android - How to rotate and flip bitmap in onPictureTaken

Question

I'm finding in onPictureTaken that the bitmap saved is mirrored about the y-axis and rotated 90 degrees clockwise even though the camera preview was not. This is on my Nexus S that's running 2.3.6. The same program running on my Nexus 4 with 4.2 has the resulting bitmap mirrored about the y-axis and rotated 180 degrees clockwise.

This is the code I'm running in onPictureTaken:

@Override
public void onPictureTaken(final byte[] data, Camera camera) {
    Bitmap picture = BitmapFactory.decodeByteArray(data, 0, data.length);
    String path = MediaStore.Images.Media.insertImage(getContentResolver(), picture, "name" , "description");
    Log.e("tag", "path: " + path); // prints something like "path: content://media/external/images/media/819"

    try {
        ExifInterface exif = new ExifInterface(path); // prints this error: "04-25 21:28:21.063: E/JHEAD(12201): can't open 'content://media/external/images/media/819'"
        int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);
        Log.e("tag", "exif orientation: " + orientation); // this is outputting orientation unknown
    } catch (IOException e) {
        e.printStackTrace();
    }
}

Can anyone show me how I rectify this given that I seem to be getting different results from different devices? How do I detect the orientation of the resulting bitmap so that I know to rotate it either 90 or 180 degrees counterclockwise?

[EDIT]

I added some more information using the ExifInterface stuff I've been reading about, but that information doesn't seem to pan out...

Answer 1

I have put a lot of work into this and thought, I'd share my solution. It is tested on a Motorola Devy, Samsung Xcover 1 and Samsung XCover 2.

As I work with a custom camera preview, the solution basically has two parts. 1. Take care of the camera preview and set rotation of the preview according to device rotation. 2. Once a picture is taken, that is the 'onPictureTaken' callback is invoked rotate the picture by the correct angle, such that it shows what the preview just showed.

1

---

private void initPreview(int width, int height) {
    if (camera != null && holder.getSurface() != null) {
        try {
            camera.setPreviewDisplay(holder);
        } catch (Throwable t) {
            Log.e("PreviewDemo-surfaceCallback",
              "Exception in setPreviewDisplay()", t);
            Toast.makeText(getContext(), t.getMessage(),
                       Toast.LENGTH_LONG).show();
        }

        try {
            Camera.Parameters parameters=camera.getParameters();

            Camera.Size size=getBestPreviewSize(width, height, parameters);
            Camera.Size pictureSize=getSmallestPictureSize(parameters);

            Display display = windowManager.getDefaultDisplay();
            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.FROYO) { // for 2.1 and before
                if (isPortrait(display)) {
                    parameters.set(CAMERA_PARAM_ORIENTATION, CAMERA_PARAM_PORTRAIT);
                } else {
                    parameters.set(CAMERA_PARAM_ORIENTATION, CAMERA_PARAM_LANDSCAPE);
                }
            } else { // for 2.2 and later
                switch (display.getRotation()) {
                    case Surface.ROTATION_0: // This is display orientation
                        if (size.height > size.width) parameters.setPreviewSize(size.height, size.width);
                        else parameters.setPreviewSize(size.width, size.height);
                        camera.setDisplayOrientation(90);
                        break;
                    case Surface.ROTATION_90:
                        if (size.height > size.width) parameters.setPreviewSize(size.height, size.width);
                        else parameters.setPreviewSize(size.width, size.height);
                        camera.setDisplayOrientation(0);
                        break;
                    case Surface.ROTATION_180:
                        if (size.height > size.width) parameters.setPreviewSize(size.height, size.width);
                        else parameters.setPreviewSize(size.width, size.height);
                        camera.setDisplayOrientation(270);
                        break;
                    case Surface.ROTATION_270:
                        if (size.height > size.width) parameters.setPreviewSize(size.height, size.width);
                        else parameters.setPreviewSize(size.width, size.height);
                        camera.setDisplayOrientation(180);
                        break;
                }
            }

            parameters.setPictureSize(pictureSize.width, pictureSize.height);
            //parameters.setPictureFormat(ImageFormat.JPEG);
            camera.setParameters(parameters);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

---

Your 'surfaceChanged' method, in your camera preview (SurfaceView), you should look like this:

---

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        stopPreview();
        initPreview(w, h);
        startPreview();
    }

---

where

stopPreview:

private void stopPreview() {
    if (camera != null) {
        camera.stopPreview();
    }
}

startPreview:

private void startPreview() {
    if (camera != null) {
        camera.startPreview();
    }
}

2

---

In your 'onPictureTaken' callback rotate the picture, using the following code:

Display display = getWindowManager().getDefaultDisplay();
    int rotation = 0;
    switch (display.getRotation()) {
        case Surface.ROTATION_0: // This is display orientation
        rotation = 90;
        break;
    case Surface.ROTATION_90:
        rotation = 0;
        break;
    case Surface.ROTATION_180:
        rotation = 270;
        break;
    case Surface.ROTATION_270:
        rotation = 180;
            break;
     }

     Bitmap bitmap = BitmapTools.toBitmap(data);
     bitmap = BitmapTools.rotate(bitmap, rotation);

---

BitmapTools.java

public class BitmapTools {

        public static Bitmap toBitmap(byte[] data) {
            return BitmapFactory.decodeByteArray(data , 0, data.length);
        }

        public static Bitmap rotate(Bitmap in, int angle) {
            Matrix mat = new Matrix();
            mat.postRotate(angle);
            return Bitmap.createBitmap(in, 0, 0, in.getWidth(), in.getHeight(), mat, true);
        }
    }