Fixed!
There was no reference to zlib in my CMakeLists.txt.
To fix the problem I added this line:
target_link_libraries(MyCV /Users/dev/Documents/_Git/opencv/build_wasm/
3rdparty/lib/libzlib.a)
Thanks for Öö Tiib which gave me the tip about zlib in stack overflow.
Em sexta-feira, 6 de março de 2020 09:38:06 UTC-3, Marcos Trinca escreveu:
>
> I've been working in a C++ Code which receives an image data (grayscale)
> from the webcam and return the number of corners detected (Fast Corners) to
> the javascript. To get success compiling the code I've download and
> compiled opencv.js to create each one of the libraries using emscripten,
> coded my own C++ class to get the image data, included OpenCV.hpp and boom.
> Works amazingly fine.
>
> My problem started when I decided to use OpenCV FeatureDetector. I'm able
> to compile the code just including the header <opencv2/features2d.hpp> but
> as soon as I insert an instruction from this module I got a link error.
> The line of code triggering the link error is:
>
> Ptr<FeatureDetector> detector = ORB::create();
>
> I've recompiled OpenCV.js as WASM and the problem persists.
> I've also ran the OpenCV.js tests and all of the components from this
> module are working fine after compiling.
>
> There is one weird thing though: when I run the "nm" command on the
> compiled libs I got a "Bad section type" error, even the OpenCV.js tests
> shows no error using the methods from this module.
>
> My C++ code:
>
> class MyCV {
> public:
> MTR(int width, int height) :
> width(width),
> height(height)
> {}
>
> int getWidth() const { return width; }
> void setWidth(int w) { width = w; }
>
> int getHeigth() const { return height; }
> void setHeight(int h) { height = h; }
>
> // get video pixels in grayscale from the heap
> int image_input(intptr_t buffer, size_t nSize) //query image input
> {
> int *imagePixels = reinterpret_cast<int*>(buffer);
>
> // convert to cv formatDigite o código aqui...
>
> Mat raw_data = cv::Mat(1, nSize, CV_8UC1, imagePixels);
> Mat img(640, 480, CV_8UC1, &raw_data);
>
> // detect keypoints
> std::vector<cv::KeyPoint> keypoints_fast;
> Ptr<FeatureDetector> detector = ORB::create(); // <<<---- Here
> I got the link error
>
> return 1;
> }
>
> private:
> int width;
> int height;
>
> };
>
> EMSCRIPTEN_BINDINGS(my_module) {
> class_<MyCV>("MyCV")
> .constructor<int, int>()
> .property("width", &MyCV::getWidth, &MyCV::setWidth)
> .property("height", &MyCV::getHeigth, &MyCV::setHeight)
> .function("image_input", &MyCV::image_input);
>
> }
>
>
> My CMakeLists.txt
>
> set( CMAKE_CXX_STANDARD 11 )
> cmake_minimum_required( VERSION 3.16 )
> project( MyCV )
>
> # Use C++ 11 by default
> set( CMAKE_CXX_STANDARD 11 )
>
> # Set Release as default build type
> if(NOT CMAKE_BUILD_TYPE)
> set(CMAKE_BUILD_TYPE Release)
> endif(NOT CMAKE_BUILD_TYPE)
>
> file( GLOB opencv_include_modules
> "/Users/dev/Documents/_Git/opencv/modules/*/include" )
> include_directories( ${opencv_include_modules} )
> include_directories( /Users/dev/Documents/_Git/opencv/include )
> include_directories( /Users/dev/Documents/_Git/opencv/build_wasm )
>
> add_executable( MyCV src/MyCV.cc )
>
> file( GLOB opencv_libs_wasm
> "/Users/dev/Documents/_Git/opencv/build_wasm/lib/*.a" )
> target_link_libraries( MyCV ${opencv_libs_wasm} )
>
> set(COMPILE_FLAGS "-Wno-missing-prototypes")
> set_target_properties( MyCV PROPERTIES COMPILE_FLAGS ${COMPILE_FLAGS})
>
> set(EMSCRIPTEN_LINK_FLAGS "${EMSCRIPTEN_LINK_FLAGS} -s WASM=1")
> set(EMSCRIPTEN_LINK_FLAGS "${EMSCRIPTEN_LINK_FLAGS} --bind")
> #set(EMSCRIPTEN_LINK_FLAGS "${EMSCRIPTEN_LINK_FLAGS} -s
> LLD_REPORT_UNDEFINED")
>
> set_target_properties( MyCV PROPERTIES LINK_FLAGS ${EMSCRIPTEN_LINK_FLAGS}
> )
>
> The link error:
>
> [100%] Linking CXX executable MyCV.js
> error: undefined symbol: gzclose
> warning: Link with `-s LLD_REPORT_UNDEFINED` to get more information on
> undefined symbols
> warning: To disable errors for undefined symbols use `-s
> ERROR_ON_UNDEFINED_SYMBOLS=0`
> error: undefined symbol: gzeof
> error: undefined symbol: gzgets
> error: undefined symbol: gzopen
> error: undefined symbol: gzputs
> error: undefined symbol: gzrewind
> Error: Aborting compilation due to previous errors
> shared:ERROR: '/Users/dev/Documents/_Git/emsdk/node/12.9.1_64bit/bin/node
> /Users/dev/Documents/_Git/emsdk/upstream/emscripten/src/compiler.js
> /var/folders/94/qc6kgl3x6r30g7y04t_9w4w00000gn/T/tmpDzc2sz.txt' failed (1)
> make[2]: *** [MyCV.js] Error 1
> make[1]: *** [CMakeFiles/MyCV.dir/all] Error 2
> make: *** [all] Error 2
>
> The message that comes from 'nm' command:
>
> dev# nm libopencv_features2d.a
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(agast.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(agast_score.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(akaze.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(bagofwords.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(blobdetector.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(brisk.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(draw.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(dynamic.cpp.o) Unexpected metadata version: 2
> (Expected: 1)
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(evaluation.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(fast.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(fast_score.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(feature2d.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(gftt.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(kaze.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(AKAZEFeatures.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(KAZEFeatures.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(fed.cpp.o) Unexpected metadata version: 2
> (Expected: 1)
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(nldiffusion_functions.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(keypoint.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(main.cpp.o) Unexpected metadata version: 2
> (Expected: 1)
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(matchers.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(mser.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(orb.cpp.o) Bad section type
> /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm:
>
> error: libopencv_features2d.a(opencl_kernels_features2d.cpp.o) Unexpected
> metadata version: 2 (Expected: 1)
>
> Thank you guys for any help.
>
>
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