Android 接入微信扫码库，实现堪比微信的扫码效果

àì夳堔傛蜴生んèń 2023-10-10 13:09 49阅读 0赞

对于Android的扫码库，我们平时都会使用ZXing或者ZBar来实现。

但是实际情况是，对于一些环境恶劣的情况下，比如 眩光、昏暗、有污渍等情况下，很难被识别。

即使是在普通情况下，扫码的识别速度、识别率依旧不甚满意的。

为了满足业务需要，故我们需要找到更好的扫码库。

[微信开源的扫码库][Link 1]，就是其中一个不错的选择。

微信的扫码库，基于开源引擎ZXing，结合计算机视觉和深度学习技术，深度优化改造的高性能扫码库。

拥有 基于CNN的二维码检测和增强，更鲁棒的定位点检测，更详细的特性可以看[基于CNN的微信二维码引擎OpenCV开源！][CNN_OpenCV]

#### 接入微信扫码库 ####

接入微信扫码库，需要接入OpenCV库，接入OpenCV库有以下几种方式

*  接入OpenCV的Java SDK包，这样可以直接在Java调用OpenCV的大部分方法，这种方法最简单
 *  使用OpenCV sdk 提供的C++头文件与.so动态库、.a静态库，自己封装jni，这样可以100%使用openCV的接口
 *  通过openCV的源码，重新编译成Android sdk库，这样能只编译生成自己需要的功能，文件比较小，缺点是编译环境啥的比较难搞。

> 关于OpenCV不同接入方式，详情请看 [Android 接入 OpenCV库的三种方式][Android _ OpenCV]

这里，我直接用方法一 + 方法二的形式，首先我们需要下载OpenCV的SDK包，附上[下载地址][Link 2]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0V0aGFuQ28_size_16_color_FFFFFF_t_70_pic_center]

这里选择的是OpenCV 4.5.2版本，选择android进行下载

下载完成解压后，我们得到了如下所示的文件  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0V0aGFuQ28_size_16_color_FFFFFF_t_70_pic_center 1]

这里的sdk文件夹，就是我们需要的OpenCV的Java SDK包了。

接着，我们新建一个项目，选择Native C++  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0V0aGFuQ28_size_16_color_FFFFFF_t_70_pic_center 2]

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0V0aGFuQ28_size_16_color_FFFFFF_t_70_pic_center 3]

接着，我们导入这个Java SDK

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L0V0aGFuQ28_size_16_color_FFFFFF_t_70_pic_center 4]

接着，在app的gradle中，依赖这个library

implementation project(':sdk')

新建一个`WeChatQRCode`的扫码类，这里有三个jni接口

*  WeChatQrCode : 初始化
 *  detectAndDecode : 发现并解析
 *  delete : 销毁

class WeChatQRCode {
        
        
        val nativeObjAddr: Long
    
        private constructor(addr: Long) {
        
            nativeObjAddr = addr
        }
    
        constructor(
            detector_prototxt_path: String,
            detector_caffe_model_path: String,
            super_resolution_prototxt_path: String,
            super_resolution_caffe_model_path: String
        ) {
        
            nativeObjAddr = WeChatQRCode(
                detector_prototxt_path,
                detector_caffe_model_path,
                super_resolution_prototxt_path,
                super_resolution_caffe_model_path
            )
        }
    
        fun detectAndDecode(img: Mat, points: List<Mat>): List<String> {
        
            val points_mat = Mat()
            val retVal = detectAndDecode(
                nativeObjAddr, img.nativeObj, points_mat.nativeObjAddr
            )
            Converters.Mat_to_vector_Mat(points_mat, points)
            points_mat.release()
            return retVal
        }
    
        @Throws(Throwable::class)
        protected fun finalize() {
        
            delete(nativeObjAddr)
        }
    
        external fun WeChatQRCode(
            detector_prototxt_path: String,
            detector_caffe_model_path: String,
            super_resolution_prototxt_path: String,
            super_resolution_caffe_model_path: String
        ): Long
    
    
        external fun detectAndDecode(
            nativeObj: Long,
            img_nativeObj: Long,
            points_mat_nativeObj: Long
        ): List<String>
    
    
        external fun delete(nativeObj: Long)
    
    }

在app模块的`cpp`文件夹中，添加头文件

*  复制`OpenCV-android-sdk\sdk\native\jni\include`下的`opencv2`文件夹到`cpp`文件夹下
 *  复制 [wechat\_qrcode.hpp][wechat_qrcode.hpp]到`cpp/opencv2`文件夹下
 *  复制[opencv\_contrib/modules/wechat\_qrcode/src/][opencv_contrib_modules_wechat_qrcode_src]下的文件到`cpp`目录下

同时，我们在`native-lib.cpp`中，实现jni方法

#include <jni.h>
    #include <string>
    #include <iostream>
    #include <opencv2/core.hpp>
    #include <opencv2/imgproc.hpp>
    #include <opencv2/wechat_qrcode.hpp>
    #include <opencv2/imgcodecs.hpp>
    #include <android/log.h>
    
    
    #define CONSTRUCTOR(ENV, CLS) ENV->GetMethodID(CLS, "<init>", "(I)V")
    #define ARRAYLIST(ENV) static_cast<jclass>(ENV->NewGlobalRef(ENV->FindClass("java/util/ArrayList")))
    #define LIST_ADD(ENV, LIST) ENV->GetMethodID(LIST, "add", "(Ljava/lang/Object;)Z")
    
    #define LOGV(...) __android_log_print(ANDROID_LOG_VERBOSE, "NativeLib", __VA_ARGS__)
    #define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG , "NativeLib", __VA_ARGS__)
    #define LOGI(...) __android_log_print(ANDROID_LOG_INFO  , "NativeLib", __VA_ARGS__)
    #define LOGW(...) __android_log_print(ANDROID_LOG_WARN  , "NativeLib", __VA_ARGS__)
    #define LOGE(...) __android_log_print(ANDROID_LOG_ERROR  , "NativeLib", __VA_ARGS__)
    
    
    using namespace std;
    using namespace cv;
    
    
    /// throw java exception
    #undef throwJavaException
    #define throwJavaException throwJavaException_wechat_qrcode
    
    static void throwJavaException(JNIEnv *env, const std::exception *e, const char *method) {
        std::string what = "unknown exception";
        jclass je = 0;
    
        if (e) {
            std::string exception_type = "std::exception";
    
            if (dynamic_cast<const cv::Exception *>(e)) {
                exception_type = "cv::Exception";
                je = env->FindClass("org/opencv/core/CvException");
            }
    
            what = exception_type + ": " + e->what();
        }
    
        if (!je) je = env->FindClass("java/lang/Exception");
        env->ThrowNew(je, what.c_str());
    
        LOGE("%s caught %s", method, what.c_str());
        (void) method;        // avoid "unused" warning
    }
    
    
    void vector_Mat_to_Mat(std::vector<cv::Mat> &v_mat, cv::Mat &mat) {
        int count = (int) v_mat.size();
        mat.create(count, 1, CV_32SC2);
        for (int i = 0; i < count; i++) {
            long long addr = (long long) new Mat(v_mat[i]);
            mat.at<Vec<int, 2> >(i, 0) = Vec<int, 2>(addr >> 32, addr & 0xffffffff);
        }
    }
    
    
    jobject vector_string_to_List(JNIEnv *env, std::vector<std::string> &vs) {
    
        static jclass juArrayList = ARRAYLIST(env);
        static jmethodID m_create = CONSTRUCTOR(env, juArrayList);
        jmethodID m_add = LIST_ADD(env, juArrayList);
    
        jobject result = env->NewObject(juArrayList, m_create, vs.size());
        for (std::vector<std::string>::iterator it = vs.begin(); it != vs.end(); ++it) {
            jstring element = env->NewStringUTF((*it).c_str());
            env->CallBooleanMethod(result, m_add, element);
            env->DeleteLocalRef(element);
        }
        return result;
    }
    
    extern "C"
    JNIEXPORT jlong JNICALL
    Java_com_heiko_opencvwxtest_WeChatQRCode_WeChatQRCode(JNIEnv *env, jobject thiz,
                                                          jstring detector_prototxt_path,
                                                          jstring detector_caffe_model_path,
                                                          jstring super_resolution_prototxt_path,
                                                          jstring super_resolution_caffe_model_path) {
        using namespace cv::wechat_qrcode;
        static const char method_name[] = "WeChatQRCode_WeChatQRCode";
        try {
            LOGD("%s", method_name);
            const char *utf_detector_prototxt_path = env->GetStringUTFChars(detector_prototxt_path, 0);
            std::string n_detector_prototxt_path(
                    utf_detector_prototxt_path ? utf_detector_prototxt_path : "");
            env->ReleaseStringUTFChars(detector_prototxt_path, utf_detector_prototxt_path);
            const char *utf_detector_caffe_model_path = env->GetStringUTFChars(
                    detector_caffe_model_path, 0);
            std::string n_detector_caffe_model_path(
                    utf_detector_caffe_model_path ? utf_detector_caffe_model_path : "");
            env->ReleaseStringUTFChars(detector_caffe_model_path, utf_detector_caffe_model_path);
            const char *utf_super_resolution_prototxt_path = env->GetStringUTFChars(
                    super_resolution_prototxt_path, 0);
            std::string n_super_resolution_prototxt_path(
                    utf_super_resolution_prototxt_path ? utf_super_resolution_prototxt_path : "");
            env->ReleaseStringUTFChars(super_resolution_prototxt_path,
                                       utf_super_resolution_prototxt_path);
            const char *utf_super_resolution_caffe_model_path = env->GetStringUTFChars(
                    super_resolution_caffe_model_path, 0);
            std::string n_super_resolution_caffe_model_path(
                    utf_super_resolution_caffe_model_path ? utf_super_resolution_caffe_model_path : "");
            env->ReleaseStringUTFChars(super_resolution_caffe_model_path,
                                       utf_super_resolution_caffe_model_path);
            cv::wechat_qrcode::WeChatQRCode *_retval_ = new cv::wechat_qrcode::WeChatQRCode(
                    n_detector_prototxt_path, n_detector_caffe_model_path,
                    n_super_resolution_prototxt_path, n_super_resolution_caffe_model_path);
            return (jlong) _retval_;
        } catch (const std::exception &e) {
            throwJavaException(env, &e, method_name);
        } catch (...) {
            throwJavaException(env, 0, method_name);
        }
        return 0;
    }
    
    extern "C"
    JNIEXPORT jobject JNICALL
    Java_com_heiko_opencvwxtest_WeChatQRCode_detectAndDecode(JNIEnv *env,
                                                             jobject thiz,
                                                             jlong self,
                                                             jlong img_nativeObj,
                                                             jlong points_mat_nativeObj) {
        using namespace cv::wechat_qrcode;
        static const char method_name[] = "WeChatQRCode_detectAndDecode";
        try {
            LOGD("%s", method_name);
            std::vector<Mat> points;
            Mat &points_mat = *((Mat *) points_mat_nativeObj);
            cv::wechat_qrcode::WeChatQRCode *me = (cv::wechat_qrcode::WeChatQRCode *) self;
            Mat &img = *((Mat *) img_nativeObj);
            std::vector<std::string> _ret_val_vector_ = me->detectAndDecode(img, points);
            vector_Mat_to_Mat(points, points_mat);
            jobject _retval_ = vector_string_to_List(env, _ret_val_vector_);
            return _retval_;
        } catch (const std::exception &e) {
            throwJavaException(env, &e, method_name);
        } catch (...) {
            throwJavaException(env, 0, method_name);
        }
        return 0;
    }
    
    extern "C"
    JNIEXPORT void JNICALL
    Java_com_heiko_opencvwxtest_WeChatQRCode_delete(JNIEnv *env, jobject thiz, jlong self) {
        delete (cv::wechat_qrcode::WeChatQRCode *) self;
    }

修改`CMakeLists.txt`文件

# For more information about using CMake with Android Studio, read the
    # documentation: https://d.android.com/studio/projects/add-native-code.html
    
    # Sets the minimum version of CMake required to build the native library.
    
    cmake_minimum_required(VERSION 3.10.2)
    
    # Declares and names the project.
    
    project("learningandroidopencv")
    
    # 注意这里的路径，需要和OpenCV sdk的路径对应
    set(ocvlibs "${PROJECT_SOURCE_DIR}/../../../../sdk/native/libs")
    include_directories(${PROJECT_SOURCE_DIR}/include)
    
    add_library(libopencv_java4 SHARED IMPORTED)
    set_target_properties(libopencv_java4 PROPERTIES
            IMPORTED_LOCATION "${ocvlibs}/${ANDROID_ABI}/libopencv_java4.so")
    
    include_directories(
            wechat
            wechat/detector
            wechat/scale
            wechat/zxing
            wechat/zxing/common
            wechat/zxing/common/binarizer
            wechat/zxing/common/reedsolomon
            wechat/zxing/qrcode
            wechat/zxing/qrcode/detector
            wechat/zxing/qrcode/decoder
    )
    
    aux_source_directory(wechat W)
    aux_source_directory(wechat/detector WD)
    aux_source_directory(wechat/scale WS)
    aux_source_directory(wechat/zxing WZ)
    aux_source_directory(wechat/zxing/common WZC)
    aux_source_directory(wechat/zxing/common/binarizer WZCB)
    aux_source_directory(wechat/zxing/common/reedsolomon WZCR)
    aux_source_directory(wechat/zxing/qrcode WZQ)
    aux_source_directory(wechat/zxing/qrcode/decoder WZQD)
    aux_source_directory(wechat/zxing/qrcode/detector WZQD2)
    
    # Creates and names a library, sets it as either STATIC
    # or SHARED, and provides the relative paths to its source code.
    # You can define multiple libraries, and CMake builds them for you.
    # Gradle automatically packages shared libraries with your APK.
    
    add_library( # Sets the name of the library.
            native-lib
    
            # Sets the library as a shared library.
            SHARED
    
            # Provides a relative path to your source file(s).
            native-lib.cpp
            ${W}
            ${WD}
            ${WS}
            ${WZ}
            ${WZC}
            ${WZCB}
            ${WZCR}
            ${WZQ}
            ${WZQD}
            ${WZQD2}
            )
    
    # Searches for a specified prebuilt library and stores the path as a
    # variable. Because CMake includes system libraries in the search path by
    # default, you only need to specify the name of the public NDK library
    # you want to add. CMake verifies that the library exists before
    # completing its build.
    
    find_library( # Sets the name of the path variable.
            log-lib
    
            # Specifies the name of the NDK library that
            # you want CMake to locate.
            log)
    
    # Specifies libraries CMake should link to your target library. You
    # can link multiple libraries, such as libraries you define in this
    # build script, prebuilt third-party libraries, or system libraries.
    
    target_link_libraries( # Specifies the target library.
            native-lib
    
            # Links the target library to the log library
            # included in the NDK.
            ${log-lib} libopencv_java4)

然后，我们需要在Application中初始化`native-lib`

init {
        
        //System.loadLibrary("opencv_java4")
        System.loadLibrary("native-lib")
    }

接着，我们需要初始化扫码模型

下载[模型文件][Link 3],并导入到`res/raw`目录下

然后在Application中进行初始化，将模型文件复制到内部存储中

MMKV.initialize(this)
    GlobalScope.launch(Dispatchers.IO) {
        
        MMKV.defaultMMKV()?.encode(
            MMKVKey.WeChatQRCodeDetectProtoTxt,
            copyFromAssets(R.raw.detect_prototxt, "wechat_qrcode", "detect.prototxt")
        )
        MMKV.defaultMMKV()?.encode(
            MMKVKey.WeChatQRCodeDetectCaffeModel,
            copyFromAssets(R.raw.detect_caffemodel, "wechat_qrcode", "detect.caffemodel")
        )
        MMKV.defaultMMKV()?.encode(
            MMKVKey.WeChatQRCodeSrProtoTxt,
            copyFromAssets(R.raw.sr_prototxt, "wechat_qrcode", "sr.prototxt")
        )
        MMKV.defaultMMKV()?.encode(
            MMKVKey.WeChatQRCodeSrCaffeModel,
            copyFromAssets(R.raw.sr_caffemodel, "wechat_qrcode", "sr.caffemodel")
        )
    }
    
    fun Context.copyFromAssets(@RawRes resId: Int, targetDir:String, targetFileName:String): String {
        
        val targetDirFile = getDir(targetDir, Context.MODE_PRIVATE)
        val targetFile = File(targetDirFile, targetFileName)
        targetFile.outputStream().use {
        
            resources.openRawResource(resId).copyTo(it)
        }
        return targetFile.absolutePath
    }

在初始化WeChatQrCode的时候，将模型路径传入

mWeChatQRCode = WeChatQRCode(
        MMKV.defaultMMKV()?.decodeString(MMKVKey.WeChatQRCodeDetectProtoTxt) ?: "",
        MMKV.defaultMMKV()?.decodeString(MMKVKey.WeChatQRCodeDetectCaffeModel) ?: "",
        MMKV.defaultMMKV()?.decodeString(MMKVKey.WeChatQRCodeSrProtoTxt) ?: "",
        MMKV.defaultMMKV()?.decodeString(MMKVKey.WeChatQRCodeSrCaffeModel) ?: ""
    )

然后，我们只需要将摄像头中的图像，传递给微信扫码库进行解析即可

override fun analyze(image: ImageProxy) {
        
        val rectangles = ArrayList<Mat>()
        //进行解析并识别，并获得解析结果results
        val results : List<String> = weChatQRCode.detectAndDecode(gray(image), rectangles)
        Toast.makeText(this, results.toString(), Toast.LENGTH_SHORT).show()
        image.close()
    }
    
    fun gray(image: ImageProxy): Mat {
        
        val planeProxy = image.planes
        val width = image.width
        val height = image.height
        val yPlane = planeProxy[0].buffer
        val yPlaneStep = planeProxy[0].rowStride
        return Mat(height, width, CvType.CV_8UC1, yPlane, yPlaneStep.toLong())
    }

最后，别忘了申请权限

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.CAMERA" />
    
    ActivityCompat.requestPermissions(
            this,
            arrayOf(Manifest.permission.CAMERA, Manifest.permission.WRITE_EXTERNAL_STORAGE),
            1
    )

完工 !

附上源码地址 [https://download.csdn.net/download/EthanCo/20618652][https_download.csdn.net_download_EthanCo_20618652]

不过接入微信扫码库还是有一定门槛的，如果想要更快速的接入扫码库，可以使用华为的扫码库，某些扫码场景下，比微信扫码还要强 ! 详见我的另一篇博客 [Android 接入华为扫码库，实现堪比微信扫码的效果][Android]

> 感谢  
> https://blog.csdn.net/qq\_35054151/article/details/113488372  
> https://mp.weixin.qq.com/s/GBXkRuS\_fPsxr0uT5tR0Sw

[Link 1]: https://github.com/opencv/opencv_contrib/tree/master/modules/wechat_qrcode
[CNN_OpenCV]: https://blog.csdn.net/qq_35054151/article/details/113488372
[Android _ OpenCV]: https://www.cnblogs.com/xiaoxiaoqingyi/p/6676096.html
[Link 2]: https://opencv.org/releases/
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[wechat_qrcode.hpp]: https://github.com/opencv/opencv_contrib/blob/master/modules/wechat_qrcode/include/opencv2/
[opencv_contrib_modules_wechat_qrcode_src]: https://github.com/opencv/opencv_contrib/tree/master/modules/wechat_qrcode/src
[Link 3]: https://github.com/WeChatCV/opencv_3rdparty
[https_download.csdn.net_download_EthanCo_20618652]: https://download.csdn.net/download/EthanCo/20618652
[Android]: https://blog.csdn.net/EthanCo/article/details/120027060