Fixed Android build with SDK tools revision 20

cmake/OpenCVDetectAndroidSDK.cmake

@@ -175,6 +175,7 @@ macro(android_get_compatible_target VAR)
   endif()
 endmacro()
 
+unset(__android_project_chain CACHE)
 #add_android_project(target_name ${path} NATIVE_DEPS opencv_core LIBRARY_DEPS ${OpenCV_BINARY_DIR} SDK_TARGET 11)
 macro(add_android_project target path)
   # parse arguments
@@ -288,17 +289,18 @@ macro(add_android_project target path)
          COMMAND ${CMAKE_COMMAND} -E touch "${android_proj_bin_dir}/bin/${target}-debug.apk" # needed because ant does not update the timestamp of updated apk
          WORKING_DIRECTORY "${android_proj_bin_dir}"
          MAIN_DEPENDENCY "${android_proj_bin_dir}/${ANDROID_MANIFEST_FILE}"
-         DEPENDS ${android_proj_file_deps} ${JNI_LIB_NAME})
+         DEPENDS ${android_proj_file_deps} ${JNI_LIB_NAME} ${__android_project_chain})
     else()
-    add_custom_command(
-       OUTPUT "${android_proj_bin_dir}/bin/${target}-debug.apk"
-       COMMAND ${ANT_EXECUTABLE} -q -noinput -k debug
-       COMMAND ${CMAKE_COMMAND} -E touch "${android_proj_bin_dir}/bin/${target}-debug.apk" # needed because ant does not update the timestamp of updated apk
-       WORKING_DIRECTORY "${android_proj_bin_dir}"
-       MAIN_DEPENDENCY "${android_proj_bin_dir}/${ANDROID_MANIFEST_FILE}"
-       DEPENDS "${OpenCV_BINARY_DIR}/bin/classes.jar" opencv_java # as we are part of OpenCV we can just force this dependency
-       DEPENDS ${android_proj_file_deps} ${JNI_LIB_NAME})
+      add_custom_command(
+         OUTPUT "${android_proj_bin_dir}/bin/${target}-debug.apk"
+         COMMAND ${ANT_EXECUTABLE} -q -noinput -k debug
+         COMMAND ${CMAKE_COMMAND} -E touch "${android_proj_bin_dir}/bin/${target}-debug.apk" # needed because ant does not update the timestamp of updated apk
+         WORKING_DIRECTORY "${android_proj_bin_dir}"
+         MAIN_DEPENDENCY "${android_proj_bin_dir}/${ANDROID_MANIFEST_FILE}"
+         DEPENDS "${OpenCV_BINARY_DIR}/bin/.classes.jar.dephelper" opencv_java # as we are part of OpenCV we can just force this dependency
+         DEPENDS ${android_proj_file_deps} ${JNI_LIB_NAME} ${__android_project_chain})
     endif()
+    set(__android_project_chain ${target} CACHE INTERNAL "auxiliary variable used for Android progects chaining")
 
     unset(JNI_LIB_NAME)
 

modules/java/CMakeLists.txt

@@ -248,9 +248,9 @@ if(ANDROID)
       # build the library project
       # normally we should do this after a native part, but for a library project we can build the java part first
       add_custom_command(
-        OUTPUT "${OpenCV_BINARY_DIR}/bin/classes.jar"
+        OUTPUT "${OpenCV_BINARY_DIR}/bin/classes.jar" "${OpenCV_BINARY_DIR}/bin/.classes.jar.dephelper"
         COMMAND ${ANT_EXECUTABLE} -q -noinput -k debug
-        COMMAND ${CMAKE_COMMAND} -E touch "${OpenCV_BINARY_DIR}/bin/classes.jar" # needed because ant does not update the timestamp of updated jar
+        COMMAND ${CMAKE_COMMAND} -E touch "${OpenCV_BINARY_DIR}/bin/.classes.jar.dephelper" # can not rely on classes.jar because different versions of SDK update timestamp at different times
         WORKING_DIRECTORY "${OpenCV_BINARY_DIR}"
         DEPENDS ${lib_proj_files} ${lib_target_files} ${java_files}
         COMMENT "Building OpenCV Android library project"