Android Jni 利用OpenCV 实现图像任意角度旋转

一，java代码，收集Bitmap 信息

private Button btnProc;private ImageView imageView;private Bitmap bmp;// Used to load the 'native-lib' library on application startup.static {    System.loadLibrary("native-lib");}@Overrideprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    // Example of a call to a native method    btnProc = (Button) findViewById(R.id.btn_gray_process);    imageView = (ImageView) findViewById(R.id.image_view);    bmp = BitmapFactory.decodeResource(getResources(), R.drawable.test7);    imageView.setImageBitmap(bmp);    btnProc.setOnClickListener(this);}/** * A native method that is implemented by the 'native-lib' native library, * which is packaged with this application. */public static native int[] grayProc(int[] pixels, int w, int h);@Overridepublic void onClick(View view) {    int w = bmp.getWidth();    int h = bmp.getHeight();    int[] pixels = new int[w*h];    bmp.getPixels(pixels, 0, w, 0, 0, w, h);    long startTime = System.currentTimeMillis();    int[] resultInt = grayProc(pixels, w, h);    long endTime = System.currentTimeMillis();    Log.e("JNITime",""+(endTime-startTime));    Bitmap resultImg = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);    //(@ColorInt int[] pixels, int offset, int stride,int x, int y, int width, int height)    resultImg.setPixels(resultInt, 0, w, 0, 0, w, h);    imageView.setImageBitmap(resultImg);}

二，jni实现

using namespace std;
using namespace cv;

Mat rotateImage1(Mat img, int degree){

degree = -degree;double angle = degree  * CV_PI / 180.; // 弧度//获取弧度对应的三角函数值double a = sin(angle);double b = cos(angle);//获取矩阵的宽高int width = img.cols;int height = img.rows;int width_rotate = int(height * fabs(a) + width * fabs(b));int height_rotate = int(width * fabs(a) + height * fabs(b));float map[6];Mat map_matrix = Mat(2, 3, CV_32F, map);// 旋转中心CvPoint2D32f center = cvPoint2D32f(width / 2 +0.5, height / 2 +0.5);CvMat map_matrix2 = map_matrix;//( CvPoint2D32f center, double angle, double scale, CvMat* map_matrix );cv2DRotationMatrix(center, degree, 1.0, &map_matrix2);Mat img_rotate;//CV_WARP_FILL_OUTLIERS - 填充所有输出图像的象素。//如果部分象素落在输入图像的边界外，那么它们的值设定为 fillval.//CV_WARP_INVERSE_MAP - 指定 map_matrix 是输出图像到输入图像的反变换，//( InputArray src, OutputArray dst, InputArray M, Size dsize,warpAffine(img, img_rotate, map_matrix, Size(width_rotate, height_rotate));return img_rotate;

}

extern “C”
JNIEXPORT jintArray JNICALL
Java_com_example_dgxq008_opencv_1readpixel_MainActivity_grayProc(JNIEnv *env, jclass type
, jintArray pixels_
, jint w
, jint h) {

jint* pixels = env->GetIntArrayElements(pixels_, NULL);if (pixels==NULL){    return 0;}//图片一进来时是ARGB  通过mat转换BGRAMat img(h,w,CV_8UC4,(uchar *)pixels);  //pixels 操作的是同一份数据Mat temp; //传入自己要实现的角度，这里实现倒影效果int degree = 180;//其实现方法，是从网上搜的工具方法Mat m_ResImg = rotateImage1(img, degree);resize(m_ResImg,img,Size( img.cols, img.rows ));//对应数据指针int size = w*h;jintArray result = env->NewIntArray(size);env->SetIntArrayRegion(result,0,size,pixels);env->ReleaseIntArrayElements(pixels_, pixels, 0);return result;

}