content: package org.opencv.samples.tutorial2;
  
  import org.opencv.android.BaseLoaderCallback;
  import org.opencv.android.CameraActivity;
  import org.opencv.android.CameraBridgeViewBase.CvCameraViewFrame;
  import org.opencv.android.LoaderCallbackInterface;
  import org.opencv.android.OpenCVLoader;
  import org.opencv.core.CvType;
  import org.opencv.core.Mat;
  import org.opencv.android.CameraBridgeViewBase;
  import org.opencv.android.CameraBridgeViewBase.CvCameraViewListener2;
  import org.opencv.imgproc.Imgproc;
  
  import android.os.Bundle;
  import android.util.Log;
  import android.view.Menu;
  import android.view.MenuItem;
  import android.view.WindowManager;
  
  import java.util.Collections;
  import java.util.List;
  
  public class Tutorial2Activity extends CameraActivity implements CvCameraViewListener2 {
      private static final String    TAG = "OCVSample::Activity";
  
      private static final int       VIEW_MODE_RGBA     = 0;
      private static final int       VIEW_MODE_GRAY     = 1;
      private static final int       VIEW_MODE_CANNY    = 2;
      private static final int       VIEW_MODE_FEATURES = 5;
  
      private int                    mViewMode;
      private Mat                    mRgba;
      private Mat                    mIntermediateMat;
      private Mat                    mGray;
  
      private MenuItem               mItemPreviewRGBA;
      private MenuItem               mItemPreviewGray;
      private MenuItem               mItemPreviewCanny;
      private MenuItem               mItemPreviewFeatures;
  
      private CameraBridgeViewBase   mOpenCvCameraView;
  
      private BaseLoaderCallback  mLoaderCallback = new BaseLoaderCallback(this) {
          @Override
          public void onManagerConnected(int status) {
              switch (status) {
                  case LoaderCallbackInterface.SUCCESS:
                  {
                      Log.i(TAG, "OpenCV loaded successfully");
  
                      // Load native library after(!) OpenCV initialization
                      System.loadLibrary("mixed_sample");
  
                      mOpenCvCameraView.enableView();
                  } break;
                  default:
                  {
                      super.onManagerConnected(status);
                  } break;
              }
          }
      };
  
      public Tutorial2Activity() {
          Log.i(TAG, "Instantiated new " + this.getClass());
      }
  
      /** Called when the activity is first created. */
      @Override
      public void onCreate(Bundle savedInstanceState) {
          Log.i(TAG, "called onCreate");
          super.onCreate(savedInstanceState);
          getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
  
          setContentView(R.layout.tutorial2_surface_view);
  
          mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.tutorial2_activity_surface_view);
          mOpenCvCameraView.setVisibility(CameraBridgeViewBase.VISIBLE);
          mOpenCvCameraView.setCvCameraViewListener(this);
      }
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
          Log.i(TAG, "called onCreateOptionsMenu");
          mItemPreviewRGBA = menu.add("Preview RGBA");
          mItemPreviewGray = menu.add("Preview GRAY");
          mItemPreviewCanny = menu.add("Canny");
          mItemPreviewFeatures = menu.add("Find features");
          return true;
      }
  
      @Override
      public void onPause()
      {
          super.onPause();
          if (mOpenCvCameraView != null)
              mOpenCvCameraView.disableView();
      }
  
      @Override
      public void onResume()
      {
          super.onResume();
          if (!OpenCVLoader.initDebug()) {
              Log.d(TAG, "Internal OpenCV library not found. Using OpenCV Manager for initialization");
              OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_0_0, this, mLoaderCallback);
          } else {
              Log.d(TAG, "OpenCV library found inside package. Using it!");
              mLoaderCallback.onManagerConnected(LoaderCallbackInterface.SUCCESS);
          }
      }
  
      @Override
      protected List<? extends CameraBridgeViewBase> getCameraViewList() {
          return Collections.singletonList(mOpenCvCameraView);
      }
  
      public void onDestroy() {
          super.onDestroy();
          if (mOpenCvCameraView != null)
              mOpenCvCameraView.disableView();
      }
  
      public void onCameraViewStarted(int width, int height) {
          mRgba = new Mat(height, width, CvType.CV_8UC4);
          mIntermediateMat = new Mat(height, width, CvType.CV_8UC4);
          mGray = new Mat(height, width, CvType.CV_8UC1);
      }
  
      public void onCameraViewStopped() {
          mRgba.release();
          mGray.release();
          mIntermediateMat.release();
      }
  
      public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
          final int viewMode = mViewMode;
          switch (viewMode) {
          case VIEW_MODE_GRAY:
              // input frame has gray scale format
              Imgproc.cvtColor(inputFrame.gray(), mRgba, Imgproc.COLOR_GRAY2RGBA, 4);
              break;
          case VIEW_MODE_RGBA:
              // input frame has RBGA format
              mRgba = inputFrame.rgba();
              break;
          case VIEW_MODE_CANNY:
              // input frame has gray scale format
              mRgba = inputFrame.rgba();
              Imgproc.Canny(inputFrame.gray(), mIntermediateMat, 80, 100);
              Imgproc.cvtColor(mIntermediateMat, mRgba, Imgproc.COLOR_GRAY2RGBA, 4);
              break;
          case VIEW_MODE_FEATURES:
              // input frame has RGBA format
              mRgba = inputFrame.rgba();
              mGray = inputFrame.gray();
              FindFeatures(mGray.getNativeObjAddr(), mRgba.getNativeObjAddr());
              break;
          }
  
          return mRgba;
      }
  
      public boolean onOptionsItemSelected(MenuItem item) {
          Log.i(TAG, "called onOptionsItemSelected; selected item: " + item);
  
          if (item == mItemPreviewRGBA) {
              mViewMode = VIEW_MODE_RGBA;
          } else if (item == mItemPreviewGray) {
              mViewMode = VIEW_MODE_GRAY;
          } else if (item == mItemPreviewCanny) {
              mViewMode = VIEW_MODE_CANNY;
          } else if (item == mItemPreviewFeatures) {
              mViewMode = VIEW_MODE_FEATURES;
          }
  
          return true;
      }
  
      public native void FindFeatures(long matAddrGr, long matAddrRgba);
  }
  