macos下命令行通过ndk编译android下可以执行的ELF程序（并验证opencl的调用）

源码如下，实现把一个JPG保存成灰度图格式的BMP

//jpg2bmp.cpp
#include <stdio.h>
#include <inttypes.h>
#include <opencv2/opencv.hpp>
#include <opencv2/core.hpp>

#ifndef P
#define P(format, ...) do 
  { 
    printf("%s %s %d " format "
", __FILE__, __FUNCTION__, __LINE__, ##__VA_ARGS__); 
    fflush(stdout); 
  } 
  while (0);
#endif

int main(int argc, char* argv[]){
    if (argc<3){
        printf("usage:%s <from> <to>
", argv[0]);
        return 0;
    }
    cv::Mat image = cv::imread(argv[1], cv::IMREAD_UNCHANGED);
    cv::UMat u_img = image.getUMat(cv::ACCESS_READ);
    if (image.empty()){
        P("load pic %s fail", argv[1]);
        return -1;
    }
    cv::UMat bmp;
    cv::cvtColor(u_img, bmp, cv::COLOR_BGR2GRAY);   
    cv::imwrite(argv[2], bmp);
    P("ok");
    return 1;
}

编译命令行如下：

/Users/ahfu/code/android/android-ndk-r14b/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/bin/arm-linux-androideabi-g++  
    -o jpg2bmp_1.o -c jpg2bmp_1.cpp -pie -fPIC 
    -I"/Users/ahfu/code/android/OpenCV-android-sdk/sdk/native/jni/include" 
    --sysroot=/Users/ahfu/code/android/android-ndk-r14b/platforms/android-22/arch-arm/ 
    -I"/Users/ahfu/code/android/android-ndk-r14b/sources/cxx-stl/gnu-libstdc++/4.9/include" 
    -I"/Users/ahfu/code/android/android-ndk-r14b/sources/cxx-stl/gnu-libstdc++/4.9/libs/armeabi-v7a/include/"

链接命令行如下：

/Users/ahfu/code/android/android-ndk-r14b/toolchains/arm-linux-androideabi-4.9/prebuilt/darwin-x86_64/bin/arm-linux-androideabi-g++ 
    -o jpg2bmp_1 jpg2bmp_1.o -pie -fPIC 
    --sysroot=/Users/ahfu/code/android/android-ndk-r14b/platforms/android-22/arch-arm/ 
    -L"/Users/ahfu/code/android/OpenCV-android-sdk/sdk/native/staticlibs/armeabi-v7a" -lopencv_core -lopencv_imgcodecs -lopencv_imgproc -lm -lz -landroid -llog 
    -L"/Users/ahfu/code/android/OpenCV-android-sdk/sdk/native/3rdparty/libs/armeabi-v7a/" -ltegra_hal -lcpufeatures -ltbb -llibpng -llibjpeg-turbo -llibtiff -llibjasper -llibwebp -lIlmImf -lopencv_core -lopencv_imgcodecs -lopencv_imgproc -ltegra_hal 
    -L"/Users/ahfu/code/android/android-ndk-r14b/sources/cxx-stl/gnu-libstdc++/4.9/libs/armeabi-v7a" -lgnustl_static -lsupc++ 
    -L"/Users/ahfu/code/android/android-ndk-r14b/platforms/android-22/arch-arm/usr/lib" -lstdc++

然后使用adb上传
adb root  #手机必要要root
adb push jpg2bmp 1.jpg /data/data/temp
adb shell
  cd /data/data/temp
  chmod +x jpg2bmp
  ./jpg2bmp 1.jpg 2.bmp

  #执行成功

ndk版本是：android-ndk-r14b
opencv android sdk版本是：opencv-3.4.6-android-sdk.zip