在 Android NDK 中编译 OpenCV

Question

请查看底部的添加内容！第一个问题在Linux下解决了，在Windows和Cygwin下还没有解决，但是又出现了一个新问题。请参阅下文！

我目前正在尝试为 Android NDK 编译 OpenCV，以便我可以在我的应用程序中使用它。为此，我尝试遵循本指南：

http://www.stanford.edu/~zxwang/ android_opencv.html

但是，当使用 ndk-build 编译下载的内容时，我收到此错误：

$ /cygdrive/u/flori/workspace/android-ndk-r5b/ndk-build
Compile++ thumb  : opencv <= cvjni.cpp
Compile++ thumb  : cxcore <= cxalloc.cpp
Compile++ thumb  : cxcore <= cxarithm.cpp
Compile++ thumb  : cxcore <= cxarray.cpp
Compile++ thumb  : cxcore <= cxcmp.cpp
Compile++ thumb  : cxcore <= cxconvert.cpp
Compile++ thumb  : cxcore <= cxcopy.cpp
Compile++ thumb  : cxcore <= cxdatastructs.cpp
Compile++ thumb  : cxcore <= cxdrawing.cpp
Compile++ thumb  : cxcore <= cxdxt.cpp
Compile++ thumb  : cxcore <= cxerror.cpp
Compile++ thumb  : cxcore <= cximage.cpp
Compile++ thumb  : cxcore <= cxjacobieigens.cpp
Compile++ thumb  : cxcore <= cxlogic.cpp
Compile++ thumb  : cxcore <= cxlut.cpp
Compile++ thumb  : cxcore <= cxmathfuncs.cpp
Compile++ thumb  : cxcore <= cxmatmul.cpp
Compile++ thumb  : cxcore <= cxmatrix.cpp
Compile++ thumb  : cxcore <= cxmean.cpp
Compile++ thumb  : cxcore <= cxmeansdv.cpp
Compile++ thumb  : cxcore <= cxminmaxloc.cpp
Compile++ thumb  : cxcore <= cxnorm.cpp
Compile++ thumb  : cxcore <= cxouttext.cpp
Compile++ thumb  : cxcore <= cxpersistence.cpp
Compile++ thumb  : cxcore <= cxprecomp.cpp
Compile++ thumb  : cxcore <= cxrand.cpp
Compile++ thumb  : cxcore <= cxsumpixels.cpp
Compile++ thumb  : cxcore <= cxsvd.cpp
Compile++ thumb  : cxcore <= cxswitcher.cpp
Compile++ thumb  : cxcore <= cxtables.cpp
Compile++ thumb  : cxcore <= cxutils.cpp
StaticLibrary  : libstdc++.a
StaticLibrary  : libcxcore.a
Compile++ thumb  : cv <= cvaccum.cpp
Compile++ thumb  : cv <= cvadapthresh.cpp
Compile++ thumb  : cv <= cvapprox.cpp
Compile++ thumb  : cv <= cvcalccontrasthistogram.cpp
Compile++ thumb  : cv <= cvcalcimagehomography.cpp
Compile++ thumb  : cv <= cvcalibinit.cpp
Compile++ thumb  : cv <= cvcalibration.cpp
Compile++ thumb  : cv <= cvcamshift.cpp
Compile++ thumb  : cv <= cvcanny.cpp
Compile++ thumb  : cv <= cvcolor.cpp
Compile++ thumb  : cv <= cvcondens.cpp
Compile++ thumb  : cv <= cvcontours.cpp
Compile++ thumb  : cv <= cvcontourtree.cpp
Compile++ thumb  : cv <= cvconvhull.cpp
Compile++ thumb  : cv <= cvcorner.cpp
Compile++ thumb  : cv <= cvcornersubpix.cpp
Compile++ thumb  : cv <= cvderiv.cpp
Compile++ thumb  : cv <= cvdistransform.cpp
Compile++ thumb  : cv <= cvdominants.cpp
Compile++ thumb  : cv <= cvemd.cpp
Compile++ thumb  : cv <= cvfeatureselect.cpp
Compile++ thumb  : cv <= cvfilter.cpp
Compile++ thumb  : cv <= cvfloodfill.cpp
Compile++ thumb  : cv <= cvfundam.cpp
Compile++ thumb  : cv <= cvgeometry.cpp
Compile++ thumb  : cv <= cvhaar.cpp
Compile++ thumb  : cv <= cvhistogram.cpp
Compile++ thumb  : cv <= cvhough.cpp
Compile++ thumb  : cv <= cvimgwarp.cpp
Compile++ thumb  : cv <= cvinpaint.cpp
Compile++ thumb  : cv <= cvkalman.cpp
Compile++ thumb  : cv <= cvlinefit.cpp
Compile++ thumb  : cv <= cvlkpyramid.cpp
Compile++ thumb  : cv <= cvmatchcontours.cpp
Compile++ thumb  : cv <= cvmoments.cpp
Compile++ thumb  : cv <= cvmorph.cpp
Compile++ thumb  : cv <= cvmotempl.cpp
Compile++ thumb  : cv <= cvoptflowbm.cpp
Compile++ thumb  : cv <= cvoptflowhs.cpp
Compile++ thumb  : cv <= cvoptflowlk.cpp
Compile++ thumb  : cv <= cvpgh.cpp
Compile++ thumb  : cv <= cvposit.cpp
Compile++ thumb  : cv <= cvprecomp.cpp
Compile++ thumb  : cv <= cvpyramids.cpp
Compile++ thumb  : cv <= cvpyrsegmentation.cpp
Compile++ thumb  : cv <= cvrotcalipers.cpp
Compile++ thumb  : cv <= cvsamplers.cpp
Compile++ thumb  : cv <= cvsegmentation.cpp
Compile++ thumb  : cv <= cvshapedescr.cpp
Compile++ thumb  : cv <= cvsmooth.cpp
Compile++ thumb  : cv <= cvsnakes.cpp
Compile++ thumb  : cv <= cvstereobm.cpp
Compile++ thumb  : cv <= cvstereogc.cpp
Compile++ thumb  : cv <= cvsubdivision2d.cpp
Compile++ thumb  : cv <= cvsumpixels.cpp
Compile++ thumb  : cv <= cvsurf.cpp
Compile++ thumb  : cv <= cvswitcher.cpp
Compile++ thumb  : cv <= cvtables.cpp
Compile++ thumb  : cv <= cvtemplmatch.cpp
Compile++ thumb  : cv <= cvthresh.cpp
Compile++ thumb  : cv <= cvundistort.cpp
Compile++ thumb  : cv <= cvutils.cpp
StaticLibrary  : libcv.a
SharedLibrary  : libopencv.so
U:/flori/workspace/android-ndk-r5b/toolchains/arm-linux-androideabi-4.4.3/prebui
lt/windows/bin/../lib/gcc/arm-linux-androideabi/4.4.3/../../../../arm-linux-andr
oideabi/bin/ld.exe: cannot find -lcxcore
collect2: ld returned 1 exit status
make: *** [/cygdrive/u/flori/workspace/android/testOpenCV/obj/local/armeabi/libo
pencv.so] Error 1

我正在尝试在 Windows 系统上使用最新的 NDK 版本编译它...

有人知道这个链接错误是什么吗意味着什么，我能做什么让它再次工作？

如果有人能提供帮助，那就太好了

---

在解决问题后，我发现还有另一种编译 Android 版 OpenCV 的方法，使用当前版本的 OpenCV（而不是上面的 1.1 版）和来自 crystaltax 的修改后的 Android NDK，其中支持STL和异常，因此支持最新的OpenCV版本。

所有相关信息都可以在这里找到： http://opencv.willowgarage.com/wiki/Android

那里说下载当前的svn trunk 和crystax-r4 android-ndk，以及我所做的swig。

我进入该文件夹，创建构建目录，运行 cmake，然后构建静态库，这似乎有效。至少它成功地运行了 make 命令，没有错误。

我现在想要构建共享库，因此我进入 android-jni 文件夹并再次运行“make”，但收到此错误：

% make -j4
OPENCV_CONFIG = ../build/android-opencv.mk
make clean-swig &&\
    mkdir -p jni/gen &&\
    mkdir -p src/com/opencv/jni &&\
    swig -java -c++ -package "com.opencv.jni" \
    -outdir src/com/opencv/jni \
    -o jni/gen/android_cv_wrap.cpp jni/android-cv.i
OPENCV_CONFIG = ../build/android-opencv.mk
make[1]: Entering directory `/home/florian/android-opencv-willowgarage/android/android-jni'
make[1]: warning: jobserver unavailable: using -j1.  Add `+' to parent make rule.
rm -f  jni/gen/android_cv_wrap.cpp
make[1]: Leaving directory `/home/florian/android-opencv-willowgarage/android/android-jni'
/home/florian/android-ndk-r4-crystax/ndk-build OPENCV_CONFIG=../build/android-opencv.mk \
    PROJECT_PATH= ARM_TARGETS="armeabi armeabi-v7a" V= 
/home/florian/android-ndk-r4-crystax/ndk-build OPENCV_CONFIG=../build/android-opencv.mk \
    PROJECT_PATH= ARM_TARGETS="armeabi armeabi-v7a" V= 
make[1]: Entering directory `/home/florian/android-opencv-willowgarage/android/android-jni'
/home/florian/android-opencv-willowgarage/android/android-jni/jni/Android.mk:10: ../build/android-opencv.mk: No such file or directory
make[1]: Entering directory `/home/florian/android-opencv-willowgarage/android/android-jni'
/home/florian/android-opencv-willowgarage/android/android-jni/jni/Android.mk:10: ../build/android-opencv.mk: No such file or directory
/home/florian/android-opencv-willowgarage/android/android-jni/jni/Android.mk:10: ../build/android-opencv.mk: No such file or directory
make[1]: warning: jobserver unavailable: using -j1.  Add `+' to parent make rule.
/home/florian/android-opencv-willowgarage/android/android-jni/jni/Android.mk:10: ../build/android-opencv.mk: No such file or directory
make[1]: *** No rule to make target `../build/android-opencv.mk'.  Stop.
make[1]: Leaving directory `/home/florian/android-opencv-willowgarage/android/android-jni'
make: *** [libs/armeabi/libandroid-opencv.so] Error 2
make: *** Waiting for unfinished jobs....
make[1]: warning: jobserver unavailable: using -j1.  Add `+' to parent make rule.
make[1]: *** No rule to make target `../build/android-opencv.mk'.  Stop.
make[1]: Leaving directory `/home/florian/android-opencv-willowgarage/android/android-jni'
make: *** [libs/armeabi-v7a/libandroid-opencv.so] Error 2

有人知道这意味着什么以及我可以做什么来构建共享库吗？

...

好吧，在查看了错误消息后，我发现构建目录中似乎缺少一些东西...但是 android 文件夹中甚至没有构建目录，所以我创建了一个，运行'在那里输入“cmake”，然后再次“make”，但出现此错误：

Compile thumb  : opencv_lapack <= /home/florian/android-opencv-willowgarage/3rdparty/lapack/sgetrf.c
Compile thumb  : opencv_lapack <= /home/florian/android-opencv-willowgarage/3rdparty/lapack/scopy.c
Compile++ thumb: opencv_core <= /home/florian/android-opencv-willowgarage/modules/core/src/matrix.cpp
cc1plus: error: /home/florian/android-opencv-willowgarage/android/../modules/index.rst/include: Not a directory
make[3]: *** [/home/florian/android-opencv-willowgarage/android/build/obj/local/armeabi/objs/opencv_core/src/matrix.o] Error 1
make[3]: *** Waiting for unfinished jobs....
make[2]: *** [android-opencv] Error 2
make[1]: *** [CMakeFiles/ndk.dir/all] Error 2
make: *** [all] Error 2

有人知道这意味着什么吗？

Answer 1

我刚刚在 Linux 上用 ndk-r5b 构建了它。您的项目目录中是否有一个 default.properties 文件（不是 jni），其内容如下：

target=android-8

如果没有，您可以尝试创建它并再次构建。

Answer 2

对于 cygwin，标准 gcc 规范文件包括 -dll-search-prefix=cyg，因此实际上我们搜索 cygxxx.dll。 （不适用于 libcxcore.a）因此您需要将 libxxx.a 复制到 cygxxx.a 并将它们放在一些可供链接器目录中。
我可以在 http:// 找到此解决方案docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/4/html/Using_ld_the_GNU_Linker/win32.html