android camera2 api image reader

Setting up the android camera2 api ImageReader for capturing a still image.

This tutorial describes setting up the android camera2 api image reader which provides the surface for capturing a still image.

Get Code

You can get it from here https://github.com/mobapptuts/recyclerview_image_gallery.git Tag camera2-imagereader

or else run this command
git clone —branch camera2-imagereader https://github.com/mobapptuts/recyclerview_image_gallery.git

Code Sampes

Create File, ImageReader, ImageReader.OnAvailableListener & ImageSaver members

private static File mImageFile;
   private ImageReader mImageReader;
   private final ImageReader.OnImageAvailableListener mOnImageAvailableListener =
          new ImageReader.OnImageAvailableListener() {
              @Override
              public void onImageAvailable(ImageReader reader) {
                  mBackgroundHandler.post(new ImageSaver(reader.acquireNextImage()));
              }
          };

   private static class ImageSaver implements Runnable {

       private final Image mImage;

       private ImageSaver(Image image) {
           mImage = image;
       }

       @Override
       public void run() {
           ByteBuffer byteBuffer = mImage.getPlanes()[0].getBuffer();
           byte[] bytes = new byte[byteBuffer.remaining()];
           byteBuffer.get(bytes);

           FileOutputStream fileOutputStream = null;

           try {
               fileOutputStream = new FileOutputStream(mImageFile);
               fileOutputStream.write(bytes);
           } catch (IOException e) {
               e.printStackTrace();
           } finally {
               mImage.close();
               if(fileOutputStream != null) {
                   try {
                       fileOutputStream.close();
                   } catch (IOException e) {
                       e.printStackTrace();
                   }
               }
           }

       }
   }

In the takePhoto method assign a new File to the Activity file.

public void takePhoto(View view) {
       try {
           mImageFile = createImageFile();

       } catch (IOException e) {
           e.printStackTrace();
       }
       lockFocus();
   }

In the setupCamera method calculate the size of the largest image the camera can capture. Then create a new instance for the ImageReader using the calculated size, then enable the ImageReader’s setOnImageAvailableListener callback.

private void setupCamera(int width, int height) {
       CameraManager cameraManager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
       try {
           for(String cameraId : cameraManager.getCameraIdList()) {
               CameraCharacteristics cameraCharacteristics = cameraManager.getCameraCharacteristics(cameraId);
               if(cameraCharacteristics.get(CameraCharacteristics.LENS_FACING) ==
                       CameraCharacteristics.LENS_FACING_FRONT){
                   continue;
               }
               StreamConfigurationMap map = cameraCharacteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);

               Size largestImageSize = Collections.max(
                       Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)),
                       new Comparator<Size>() {
                           @Override
                           public int compare(Size lhs, Size rhs) {
                               return Long.signum(lhs.getWidth() * lhs.getHeight() -
                                       rhs.getWidth() * rhs.getHeight());
                           }
                       }
               );
               mImageReader = ImageReader.newInstance(largestImageSize.getWidth(),
                       largestImageSize.getHeight(),
                       ImageFormat.JPEG,
                       1);
               mImageReader.setOnImageAvailableListener(mOnImageAvailableListener,
                       mBackgroundHandler);

               mPreviewSize = getPreferredPreviewSize(map.getOutputSizes(SurfaceTexture.class), width, height);
               mCameraId = cameraId;
               return;
           }
       } catch (CameraAccessException e) {
           e.printStackTrace();
       }
   }