使用gyp链接c++节点外接程序时对v8的引用未定义

Question

我正在尝试使用opencv库构建一个节点插件。我正在使用node-gyp编译它。我已经实现了使用binding.gyp配置文件链接opencv，但是我在使用v8库时遇到了一些问题。

这是我的binding.gyp文件：

    "targets": [
        {
            "target_name": "test",
            "sources": [ "src/native/test.cpp" ],
            "include_dirs": [
                "/usr/local/include/opencv4",
                "/usr/local/include/node",
                "/usr/include"
            ],
            "library_dirs": [ "/usr/local/lib", "/usr/lib" ],
            "libraries": [
                "/usr/local/lib/libopencv_core.so",
                "/usr/local/lib/libopencv_videoio.so",
                "/usr/local/lib/libopencv_highgui.so",
                "/usr/lib/libv8.so"
            ],
            "ldflags": [ "-Wl,-z,defs" ],
            "link_settings": {
                "libraries": [
                    "-lopencv_core",
                    "-lopencv_videoio",
                    "-lopencv_highgui",
                    "-lv8",
                    "-lpthread"
                 ]
            }
        }
    ]
}

如果不链接opencv，构建和运行我的插件没有任何问题，但是一旦我链接了opencv，构建就失败了，因为v8：

test.cpp:(.text+0x1f9): undefined reference to `v8::V8::ToLocalEmpty()'
test.cpp:(.text+0x209): undefined reference to `v8::V8::FromJustIsNothing()'
test.cpp:(.text+0x219): undefined reference to `v8::V8::ToLocalEmpty()'
test.cpp:(.text+0x229): undefined reference to `v8::V8::ToLocalEmpty()'
test.cpp:(.text+0x239): undefined reference to `v8::V8::FromJustIsNothing()'
... and so on

正如您在binding.gyp文件中看到的，我已经尝试为v8链接相应的库和include，但是没有成功。

我很确定这是一个问题或者与配置本身的冲突，因为在没有链接opencv的情况下，构建工作得很好，而且我在nodeJS文件中使用这个插件也没有问题。

我的c++文件非常简单，它尽可能简单，因为我只想让它正确地构建和链接库：

#include <opencv4/opencv2/core.hpp>
#include <opencv4/opencv2/videoio.hpp>
#include <opencv4/opencv2/highgui.hpp>

#include <node/v8.h>
#include <node/node.h>
#include <iostream>
#include <stdio.h>

void capture(const v8::FunctionCallbackInfo<v8::Value>& args)
{
    v8::Isolate* isolate = v8::Isolate::GetCurrent();
    v8::HandleScope scope(isolate);

    cv::Mat frame;
    cv::VideoCapture cap;
}

void Initialize(v8::Local<v8::Object> exports) {
    NODE_SET_METHOD(exports, "capture", capture);
}

NODE_MODULE(NODE_GYP_MODULE_NAME, Initialize)

如果你对这个构建错误有任何想法，以及为什么v8在链接opencv时不能正确链接，我将非常感谢你的帮助。

谢谢

Answer 1

那么，你为什么不静态地链接OpenCV呢，它是在Apache许可下授权的。Apache许可对链接没有任何限制

rm -rf 3rdparty/opencv
mkdir -p 3rdparty/opencv
rm -rf tmp
mkdir tmp
cd tmp
rm -rf opencv-master
rm -rf opencv_contrib-master
git clone --branch 3.4 --depth 1 https://github.com/opencv/opencv.git opencv-master
git clone --branch 3.4 --depth 1 https://github.com/opencv/opencv_contrib.git opencv_contrib-master
mkdir build
cd build
cmake \
    -DCMAKE_INSTALL_PREFIX="$(pwd)/../../3rdparty/opencv\@3.4" \
    -DBUILD_SHARED_LIBS=OFF \
    -DENABLE_PRECOMPILED_HEADERS=YES \
    -DOPENCV_EXTRA_MODULES_PATH=../opencv_contrib-master/modules \
    ../opencv-master
cmake --build .
make install

我创建了一个简单的脚本，它将编译OpenCV 3.4与opencv_contrib (SIFT，冲浪可用)与Native Abstractions for Node.js静态链接。

{
    "targets": [
    {
        "target_name": "addon",
        "cflags": [
            "-std=c++11",
            "-stdlib=libc++"
        ],
        "cflags_cc!": [
            "-fno-rtti",
            "-fno-exceptions"
        ],
        "xcode_settings": {
            "GCC_ENABLE_CPP_RTTI": "YES",
            "GCC_ENABLE_CPP_EXCEPTIONS": "YES",
        },
        "include_dirs": [
            "../../3rdparty/opencv/@3.4/include",
            "<!(node -e \"require('nan')\")"
        ],
        'libraries': [
            "<!@(node utils/find-libs.js)",
            "-framework OpenCL"
        ],
        "sources": [
            "./src/main.cc",
            "./src/lib/MainAddon.cc"
        ],
    }
  ]
}

完整的源代码足够大，所以它发布在this GitHub repository上