jimmyhalimi / androidopencv

This is an example on how to compile an .so for AOSP

In order to use the .so in android, we need to compile it with the toolchain, and push the files to /vendor/lib/

In the code we should call it like this:

First include the header and define the typedef for the prototype of our function

#include "dlfcn.h"
typedef int (*CAC_FUNC)(unsigned char *data, int width, int height);

After that we need to open it like

{
    void *data = NULL;
    data = (void *)(uint8_t *)frame->bufs[0]->buffer;

    void *handle;
    char *error;

    CAC_FUNC cac_func = NULL;

    handle = dlopen("/system/vendor/lib/libreadFrame.so", RTLD_NOW);

    if(!handle)
    {
        error = (char *)dlerror();
        LOGE("DL Open Error for libreadFrame: %s", error);
    }

    dlerror();
    *(void**)(&cac_func) = dlsym(handle, "readFrameCV");
    if(dlsym(handle, "readFrameCV") == NULL)
    {
        LOGE("readFrameCV DL Error: %s", error);
    }

    if((error = (char *)dlerror()) != NULL)
    {
        LOGE("readFrameCV dl error, exit failure: %s", error);
    }

    int tmp = cac_func((unsigned char *)data+4096, mFrameLenOffset.mp[0].width, mFrameLenOffset.mp[0].height);

    dlclose(handle);

    switch (tmp)
    {
    case 0:
        LOGE("---MERGIM_LOGS--- Function finished with return 0, image empty. tmp = %d", tmp);
        break;
    case 1:
        LOGE("---MERGIM_LOGS--- Function finished with return 1, image success. tmp = %d", tmp);
        break;
    default:
        LOGE("---MERGIM_LOGS--- Switch returned default. tmp = %d", tmp);
        break;
    }
}

To compile the example we need to call the cmake .. with the toolchain file. E.g.:

cmake .. -DCMAKE_TOOLCHAIN_FILE=/home/jimmyhalimi/Desktop/Desktop/capture_write/toolchain/android-ndk-r17c/build/cmake/android.toolchain.cmake 

Note: please update the path for your user