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Android基于opencv4.6.0实现人脸识别功能_android opencv 人脸对比 github

作者：你好赵伟 | 2024-05-14 02:07:31

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android opencv 人脸对比 github

前言

步骤：

1.整合opencv

2.获取相机的SurfaceView传到native层去检测(亦或是不断的获取SurfaceView的Bitmap，传到native层)

3.检测人脸，在本地保存人脸特征信息

4.上传至后台(不实现)

人脸识别实现的思路(例：人脸登录)

1.人脸信息录入

1.1获取相机的Bitmap，检测人脸(保证人脸信息比较精准) 人脸要足够大，当前范围内人脸只能有一张人脸，正常、眨眼睛、张嘴巴(3张人脸信息)

1.2获取到人脸必须要保存人脸特征信息，然后上传至后台(后台会再次做算法优化)，保存到数据库

2.人脸特征值匹配

2.1获取相机的Bitmap，检测人脸(保证人脸信息比较精准) 人脸要足够大，当前范围内人脸只能有一张人脸，正常、眨眼睛、张嘴巴(3张人脸信息)

2.2从后台去查询用户进行登录

一.Android Studio配置opencv

1.opencv资源获取

opencv官网：Home - OpenCV 

opencv最新的版本是4.6.0于2022年06月07日发布，4.6.0网址：OpenCV 4.6.0 Is Now Available! - OpenCV

opencv 4.6.0android sdk 下载链接https://nchc.dl.sourceforge.net/project/opencvlibrary/4.6.0/opencv-4.6.0-android-sdk.zip

2.解压opencv-4.6.0-android-sdk.zip文件

解压之后的文件夹:OpenCV-android-sdk

​

​

samples： 所有与android相关的一些示例代码，基本全部是java代码，封装了很多功能(图片转成灰度，高斯模糊，边缘检测)

sdk：所有的资源，so库，头文件，NDK自己动手写

源码下载链接：https://github.com/opencv/opencv/archive/4.6.0.zip

3.新建Android项目(native c++)

C++ Standard 选择C++11

 

 在main目录下新建jni文件夹

 将OpenCV-android-sdk\sdk\native\jni下的include文件夹复制至项目中的jni文件夹下

 

 将OpenCV-android-sdk\sdk\native\libs下的armeabi-v7a文件夹复制至jni文件夹下

 

 3.1配置CMakeLists.txt

引入头文件

 添加opencv库并设置目标属性(注意路径)

 添加目标链接库opencv-lib

 CMakeLists.txt内容：

  1. # For more information about using CMake with Android Studio, read the
  2. # documentation: https://d.android.com/studio/projects/add-native-code.html
  3.  
  4. # Sets the minimum version of CMake required to build the native library.
  5.  
  6. cmake_minimum_required(VERSION 3.10.2)
  7.  
  8. # Declares and names the project.
  9.  
  10. project("opencvtestapplication")
  11. #需要引入我们头文件，以这个配置的目录为基准
  12. include_directories(${CMAKE_SOURCE_DIR}/../jni/include)
  13.  
  14. # Creates and names a library, sets it as either STATIC
  15. # or SHARED, and provides the relative paths to its source code.
  16. # You can define multiple libraries, and CMake builds them for you.
  17. # Gradle automatically packages shared libraries with your APK.
  18.  
  19. add_library( # Sets the name of the library.
  20.              native-lib
  21.  
  22.              # Sets the library as a shared library.
  23.              SHARED
  24.  
  25.              # Provides a relative path to your source file(s).
  26.              native-lib.cpp )
  27. # 添加opencv的库
  28. add_library(
  29.         opencv-lib
  30.         SHARED
  31.         IMPORTED)
  32. set_target_properties(
  33.         opencv-lib
  34.         PROPERTIES IMPORTED_LOCATION
  35.         ${CMAKE_SOURCE_DIR}/../jni/armeabi-v7a/libopencv_java4.so)
  36.  
  37. # Searches for a specified prebuilt library and stores the path as a
  38. # variable. Because CMake includes system libraries in the search path by
  39. # default, you only need to specify the name of the public NDK library
  40. # you want to add. CMake verifies that the library exists before
  41. # completing its build.
  42.  
  43. find_library( # Sets the name of the path variable.
  44.               log-lib
  45.  
  46.               # Specifies the name of the NDK library that
  47.               # you want CMake to locate.
  48.               log )
  49.  
  50. # Specifies libraries CMake should link to your target library. You
  51. # can link multiple libraries, such as libraries you define in this
  52. # build script, prebuilt third-party libraries, or system libraries.
  53.  
  54. target_link_libraries( # Specifies the target library.
  55.                        native-lib opencv-lib
  56.  
  57.                        # Links the target library to the log library
  58.                        # included in the NDK.
  59.                        ${log-lib} )

3.2修改app下的build.gradle文件 只支持armv7

 同步运行项目至手机设备

出现如下图所示错误：

 java.lang.UnsatisfiedLinkError: dlopen failed: library "libc++_shared.so" not found

解决方式如下：

修改app下的build.gradle文件

 重新同步项目并运行项目至手机设备

3.3新建FaceDetection类

FaceDetection内容如下：

  1. package com.suoer.ndk.opencvtestapplication;
  2.  
  3. import android.graphics.Bitmap;
  4.  
  5. public class FaceDetection {
  6.     // Used to load the 'native-lib' library on application startup.
  7.     static {
  8.         System.loadLibrary("native-lib");
  9.     }
  10.     /**
  11.      * 检测人脸并保存人脸信息
  12.      * @param faceBitmap
  13.      */
  14.  
  15.     public native int faceDetectionSaveInfo(Bitmap faceBitmap);
  16.  
  17.     /**
  18.      * 加载人脸识别的分类器文件
  19.      * @param filePath
  20.      */
  21.     public native boolean loadCascade(String filePath);
  22.  
  23.  
  24. }

3.4修改MainActivity类

因为需要拍照以及保存图片，所以需要权限处理。这里使用rxpermissions

rxpermissions的具体使用请参照github链接：GitHub - tbruyelle/RxPermissions: Android runtime permissions powered by RxJava2

因为保存图片是耗时操作，需要开启子线程完成，所以需要处理线程问题。这里使用rxandroid

rxandroid的具体使用请参照github链接：GitHub - ReactiveX/RxAndroid: RxJava bindings for Android

修改app下的build.gradle文件

 app下的build.gradle文件内容：

  1. plugins {
  2.     id 'com.android.application'
  3. }
  4.  
  5. android {
  6.     compileSdkVersion 32
  7.     buildToolsVersion "32.0.0"
  8.  
  9.     defaultConfig {
  10.         applicationId "com.suoer.ndk.opencvtestapplication"
  11.         minSdkVersion 16
  12.         targetSdkVersion 32
  13.         versionCode 1
  14.         versionName "1.0"
  15.  
  16.         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
  17.         externalNativeBuild {
  18.             cmake {
  19.                 cppFlags "-std=c++11 -Wno-nonportable-include-path -Wno-deprecated-register -Wno-writable-strings"
  20.                 //远程下载
  21.                 arguments "-DANDROID_STL=c++_shared"
  22.  
  23.             }
  24.         }
  25.         ndk {
  26.             abiFilters("armeabi-v7a")
  27.         }
  28.     }
  29.  
  30.     buildTypes {
  31.         release {
  32.             minifyEnabled false
  33.             proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
  34.         }
  35.     }
  36.     externalNativeBuild {
  37.         cmake {
  38.             path "src/main/cpp/CMakeLists.txt"
  39.             version "3.10.2"
  40.         }
  41.     }
  42.     compileOptions {
  43.         sourceCompatibility JavaVersion.VERSION_1_8
  44.         targetCompatibility JavaVersion.VERSION_1_8
  45.     }
  46. }
  47.  
  48. dependencies {
  49.  
  50.     implementation 'androidx.appcompat:appcompat:1.1.0'
  51.     implementation 'com.google.android.material:material:1.1.0'
  52.     implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
  53.     testImplementation 'junit:junit:4.+'
  54.     androidTestImplementation 'androidx.test.ext:junit:1.1.1'
  55.     androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
  56.     implementation 'com.github.tbruyelle:rxpermissions:0.12'
  57.     implementation 'io.reactivex.rxjava3:rxandroid:3.0.0'
  58. }

修改项目下的build.gradle文件

 项目下的build.gradle文件内容：

  1. // Top-level build file where you can add configuration options common to all sub-projects/modules.
  2. buildscript {
  3.     repositories {
  4.         google()
  5.         jcenter()
  6.     }
  7.     dependencies {
  8.         classpath "com.android.tools.build:gradle:4.1.0"
  9.  
  10.         // NOTE: Do not place your application dependencies here; they belong
  11.         // in the individual module build.gradle files
  12.     }
  13. }
  14.  
  15. allprojects {
  16.     repositories {
  17.         google()
  18.         jcenter()
  19.         maven { url 'https://jitpack.io' }
  20.         maven { url "https://oss.jfrog.org/libs-snapshot" }
  21.     }
  22. }
  23.  
  24. task clean(type: Delete) {
  25.     delete rootProject.buildDir
  26. }

修改AndroidManifest.xml添加权限

 

  1.     <uses-permission android:name="android.permission.CAMERA" />
  2.     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
  3.     <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

MainActivity类内容如下：

  1. package com.suoer.ndk.opencvtestapplication;
  2.  
  3. import android.Manifest;
  4. import android.content.Context;
  5. import android.content.pm.PackageManager;
  6. import android.graphics.Bitmap;
  7. import android.os.Bundle;
  8. import android.util.Log;
  9. import android.view.SurfaceView;
  10. import android.view.View;
  11. import android.view.Window;
  12. import android.view.WindowManager;
  13. import android.widget.Button;
  14. import android.widget.ImageView;
  15. import android.widget.Toast;
  16.  
  17. import com.suoer.ndk.opencvtestapplication.camerahandle.BitmapInterface;
  18. import com.suoer.ndk.opencvtestapplication.camerahandle.CameraSurfaceHolder;
  19. import com.suoer.ndk.opencvtestapplication.camerahandle.FrontCamera;
  20. import com.suoer.ndk.opencvtestapplication.camerahandle.SaveImageTask;
  21. import com.suoer.ndk.opencvtestapplication.camerahandle.SurfaceViewCallback;
  22. import com.tbruyelle.rxpermissions3.RxPermissions;
  23.  
  24. import java.io.ByteArrayOutputStream;
  25. import java.io.File;
  26. import java.io.FileOutputStream;
  27. import java.io.IOException;
  28. import java.io.InputStream;
  29.  
  30. import androidx.appcompat.app.AppCompatActivity;
  31. import io.reactivex.rxjava3.functions.Consumer;
  32.  
  33. public class MainActivity extends AppCompatActivity {
  34.     private static final String TAG = "MainActivity";
  35.     private SurfaceView mSurfaceView;
  36.     private ImageView faceImg;
  37.     private Button faceDetectionBtn;
  38.  
  39.     private FaceDetection mFaceDetection;
  40.     private File mCascadeFile;
  41.  
  42.     private CameraSurfaceHolder mCameraSurfaceHolder=new CameraSurfaceHolder();
  43.     private SurfaceViewCallback mSurfaceViewCallback;
  44.     private FrontCamera mFrontCamera;
  45.  
  46.  
  47.  
  48.     @Override
  49.     protected void onCreate(Bundle savedInstanceState) {
  50.         super.onCreate(savedInstanceState);
  51.         requestWindowFeature(Window.FEATURE_NO_TITLE);
  52.         getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
  53.         initView();
  54.         applyPermission();
  55.         initFaceDetection();
  56.     }
  57.  
  58.     private void initFaceDetection() {
  59.         copyCascadeFile();
  60.         mFaceDetection = new FaceDetection();
  61.         if (mFaceDetection != null) {
  62.             boolean load = mFaceDetection.loadCascade(mCascadeFile.getAbsolutePath());
  63.             if (load) {
  64.                 Toast.makeText(this, "加载分类器文件成功！", Toast.LENGTH_SHORT).show();
  65.             } else {
  66.                 Toast.makeText(this, "加载分类器文件失败！", Toast.LENGTH_SHORT).show();
  67.             }
  68.         }
  69.  
  70.     }
  71.  
  72.     //申请权限
  73.     private void applyPermission() {
  74.         if (!checkCameraHardware(this)) {
  75.             return;
  76.         }
  77.         RxPermissions rxPermissions = new RxPermissions(this);
  78.         rxPermissions.request(Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE, Manifest.permission.CAMERA).subscribe(new Consumer<Boolean>() {
  79.             @Override
  80.             public void accept(Boolean aBoolean) throws Throwable {
  81.                 if (aBoolean) {
  82.                     Log.e(TAG, "accept: " + aBoolean);
  83.                     faceDetectionBtn.setVisibility(View.VISIBLE);
  84.                     mSurfaceView.setVisibility(View.VISIBLE);
  85.                     //权限全部获取
  86.                     initSurfaceViewPreView();
  87.  
  88.  
  89.                 }
  90.  
  91.             }
  92.         });
  93.  
  94.  
  95.     }
  96.  
  97.     private void initSurfaceViewPreView() {
  98.         mCameraSurfaceHolder.setCameraSurfaceHolder(MainActivity.this, mSurfaceView);
  99.         mSurfaceViewCallback = mCameraSurfaceHolder.mSurfaceViewCallback;
  100.         if (mSurfaceViewCallback != null) {
  101.             mFrontCamera = mSurfaceViewCallback.mFrontCamera;
  102.         }
  103.     }
  104.  
  105.     ;
  106.  
  107.     private void initView() {
  108.         setContentView(R.layout.activity_main);
  109.         mSurfaceView = findViewById(R.id.face_surfaceView);
  110.         mSurfaceView.setVisibility(View.GONE);
  111.         faceDetectionBtn = findViewById(R.id.faceDetectionBtn);
  112.         faceImg = findViewById(R.id.faceImg);
  113.         faceDetectionBtn.setOnClickListener(new View.OnClickListener() {
  114.             @Override
  115.             public void onClick(View v) {
  116.                 if (mFrontCamera != null) {
  117.                     //拍照的时候进行人脸识别
  118.                     mFrontCamera.takePicture(new BitmapInterface() {
  119.                         @Override
  120.                         public void setBitMap(Bitmap bitMap) {
  121.                             if(bitMap==null){
  122.                                 Toast.makeText(MainActivity.this,"拍照失败！",Toast.LENGTH_SHORT).show();
  123.                                 return;
  124.                             }
  125.                             //人脸识别
  126.                             int result = mFaceDetection.faceDetectionSaveInfo(bitMap);
  127.                             if (result != 0) {
  128.                                 Toast.makeText(MainActivity.this, "检测人脸失败!", Toast.LENGTH_SHORT).show();
  129.                                 return;
  130.                             }
  131.  
  132.                             faceImg.setVisibility(View.VISIBLE);
  133.                             faceImg.setImageBitmap(bitMap);
  134.                             byte[]data= bitmap2byte(bitMap);
  135.                             //rxandroid实现开启子线程保存文件
  136.                             new SaveImageTask(MainActivity.this,faceImg).saveImage(data);
  137.                             //AsyncTask异步任务实现开启子线程保存文件
  138.                             //new SaveImageAsyncTask(MainActivity.this,faceImg).execute(data);
  139.                         }
  140.                     });
  141.                 }
  142.  
  143.  
  144.             }
  145.         });
  146.  
  147.     }
  148.     private byte[] bitmap2byte(Bitmap photoBitmap){
  149.         创建对应的流对象
  150.         ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
  151.         photoBitmap.compress(Bitmap.CompressFormat.JPEG,100,byteArrayOutputStream);//将流对象与Bitmap对象进行关联。
  152.         byte [] array=byteArrayOutputStream.toByteArray();//使用流对象，将Bitmap对象转换为byte[]数组
  153.         return array;
  154.  
  155.     }
  156.  
  157.  
  158.  
  159.  
  160.     private void copyCascadeFile() {
  161.  
  162.         try {
  163.             // load cascade file from application resources
  164.             InputStream is = getResources().openRawResource(R.raw.lbpcascade_frontalface);
  165.             File cascadeDir = getDir("cascade", Context.MODE_PRIVATE);
  166.             mCascadeFile = new File(cascadeDir, "lbpcascade_frontalface.xml");
  167.             if (mCascadeFile.exists()) return;
  168.             FileOutputStream os = new FileOutputStream(mCascadeFile);
  169.  
  170.             byte[] buffer = new byte[4096];
  171.             int bytesRead;
  172.             while ((bytesRead = is.read(buffer)) != -1) {
  173.                 os.write(buffer, 0, bytesRead);
  174.             }
  175.             is.close();
  176.             os.close();
  177.             cascadeDir.delete();
  178.  
  179.         } catch (IOException e) {
  180.             e.printStackTrace();
  181.             Log.e(TAG, "Failed to load cascade. Exception thrown: " + e);
  182.         }
  183.     }
  184.  
  185.     /**
  186.      * 检测是否存在摄像头
  187.      *
  188.      * @param context
  189.      * @return
  190.      */
  191.     private boolean checkCameraHardware(Context context) {
  192.         if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {
  193.             return true;
  194.         } else {
  195.             Toast.makeText(this, "不具备摄像头硬件", Toast.LENGTH_SHORT).show();
  196.             return false;
  197.         }
  198.     }
  199.  
  200. }


布局activity_main.xml

  1. <?xml version="1.0" encoding="utf-8"?>
  2. <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
  3.     xmlns:app="http://schemas.android.com/apk/res-auto"
  4.     xmlns:tools="http://schemas.android.com/tools"
  5.     android:layout_width="match_parent"
  6.     android:layout_height="match_parent"
  7.     tools:context=".MainActivity">
  8.     <SurfaceView
  9.         app:layout_constraintTop_toTopOf="@+id/faceDetectionBtn"
  10.         android:id="@+id/face_surfaceView"
  11.         android:layout_width="match_parent"
  12.         android:layout_height="match_parent"/>
  13.     <ImageView
  14.         app:layout_constraintTop_toTopOf="@+id/faceDetectionBtn"
  15.         android:visibility="gone"
  16.         android:id="@+id/faceImg"
  17.         android:src="@drawable/face"
  18.         android:layout_width="match_parent"
  19.         android:layout_height="match_parent"></ImageView>
  20.     <Button
  21.         android:visibility="gone"
  22.         android:id="@+id/faceDetectionBtn"
  23.         android:layout_width="match_parent"
  24.         android:layout_height="wrap_content"
  25.         android:text="人脸识别"
  26.         app:layout_constraintBottom_toBottomOf="parent"
  27.         app:layout_constraintLeft_toLeftOf="parent"
  28.         app:layout_constraintRight_toRightOf="parent"
  29.          />
  30.  
  31. </androidx.constraintlayout.widget.ConstraintLayout>

3.5修改native-lib.cpp

  1. #include <jni.h>
  2. #include <string>
  3. #include <opencv2/opencv.hpp>
  4. #include <android/bitmap.h>
  5. #include <android/log.h>
  6. #include <opencv2/imgcodecs/legacy/constants_c.h>
  7.  
  8. #define TAG "JNI_LOG"
  9. #define LOGE(...)__android_log_print(ANDROID_LOG_ERROR,TAG,__VA_ARGS__)
  10. using namespace cv;
  11. CascadeClassifier cascadeClassifier;
  12.  
  13.  
  14. //使用命名空间
  15. void bitmap2Mat(JNIEnv *env, Mat &mat, jobject bitmap);
  16.  
  17. //mat转成bitmap
  18. void mat2Bitmap(JNIEnv *env, Mat mat, jobject bitmap);
  19.  
  20. //bitmap转成mat
  21. void bitmap2Mat(JNIEnv *env, Mat &mat, jobject bitmap) {
  22. //Mat里面有个type:CV_8UC4 刚好对上bitmap中的ARGB_8888 CV_8UC2 刚好匹配bitmap中的RGB_565
  23. //1.获取bitmap信息
  24. AndroidBitmapInfo info;
  25. void *pixels;
  26. AndroidBitmap_getInfo(env,bitmap,&info);
  27.  
  28. //锁定bitmap画布
  29. AndroidBitmap_lockPixels(env,bitmap,&pixels);
  30. //指定mat的宽高和type BGRA
  31. mat.create(info.height,info.width,CV_8UC4);
  32.  
  33. if(info.format==ANDROID_BITMAP_FORMAT_RGBA_8888){
  34. //对应的mat应该是CV_8UC4
  35. Mat temp(info.height,info.width,CV_8UC4,pixels);
  36. //把数据temp复制到mat里面
  37. temp.copyTo(mat);
  38.  
  39. }else if(info.format==ANDROID_BITMAP_FORMAT_RGB_565){
  40.     //对应的mat应该是CV_8UC2
  41.     Mat temp(info.height,info.width,CV_8UC2,pixels);
  42.     //上面mat创建的是CV_8UC4 要改为CV_8UC2  CV_8UC2数据拷贝到CV_8UC4
  43.     cvtColor(temp,mat,COLOR_BGR5652BGRA);
  44. }
  45. //其他需要自己去转
  46. //解锁画布
  47. AndroidBitmap_unlockPixels(env,bitmap);
  48. }
  49.  
  50. extern "C"
  51. JNIEXPORT jint JNICALL
  52. Java_com_suoer_ndk_opencvtestapplication_FaceDetection_faceDetectionSaveInfo(JNIEnv *env,
  53.                                                                              jobject thiz,
  54.                                                                              jobject face_bitmap) {
  55.     // TODO: implement faceDetectionSaveInfo()
  56.     //检测人脸 opencv有关键的类是Mat,opencv是c和c++写的，只会处理Mat,android里面是Bitmap
  57.     //1.Bitmap转成opencv能操作的c++对象 Mat ,Mat是一个矩阵
  58.     Mat mat;
  59.     bitmap2Mat(env,mat,face_bitmap);
  60.     //处理灰度opencv 处理灰度图 提高效率,一般所有的操作都会对齐进行处理
  61.     Mat gray_mat;
  62.     cvtColor(mat,gray_mat,COLOR_BGRA2GRAY);
  63.  
  64.     //再次处理直方均衡补偿
  65.     Mat equalize_mat;
  66.     equalizeHist(gray_mat,equalize_mat);
  67.     //识别人脸 当然我们可以直接用彩色图去做，识别人脸要加载人脸分类器文件
  68.     std::vector<Rect> faces;
  69.     cascadeClassifier.detectMultiScale(equalize_mat,faces,1.1,5);
  70.     LOGE("人脸个数:%d",faces.size());
  71.     if(faces.size()!=1){
  72.         return -1;
  73.     }
  74.  
  75.         Rect faceRect=faces[0];
  76.         //在人脸部分画个图
  77.         rectangle(mat,faceRect,Scalar(255,155,155),8);
  78.         //把mat 放到bitmap中 图片展示出来
  79.         //mat2Bitmap(env,mat,face_bitmap);
  80.         //保存人脸信息 Mat,图片
  81.         Mat face_info_mat(equalize_mat,faceRect);
  82.         //保存face_info_mat
  83.         mat2Bitmap(env,face_info_mat,face_bitmap);
  84.         //mat2Bitmap(env,equalize_mat,face_bitmap);
  85.  
  86.  
  87.  
  88.  
  89.  
  90.  
  91.  
  92.     //保存人脸信息
  93.     return 0;
  94. }
  95.  
  96. void mat2Bitmap(JNIEnv *env, Mat mat, jobject bitmap) {
  97. //Mat里面有个type:CV_8UC4 刚好对上bitmap中的ARGB_8888 CV_8UC2 刚好匹配bitmap中的RGB_565
  98. //1.获取bitmap信息
  99.     AndroidBitmapInfo info;
  100.     void *pixels;
  101.     AndroidBitmap_getInfo(env,bitmap,&info);
  102.  
  103. //锁定bitmap画布
  104.     AndroidBitmap_lockPixels(env,bitmap,&pixels);
  105.  
  106.  
  107.     if(info.format==ANDROID_BITMAP_FORMAT_RGBA_8888){
  108. //对应的mat应该是CV_8UC4
  109.         Mat temp(info.height,info.width,CV_8UC4,pixels);
  110.         if(mat.type()==CV_8UC4){
  111.             mat.copyTo(temp);
  112.         }else if(mat.type()==CV_8UC2){
  113.             cvtColor(mat,temp,COLOR_BGR5652BGRA);
  114.         }
  115.         else if(mat.type()==CV_8UC1){//灰度mat
  116.             cvtColor(mat,temp,COLOR_GRAY2BGRA);
  117.         }
  118.     }else if(info.format==ANDROID_BITMAP_FORMAT_RGB_565){
  119.         //对应的mat应该是CV_8UC2
  120.         Mat temp(info.height,info.width,CV_8UC2,pixels);
  121.         if(mat.type()==CV_8UC4){
  122.             cvtColor(mat,temp,COLOR_BGRA2BGR565);
  123.         }else if(mat.type()==CV_8UC2){
  124.             mat.copyTo(temp);
  125.         }
  126.         else if(mat.type()==CV_8UC1){//灰度mat
  127.             cvtColor(mat,temp,COLOR_GRAY2BGR565);
  128.         }
  129.  
  130.     }
  131. //其他需要自己去转
  132. //解锁画布
  133.     AndroidBitmap_unlockPixels(env,bitmap);
  134. }
  135.  
  136. extern "C"
  137. JNIEXPORT jboolean JNICALL
  138. Java_com_suoer_ndk_opencvtestapplication_FaceDetection_loadCascade(JNIEnv *env, jobject thiz,
  139.                                                                    jstring file_path) {
  140.     // TODO: implement loadCascade()
  141.     const char *filePath=env->GetStringUTFChars(file_path,0);
  142.     bool load=cascadeClassifier.load(filePath);
  143.     env->ReleaseStringUTFChars(file_path,filePath);
  144.     return load;
  145. }

运行app至手机设备出现如下图所示错误

error: undefined reference to 'AndroidBitmap_getInfo'

 解决方式修改CMakeLists.txt

 

  1. target_link_libraries( # Specifies the target library.
  2.                        native-lib opencv-lib
  3.                        #加入该依赖库
  4.                        jnigraphics
  5.  
  6.                        # Links the target library to the log library
  7.                        # included in the NDK.
  8.                        ${log-lib} )

CMakeLists.txt内容如下：

  1. # For more information about using CMake with Android Studio, read the
  2. # documentation: https://d.android.com/studio/projects/add-native-code.html
  3.  
  4. # Sets the minimum version of CMake required to build the native library.
  5.  
  6. cmake_minimum_required(VERSION 3.10.2)
  7.  
  8. # Declares and names the project.
  9.  
  10. project("opencvtestapplication")
  11. #需要引入我们头文件，以这个配置的目录为基准
  12. include_directories(${CMAKE_SOURCE_DIR}/../jni/include)
  13.  
  14. # Creates and names a library, sets it as either STATIC
  15. # or SHARED, and provides the relative paths to its source code.
  16. # You can define multiple libraries, and CMake builds them for you.
  17. # Gradle automatically packages shared libraries with your APK.
  18.  
  19. add_library( # Sets the name of the library.
  20.              native-lib
  21.  
  22.              # Sets the library as a shared library.
  23.              SHARED
  24.  
  25.              # Provides a relative path to your source file(s).
  26.              native-lib.cpp )
  27. # 添加opencv的库
  28. add_library(
  29.         opencv-lib
  30.         SHARED
  31.         IMPORTED)
  32. set_target_properties(
  33.         opencv-lib
  34.         PROPERTIES IMPORTED_LOCATION
  35.         ${CMAKE_SOURCE_DIR}/../jni/armeabi-v7a/libopencv_java4.so)
  36.  
  37. # Searches for a specified prebuilt library and stores the path as a
  38. # variable. Because CMake includes system libraries in the search path by
  39. # default, you only need to specify the name of the public NDK library
  40. # you want to add. CMake verifies that the library exists before
  41. # completing its build.
  42.  
  43. find_library( # Sets the name of the path variable.
  44.               log-lib
  45.  
  46.               # Specifies the name of the NDK library that
  47.               # you want CMake to locate.
  48.               log )
  49.  
  50. # Specifies libraries CMake should link to your target library. You
  51. # can link multiple libraries, such as libraries you define in this
  52. # build script, prebuilt third-party libraries, or system libraries.
  53.  
  54. target_link_libraries( # Specifies the target library.
  55.                        native-lib opencv-lib
  56.                        #加入该依赖库
  57.                        jnigraphics
  58.  
  59.                        # Links the target library to the log library
  60.                        # included in the NDK.
  61.                        ${log-lib} )

其他详细内容可见Demo。

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