Add experimental support for desktop Java

Based on pull request #31 (thanks to Eric Christiansen)
Support for Java is turned off by default and can be enabled setting
BUILD_opencv_java to ON (e.g. cmake -DBUILD_opencv_java=ON ..)

CMakeLists.txt

@@ -396,14 +396,16 @@ endif(BUILD_DOCS)
 include(cmake/OpenCVDetectPython.cmake)
 
 # --- Java Support ---
+include(cmake/OpenCVDetectApacheAnt.cmake)
 if(ANDROID)
-  include(cmake/OpenCVDetectApacheAnt.cmake)
   include(cmake/OpenCVDetectAndroidSDK.cmake)
 
   if(NOT ANDROID_TOOLS_Pkg_Revision GREATER 13)
     message(WARNING "OpenCV requires Android SDK tools revision 14 or newer. Otherwise tests and samples will no be compiled.")
   endif()
-endif(ANDROID)
+elseif(ANT_EXECUTABLE)
+  find_package(JNI)
+endif()
 
 if(ANDROID AND ANDROID_EXECUTABLE AND ANT_EXECUTABLE AND (ANT_VERSION VERSION_GREATER 1.7) AND (ANDROID_TOOLS_Pkg_Revision GREATER 13))
   SET(CAN_BUILD_ANDROID_PROJECTS TRUE)

modules/java/CMakeLists.txt

 # ----------------------------------------------------------------------------
 #  CMake file for java support
 # ----------------------------------------------------------------------------
-if(NOT ANDROID OR NOT PYTHON_EXECUTABLE OR ANDROID_NATIVE_API_LEVEL LESS 8)
+if(IOS OR NOT PYTHON_EXECUTABLE OR NOT (JNI_FOUND OR (ANDROID AND ANDROID_NATIVE_API_LEVEL GREATER 7)))
   ocv_module_disable(java)
 endif()
 
+if(NOT ANDROID)
+  # disable java by default because java support on desktop is experimental
+  set(BUILD_opencv_java_INIT OFF)
+endif()
+
 set(the_description "The java bindings")
 ocv_add_module(java BINDINGS opencv_core opencv_imgproc OPTIONAL opencv_objdetect opencv_features2d opencv_video opencv_highgui opencv_ml opencv_calib3d opencv_photo opencv_nonfree opencv_contrib)
 ocv_module_include_directories("${CMAKE_CURRENT_SOURCE_DIR}/generator/src/cpp")
 
+if(NOT ANDROID)
+  include_directories(${JNI_INCLUDE_DIRS})
+endif()
+
 # get list of modules to wrap
 string(REPLACE "opencv_" "" OPENCV_JAVA_MODULES "${OPENCV_MODULE_${the_module}_REQ_DEPS};${OPENCV_MODULE_${the_module}_OPT_DEPS}")
 foreach(module ${OPENCV_JAVA_MODULES})
@@ -123,7 +132,12 @@ set(JNI_INSTALL_ROOT "sdk/native")
 
 # copy each documented header to the final destination
 set(java_files "")
-foreach(java_file ${documented_java_files} ${handwrittren_aidl_sources})
+set(source_java_files ${documented_java_files} ${handwrittren_aidl_sources})
+if(NOT ANDROID)
+  ocv_list_filterout(source_java_files "/(engine|android)\\\\+")
+endif()
+
+foreach(java_file ${source_java_files})
   get_filename_component(java_file_name "${java_file}" NAME)
   string(REPLACE "-jdoc.java" ".java" java_file_name "${java_file_name}")
   string(REPLACE "+" "/" java_file_name "${java_file_name}")
@@ -175,6 +189,7 @@ set_target_properties(${the_module} PROPERTIES
 
 install(TARGETS ${the_module} LIBRARY DESTINATION ${OPENCV_LIB_INSTALL_PATH} COMPONENT main)
 
+set(lib_target ${the_module}_library)
 if(ANDROID)
   target_link_libraries(${the_module} jnigraphics) # for Mat <=> Bitmap converters
 
@@ -223,8 +238,6 @@ if(ANDROID)
 
   # create Android library project in build folder
   if(ANDROID_EXECUTABLE)
-    set(lib_target ${the_module}_android_library)
-
     set(lib_target_files ${ANDROID_LIB_PROJECT_FILES})
     ocv_list_add_prefix(lib_target_files "${OpenCV_BINARY_DIR}/")
 
@@ -263,12 +276,26 @@ if(ANDROID)
     endif()
 
     add_custom_target(${lib_target} SOURCES ${lib_proj_files} ${lib_target_files} "${OpenCV_BINARY_DIR}/${ANDROID_MANIFEST_FILE}")
-
-    add_dependencies(${lib_target} ${api_target})
-    add_dependencies(${the_module} ${lib_target})
   endif()
+else(ANDROID)
+  configure_file("${CMAKE_CURRENT_SOURCE_DIR}/jar/build.xml" "${OpenCV_BINARY_DIR}/build.xml" IMMEDIATE @ONLY)
+  set(JAR_NAME opencv-${OPENCV_VERSION_MAJOR}.${OPENCV_VERSION_MINOR}.${OPENCV_VERSION_PATCH}.jar)
+
+  add_custom_command(
+    OUTPUT "${OpenCV_BINARY_DIR}/bin/${JAR_NAME}" "${OpenCV_BINARY_DIR}/bin/.${JAR_NAME}.dephelper"
+    COMMAND ${ANT_EXECUTABLE} -q -noinput -k jar
+    COMMAND ${CMAKE_COMMAND} -E touch "${OpenCV_BINARY_DIR}/bin/.${JAR_NAME}.dephelper"
+    WORKING_DIRECTORY "${OpenCV_BINARY_DIR}"
+    DEPENDS "${OpenCV_BINARY_DIR}/build.xml" ${java_files}
+    COMMENT "Generating ${JAR_NAME}"
+    )
+
+  add_custom_target(${lib_target} SOURCES "${OpenCV_BINARY_DIR}/bin/${JAR_NAME}")
 endif(ANDROID)
 
+add_dependencies(${lib_target} ${api_target})
+add_dependencies(${the_module} ${lib_target})
+
 #android test project
 if(ANDROID AND BUILD_TESTS)
   add_subdirectory(android_test)

modules/java/generator/gen_java.py

@@ -871,7 +871,7 @@ public class %(jc)s {
 
 #include "converters.h"
 
-#ifdef DEBUG
+#if defined DEBUG && defined ANDROID
 #include <android/log.h>
 #define MODULE_LOG_TAG "OpenCV.%(m)s"
 #define LOGD(...) ((void)__android_log_print(ANDROID_LOG_DEBUG, MODULE_LOG_TAG, __VA_ARGS__))

modules/java/generator/src/cpp/Mat.cpp

@@ -2,6 +2,8 @@
 
 #include "converters.h"
 
+#ifdef ANDROID
+
 #include <android/log.h>
 #define LOG_TAG "org.opencv.core.Mat"
 #define LOGE(...) ((void)__android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__))
@@ -11,6 +13,11 @@
 #define LOGD(...)
 #endif //DEBUG
 
+#else
+#define LOGE(...)
+#define LOGD(...)
+#endif
+
 #include "opencv2/core/core.hpp"
 
 using namespace cv;

modules/java/generator/src/cpp/utils.cpp

@@ -3,6 +3,8 @@
 #include "opencv2/core/core.hpp"
 #include "opencv2/imgproc/imgproc.hpp"
 
+#ifdef ANDROID
+
 #include <android/bitmap.h>
 
 #include <android/log.h>
@@ -165,3 +167,5 @@ JNIEXPORT void JNICALL Java_org_opencv_android_Utils_nMatToBitmap
 }
 
 } // extern "C"
+
+#endif //ANDROID
\ No newline at end of file

modules/java/jar/build.xml

+<!-- This is an Apache Ant build file. As part of the desktop java build -->
+<!-- process, this config is used to package the autogenerated .java -->
+<!-- interface files into OpenCV.jar -->
+<project name="OpenCV">
+  <target name="jar">
+    <!-- This is to make a jar with a source attachment, for e.g. easy -->
+    <!-- navigation in Eclipse. See this question: -->
+    <!-- http://stackoverflow.com/questions/3584968/ant-how-to-compile-jar-that-includes-source-attachment -->
+    <javac sourcepath="" srcdir="src" destdir="src" debug="on" includeantruntime="false" >
+      <include name="**/*.java"/>
+    </javac>
+
+    <jar basedir="src" destfile="bin/opencv-@OPENCV_VERSION_MAJOR@.@OPENCV_VERSION_MINOR@.@OPENCV_VERSION_PATCH@.jar"/>
+  </target>
+</project>
\ No newline at end of file