OpenCV学习记录——2.使用OpenCV的Stitcher类来实现Android平台上的全景图拼接

电玩女神 2023-07-05 10:08 12阅读 0赞

### 文章目录 ###

*  1.前言
 *  2.常见的坑
 *  3.代码实现
 *  4.效果展示
 *  5.源码地址

# 1.前言 #

现在回看起来，距离之前的那篇博客，竟然已经整整隔了一个月！在这一个月里，为了编写这个完全没有接触过的跨平台程序，作者踩了许多（**超级多**）的坑，这里就简单记录一下，希望能帮助到读者

# 2.常见的坑 #

1.  安装OpenCV建议**直接引入第三方.so**，若想引入.a文件的话极其麻烦，集成的教程建议以下博客：  
    https://www.jianshu.com/p/697def71d779
2.  若build中出现错误，基本上都是**CMakeList**（在Android Studio现在用的是CMakeList而不是之前的Android.mk和Applicaiotn.mk）中的引用路径写错了，这里建议在写好路径时使用Ctrl+鼠标左键点击那个文件，查看是否可用进入到那个文件中，可用参考以下博客：  
    https://blog.csdn.net/qq\_34950682/article/details/95538383
3.  其他的常见错误，参考以下博客：  
    https://cloud.tencent.com/developer/article/1381003  
    https://blog.csdn.net/qq\_35366269/article/details/83275471

# 3.代码实现 #

1.  MainActivity.java:

package com.example.finalopencvproject;
    
    import androidx.annotation.NonNull;
    import androidx.annotation.Nullable;
    import androidx.appcompat.app.AppCompatActivity;
    import androidx.core.app.ActivityCompat;
    import androidx.core.content.ContextCompat;
    
    import android.Manifest;
    import android.annotation.TargetApi;
    import android.content.ContentUris;
    import android.content.Intent;
    import android.content.pm.PackageManager;
    import android.database.Cursor;
    import android.graphics.Bitmap;
    import android.graphics.BitmapFactory;
    import android.graphics.Canvas;
    import android.net.Uri;
    import android.os.Build;
    import android.os.Bundle;
    import android.provider.DocumentsContract;
    import android.provider.MediaStore;
    import android.util.Log;
    import android.view.View;
    import android.widget.Button;
    import android.widget.ImageView;
    import android.widget.TextView;
    import android.widget.Toast;
    
    import java.io.File;
    
    public class MainActivity extends AppCompatActivity { 
    
        /** * “选择图片”时的标识位 */
        private static final int CHOOSE_PHOTO = 1;
    
        /** * 显示图片位置的标识位 */
        private int DISPLAY_IMAGE = 1;
    
        /** * 图片拼接成功的标识位 */
        public final static int OK = 0;
    
        /** * 需要更多图片进行拼接的标识位 */
        public final static int ERR_NEED_MORE_IMGS = 1;
    
        /** * 图片不符合拼接标准的标识位 */
        public final static int ERR_HOMOGRAPHY_EST_FAIL = 2;
    
        /** * 图片参数处理失败的标识位 */
        public final static int ERR_CAMERA_PARAMS_ADJUST_FAIL = 3;
    
        /** * “选择图片1”的按钮实例 */
        private Button mBtnSelect;
    
        /** * “选择图片2”的按钮实例 */
        private Button mBtnSelect2;
    
        /** * “拼接图像”的按钮实例 */
        private Button mMerge;
    
        /** * 显示图像1的实例 */
        private ImageView mImageView;
    
        /** * 显示图像2的实例 */
        private ImageView mImageView2;
    
        /** * 图像1的实例 */
        private Bitmap mBitmap;
    
        /** * 图像2的实例 */
        private Bitmap mBitmap2;
    
        /** * 存储待拼接的图像集合 */
        private String[] mImagePath = new String[]{ "abc","abc"};
    
        /** * 存储待拼接的图像集合的索引 */
        private static int i = 0;
    
        // 引用native方法
        static { 
            System.loadLibrary("native-lib");
        }
    
        @Override
        protected void onCreate(Bundle savedInstanceState) { 
            // 初始化布局
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            // 初始化控件实例
            mBtnSelect = findViewById(R.id.btn_select);
            mBtnSelect2 = findViewById(R.id.btn_select2);
            mMerge = findViewById(R.id.btn_merge);
            mImageView = findViewById(R.id.imageView);
            mImageView2 = findViewById(R.id.imageView2);
    
            // “选择图片1”的点击方法
            mBtnSelect.setOnClickListener(new View.OnClickListener() { 
                @Override
                public void onClick(View v) { 
                    if(ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED){ 
                        ActivityCompat.requestPermissions(MainActivity.this,new String[]{ Manifest.permission.WRITE_EXTERNAL_STORAGE},1);
                    }else{ 
                        DISPLAY_IMAGE = 1;
                        openAlbum();
                    }
                }
            });
    
            // “选择图片2”的点击方法
            mBtnSelect2.setOnClickListener(new View.OnClickListener() { 
                @Override
                public void onClick(View v) { 
                    if(ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED){ 
                        ActivityCompat.requestPermissions(MainActivity.this,new String[]{ Manifest.permission.WRITE_EXTERNAL_STORAGE},1);
                    }else{ 
                        DISPLAY_IMAGE = 2;
                        openAlbum();
                    }
                }
            });
    
            // “拼接图像”的点击事件
            mMerge.setOnClickListener(new View.OnClickListener() { 
                @Override
                public void onClick(View v) { 
                    mergeBitmap(mImagePath,new onStitchResultListener(){ 
    
                        @Override
                        public void onSuccess(Bitmap bitmap) { 
                            Toast.makeText(MainActivity.this,"图片拼接成功！",Toast.LENGTH_LONG).show();
                            replaceImage(bitmap);
                        }
    
                        @Override
                        public void onError(String errorMsg) { 
                            Toast.makeText(MainActivity.this,"图片拼接失败！",Toast.LENGTH_LONG).show();
                            System.out.println(errorMsg);
                        }
                    });
                }
            });
    
            // 调用Native程序的示例
            /* TextView tv = findViewById(R.id.sample_text); tv.setText(stringFromJNI()); */
        }
    
        /** * 动态申请权限的处理方法 * @param requestCode * @param permissions * @param grantResults */
        @Override
        public void onRequestPermissionsResult(int requestCode,String[] permissions,int[] grantResults){ 
            switch (requestCode){ 
                case 1:
                    if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){ 
                        openAlbum();
                    }else { 
                        Toast.makeText(this,"拒绝授权将无法使用程序",Toast.LENGTH_SHORT).show();
                        finish();
                    }
                    break;
                default:
                    break;
            }
        }
    
        /** * 打开相册 */
        private void openAlbum(){ 
            Intent intent = new Intent("android.intent.action.GET_CONTENT");
            intent.setType("image/*");
            startActivityForResult(intent,CHOOSE_PHOTO);
        }
    
        /* OpenCV的测试方法 private Bitmap hivePic() { Log.e(TAG, "hivePic: HHHA:0====>"); Mat des = new Mat(); Mat src = new Mat(); Bitmap srcBit = BitmapFactory.decodeResource(getResources(), R.drawable.test2); Utils.bitmapToMat(srcBit, src); Bitmap grayBit = Bitmap.createBitmap(src.cols(), src.rows(), Bitmap.Config.ARGB_8888); Imgproc.cvtColor(src, des, Imgproc.COLOR_BGR2GRAY); Utils.matToBitmap(des, grayBit); return grayBit; } */
    
        /** * Activity的回调处理 * @param requestCode 请求参数 * @param resultCode 结果参数 * @param data 数据 */
        @Override
        protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) { 
            super.onActivityResult(requestCode, resultCode, data);
            switch (requestCode) { 
                case CHOOSE_PHOTO:
                    if (resultCode  == RESULT_OK) { 
                        if (Build.VERSION.SDK_INT >= 19) { 
                            handleImageOnKitKat(data); /* 4.4及以上系统使用这个方法处理图片 */
                        } else { 
                            handleImageBeforeKitKat(data); /* 4.4及以下系统使用这个方法处理图片 */
                        }
                    }
                    break;
                default:
                    break;
            }
        }
    
        /** * 4.4及以上系统处理图片的方法 * @param data 数据 */
        @TargetApi(19)
        private void handleImageOnKitKat(Intent data){ 
            String imagePath = null;
            Uri uri = data.getData();
            if(DocumentsContract.isDocumentUri(this,uri)){ 
                String docId = DocumentsContract.getDocumentId(uri);
                if("com.android.providers.media.documents".equals(uri.getAuthority())){ 
                    String id = docId.split(":")[1];
                    String selection = MediaStore.Images.Media._ID + "=" + id;
                    imagePath = getImagePath(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,selection);
                }else if ("com.android.provideres.downloads.documents".equals(uri.getAuthority())){ 
                    Uri contentUri = ContentUris.withAppendedId(Uri.parse("content://downloads/public_downloads"),Long.valueOf(docId));
                    imagePath = getImagePath(contentUri,null);
                }
            }else if ("content".equalsIgnoreCase(uri.getScheme())){ 
                imagePath = getImagePath(uri,null);
            }else if ("file".equalsIgnoreCase(uri.getScheme())){ 
                imagePath = uri.getPath();
            }
            displayImage(imagePath);
        }
    
        /** * 4.4以下系统处理图片的方法 * @param data 数据 */
        private void handleImageBeforeKitKat(Intent data){ 
            Uri uri = data.getData();
            String imagePath = getImagePath(uri,null);
            displayImage(imagePath);
        }
    
        /** * 获取图片路径 * @param uri 图片Url * @param selection 默认为空值 * @return */
        private String getImagePath(Uri uri,String selection){ 
            String path = null;
            Cursor cursor = getContentResolver().query(uri,null,selection,null,null);
            if(cursor != null){ 
                if(cursor.moveToFirst()){ 
                    path = cursor.getString(cursor.getColumnIndex(MediaStore.Images.Media.DATA));
                }
                cursor.close();
            }
            mImagePath[i++] = path;
            return path;
        }
    
        /** * 图片显示的方法 * @param imagePath 图片路径 */
        private void displayImage(String imagePath){ 
            if(imagePath != null){ 
                Bitmap bitmap = BitmapFactory.decodeFile(imagePath);
                if (DISPLAY_IMAGE == 1){ 
                    mImageView.setImageBitmap(bitmap);
                    mBitmap = bitmap;
                }
                else { 
                    mImageView2.setImageBitmap(bitmap);
                    mBitmap2 = bitmap;
                }
            }else{ 
                Toast.makeText(this,"获取图片失败",Toast.LENGTH_SHORT).show();
            }
        }
    
        /** * 拼接图片的方法 * @param paths 图像URL的集合 * @param listener 监听器回调 * @return */
        private void mergeBitmap(String paths[], @NonNull onStitchResultListener listener) { 
            for (String path : paths) { 
                if (!new File(path).exists()) { 
                    listener.onError("无法读取文件或文件不存在:" + path);
                    return;
                }
            }
            int wh[] = stitchImages(paths);
            switch (wh[0]) { 
                case OK: { 
                    Bitmap bitmap = Bitmap.createBitmap(wh[1], wh[2], Bitmap.Config.ARGB_8888);
                    int result = getBitmap(bitmap);
                    if (result == OK && bitmap != null){ 
                        listener.onSuccess(bitmap);
                    }else{ 
                        listener.onError("图片合成失败");
                    }
                }
                break;
                case ERR_NEED_MORE_IMGS: { 
                    listener.onError("需要更多图片");
                    return;
                }
                case ERR_HOMOGRAPHY_EST_FAIL: { 
                    listener.onError("图片对应不上");
                    return;
                }
                case ERR_CAMERA_PARAMS_ADJUST_FAIL: { 
                    listener.onError("图片参数处理失败");
                    return;
                }
            }
        }
    
        /** * 拼接监听回调的接口 */
        public interface onStitchResultListener { 
    
            void onSuccess(Bitmap bitmap);
    
            void onError(String errorMsg);
        }
    
        /** * 替换图片的方法 * @param bitmap 拼接后的图像 */
        private void replaceImage(Bitmap bitmap) { 
            mImageView.setImageBitmap(bitmap);
            mImageView2.setVisibility(View.GONE);
            mBtnSelect.setVisibility(View.GONE);
            mBtnSelect2.setVisibility(View.GONE);
            mMerge.setVisibility(View.GONE);
        }
    
        /** * 调用底层的JNI方法（示例） * @return */
        // public native String stringFromJNI();
        private native static int[] stitchImages(String path[]);
    
        private native static void getMat(long mat);
    
        private native static int getBitmap(Bitmap bitmap);
    }

1.  CMakeList.txt

# 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 3.4.1)
    
    # 包含opencv的头文件
    include_directories(../../../opencv/jni/include)
    
    # 静态方式导入库
    #add_library(opencv_calib3d STATIC IMPORTED)
    #add_library(opencv_core STATIC IMPORTED)
    #add_library(opencv_features2d STATIC IMPORTED)
    #add_library(opencv_flann STATIC IMPORTED)
    #add_library(opencv_imgcodecs STATIC IMPORTED)
    #add_library(opencv_imgproc STATIC IMPORTED)
    #add_library(opencv_stitching STATIC IMPORTED)
    #
    #add_library(IlmImf STATIC IMPORTED)
    #add_library(libjasper STATIC IMPORTED)
    #add_library(libjpeg STATIC IMPORTED)
    #add_library(libpng STATIC IMPORTED)
    ##add_library(libprotobuf STATIC IMPORTED)
    #add_library(libtiff STATIC IMPORTED)
    #add_library(libwebp STATIC IMPORTED)
    #add_library(tbb STATIC IMPORTED)
    #add_library(tegra_hal STATIC IMPORTED)
    #
    ## 设置库路径
    #set_target_properties(opencv_calib3d PROPERTIES IMPORTED_LOCATION ../../../libs/armeabi-v7a/libopencv_calib3d.a)
    #set_target_properties(opencv_core PROPERTIES IMPORTED_LOCATION ../../../libs/armeabi-v7a/libopencv_core.a)
    #set_target_properties(opencv_features2d PROPERTIES IMPORTED_LOCATION ../../../libs/armeabi-v7a/libopencv_features2d.a)
    #set_target_properties(opencv_flann PROPERTIES IMPORTED_LOCATION ../../../libs/armeabi-v7a/libopencv_flann.a)
    #set_target_properties(opencv_imgcodecs PROPERTIES IMPORTED_LOCATION ../../../libs/armeabi-v7a/libopencv_imgcodecs.a)
    #set_target_properties(opencv_imgproc PROPERTIES IMPORTED_LOCATION ../../../libs/armeabi-v7a/libopencv_imgproc.a)
    #set_target_properties(opencv_stitching PROPERTIES IMPORTED_LOCATION ../../../libs/armeabi-v7a/libopencv_stitching.a)
    #
    #
    #set_target_properties(IlmImf PROPERTIES IMPORTED_LOCATION ../../../opencv/3rdparty/libs/armeabi-v7a/libIlmImf.a)
    #set_target_properties(libjasper PROPERTIES IMPORTED_LOCATION ../../../opencv/3rdparty/libs/armeabi-v7a/liblibjasper.a)
    #set_target_properties(libjpeg PROPERTIES IMPORTED_LOCATION ../../../opencv/3rdparty/libs/armeabi-v7a/liblibjpeg.a)
    #set_target_properties(libpng PROPERTIES IMPORTED_LOCATION ../../../opencv/3rdparty/libs/armeabi-v7a/liblibpng.a)
    ##set_target_properties(libprotobuf PROPERTIES IMPORTED_LOCATION ${PROJECT_SOURCE_DIR}/opencv/3rdparty/libs/${ANDROID_ABI}/liblibprotobuf.a)
    #set_target_properties(libtiff PROPERTIES IMPORTED_LOCATION ../../../opencv/3rdparty/libs/armeabi-v7a/liblibtiff.a)
    #set_target_properties(libwebp PROPERTIES IMPORTED_LOCATION ../../../opencv/3rdparty/libs/armeabi-v7a/liblibwebp.a)
    #set_target_properties(tbb PROPERTIES IMPORTED_LOCATION ../../../opencv/3rdparty/libs/armeabi-v7a/libtbb.a)
    #set_target_properties(tegra_hal PROPERTIES IMPORTED_LOCATION ../../../opencv/3rdparty/libs/armeabi-v7a/libtegra_hal.a)
    #
    #set(SRC_DIR ../../../src/main/cpp)
    #
    #file(GLOB_RECURSE CPP_SRCS "${SRC_DIR}/*.cpp")  #指定当前目录下的所有.cpp文件（包括子目录）
    
    
    # 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)
    
    
    add_library(
            opencvc7 #最终在build中生成的so名字
            SHARED
            IMPORTED)
    set_target_properties(
            opencvc7 #最终在build中生成的so名字
            PROPERTIES IMPORTED_LOCATION
            ${CMAKE_CURRENT_SOURCE_DIR}../../../../libs/${ANDROID_ABI}/libopencv_java3.so)
    # 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
            opencvc7
    
    #        opencv_stitching
    #        opencv_features2d
    #        opencv_flann
    #        opencv_imgcodecs
    #        opencv_imgproc
    #        opencv_core
    #        opencv_calib3d
    #
    #        IlmImf
    #        libjasper
    #        libjpeg
    #        libpng
    #        #libprotobuf
    #        libtiff
    #        libwebp
    #        tbb
    #        tegra_hal
    
            # Links the target library to the log library
            # included in the NDK.
            jnigraphics
            ${log-lib})

1.  native-lib.cpp，注意修改相应的方法名，不然**MainActivity无法调用**

//#include <jni.h>
    //#include <string>
    //
    //extern "C" JNIEXPORT jstring JNICALL
    //Java_com_example_finalopencvproject_MainActivity_stringFromJNI(
    // JNIEnv *env,
    // jobject /* this */) { 
    // std::string hello = "Hello from C++";
    // return env->NewStringUTF(hello.c_str());
    //}
    #include <jni.h>
    #include <opencv2/opencv.hpp>
    #include <opencv2/core/base.hpp>
    #import "opencv2/stitching.hpp"
    #import "opencv2/imgcodecs.hpp"
    
    #define BORDER_GRAY_LEVEL 0
    
    #include <android/log.h>
    #include <android/bitmap.h>
    
    #define LOG_TAG "DDLog-jni"
    #define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG, __VA_ARGS__)
    #define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG,LOG_TAG, __VA_ARGS__)
    #define LOGW(...) __android_log_print(ANDROID_LOG_WARN,LOG_TAG, __VA_ARGS__)
    #define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG, __VA_ARGS__)
    #define LOGF(...) __android_log_print(ANDROID_LOG_FATAL,LOG_TAG, __VA_ARGS__)
    using namespace cv;
    using namespace std;
    char filepath1[100] = "/storage/emulated/0/panorama_stitched.jpg";
    cv::Mat finalMat;
    extern "C"
    JNIEXPORT jintArray JNICALL
    Java_com_example_finalopencvproject_MainActivity_stitchImages(JNIEnv *env, jclass type,
                                                            jobjectArray paths) { 
        jstring jstr;
        jsize len = env->GetArrayLength(paths);
        std::vector<cv::Mat> mats;
        for (int i = 0; i < len; i++) { 
            jstr = (jstring) env->GetObjectArrayElement(paths, i);
            const char *path = (char *) env->GetStringUTFChars(jstr, 0);
            LOGI("path %s", path);
            cv::Mat mat = cv::imread(path);
    // cvtColor(mat, mat, CV_RGBA2RGB);
            mats.push_back(mat);
        }
        LOGI("开始拼接......");
        cv::Stitcher stitcher = cv::Stitcher::createDefault(false);
        //stitcher.setRegistrationResol(0.6);
        // stitcher.setWaveCorrection(false);
        /*=match_conf默认是0.65，我选0.8，选太大了就没特征点啦,0.8都失败了*/
        detail::BestOf2NearestMatcher *matcher = new detail::BestOf2NearestMatcher(false, 0.5f);
        stitcher.setFeaturesMatcher(matcher);
        stitcher.setBundleAdjuster(new detail::BundleAdjusterRay());
        stitcher.setSeamFinder(new detail::NoSeamFinder);
        stitcher.setExposureCompensator(new detail::NoExposureCompensator());//曝光补偿
        stitcher.setBlender(new detail::FeatherBlender());
        Stitcher::Status state = stitcher.stitch(mats, finalMat);
        //此时finalMat是bgr类型
        LOGI("拼接结果: %d", state);
    // finalMat = clipping(finalMat);
        jintArray jint_arr = env->NewIntArray(3);
        jint *elems = env->GetIntArrayElements(jint_arr, NULL);
        elems[0] = state;//状态码
        elems[1] = finalMat.cols;//宽
        elems[2] = finalMat.rows;//高
        if (state == cv::Stitcher::OK){ 
            LOGI("拼接成功: OK");
        }else{ 
            LOGI("拼接失败:fail code %d",state);
        }
        //同步
        env->ReleaseIntArrayElements(jint_arr, elems, 0);
    // bool isSave = cv::imwrite(filepath1, finalMat);
    // LOGI("是否存储成功:%d",isSave);
        return jint_arr;
    }
    extern "C"
    JNIEXPORT void JNICALL
    Java_com_example_finalopencvproject_MainActivity_getMat(JNIEnv *env, jclass type, jlong mat) { 
        LOGI("开始获取mat...");
        Mat *res = (Mat *) mat;
        res->create(finalMat.rows, finalMat.cols, finalMat.type());
        memcpy(res->data, finalMat.data, finalMat.rows * finalMat.step);
        LOGI("获取成功");
    }
    //将mat转化成bitmap
    void MatToBitmap(JNIEnv *env, Mat &mat, jobject &bitmap, jboolean needPremultiplyAlpha) { 
        AndroidBitmapInfo info;
        void *pixels = 0;
        Mat &src = mat;
        try { 
            LOGD("nMatToBitmap");
            CV_Assert(AndroidBitmap_getInfo(env, bitmap, &info) >= 0);
            LOGD("nMatToBitmap1");
            CV_Assert(info.format == ANDROID_BITMAP_FORMAT_RGBA_8888 ||
                      info.format == ANDROID_BITMAP_FORMAT_RGB_565);
            LOGD("nMatToBitmap2 :%d : %d :%d", src.dims, src.rows, src.cols);
            CV_Assert(src.dims == 2 && info.height == (uint32_t) src.rows &&
                      info.width == (uint32_t) src.cols);
            LOGD("nMatToBitmap3");
            CV_Assert(src.type() == CV_8UC1 || src.type() == CV_8UC3 || src.type() == CV_8UC4);
            LOGD("nMatToBitmap4");
            CV_Assert(AndroidBitmap_lockPixels(env, bitmap, &pixels) >= 0);
            LOGD("nMatToBitmap5");
            CV_Assert(pixels);
            LOGD("nMatToBitmap6");
            if (info.format == ANDROID_BITMAP_FORMAT_RGBA_8888) { 
                Mat tmp(info.height, info.width, CV_8UC4, pixels);
    // Mat tmp(info.height, info.width, CV_8UC3, pixels);
                if (src.type() == CV_8UC1) { 
                    LOGD("nMatToBitmap: CV_8UC1 -> RGBA_8888");
                    cvtColor(src, tmp, COLOR_GRAY2RGBA);
                } else if (src.type() == CV_8UC3) { 
                    LOGD("nMatToBitmap: CV_8UC3 -> RGBA_8888");
    // cvtColor(src, tmp, COLOR_RGB2RGBA);
    // cvtColor(src, tmp, COLOR_RGB2RGBA);
                    cvtColor(src, tmp, COLOR_BGR2RGBA);
    // src.copyTo(tmp);
                } else if (src.type() == CV_8UC4) { 
                    LOGD("nMatToBitmap: CV_8UC4 -> RGBA_8888");
                    if (needPremultiplyAlpha)
                        cvtColor(src, tmp, COLOR_RGBA2mRGBA);
                    else
                        src.copyTo(tmp);
                }
            } else { 
                // info.format == ANDROID_BITMAP_FORMAT_RGB_565
                Mat tmp(info.height, info.width, CV_8UC2, pixels);
                if (src.type() == CV_8UC1) { 
                    LOGD("nMatToBitmap: CV_8UC1 -> RGB_565");
                    cvtColor(src, tmp, COLOR_GRAY2BGR565);
                } else if (src.type() == CV_8UC3) { 
                    LOGD("nMatToBitmap: CV_8UC3 -> RGB_565");
    // src.copyTo(tmp);
                    cvtColor(src, tmp, COLOR_RGB2BGR565);
                } else if (src.type() == CV_8UC4) { 
                    LOGD("nMatToBitmap: CV_8UC4 -> RGB_565");
                    cvtColor(src, tmp, COLOR_RGBA2BGR565);
                }
            }
            AndroidBitmap_unlockPixels(env, bitmap);
            return;
        } catch (const cv::Exception &e) { 
            AndroidBitmap_unlockPixels(env, bitmap);
            LOGE("nMatToBitmap catched cv::Exception: %s", e.what());
            jclass je = env->FindClass("org/opencv/core/CvException");
            if (!je) je = env->FindClass("java/lang/Exception");
            env->ThrowNew(je, e.what());
            return;
        } catch (...) { 
            AndroidBitmap_unlockPixels(env, bitmap);
            LOGE("nMatToBitmap catched unknown exception (...)");
            jclass je = env->FindClass("java/lang/Exception");
            env->ThrowNew(je, "Unknown exception in JNI code {nMatToBitmap}");
            return;
        }
    }
    
    extern "C"
    JNIEXPORT jint JNICALL
    Java_com_example_finalopencvproject_MainActivity_getBitmap(JNIEnv *env, jclass type, jobject bitmap) { 
        if (finalMat.dims != 2){ 
            return -1;
        }
        MatToBitmap(env,finalMat,bitmap,false);
        return 0;
    }

1.  activity\_main.xml

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical">
    
        <Button android:id="@+id/btn_select" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="选择图片1"/>
    
        <Button android:id="@+id/btn_select2" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="选择图片2"/>
    
        <Button android:id="@+id/btn_merge" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="拼接图像"/>
    
        <LinearLayout android:layout_width="match_parent" android:layout_height="match_parent">
    
    
            <ImageView android:id="@+id/imageView" android:layout_width="0dp" android:layout_height="match_parent" android:layout_weight="1" />
    
            <ImageView android:id="@+id/imageView2" android:layout_width="0dp" android:layout_height="match_parent" android:layout_weight="1"/>
        </LinearLayout>
    
    </LinearLayout>

1.  build.gradle

apply plugin: 'com.android.application'
    
    android { 
        compileSdkVersion 29
        buildToolsVersion "29.0.3"
        defaultConfig { 
            applicationId "com.example.finalopencvproject"
            minSdkVersion 15
            targetSdkVersion 27
            versionCode 1
            versionName "1.0"
            testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
            externalNativeBuild { 
                cmake { 
                    cppFlags "-std=c++11 -frtti -fexceptions -lz"
                    //cppFlags "-fexceptions"
                    abiFilters 'armeabi-v7a','x86'
                }
            }
        }
        buildTypes { 
            release { 
                minifyEnabled false
                proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
                ndk{ 
                    abiFilters "armeabi-v7a",'x86'
                }
            }
            debug{ 
                ndk{ 
                    abiFilters "armeabi-v7a",'x86'
                }
            }
        }
        sourceSets{ 
            main{ 
                jniLibs.srcDirs=['libs']
            }
        }
        externalNativeBuild { 
            cmake { 
                path "src/main/cpp/CMakeLists.txt"
                version "3.10.2"
            }
        }
    }
    
    dependencies { 
        implementation fileTree(dir: 'libs', include: ['*.jar'])
        implementation 'androidx.appcompat:appcompat:1.1.0'
        implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
        testImplementation 'junit:junit:4.12'
        androidTestImplementation 'androidx.test.ext:junit:1.1.1'
        androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
    }

# 4.效果展示 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70 1]

# 5.源码地址 #

为了满足读者的需要，这里放出源码的仓库地址，仅供参考：  
[Android平台上实现全景图拼接][Android]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200213174534729.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20200213174545917.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxMTUxNjU5,size_16,color_FFFFFF,t_70
[Android]: https://gitee.com/moxitao/AndroidOpenCV/tree/master