Android Studio3.5集成OpenCV-android-sdk的使用

一、OpenCV Android开发环境的搭建
Android Studio3.5.2
OpenCV Android Sdk 3.4.10版本
JDK8:64位
Android NDK r17c
从官网下载的SDK后解压如下所示

• apk文件夹中存储的是对应不同cpu的代理（manager）应用
• samples中存储的是官方给出Demo源码示例，但是遗憾的是这里都是Eclipse项目
• sdk中存储的就是我们接下来搭建环境需要使用的一些材料

1、新建一个项目OpenCVTest工程，然后选择Empty Activity,然后一直点击下一步。
2、将下载的OpenCV-android-sdk\sdk\中的java模块导入到该项目中，点击 File -> new -> Import Module, 选中 OpenCV-Android-SDK/sdk/java 文件夹,点击确定，就会自动识别处模块，如下图所示：
3、将OpenCV的SDK导入进来后，就修改openCVLibrary3410项目中的build.gradle文件，修改内容如下所示：

apply plugin: 'com.android.library'

android {
    compileSdkVersion 26
    buildToolsVersion "26"

    defaultConfig {
        minSdkVersion 14
        targetSdkVersion 26
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }
}

4、修改openCVLibrary3410项目中的AndroidManifest.xml文件。

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="org.opencv"
      android:versionCode="34100"
      android:versionName="3.4.10">
	//该行注释掉
    //<uses-sdk android:minSdkVersion="14" android:targetSdkVersion="26" />
</manifest>

5、在Mouble app中修改build.gradle文件

dependencies {
    implementation project(path: ':openCVLibrary3410')
    implementation fileTree(dir: "$buildDir/native-libs", include: 'native-libs.jar')
}
task nativeLibsToJar(type: Jar, description: 'create a jar archive of the native libs') {
    destinationDir file("$buildDir/native-libs")
    baseName 'native-libs'
    from fileTree(dir: 'libs', include: '**/*.so')
    into 'lib/'
}

6、点击 File -> Project Structure，在 Modules app下点击依赖 openCVLibrary3410的模块，然后点击Dependencies中 Module dependency 后选择 openCVLibrary341 后点击完成。
二、代码示例测试
1、先写一个布局文件，里面一个按钮是选择本地相册里面的图片，另外一个按钮是实现图片的处理。

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    >
    <Button
        android:id="@+id/select_btn"
        android:text="选择图片"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />
    <Button
        android:id="@+id/process_btn"
        android:text="处理"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />
    <ImageView
        android:id="@+id/imageView"
        android:src="@mipmap/ic_launcher"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />
</LinearLayout>

2、MainActivity.java中代码如下

public class MainActivity extends AppCompatActivity {
    private static final  String TAG = "wq892373445";

    private double max_size = 1024;
    private int PICK_IMAGE_REQUEST = 1;
    private ImageView myImageView;
    private Bitmap selectbp;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        staticLoadCVLibraries();
        myImageView = (ImageView)findViewById(R.id.imageView);
        myImageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
        Button selectImageBtn = (Button)findViewById(R.id.select_btn);
        selectImageBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // makeText(MainActivity.this.getApplicationContext(), "start to browser image", Toast.LENGTH_SHORT).show();
                selectImage();
            }
        });

        Button processBtn = (Button)findViewById(R.id.process_btn);
        processBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // makeText(MainActivity.this.getApplicationContext(), "hello, image process", Toast.LENGTH_SHORT).show();
                convertGray();
            }
        });

    }

    //OpenCV库静态加载并初始化
    private void staticLoadCVLibraries(){
        boolean load = OpenCVLoader.initDebug();
        if(load) {
            Log.e(TAG, "Open CV Libraries loaded...");
        }
    }

    private void convertGray() {
        Mat src = new Mat();
        Mat temp = new Mat();
        Mat dst = new Mat();
        Utils.bitmapToMat(selectbp, src);
        Imgproc.cvtColor(src, temp, Imgproc.COLOR_BGRA2BGR);
        Log.i("CV", "image type:" + (temp.type() == CvType.CV_8UC3));
        Imgproc.cvtColor(temp, dst, Imgproc.COLOR_BGR2GRAY);
        Utils.matToBitmap(dst, selectbp);
        myImageView.setImageBitmap(selectbp);
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(requestCode == PICK_IMAGE_REQUEST && resultCode == RESULT_OK && data != null && data.getData() != null) {
            Uri uri = data.getData();
            try {
                Log.d("image-tag", "start to decode selected image now...");
                InputStream input = getContentResolver().openInputStream(uri);
                BitmapFactory.Options options = new BitmapFactory.Options();
                options.inJustDecodeBounds = true;
                BitmapFactory.decodeStream(input, null, options);
                int raw_width = options.outWidth;
                int raw_height = options.outHeight;
                int max = Math.max(raw_width, raw_height);
                int newWidth = raw_width;
                int newHeight = raw_height;
                int inSampleSize = 1;
                if(max > max_size) {
                    newWidth = raw_width / 2;
                    newHeight = raw_height / 2;
                    while((newWidth/inSampleSize) > max_size || (newHeight/inSampleSize) > max_size) {
                        inSampleSize *=2;
                    }
                }

                options.inSampleSize = inSampleSize;
                options.inJustDecodeBounds = false;
                options.inPreferredConfig = Bitmap.Config.ARGB_8888;
                selectbp = BitmapFactory.decodeStream(getContentResolver().openInputStream(uri), null, options);

                myImageView.setImageBitmap(selectbp);

            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 跳转到系统相册选择图片
     */
    private void selectImage() {
        Intent intent = new Intent();
        intent.setType("image/*");
        intent.setAction(Intent.ACTION_GET_CONTENT);
        startActivityForResult(Intent.createChooser(intent,"选择图像..."), PICK_IMAGE_REQUEST);
    }
}

备注：本想下载最新的SDK为4.3.0的，但是不知道为什么SDK的依赖不显示，所以就用OpenCV Android Sdk 3.4.10版本