native.h

//
// Created by fujiayi on 2020/7/5.
//

#pragma once


#include <jni.h>
#include <string>
#include <vector>
#include <android/bitmap.h>
#include <opencv2/opencv.hpp>
#include "common.h"

inline std::string jstring_to_cpp_string(JNIEnv *env, jstring jstr) {
    // In java, a unicode char will be encoded using 2 bytes (utf16).
    // so jstring will contain characters utf16. std::string in c++ is
    // essentially a string of bytes, not characters, so if we want to
    // pass jstring from JNI to c++, we have convert utf16 to bytes.
    if (!jstr) {
        return "";
    }
    const jclass stringClass = env->GetObjectClass(jstr);
    const jmethodID getBytes =
        env->GetMethodID(stringClass, "getBytes", "(Ljava/lang/String;)[B");
    const jbyteArray stringJbytes = (jbyteArray) env->CallObjectMethod(
        jstr, getBytes, env->NewStringUTF("UTF-8"));

    size_t length = (size_t) env->GetArrayLength(stringJbytes);
    jbyte *pBytes = env->GetByteArrayElements(stringJbytes, NULL);

    std::string ret = std::string(reinterpret_cast<char *>(pBytes), length);
    env->ReleaseByteArrayElements(stringJbytes, pBytes, JNI_ABORT);

    env->DeleteLocalRef(stringJbytes);
    env->DeleteLocalRef(stringClass);
    return ret;
}

inline jstring cpp_string_to_jstring(JNIEnv *env, std::string str) {
    auto *data = str.c_str();
    jclass strClass = env->FindClass("java/lang/String");
    jmethodID strClassInitMethodID =
        env->GetMethodID(strClass, "<init>", "([BLjava/lang/String;)V");

    jbyteArray bytes = env->NewByteArray(strlen(data));
    env->SetByteArrayRegion(bytes, 0, strlen(data),
                            reinterpret_cast<const jbyte *>(data));

    jstring encoding = env->NewStringUTF("UTF-8");
    jstring res = (jstring) (
        env->NewObject(strClass, strClassInitMethodID, bytes, encoding));

    env->DeleteLocalRef(strClass);
    env->DeleteLocalRef(encoding);
    env->DeleteLocalRef(bytes);

    return res;
}

inline jfloatArray cpp_array_to_jfloatarray(JNIEnv *env, const float *buf,
                                            int64_t len) {
    if (len == 0) {
        return env->NewFloatArray(0);
    }
    jfloatArray result = env->NewFloatArray(len);
    env->SetFloatArrayRegion(result, 0, len, buf);
    return result;
}

inline jintArray cpp_array_to_jintarray(JNIEnv *env, const int *buf,
                                        int64_t len) {
    jintArray result = env->NewIntArray(len);
    env->SetIntArrayRegion(result, 0, len, buf);
    return result;
}

inline jbyteArray cpp_array_to_jbytearray(JNIEnv *env, const int8_t *buf,
                                          int64_t len) {
    jbyteArray result = env->NewByteArray(len);
    env->SetByteArrayRegion(result, 0, len, buf);
    return result;
}

inline jlongArray int64_vector_to_jlongarray(JNIEnv *env,
                                             const std::vector<int64_t> &vec) {
    jlongArray result = env->NewLongArray(vec.size());
    jlong *buf = new jlong[vec.size()];
    for (size_t i = 0; i < vec.size(); ++i) {
        buf[i] = (jlong) vec[i];
    }
    env->SetLongArrayRegion(result, 0, vec.size(), buf);
    delete[] buf;
    return result;
}

inline std::vector<int64_t> jlongarray_to_int64_vector(JNIEnv *env,
                                                       jlongArray data) {
    int data_size = env->GetArrayLength(data);
    jlong *data_ptr = env->GetLongArrayElements(data, nullptr);
    std::vector<int64_t> data_vec(data_ptr, data_ptr + data_size);
    env->ReleaseLongArrayElements(data, data_ptr, 0);
    return data_vec;
}

inline std::vector<float> jfloatarray_to_float_vector(JNIEnv *env,
                                                      jfloatArray data) {
    int data_size = env->GetArrayLength(data);
    jfloat *data_ptr = env->GetFloatArrayElements(data, nullptr);
    std::vector<float> data_vec(data_ptr, data_ptr + data_size);
    env->ReleaseFloatArrayElements(data, data_ptr, 0);
    return data_vec;
}

inline cv::Mat bitmap_to_cv_mat(JNIEnv *env, jobject bitmap) {
    AndroidBitmapInfo info;
    int result = AndroidBitmap_getInfo(env, bitmap, &info);
    if (result != ANDROID_BITMAP_RESULT_SUCCESS) {
        LOGE("AndroidBitmap_getInfo failed, result: %d", result);
        return cv::Mat{};
    }
    if (info.format != ANDROID_BITMAP_FORMAT_RGBA_8888) {
        LOGE("Bitmap format is not RGBA_8888 !");
        return cv::Mat{};
    }
    unsigned char *srcData = NULL;
    AndroidBitmap_lockPixels(env, bitmap, (void **) &srcData);
    cv::Mat mat = cv::Mat::zeros(info.height, info.width, CV_8UC4);
    memcpy(mat.data, srcData, info.height * info.width * 4);
    AndroidBitmap_unlockPixels(env, bitmap);
    cv::cvtColor(mat, mat, cv::COLOR_RGBA2BGR);
    /**
    if (!cv::imwrite("/sdcard/1/copy.jpg", mat)){
        LOGE("Write image failed " );
    }
     */
    return mat;
}