I need to use the protobuf library in the c++ code of android ndk. In other words, let my auto-generated something.pb.h be happy when it wants to include files like #include <google/protobuf/port_def.inc>.
I do see some methods, but they all use the old Android.mk approach, while I need to use the new CMakeLists.txt approach (and there is completely no such thing as Android.mk in my project).
Therefore, what should I do? Thanks for any suggestions!
What I have tried:
Firstly brew install protobuf. Then, in CMakelists.txt
SET(PROTOBUF_INCLUDE_DIR "/usr/local/include/")
# have also tried this: find_package(Protobuf REQUIRED)
# have also tried this: find_package(protobuf CONFIG REQUIRED)
find_package(protobuf REQUIRED)
message(STATUS "Using Protocol Buffers ${Protobuf_VERSION}")
target_link_libraries(vision_utils
${PROTOBUF_LIBRARIES}
# have also tried this: protobuf::libprotobuf
)
but various errors with different attempts above:
CMake Error at CMakeLists.txt:25 (find_package):
Could not find a package configuration file provided by "protobuf" with any
of the following names:
or
CMake Error at CMakeLists.txt:107 (add_library):
Target "vision_utils" links to target "protobuf::libprotobuf" but the
target was not found. Perhaps a find_package() call is missing for an
IMPORTED target, or an ALIAS target is missing?
Try generating protobuf buildfiles manually with
cmake -G "MinGW Makefiles" \
-DCMAKE_TOOLCHAIN_FILE={NDK PATH}/build/cmake/android.toolchain.cmake \
-DCMAKE_MAKE_PROGRAM={NDK PATH}/prebuilt/{YOUR PLATFORM}/bin/make \
-Dprotobuf_BUILD_TESTS=OFF \
{PROTOBUF SOURCE PATH}/cmake
build
cmake --build . --target libprotobuf
then in CMakeLists.txt set
set(Protobuf_INCLUDE_DIR {{PROTOBUF SOURCE PATH}/src})
set(Protobuf_LIBRARIES {build files path})
Got this solution from here
Related
I use Qt Creator to compile an Android application. I needed to integrate OpenCV into it, and it took me half a day to configure it properly, so I want to document the steps I took here, in case somebody else ever has to do it.
Edit: For OpenCV 4.x see the answers below. My answer was tested on OpenCV 2.4 only.
Original answer:
First, I downloaded OpenCV-2.4.10-android-sdk, and put into my project directory. It contains static libraries, and link order matters for static libraries for GCC. So you need to order them just so. This is how my .pro file looked in the end ($$_PRO_FILE_PWD_ refers to the project directory):
INCLUDEPATH += "$$_PRO_FILE_PWD_/OpenCV-2.4.10-android-sdk/sdk/native/jni/include"
android {
LIBS += \
-L"$$_PRO_FILE_PWD_/OpenCV-2.4.10-android-sdk/sdk/native/3rdparty/libs/armeabi-v7a"\
-L"$$_PRO_FILE_PWD_/OpenCV-2.4.10-android-sdk/sdk/native/libs/armeabi-v7a"\
-llibtiff\
-llibjpeg\
-llibjasper\
-llibpng\
-lIlmImf\
-ltbb\
-lopencv_core\
-lopencv_androidcamera\
-lopencv_flann\
-lopencv_imgproc\
-lopencv_highgui\
-lopencv_features2d\
-lopencv_calib3d\
-lopencv_ml\
-lopencv_objdetect\
-lopencv_video\
-lopencv_contrib\
-lopencv_photo\
-lopencv_java\
-lopencv_legacy\
-lopencv_ocl\
-lopencv_stitching\
-lopencv_superres\
-lopencv_ts\
-lopencv_videostab
ANDROID_PACKAGE_SOURCE_DIR=$$_PRO_FILE_PWD_/android
}
After that the project will compile but it will fail to run with the error
E/AndroidRuntime(11873): java.lang.UnsatisfiedLinkError: Cannot load library: link_image[1891]: 176 could not load needed library 'libopencv_java.so' for 'libMyProject.so' (load_library[1093]: Library 'libopencv_java.so' not found)
To overcome this, you need to add libopencv_java.so to your APK, and then manually load it from QtActivity.java. That's what the ANDROID_PACKAGE_SOURCE_DIR=$$_PRO_FILE_PWD_/android line at the end was for. Now you need to place libopencv_java.so here:
project_root/android/libs/armeabi-v7a/libopencv_java.so
project_root/android/src/org/qtproject/qt5/android/bindings/QtActivity.java
You can get QtActivity.java from the Android target build directory, in my case the full path was c:\Workspace\build-MyProject-Android_for_armeabi_v7a_GCC_4_9_Qt_5_4_0-Debug\android-build\src\org\qtproject\qt5\android\bindings\QtActivity.java, and just copy it.
Then you find those lines in it:
// now load the application library so it's accessible from this class loader
if (libName != null)
System.loadLibrary(libName);
And load libopencv_java.so before them, so they become:
// This is needed for OpenCV!!!
System.loadLibrary("opencv_java");
// now load the application library so it's accessible from this class loader
if (libName != null)
System.loadLibrary(libName);
Note that you pass opencv_java to System.loadLibrary(), even though the file is libopencv_java.so.
Edit: I forgot to mention, but I already had installed OpenCV Manager on my phone when trying to run one of the samples that come with OpenCV-2.4.10-android-sdk, so I don't know if it's needed or not. In any event, keep it in mind, if it fail even after my steps, you might need to download OpenCV Manager (it's available on the Google Store).
Edit 2: I'm using adt-bundle-windows-x86-20140702, android-ndk-r10d, OpenCV-2.4.10-android-sdk, Qt Creator 3.3.0, and my build target is "Android for armeabi-v7a (GCC 4.9, Qt 5.4.0)".
Edit 3: From Daniel Saner's comment:
In OpenCV 3.x, opencv_java has been renamed to opencv_java3. Also, while I didn't look into the specific changes that might have effected this, the workaround regarding that library in the final step seems to no longer be necessary. The app compiles and runs without the ANDROID_PACKAGE_SOURCE_DIR line
Edit 4: #myk's comment:
Worked for me with OpenCV 3.2. To workaround the build issues with carotene finish the LIBS+ section with: -lopencv_videostab\ -ltegra_hal\ – myk 2 hours ago
For OpenCV 4, sashoalm's approach did not work for me until I adapted it:
Download the Android-Pack and unzip it somewhere. We'll create a qmake-variable OPENCV_ANDROID which points to that directory later.
Add the following snippet to your *.pro-file:
android {
contains(ANDROID_TARGET_ARCH,arm64-v8a) {
isEmpty(OPENCV_ANDROID) {
error("Let OPENCV_ANDROID point to the opencv-android-sdk, recommended: v4.0")
}
INCLUDEPATH += "$$OPENCV_ANDROID/sdk/native/jni/include"
LIBS += \
-L"$$OPENCV_ANDROID/sdk/native/libs/arm64-v8a" \
-L"$$OPENCV_ANDROID/sdk/native/3rdparty/libs/arm64-v8a" \
-llibtiff \
-llibjpeg-turbo \
-llibjasper \
-llibpng \
-lIlmImf \
-ltbb \
-lopencv_java4 \
ANDROID_EXTRA_LIBS = $$OPENCV_ANDROID/sdk/native/libs/arm64-v8a/libopencv_java4.so
} else {
error("Unsupported architecture: $$ANDROID_TARGET_ARCH")
}
}
This will work for the arm64-v8a only. If you happen to build for another architecture (apparently 32-Bit is still the default for Qt#Android), you must change the .../libs/arm64-v8a part of the paths (occurs 3 times) and the same to match your actual target-architecture (the contains(...)-part in the second line of the snippet).
Tell qmake where to find the SDK. Add the following to qmake-call: "OPENCV_ANDROID=/path/to/OpenCV-android-sdk".
e.g., this looks like qmake example.pro "OPENCV_ANDROID=/home/user/OpenCV-android-sdk" from command line.
when you use QtCreator, add "OPENCV_ANDROID=..." to the "Additional arguments"-field. You can find it after enabling the Project-Mode in the Build-section of the android-kit. Expand the qmake-field under Build Steps
Starting from Android android-ndk-r18b, with Qt Creator 4.9.x kits, I could not use the openCV-4.1.1 pre-compiled shared libraries (.so) with Qt Android ABI armeabi-v7a target and ABI arm64-v8a, as Opencv standard is based on GCC, While the NDK-r18b removed gcc and uses clang compiler. ( I am getting
Fatal signal 11 (SIGSEGV), code 1
On initialize calling android_getCpuFeatures() when the application starts)
Thus, openCV shared libs must be compiled from sources for clang in order to be used with Qt Android kits.
This reference Compiling OpenCV on Android from C++ (Without OpenCVManager) was of real help. I would leave a reference here as well for a simple procedure I used under windows 10, to get opencv compiled with NDK 18 (clang) for Qt Android:
Downloaded openCV source code
Downloaded openCV contrib source for selected openCV version
Used cmake for windows
in the unzipped opencv source folder, created a new build folder.
MinGW from Qt installation can generally be used for building, So I used Qt 5.11.x (MinGW 5.3.0 32 bit) command line tool from Qt menu.
from command line, in new build folder, I could generate cmake configuration :
C:\opencv-4.1.1\build> "C:\program files\cmake\bin\cmake" .. -G"MinGW Makefiles"
-DBUILD_SHARED_LIBS=ON
-DANDROID_STL=c++_shared
-DANDROID_ABI="armeabi-v7a with NEON"
-DANDROID_NATIVE_API_LEVEL=23
-DANDROID_TOOLCHAIN=clang
-DCMAKE_TOOLCHAIN_FILE=D:\Qt\android-ndk-r18b\build\cmake\android.toolchain.cmake
-DANDROID_NDK=D:\Qt\android-ndk-r18b
-DANDROID_SDK=C:\Users\moham\AppData\Local\Android\sdk
-DCMAKE_BUILD_TYPE=Debug
-DBUILD_ANDROID_PROJECTS=OFF
-DWITH_OPENCL=ON -DWITH_TBB=ON -DENABLE_NEON=ON
-DBUILD_TESTS=OFF -DBUILD_PERF_TESTS=OFF
-DBUILD_FAT_JAVA_LIB=OFF
Then , C:\opencv-4.1.1\build>\mingw32-make -jx and C:\opencv-4.1.1\build>\mingw32-make install
the result libs can be picked from opencv-4.1.1\build\install folder
Link in Qt Android project:
android {
#opencv
OPENCVLIBS = $$PWD/../opencv-4.1.1\build\install/sdk/native
INCLUDEPATH = $$OPENCVLIBS/jni/include
contains(ANDROID_TARGET_ARCH,armeabi-v7a) {
# might need libs to be copied into app's library folder and loaded on start-up, in case android ships older libs??!
ANDROID_EXTRA_LIBS = \
$$OPENCVLIBS/libs/armeabi-v7a/libopencv_core.so \
$$OPENCVLIBS/libs/armeabi-v7a/libopencv_imgproc.so \
$$OPENCVLIBS/libs/armeabi-v7a/libtbb.so
LIBS += -L"$$OPENCVLIBS/libs/armeabi-v7a"\
-lopencv_core -lopencv_imgproc -ltbb
}
ANDROID_PACKAGE_SOURCE_DIR = $$PWD/android
}
Also, copy the libs to ANDROID_PACKAGE_SOURCE_DIR
Note: If detailed control over cmake configuration is needed, cmake windows gui can be used, while not a must and not tested. AmMIN's procedure is helpful for cmake tool, remember to add flag for shared Android STL.
I've spent a day on this and can't seem to configure my dev environment for a NDK toolchain that will support standard C++ libraries. The story is I'm trying to cross compile libnfnetlink and libnetfilter_queue for ARM (Android).
First I'm using the following:
Nexus 5 with CyanogenMod 11 (I forget, doesn't matter I'm not even on the device yet)
Ubuntu 12.04 32-bit
Android SDK bundle: adt-bundle-linux-x86-20140702
Android NDK: android-ndk-r10c
There is a great blog on doing this here but its incomplete as Netfilter uses stlc++ and there's no word on a NDK install/setup that would work with simply calling ndk-build. Just copying the files into /jni and calling ndk-build won't work alone.
Anyways, my specific problem is when I straight copy the Netfilter lib source structure into an empty Project's /jni directory, I get this:
user#ubuntu:~/Projects/NetfilterTest/NetfilterNativeTest/jni$ ndk-build
[armeabi] Compile thumb : netfilter_queue <= libnetfilter_queue.c
In file included from /home/user/Projects/NetfilterTest/NetfilterNativeTest/jni/libnetfilter_queue/src/libnetfilter_queue.c:35:0:
/home/user/Projects/NetfilterTest/NetfilterNativeTest/jni/libnetfilter_queue/src/internal.h:4:20: fatal error: config.h: No such file or directory
compilation terminated.
make: *** [/home/user/Projects/NetfilterTest/NetfilterNativeTest/obj/local/armeabi/objs/netfilter_queue/libnetfilter_queue/src/libnetfilter_queue.o] Error 1
The config.h file can't be found. After some googling I realize its because the standard C++ libraries aren't available in the prebuilt tool chains.
Everything points to me creating my own tool chain. So I build my own cross compiler using the scripts that the NDK includes.
cd /home/user/android-ndk-r10c/build/tools
./make-standalone-toolchain.sh --platform=android-19 --ndk-dir=/home/user/android-ndk-r10c/ --install-dir=/home/user/android-ndk-r10c/prebuilt/android-arm/android-19
To confirm that config.h is included in my tool chain I searched for it. It's there:
user#ubuntu:~/Projects/NetfilterTest/NetfilterNativeTest/jni$ find /home/user/android-ndk-r10c/prebuilt/android-arm/android-19/ -iname config.h
/home/user/android-ndk-r10c/prebuilt/android-arm/android-19/sysroot/usr/include/linux/config.h
Naturally I need to setup my environment and the Android.mk
JAVA_HOME=/usr/local/java/jdk1.6.0_45
JRE_HOME=$JAVA_HOME/jre
ANDROID_SDK=/home/user/adt-bundle-linux-x86-20140702
ANDROID_NDK=/home/user/android-ndk-r10c
ANDROID_CHAIN=/home/user/android-ndk-r10c/prebuilt/android-arm/android-19
PATH=$PATH:$JAVA_HOME/bin:$JRE_HOME/bin:$ANDROID_SDK/sdk/platform-tools:$ANDROID_SDK/sdk/tools:$ANDROID_NDK:$ANDROID_CHAIN/bin
SYSROOT=$ANDROID_NDK/platforms/android-19/arch-arm
CC=arm-linux-androideabi-gcc
export CC
export ANDROID_SDK
export ANDROID_NDK
export SYSROOT
export JAVA_HOME
export JRE_HOME
export PATH
Here's my Android.mk (based on Roman10's blog:
LOCAL_PATH:=$(call my-dir)
#####################################################################
# build libnflink #
#####################################################################
include $(CLEAR_VARS)
LOCAL_MODULE:=nflink
LOCAL_C_INCLUDES:= $(LOCAL_PATH)/libnfnetlink/include
LOCAL_SRC_FILES:=\
libnfnetlink/src/iftable.c \
libnfnetlink/src/rtnl.c \
libnfnetlink/src/libnfnetlink.c
include $(BUILD_STATIC_LIBRARY)
#####################################################################
# build libnetfilter_queue #
#####################################################################
include $(CLEAR_VARS)
LOCAL_C_INCLUDES := $(LOCAL_PATH)/libnfnetlink/include \
$(LOCAL_PATH)/libnetfilter_queue/include
LOCAL_MODULE:=netfilter_queue
LOCAL_SRC_FILES:=libnetfilter_queue/src/libnetfilter_queue.c
LOCAL_STATIC_LIBRARIES:=libnflink
include $(BUILD_STATIC_LIBRARY)
#####################################################################
# build our code #
#####################################################################
include $(CLEAR_VARS)
LOCAL_C_INCLUDES := $(LOCAL_PATH)/libnfnetlink/include \
$(LOCAL_PATH)/libnetfilter_queue/include
LOCAL_MODULE:=nfqnltest
#LOCAL_LDLIBS:=-lstdc++
LOCAL_SRC_FILES:=nfqnl_test.c
LOCAL_STATIC_LIBRARIES:=libnetfilter_queue
LOCAL_LDLIBS:=-llog -lm
include $(BUILD_EXECUTABLE)
I still get config.h not found using ndk-build.
I've read that the ndk-build command leverages a config.mk/setup.mk that Google includes in the NDK and has to be modified to point to an alternative toolchain.
I'm completely floored that Google's own tools can't simply point to a custom toolchain that they give you scripts to create. If anyone has any suggestions on how I can use my toolchain to compile Netfilter or just in general it would be a great help.
Thanks in advance!
I can't find any reference to either internal.h or config.h when I search for a version of libnetfilter_queue.c on the web, so I'm not sure what version of the file you're using - can you point to which one you have?
Also, the config.h it looks for isn't the one you found in your toolchain (which should be included as linux/config.h) but most probably is one that you're expected to generate by running a configure script. So unless you've run the configure script (or have a pregenerated config.h from elsewhere) you can't really build it.
Finally, nothing of this has anything to do with libstdc++ since all your source files seem to be pure C, not C++.
I use Qt Creator to compile an Android application. I needed to integrate OpenCV into it, and it took me half a day to configure it properly, so I want to document the steps I took here, in case somebody else ever has to do it.
Edit: For OpenCV 4.x see the answers below. My answer was tested on OpenCV 2.4 only.
Original answer:
First, I downloaded OpenCV-2.4.10-android-sdk, and put into my project directory. It contains static libraries, and link order matters for static libraries for GCC. So you need to order them just so. This is how my .pro file looked in the end ($$_PRO_FILE_PWD_ refers to the project directory):
INCLUDEPATH += "$$_PRO_FILE_PWD_/OpenCV-2.4.10-android-sdk/sdk/native/jni/include"
android {
LIBS += \
-L"$$_PRO_FILE_PWD_/OpenCV-2.4.10-android-sdk/sdk/native/3rdparty/libs/armeabi-v7a"\
-L"$$_PRO_FILE_PWD_/OpenCV-2.4.10-android-sdk/sdk/native/libs/armeabi-v7a"\
-llibtiff\
-llibjpeg\
-llibjasper\
-llibpng\
-lIlmImf\
-ltbb\
-lopencv_core\
-lopencv_androidcamera\
-lopencv_flann\
-lopencv_imgproc\
-lopencv_highgui\
-lopencv_features2d\
-lopencv_calib3d\
-lopencv_ml\
-lopencv_objdetect\
-lopencv_video\
-lopencv_contrib\
-lopencv_photo\
-lopencv_java\
-lopencv_legacy\
-lopencv_ocl\
-lopencv_stitching\
-lopencv_superres\
-lopencv_ts\
-lopencv_videostab
ANDROID_PACKAGE_SOURCE_DIR=$$_PRO_FILE_PWD_/android
}
After that the project will compile but it will fail to run with the error
E/AndroidRuntime(11873): java.lang.UnsatisfiedLinkError: Cannot load library: link_image[1891]: 176 could not load needed library 'libopencv_java.so' for 'libMyProject.so' (load_library[1093]: Library 'libopencv_java.so' not found)
To overcome this, you need to add libopencv_java.so to your APK, and then manually load it from QtActivity.java. That's what the ANDROID_PACKAGE_SOURCE_DIR=$$_PRO_FILE_PWD_/android line at the end was for. Now you need to place libopencv_java.so here:
project_root/android/libs/armeabi-v7a/libopencv_java.so
project_root/android/src/org/qtproject/qt5/android/bindings/QtActivity.java
You can get QtActivity.java from the Android target build directory, in my case the full path was c:\Workspace\build-MyProject-Android_for_armeabi_v7a_GCC_4_9_Qt_5_4_0-Debug\android-build\src\org\qtproject\qt5\android\bindings\QtActivity.java, and just copy it.
Then you find those lines in it:
// now load the application library so it's accessible from this class loader
if (libName != null)
System.loadLibrary(libName);
And load libopencv_java.so before them, so they become:
// This is needed for OpenCV!!!
System.loadLibrary("opencv_java");
// now load the application library so it's accessible from this class loader
if (libName != null)
System.loadLibrary(libName);
Note that you pass opencv_java to System.loadLibrary(), even though the file is libopencv_java.so.
Edit: I forgot to mention, but I already had installed OpenCV Manager on my phone when trying to run one of the samples that come with OpenCV-2.4.10-android-sdk, so I don't know if it's needed or not. In any event, keep it in mind, if it fail even after my steps, you might need to download OpenCV Manager (it's available on the Google Store).
Edit 2: I'm using adt-bundle-windows-x86-20140702, android-ndk-r10d, OpenCV-2.4.10-android-sdk, Qt Creator 3.3.0, and my build target is "Android for armeabi-v7a (GCC 4.9, Qt 5.4.0)".
Edit 3: From Daniel Saner's comment:
In OpenCV 3.x, opencv_java has been renamed to opencv_java3. Also, while I didn't look into the specific changes that might have effected this, the workaround regarding that library in the final step seems to no longer be necessary. The app compiles and runs without the ANDROID_PACKAGE_SOURCE_DIR line
Edit 4: #myk's comment:
Worked for me with OpenCV 3.2. To workaround the build issues with carotene finish the LIBS+ section with: -lopencv_videostab\ -ltegra_hal\ – myk 2 hours ago
For OpenCV 4, sashoalm's approach did not work for me until I adapted it:
Download the Android-Pack and unzip it somewhere. We'll create a qmake-variable OPENCV_ANDROID which points to that directory later.
Add the following snippet to your *.pro-file:
android {
contains(ANDROID_TARGET_ARCH,arm64-v8a) {
isEmpty(OPENCV_ANDROID) {
error("Let OPENCV_ANDROID point to the opencv-android-sdk, recommended: v4.0")
}
INCLUDEPATH += "$$OPENCV_ANDROID/sdk/native/jni/include"
LIBS += \
-L"$$OPENCV_ANDROID/sdk/native/libs/arm64-v8a" \
-L"$$OPENCV_ANDROID/sdk/native/3rdparty/libs/arm64-v8a" \
-llibtiff \
-llibjpeg-turbo \
-llibjasper \
-llibpng \
-lIlmImf \
-ltbb \
-lopencv_java4 \
ANDROID_EXTRA_LIBS = $$OPENCV_ANDROID/sdk/native/libs/arm64-v8a/libopencv_java4.so
} else {
error("Unsupported architecture: $$ANDROID_TARGET_ARCH")
}
}
This will work for the arm64-v8a only. If you happen to build for another architecture (apparently 32-Bit is still the default for Qt#Android), you must change the .../libs/arm64-v8a part of the paths (occurs 3 times) and the same to match your actual target-architecture (the contains(...)-part in the second line of the snippet).
Tell qmake where to find the SDK. Add the following to qmake-call: "OPENCV_ANDROID=/path/to/OpenCV-android-sdk".
e.g., this looks like qmake example.pro "OPENCV_ANDROID=/home/user/OpenCV-android-sdk" from command line.
when you use QtCreator, add "OPENCV_ANDROID=..." to the "Additional arguments"-field. You can find it after enabling the Project-Mode in the Build-section of the android-kit. Expand the qmake-field under Build Steps
Starting from Android android-ndk-r18b, with Qt Creator 4.9.x kits, I could not use the openCV-4.1.1 pre-compiled shared libraries (.so) with Qt Android ABI armeabi-v7a target and ABI arm64-v8a, as Opencv standard is based on GCC, While the NDK-r18b removed gcc and uses clang compiler. ( I am getting
Fatal signal 11 (SIGSEGV), code 1
On initialize calling android_getCpuFeatures() when the application starts)
Thus, openCV shared libs must be compiled from sources for clang in order to be used with Qt Android kits.
This reference Compiling OpenCV on Android from C++ (Without OpenCVManager) was of real help. I would leave a reference here as well for a simple procedure I used under windows 10, to get opencv compiled with NDK 18 (clang) for Qt Android:
Downloaded openCV source code
Downloaded openCV contrib source for selected openCV version
Used cmake for windows
in the unzipped opencv source folder, created a new build folder.
MinGW from Qt installation can generally be used for building, So I used Qt 5.11.x (MinGW 5.3.0 32 bit) command line tool from Qt menu.
from command line, in new build folder, I could generate cmake configuration :
C:\opencv-4.1.1\build> "C:\program files\cmake\bin\cmake" .. -G"MinGW Makefiles"
-DBUILD_SHARED_LIBS=ON
-DANDROID_STL=c++_shared
-DANDROID_ABI="armeabi-v7a with NEON"
-DANDROID_NATIVE_API_LEVEL=23
-DANDROID_TOOLCHAIN=clang
-DCMAKE_TOOLCHAIN_FILE=D:\Qt\android-ndk-r18b\build\cmake\android.toolchain.cmake
-DANDROID_NDK=D:\Qt\android-ndk-r18b
-DANDROID_SDK=C:\Users\moham\AppData\Local\Android\sdk
-DCMAKE_BUILD_TYPE=Debug
-DBUILD_ANDROID_PROJECTS=OFF
-DWITH_OPENCL=ON -DWITH_TBB=ON -DENABLE_NEON=ON
-DBUILD_TESTS=OFF -DBUILD_PERF_TESTS=OFF
-DBUILD_FAT_JAVA_LIB=OFF
Then , C:\opencv-4.1.1\build>\mingw32-make -jx and C:\opencv-4.1.1\build>\mingw32-make install
the result libs can be picked from opencv-4.1.1\build\install folder
Link in Qt Android project:
android {
#opencv
OPENCVLIBS = $$PWD/../opencv-4.1.1\build\install/sdk/native
INCLUDEPATH = $$OPENCVLIBS/jni/include
contains(ANDROID_TARGET_ARCH,armeabi-v7a) {
# might need libs to be copied into app's library folder and loaded on start-up, in case android ships older libs??!
ANDROID_EXTRA_LIBS = \
$$OPENCVLIBS/libs/armeabi-v7a/libopencv_core.so \
$$OPENCVLIBS/libs/armeabi-v7a/libopencv_imgproc.so \
$$OPENCVLIBS/libs/armeabi-v7a/libtbb.so
LIBS += -L"$$OPENCVLIBS/libs/armeabi-v7a"\
-lopencv_core -lopencv_imgproc -ltbb
}
ANDROID_PACKAGE_SOURCE_DIR = $$PWD/android
}
Also, copy the libs to ANDROID_PACKAGE_SOURCE_DIR
Note: If detailed control over cmake configuration is needed, cmake windows gui can be used, while not a must and not tested. AmMIN's procedure is helpful for cmake tool, remember to add flag for shared Android STL.
I've been trying for a couple days to compile a native ARM Android binary that will execute on my phone using a terminal application. I want to generate the same type of binary as the standard Posix binaries installed on the phone like ls, mkdir etc. I've downloaded the Android NDK under Mac OS X and have been able to compile simple ELF binaries without errors. However, when I transfer them to the phone, they always segfault. That is, they segfault when compiled with -static in GCC. If I don't use -static, they complain about not being linked, etc. Put simply, they don't work.
My hypothesis is that they are not linking to the Android standard C library properly. Even though I am linking my binaries with the libc provided by the NDK, they still don't work. I read that Android uses the Bionic C library, and tried to download source for it but I'm not sure how to build a library from it (it's all ARM assembly, it seems).
Is it true that the Android C library on the phone is different from the one provided with the Android NDK? Will the one included with the NDK not allow me to compile native binaries I can execute through a terminal? Any guidance here is greatly appreciated!
Update:
I finally got this to work using GCC 4.7.0 on Mac OS X. I downloaded the Bionic headers and then compiled a dynamically linked binary using the C library that comes with the Android NDK. I was able to get a test app to work on the phone using the phone's C lib (the binary was 33K). I also tried to statically link against the NDK's C library, and that also worked.
In order to get this all working I had to pass -nostdlib to GCC and then manually add crtbegin_dynamic.o and crtend_android.o to GCC's command line. It works something like this:
$CC \
$NDK_PATH/usr/lib/crtbegin_dynamic.o \
hello.c -o hello \
$CFLAGS \
$NDK_PATH/usr/lib/crtend_android.o
For static binaries, use "crtbegin_static.o." This is explained in the crtbegin_dynamic.S/crtbegin_static.S source.
For this experiment, I only used plain 'ol GCC 4.7.0 and Binutils 2.22. I also compiled GCC with newlib, but I am not actually linking my ARM binaries with newlib at all. I am forcing GCC/ld to link directly to the libc provided with the Android NDK, or in the case of dynamic binaries, to the libc on the phone.
Just use the android-ndk. And build a Android.mk like so.
include $(BUILD_EXECUTABLE) is what tells it build a executable instead of a JNI .lib
Android.mk
ifneq ($(TARGET_SIMULATOR),true)
LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)
LOCAL_CFLAGS += -Wall
LOCAL_LDLIBS := -L$(LOCAL_PATH)/lib -llog -g
LOCAL_C_INCLUDES := bionic
LOCAL_C_INCLUDES += $(LOCAL_PATH)/include
LOCAL_SRC_FILES:= main.cpp
LOCAL_MODULE := mycmd
include $(BUILD_EXECUTABLE)
endif # TARGET_SIMULATOR != true
First, make sure you have the NDK:
http://developer.android.com/tools/sdk/ndk/index.html
Here is the easiest way to compile a C binary for your phone:
http://developer.android.com/tools/sdk/ndk/index.html
http://www.kandroid.org/ndk/docs/STANDALONE-TOOLCHAIN.html
Usually $NDK(may be different) =
Linux:
/home/<user>/android-ndk
Mac OS X:
/Users/<user>/android-ndk
In Terminal:
# create tool-chain - one line
# New method in ndk 12.
$NDK/build/tools/make_standalone_toolchain.py --arch arm --install-dir=/tmp/my-android-toolchain
# Old method.
#$NDK/build/tools/make-standalone-toolchain.sh --platform=android-3 --install-dir=/tmp/my-android-toolchain
# add to terminal PATH variable
export PATH=/tmp/my-android-toolchain/bin:$PATH
# make alias CC be the new gcc binary
export CC=arm-linux-androideabi-gcc
# compile your C code(I tried hello world)
$CC -o foo.o -c foo.c
# push binary to phone
adb push foo.o /data/local/tmp
# execute binary
adb /data/local/tmp/foo.o
Using CMake with the Android NDK is a nice way to compile Android console applications.
Download CMake and android-cmake (set it up like this). If your program is called main.c, then write the following in file CMakeLists.txt:
project(test)
cmake_minimum_required(VERSION 2.8)
add_executable(test ./main.c)
and run cmake -DCMAKE_TOOLCHAIN_FILE=$ANDTOOLCHAIN .
You will then have a Makefile for your program, you can run make to have your test executable.
In CMake, you can cross build using toolchain files.
From google developers:
cmake \
-DCMAKE_TOOLCHAIN_FILE=$NDK/build/cmake/android.toolchain.cmake \
-DANDROID_ABI=$ABI \
-DANDROID_PLATFORM=android-$MINSDKVERSION \
$OTHER_ARGS
CMake has its own built-in NDK support. Before CMake 3.21, this workflow is not supported by Android and is often broken with new NDK releases. Starting from CMake 3.21, the implementations are merged.
Starting from cmake 3.21 you can:
mkdir build
cd build
cmake ..
-DCMAKE_SYSTEM_NAME=Android
-DCMAKE_SYSTEM_VERSION=23 # API level. optional, recommanded
-DCMAKE_ANDROID_NDK=path/to/ndk
-DCMAKE_ANDROID_ARCH=arm # optional, recommanded
-DCMAKE_ANDROID_ARCH_ABI=armeabi # optional, recommanded
Note: in the command above, line endings (<line feed>) are not escaped, please don't copy-paste this command directly in your shell
See Cross Compiling for Android with the NDK for more information about variables, possible values, and determenation algorithms.
Try if if the agcc wrapper can help you as referenced in the Android-tricks blog. According to the blog post you want to use the bionic library, but the one already installed on the phone, not some separately compiled version.
I am developing an Android app on windows, using eclipse.
I would like to use OpenSSL for my Android application. It needs to be used with C++ via NDK.
I tried to download fries' OpenSSL source code from https://github.com/fries/android-external-openssl and build it.
I read the README.android file, but I didn't understand what these instructions are for.
Do I need to download the OpenSSL source code in addition to the fries source code?
I have tried putting all the files from Fries' into my jni folder of the Android project. It complained about not finding e_os.h and openssl/crypto.h and others like that.
More specifically:
In file included from D:/Projects/Fatal/Android/OpenSSL/jni/ssl/s2_meth.c:59:
D:/Projects/Fatal/Android/OpenSSL/jni/ssl/ssl_locl.h:124:18: error: e_os.h: No such file or directory
D:/Projects/Fatal/Android/OpenSSL/jni/ssl/ssl_locl.h:126:28: error: openssl/buffer.h: No such file or directory
D:/Projects/Fatal/Android/OpenSSL/jni/ssl/ssl_locl.h:127:26: error: openssl/comp.h: No such file or directory
I am not sure why it doesn't find those files, I tried to add all sort of paths into LOCAL_C_INCLUDES in all sort of Android.mk files, but nothing worked.
I would like to know how to build OpenSSL for Android. Thank you.
I know this is old, but I kept coming across this when I was searching for this problem. In the case that you are building a standalone OpenSSL to go with your project and are getting this error, I found a solution as per this thread:
In openssl-android/crypto, openssl-android/ssl, and openssl-android/apps, you'll find a variable declaration for local_c_includes that is something like this:
local_c_includes := \
$(NDK_PROJECT_PATH) \
$(NDK_PROJECT_PATH)/crypto/asn1 \
$(NDK_PROJECT_PATH)/crypto/evp \
$(NDK_PROJECT_PATH)/include \
$(NDK_PROJECT_PATH)/include/openssl
If you've placed your openssl-android directory in your Android project in the project/jni directory, then these variables no longer point to the correct location. The way I solved it was to modify these paths to be relative to LOCAL_PATH:
local_c_includes := \
$(LOCAL_PATH)/.. \
$(LOCAL_PATH)/asn1 \
$(LOCAL_PATH)/evp \
$(LOCAL_PATH)/../include \
$(LOCAL_PATH)/../include/openssl
Remember, you'll have to do this for each of the directories you're trying to build (crypto, ssl, or apps).
I realized that the fries' github is just something to patch the source of OpenSSL, it's not a stand alone OpenSSL for android.
It is required because it provide Android.mk files which are required by ndk-build of ndk. You don't want to build it using standard gcc because you want to build it for Android.