GRADLE_PLUGIN_VERSION "3.2.1" CACHE STRING "Android Gradle Plugin version")
+set(ANDROID_GRADLE_PLUGIN_VERSION "7.3.1" 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")
+set(KOTLIN_PLUGIN_VERSION "1.5.20" CACHE STRING "Kotlin Plugin version")
 message(STATUS "Kotlin Plugin version: ${KOTLIN_PLUGIN_VERSION}")
 
 if(BUILD_KOTLIN_EXTENSIONS)
@@ -13,7 +13,7 @@ else()
   set(KOTLIN_STD_LIB "" CACHE STRING "Kotlin Standard Library dependency")
 endif()
 
-set(GRADLE_VERSION "5.6.4" CACHE STRING "Gradle version")
+set(GRADLE_VERSION "7.6.3" CACHE STRING "Gradle version")
 message(STATUS "Gradle version: ${GRADLE_VERSION}")
 
 set(ANDROID_COMPILE_SDK_VERSION "26" CACHE STRING "Android compileSdkVersion")
@@ -22,7 +22,7 @@ if(ANDROID_NATIVE_API_LEVEL GREATER 21)
 else()
   set(ANDROID_MIN_SDK_VERSION "21" CACHE STRING "Android minSdkVersion")
 endif()
-set(ANDROID_TARGET_SDK_VERSION "26" CACHE STRING "Android minSdkVersion")
+set(ANDROID_TARGET_SDK_VERSION "31" 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}${CMAKE_FILES_DIRECTORY}/install/opencv_android")
@@ -109,21 +109,41 @@ if(NOT OPENCV_SKIP_ANDROID_FORCE_CMAKE)
     get_filename_component(_CMAKE_INSTALL_DIR "${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=${_CMAKE_INSTALL_DIR}")
+  ocv_update_file("${ANDROID_BUILD_BASE_DIR}/local.properties" "cmake.dir=${_CMAKE_INSTALL_DIR}\nndk.dir=${ANDROID_NDK}")
 endif()
 
 file(WRITE "${ANDROID_BUILD_BASE_DIR}/settings.gradle" "
+gradle.ext {
+    //opencv_source = 'maven_central'
+    //opencv_source = 'maven_local'
+    opencv_source = 'sdk_path'
+}
+
 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')
+gradle.ext {
+    //opencv_source = 'maven_central'
+    //opencv_source = 'maven_local'
+    opencv_source = 'sdk_path'
+}
+
+if (gradle.opencv_source == 'maven_local') {
+    gradle.ext {
+        opencv_maven_path = '/<path_to_maven_repo>'
+    }
+}
+
+if (gradle.opencv_source == 'sdk_path') {
+    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)