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='../'
+gradle.ext {
-//def opencvsdk='/<path to OpenCV-android-sdk>'
+    //opencv_source = 'maven_central'
-//println opencvsdk
+    //opencv_source = 'maven_local'
-include ':opencv'
+    opencv_source = 'sdk_path'
-project(':opencv').projectDir = new File(opencvsdk + '/sdk')
+}
+
+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)

platforms/android/build-tests/test_gradle.sh

@@ -29,6 +29,9 @@ rm -rf "test-gradle"
 cp -rp "${SDK_DIR}" "test-gradle"
 echo "Cloning OpenCV Android SDK ... Done!"
 
+echo "Force Current CMake for Gradle project"
+# drop cmake bin name and "bin" folder from path
+echo "cmake.dir=$(dirname $(dirname $(which cmake)))" > "test-gradle/samples/local.properties"
 echo "Run gradle ..."
 (cd "test-gradle/samples"; ./gradlew -i assemble)
 

samples/android/15-puzzle/build.gradle.in

@@ -1,6 +1,7 @@
 apply plugin: 'com.android.application'
 
 android {
+    namespace 'org.opencv.samples.puzzle15'
     compileSdkVersion @ANDROID_COMPILE_SDK_VERSION@
     defaultConfig {
         applicationId "org.opencv.samples.puzzle15"
@@ -27,5 +28,9 @@ android {
 
 dependencies {
     //implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation project(':opencv')
+    if (gradle.opencv_source == "sdk_path") {
+        implementation project(':opencv')
+    } else if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+        implementation 'org.opencv:opencv:@OPENCV_VERSION_PLAIN@'
+    }
 }

samples/android/build.gradle.in

@@ -19,6 +19,11 @@ allprojects {
     repositories {
         google()
         jcenter()
+        if (gradle.opencv_source == "maven_local") {
+            maven {
+                url gradle.opencv_maven_path
+            }
+        }
     }
 }
 

samples/android/camera-calibration/build.gradle.in

@@ -1,6 +1,7 @@
 apply plugin: 'com.android.application'
 
 android {
+    namespace 'org.opencv.samples.cameracalibration'
     compileSdkVersion @ANDROID_COMPILE_SDK_VERSION@
     defaultConfig {
         applicationId "org.opencv.samples.cameracalibration"
@@ -27,5 +28,9 @@ android {
 
 dependencies {
     //implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation project(':opencv')
+    if (gradle.opencv_source == "sdk_path") {
+        implementation project(':opencv')
+    } else if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+        implementation 'org.opencv:opencv:@OPENCV_VERSION_PLAIN@'
+    }
 }

samples/android/camera-calibration/src/org/opencv/samples/cameracalibration/CameraCalibrationActivity.java

@@ -136,23 +136,22 @@ public class CameraCalibrationActivity extends CameraActivity implements CvCamer
 
     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
-        switch (item.getItemId()) {
+        if (item.getItemId() == R.id.calibration) {
-        case R.id.calibration:
             mOnCameraFrameRender =
                 new OnCameraFrameRender(new CalibrationFrameRender(mCalibrator));
             item.setChecked(true);
             return true;
-        case R.id.undistortion:
+        } else if (item.getItemId() == R.id.undistortion) {
             mOnCameraFrameRender =
                 new OnCameraFrameRender(new UndistortionFrameRender(mCalibrator));
             item.setChecked(true);
             return true;
-        case R.id.comparison:
+        } else if (item.getItemId() == R.id.comparison) {
             mOnCameraFrameRender =
                 new OnCameraFrameRender(new ComparisonFrameRender(mCalibrator, mWidth, mHeight, getResources()));
             item.setChecked(true);
             return true;
-        case R.id.calibrate:
+        } else if (item.getItemId() == R.id.calibrate) {
             final Resources res = getResources();
             if (mCalibrator.getCornersBufferSize() < 2) {
                 (Toast.makeText(this, res.getString(R.string.more_samples), Toast.LENGTH_SHORT)).show();
@@ -196,7 +195,7 @@ public class CameraCalibrationActivity extends CameraActivity implements CvCamer
                 }
             }.execute();
             return true;
-        default:
+        } else {
             return super.onOptionsItemSelected(item);
         }
     }

samples/android/color-blob-detection/build.gradle.in

@@ -1,6 +1,7 @@
 apply plugin: 'com.android.application'
 
 android {
+    namespace 'org.opencv.samples.colorblobdetect'
     compileSdkVersion @ANDROID_COMPILE_SDK_VERSION@
     defaultConfig {
         applicationId "org.opencv.samples.colorblobdetect"
@@ -27,5 +28,9 @@ android {
 
 dependencies {
     //implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation project(':opencv')
+    if (gradle.opencv_source == "sdk_path") {
+        implementation project(':opencv')
+    } else if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+        implementation 'org.opencv:opencv:@OPENCV_VERSION_PLAIN@'
+    }
 }

samples/android/face-detection/build.gradle.in

@@ -1,6 +1,7 @@
 apply plugin: 'com.android.application'
 
 android {
+    namespace 'org.opencv.samples.facedetect'
     compileSdkVersion @ANDROID_COMPILE_SDK_VERSION@
     defaultConfig {
         applicationId "org.opencv.samples.facedetect"
@@ -11,7 +12,14 @@ android {
 
         externalNativeBuild {
             cmake {
-                arguments "-DOpenCV_DIR=" + project(':opencv').projectDir + "/@ANDROID_PROJECT_JNI_PATH@"@OPENCV_ANDROID_CMAKE_EXTRA_ARGS@
+                if (gradle.opencv_source == "sdk_path") {
+                    arguments "-DOpenCV_DIR=" + project(':opencv').projectDir + "/@ANDROID_PROJECT_JNI_PATH@",
+                              "-DOPENCV_FROM_SDK=TRUE"@OPENCV_ANDROID_CMAKE_EXTRA_ARGS@
+
+                } else {
+                    arguments "-DOPENCV_VERSION_MAJOR=@OPENCV_VERSION_MAJOR@",
+                              "-DOPENCV_FROM_SDK=FALSE"@OPENCV_ANDROID_CMAKE_EXTRA_ARGS@
+                }
                 targets "detection_based_tracker"
             }
         }
@@ -35,9 +43,18 @@ android {
              path '@ANDROID_SAMPLE_JNI_PATH@/CMakeLists.txt'
         }
     }
+    buildFeatures {
+        if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+            prefab true
+        }
+    }
 }
 
 dependencies {
     //implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation project(':opencv')
+    if (gradle.opencv_source == "sdk_path") {
+        implementation project(':opencv')
+    } else if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+        implementation 'org.opencv:opencv:@OPENCV_VERSION_PLAIN@'
+    }
 }

samples/android/face-detection/jni/CMakeLists.txt

@@ -3,7 +3,12 @@ cmake_minimum_required(VERSION 3.6)
 set(target detection_based_tracker)
 project(${target} CXX)
 
-set(ANDROID_OPENCV_COMPONENTS "opencv_java" CACHE STRING "")
+if (OPENCV_FROM_SDK)
+  set(ANDROID_OPENCV_COMPONENTS "opencv_java" CACHE STRING "")
+else()
+  set(ANDROID_OPENCV_COMPONENTS "OpenCV::opencv_java${OPENCV_VERSION_MAJOR}" CACHE STRING "")
+endif()
+
 message(STATUS "ANDROID_ABI=${ANDROID_ABI}")
 find_package(OpenCV REQUIRED COMPONENTS ${ANDROID_OPENCV_COMPONENTS})
 
@@ -12,4 +17,5 @@ file(GLOB hdrs *.hpp *.h)
 
 include_directories("${CMAKE_CURRENT_LIST_DIR}")
 add_library(${target} SHARED ${srcs} ${hdrs})
-target_link_libraries(${target} ${ANDROID_OPENCV_COMPONENTS})
+find_library(log_lib log)
+target_link_libraries(${target} ${ANDROID_OPENCV_COMPONENTS} ${log_lib})

samples/android/image-manipulations/build.gradle.in

@@ -1,6 +1,7 @@
 apply plugin: 'com.android.application'
 
 android {
+    namespace 'org.opencv.samples.imagemanipulations'
     compileSdkVersion @ANDROID_COMPILE_SDK_VERSION@
     defaultConfig {
         applicationId "org.opencv.samples.imagemanipulations"
@@ -27,5 +28,9 @@ android {
 
 dependencies {
     //implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation project(':opencv')
+    if (gradle.opencv_source == "sdk_path") {
+        implementation project(':opencv')
+    } else if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+        implementation 'org.opencv:opencv:@OPENCV_VERSION_PLAIN@'
+    }
 }

samples/android/mobilenet-objdetect/build.gradle.in

@@ -1,6 +1,7 @@
 apply plugin: 'com.android.application'
 
 android {
+    namespace 'org.opencv.samples.opencv_mobilenet'
     compileSdkVersion @ANDROID_COMPILE_SDK_VERSION@
     defaultConfig {
         applicationId "org.opencv.samples.opencv_mobilenet"
@@ -27,5 +28,9 @@ android {
 
 dependencies {
     //implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation project(':opencv')
+    if (gradle.opencv_source == "sdk_path") {
+        implementation project(':opencv')
+    } else if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+        implementation 'org.opencv:opencv:@OPENCV_VERSION_PLAIN@'
+    }
 }

samples/android/tutorial-1-camerapreview/build.gradle.in

@@ -1,6 +1,7 @@
 apply plugin: 'com.android.application'
 
 android {
+    namespace 'org.opencv.samples.tutorial1'
     compileSdkVersion @ANDROID_COMPILE_SDK_VERSION@
     defaultConfig {
         applicationId "org.opencv.samples.tutorial1"
@@ -27,5 +28,9 @@ android {
 
 dependencies {
     //implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation project(':opencv')
+    if (gradle.opencv_source == "sdk_path") {
+        implementation project(':opencv')
+    } else if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+        implementation 'org.opencv:opencv:@OPENCV_VERSION_PLAIN@'
+    }
 }

samples/android/tutorial-2-mixedprocessing/build.gradle.in

@@ -1,6 +1,7 @@
 apply plugin: 'com.android.application'
 
 android {
+    namespace 'org.opencv.samples.tutorial2'
     compileSdkVersion @ANDROID_COMPILE_SDK_VERSION@
     defaultConfig {
         applicationId "org.opencv.samples.tutorial2"
@@ -11,7 +12,14 @@ android {
 
         externalNativeBuild {
             cmake {
-                arguments "-DOpenCV_DIR=" + project(':opencv').projectDir + "/@ANDROID_PROJECT_JNI_PATH@"@OPENCV_ANDROID_CMAKE_EXTRA_ARGS@
+                if (gradle.opencv_source == "sdk_path") {
+                    arguments "-DOpenCV_DIR=" + project(':opencv').projectDir + "/@ANDROID_PROJECT_JNI_PATH@",
+                              "-DOPENCV_FROM_SDK=TRUE"@OPENCV_ANDROID_CMAKE_EXTRA_ARGS@
+
+                } else {
+                    arguments "-DOPENCV_VERSION_MAJOR=@OPENCV_VERSION_MAJOR@",
+                              "-DOPENCV_FROM_SDK=FALSE"@OPENCV_ANDROID_CMAKE_EXTRA_ARGS@
+                }
                 targets "mixed_sample"
             }
         }
@@ -35,9 +43,18 @@ android {
              path '@ANDROID_SAMPLE_JNI_PATH@/CMakeLists.txt'
         }
     }
+    buildFeatures {
+        if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+            prefab true
+        }
+    }
 }
 
 dependencies {
     //implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation project(':opencv')
+    if (gradle.opencv_source == "sdk_path") {
+        implementation project(':opencv')
+    } else if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+        implementation 'org.opencv:opencv:@OPENCV_VERSION_PLAIN@'
+    }
 }

samples/android/tutorial-2-mixedprocessing/jni/CMakeLists.txt

@@ -3,7 +3,12 @@ cmake_minimum_required(VERSION 3.6)
 set(target mixed_sample)
 project(${target} CXX)
 
-set(ANDROID_OPENCV_COMPONENTS "opencv_java" CACHE STRING "")
+if (OPENCV_FROM_SDK)
+  set(ANDROID_OPENCV_COMPONENTS "opencv_java" CACHE STRING "")
+else()
+  set(ANDROID_OPENCV_COMPONENTS "OpenCV::opencv_java${OPENCV_VERSION_MAJOR}" CACHE STRING "")
+endif()
+
 message(STATUS "ANDROID_ABI=${ANDROID_ABI}")
 find_package(OpenCV REQUIRED COMPONENTS ${ANDROID_OPENCV_COMPONENTS})
 

samples/android/tutorial-3-cameracontrol/build.gradle.in

@@ -1,6 +1,7 @@
 apply plugin: 'com.android.application'
 
 android {
+    namespace 'org.opencv.samples.tutorial3'
     compileSdkVersion @ANDROID_COMPILE_SDK_VERSION@
     defaultConfig {
         applicationId "org.opencv.samples.tutorial3"
@@ -27,5 +28,9 @@ android {
 
 dependencies {
     //implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation project(':opencv')
+    if (gradle.opencv_source == "sdk_path") {
+        implementation project(':opencv')
+    } else if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+        implementation 'org.opencv:opencv:@OPENCV_VERSION_PLAIN@'
+    }
 }

samples/android/tutorial-4-opencl/build.gradle.in

@@ -1,6 +1,7 @@
 apply plugin: 'com.android.application'
 
 android {
+    namespace 'org.opencv.samples.tutorial4'
     compileSdkVersion @ANDROID_COMPILE_SDK_VERSION@
     defaultConfig {
         applicationId "org.opencv.samples.tutorial4"
@@ -11,7 +12,14 @@ android {
 
         externalNativeBuild {
             cmake {
-                arguments "-DOpenCV_DIR=" + project(':opencv').projectDir + "/@ANDROID_PROJECT_JNI_PATH@"@OPENCV_ANDROID_CMAKE_EXTRA_ARGS@
+                if (gradle.opencv_source == "sdk_path") {
+                    arguments "-DOpenCV_DIR=" + project(':opencv').projectDir + "/@ANDROID_PROJECT_JNI_PATH@",
+                              "-DOPENCV_FROM_SDK=TRUE"@OPENCV_ANDROID_CMAKE_EXTRA_ARGS@
+
+                } else {
+                    arguments "-DOPENCV_VERSION_MAJOR=@OPENCV_VERSION_MAJOR@",
+                              "-DOPENCV_FROM_SDK=FALSE"@OPENCV_ANDROID_CMAKE_EXTRA_ARGS@
+                }
                 targets "JNIpart"
             }
         }
@@ -35,9 +43,18 @@ android {
              path '@ANDROID_SAMPLE_JNI_PATH@/CMakeLists.txt'
         }
     }
+    buildFeatures {
+        if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+            prefab true
+        }
+    }
 }
 
 dependencies {
     //implementation fileTree(dir: 'libs', include: ['*.jar'])
-    implementation project(':opencv')
+    if (gradle.opencv_source == "sdk_path") {
+        implementation project(':opencv')
+    } else if (gradle.opencv_source == "maven_local" || gradle.opencv_source == "maven_cenral") {
+        implementation 'org.opencv:opencv:@OPENCV_VERSION_PLAIN@'
+    }
 }

samples/android/tutorial-4-opencl/jni/CMakeLists.txt

@@ -1,9 +1,14 @@
 cmake_minimum_required(VERSION 3.6)
 
-set(target mixed_sample)
+set(target JNIpart)
 project(${target} CXX)
 
-set(ANDROID_OPENCV_COMPONENTS "opencv_java" CACHE STRING "")
+if (OPENCV_FROM_SDK)
+  set(ANDROID_OPENCV_COMPONENTS "opencv_java" CACHE STRING "")
+else()
+  set(ANDROID_OPENCV_COMPONENTS "OpenCV::opencv_java${OPENCV_VERSION_MAJOR}" CACHE STRING "")
+endif()
+
 message(STATUS "ANDROID_ABI=${ANDROID_ABI}")
 find_package(OpenCV REQUIRED COMPONENTS ${ANDROID_OPENCV_COMPONENTS})