Android Studio使用OpenCV库

概要

在android添加OpenCV库，并运行自带色块识别例程

下载OpenCV包

https://opencv.org/releases/
下载opencv-4.9.0-android-sdk.zip并解压到一个目录（英文）

在Android Studio新建空工程

选择选择选择选择Empty Activity，最小版本选择Android5.0

导入OpenCV库，选择sdk路径
如果添加后提示kotlin-android错误，删掉build.gradle中的该句即可，修改compileSdkVersion，minSdkVersion，targetSdkVersion三个属性和工程保持一致

添加module依赖
在菜单file-》Project Structure窗口选择dependencies，选择sdk

测试加载OpenCV库

在activity的onCreate()调用

private void loadOpenCV() {    boolean success = OpenCVLoader.initDebug();   //对OpenCV库进行初始化加载，bool返回值可以判断是否加载成功。    if (success) {        Toast.makeText(this.getApplicationContext(), "OpenCV库加载成功", Toast.LENGTH_SHORT).show();    } else {        Toast.makeText(this.getApplicationContext(), "OpenCV库加载失败", Toast.LENGTH_SHORT).show();    }}

测试自带samples

将color-blob-detection下ColorBlobDetectionActivity.java和ColorBlobDetector.java拷贝到工程src下，修改activity的layout

MainActivity的完整代码如下：
package com.gaoda.cameracv;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AlertDialog;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;

import android.Manifest;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.net.Uri;
import android.os.Bundle;
import android.provider.Settings;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceView;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Toast;

import org.opencv.android.CameraActivity;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.MatOfPoint;
import org.opencv.core.Rect;
import org.opencv.core.Scalar;
import org.opencv.core.Size;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewListener2;
import org.opencv.imgproc.Imgproc;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class MainActivity extends CameraActivity implements View.OnTouchListener, CvCameraViewListener2{
private static final String TAG = “MainActivity”;
private final int mRequestCode = 100;//权限请求码
List mPermissionList = new ArrayList<>();
String[] permissions = new String[]{
Manifest.permission.READ_EXTERNAL_STORAGE,
Manifest.permission.WRITE_EXTERNAL_STORAGE,
Manifest.permission.CAMERA,
Manifest.permission.INTERNET};

private boolean              mIsColorSelected = false;private Mat                  mRgba;private Scalar               mBlobColorRgba;private Scalar               mBlobColorHsv;private ColorBlobDetector    mDetector;private Mat                  mSpectrum;private Size                 SPECTRUM_SIZE;private Scalar               CONTOUR_COLOR;private CameraBridgeViewBase mOpenCvCameraView;@Overrideprotected void onCreate(Bundle savedInstanceState) {    Log.i(TAG, "called onCreate");    super.onCreate(savedInstanceState);    requestWindowFeature(Window.FEATURE_NO_TITLE);    getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);    setContentView(R.layout.activity_main);    initPermission();    mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.color_blob_detection_activity_surface_view);    mOpenCvCameraView.setVisibility(SurfaceView.VISIBLE);    mOpenCvCameraView.setCvCameraViewListener(this);}//初始化private void init(){    loadOpenCV();    //new TimeThread().start(); //启动新的线程}private void initPermission(){    int osVersion = Integer.valueOf(android.os.Build.VERSION.SDK);    if (osVersion>22) {        mPermissionList.clear();//清空已经允许的没有通过的权限        //逐个判断是否还有未通过的权限        for (int i = 0; i < permissions.length; i++) {            if (ContextCompat.checkSelfPermission(this, permissions[i]) !=                    PackageManager.PERMISSION_GRANTED) {                mPermissionList.add(permissions[i]);//添加还未授予的权限到mPermissionList中            }        }        //申请权限        if (mPermissionList.size() > 0) {//有权限没有通过，需要申请            ActivityCompat.requestPermissions(this, permissions, mRequestCode);} else {            //权限已经都通过了，可以将程序继续打开了            init();        }    }else        init();}/** * 5.请求权限后回调的方法 * @param requestCode 是我们自己定义的权限请求码 * @param permissions 是我们请求的权限名称数组 * @param grantResults 是我们在弹出页面后是否允许权限的标识数组，数组的长度对应的是权限 *                     名称数组的长度，数组的数据0表示允许权限，-1表示我们点击了禁止权限 */@Overridepublic void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,                                       @NonNull int[] grantResults) {    super.onRequestPermissionsResult(requestCode, permissions, grantResults);    boolean hasPermissionDismiss = false;//有权限没有通过    if (mRequestCode==requestCode){        for (int i=0;i<grantResults.length;i++){            if (grantResults[i]==-1){                hasPermissionDismiss=true;                break;            }        }    }    if (hasPermissionDismiss){//如果有没有被允许的权限        showPermissionDialog();}else {        //权限已经都通过了，可以将程序继续打开了        init();    }}/** *  6.不再提示权限时的展示对话框 */AlertDialog mPermissionDialog;String mPackName = "com.gaoda.opencvtest";private void showPermissionDialog() {    if (mPermissionDialog == null) {        mPermissionDialog = new AlertDialog.Builder(this)                .setMessage("已禁用权限，请手动授予")                .setPositiveButton("设置", new DialogInterface.OnClickListener() {                    @Override                    public void onClick(DialogInterface dialog, int which) {                        cancelPermissionDialog();                        Uri packageURI = Uri.parse("package:" + mPackName);                        Intent intent = new Intent(Settings.                                ACTION_APPLICATION_DETAILS_SETTINGS, packageURI);                        startActivity(intent);                    }                })                .setNegativeButton("取消", new DialogInterface.OnClickListener() {                    @Override                    public void onClick(DialogInterface dialog, int which) {                        //关闭页面或者做其他操作                        cancelPermissionDialog();                        MainActivity.this.finish();                    }                })                .create();    }    mPermissionDialog.show();}private void cancelPermissionDialog() {    mPermissionDialog.cancel();}private void loadOpenCV() {    boolean success = OpenCVLoader.initDebug();   //对OpenCV库进行初始化加载，bool返回值可以判断是否加载成功。