在Android上如何使用OpenCV

cmake_minimum_required(VERSION 3.6.0)

include_directories(
    ${CMAKE_SOURCE_DIR}/src/main/cpp/include
)

add_library(libopencv_java4 SHARED IMPORTED)
set_target_properties(
    libopencv_java4
    PROPERTIES IMPORTED_LOCATION
    ${CMAKE_SOURCE_DIR}/src/main/jniLibs/libs/${ANDROID_ABI}/libopencv_java4.so)

add_library(libc++_shared SHARED IMPORTED)
set_target_properties(
    libc++_shared
    PROPERTIES IMPORTED_LOCATION
    ${CMAKE_SOURCE_DIR}/src/main/jniLibs/libs/${ANDROID_ABI}/libc++_shared.so)


add_library(
    detect

    SHARED

    src/main/cpp/detect-lib.cpp
    src/main/cpp/detect-phone.cpp
)


find_library(
    log-lib
    log
)

target_link_libraries(
    detect libopencv_java4 libc++_shared jnigraphics
    ${log-lib}
)

extern "C"
JNIEXPORT jstring JNICALL
Java_com_xxx_sdk_utils_DetectUtils_qrDetect(JNIEnv *env, jclass jc,jstring filePath) {

  const char *file_path_str = env->GetStringUTFChars(filePath, 0);
  string path = file_path_str;
  Mat src = imread(path);

  Mat gray, qrcode_roi;
  cvtColor(src, gray, COLOR_BGR2GRAY);
  QRCodeDetector qrcode_detector;
  vector<Point> pts;
  string detect_info;
  bool det_result = qrcode_detector.detect(gray, pts);
  if (det_result) {
    detect_info = qrcode_detector.decode(gray, pts, qrcode_roi);
    return env->NewStringUTF(detect_info.c_str());
  } else {
    detect_info = "";
    return env->NewStringUTF(detect_info.c_str());
  }
}

public class DetectUtils {

  static {
    System.loadLibrary("detect");
  }

  /**
   * 識別二維碼
   * @param filePath
   * @return
   */
  public static native String qrDetect(String filePath);

  ......
}

// 使用 OpenCV 進行二維碼識別
val result = DetectUtils.qrDetect(filePath)
L.d("opencvs識別二維碼: $result")

extern "C"
JNIEXPORT jboolean JNICALL
Java_com_xxx_sdk_utils_DetectUtils_checkPhoneInMTA(JNIEnv *env, jclass jc,jstring baseImgPath,jstring filePath) {

  jboolean tRet = false;
  const char *file_path_str = env->GetStringUTFChars(filePath, 0);
  string path = file_path_str;
  Mat src = imread(path);

  const char *base_img_path_str = env->GetStringUTFChars(baseImgPath, 0);
  string basePath = base_img_path_str;
  Mat baseImg = imread(basePath);

  int result = checkPhoneInBox(baseImg,src,40,0.1);

  LOGI("checkPhoneInBox result = %d",result);
  if (result == 0) {
    tRet = true;
  }

  return tRet;
}

int checkPhoneInBox(cv::Mat baseImg, cv::Mat snapImg, int diffThresh, double threshRatio) {

  cv::Mat baseMaxImg, snapMaxImg,baseGausImg, snapGausImg;
  if (baseImg.empty()|| snapImg.empty())
  {
    return -1;
  }

  try {
    maxFilter(baseImg, baseMaxImg);
    maxFilter(snapImg, snapMaxImg);
  } catch (...) {
    return -1;
  }

  cv::GaussianBlur(baseMaxImg, baseGausImg, cv::Size(5, 5),0);
  cv::GaussianBlur(snapMaxImg, snapGausImg, cv::Size(5, 5),0);

  cv::Mat diff,diffBin;
  cv::Mat noMax;
  cv::absdiff(baseGausImg, snapGausImg, diff);
  cv::threshold(diff, diffBin, diffThresh, 255, cv::THRESH_BINARY);

  float ratio = (float)cv::countNonZero(diffBin) / (long)diffBin.total();

  LOGI("ratio = %f,%d,%ld",ratio,cv::countNonZero(diffBin),(long)diffBin.total());

  if (ratio > threshRatio)
  {
    return 0;
  }
  else
  {
    return 1;
  }
}

int maxFilter(cv::Mat baseImg, cv::Mat &maxImg)
{
  if (baseImg.channels() <3)
  {
    maxImg = baseImg.clone();
  }
  else
  {
    maxImg.create(baseImg.size(), CV_8UC1);
    for (int r=0;r<baseImg.rows;r++)
    {
      for (int c = 0; c < baseImg.cols; c++)
      {
        uchar maxTmp=0;
        cv::Vec3b s = baseImg.at<cv::Vec3b>(r, c);
        maxTmp = (std::max)(s[0],s[1]);
        maxTmp = (std::max)(maxTmp,s[2]);

        maxImg.at<uchar>(r, c) = maxTmp;
      }
    }
  }
  return 0;
}

public class DetectUtils {

  static {
    System.loadLibrary("detect");
  }

  /**
   * 判斷MTA中是否有手機
   * @param baseImageFilePath 基準(zhǔn)的圖片
   * @param filePath     拍攝的圖片
   * @return
   */
  public static native boolean checkPhoneInMTA(String baseImageFilePath, String filePath);

  ......
}

val result = DetectUtils.checkPhoneInMTA(Constants.OPENCV_PHOTO_PATH, it.absolutePath)