How can i find the orientation of a picture taken

问题:

When I take a picture with Androids camera app, it detects the phone's orientation and saves the pic accordingly. So if i take a picture of a building, the roof will be on the topside, whether I hold the phone in landscape position or portrait.

However, when i use

Intent imageCaptureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

to get a picture, the camera app doesn't react to orientation. If i hold the phone vertically (portrait), the resulting pic will be rotated, with said building's roof to the left of the screen.

How can I set the intent so that the camera will take orientation into account?

Or can I deduce in some way in what orientation the pic was taken and rotate it myself afterward?

Or any other suggestion will be greatly appreciated.

~Thanks in advance, best regards.

回答1:

Found the answer. The exif of the image has an indicator of the orientation. Just in case, exif can be viewed in Android like this:

ExifInterface exif = new ExifInterface("filepath");  
exif.getAttribute(ExifInterface.TAG_ORIENTATION);

回答2:

Read from Exif if available, otherwise read from MediaStore

public static int getImageOrientation(Context context, String imagePath) {
    int orientation = getOrientationFromExif(imagePath);
    if(orientation <= 0) {
        orientation = getOrientationFromMediaStore(context, imagePath);
    }

    return orientation;
}

private static int getOrientationFromExif(String imagePath) {
    int orientation = -1;
    try {
        ExifInterface exif = new ExifInterface(imagePath);
        int exifOrientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, 
                ExifInterface.ORIENTATION_NORMAL);

        switch (exifOrientation) {
            case ExifInterface.ORIENTATION_ROTATE_270:
                orientation = 270;

                break;
            case ExifInterface.ORIENTATION_ROTATE_180:
                orientation = 180;

                break;
            case ExifInterface.ORIENTATION_ROTATE_90:
                orientation = 90;

                break;

            case ExifInterface.ORIENTATION_NORMAL:
                orientation = 0;

                break;
            default:
                break;
        }
    } catch (IOException e) {
        Log.e(LOG_TAG, "Unable to get image exif orientation", e);
    }

    return orientation;
}

private static int getOrientationFromMediaStore(Context context, String imagePath) {
    Uri imageUri = getImageContentUri(context, imagePath);
    if(imageUri == null) {
        return -1;
    }

    String[] projection = {MediaStore.Images.ImageColumns.ORIENTATION};
    Cursor cursor = context.getContentResolver().query(imageUri, projection, null, null, null);

    int orientation = -1;
    if (cursor != null && cursor.moveToFirst()) {
        orientation = cursor.getInt(0);
        cursor.close();
    }

    return orientation;
}

private static Uri getImageContentUri(Context context, String imagePath) {
    String[] projection = new String[] {MediaStore.Images.Media._ID};
    String selection = MediaStore.Images.Media.DATA + "=? ";
    String[] selectionArgs = new String[] {imagePath};
    Cursor cursor = context.getContentResolver().query(IMAGE_PROVIDER_URI, projection, 
            selection, selectionArgs, null);

    if (cursor != null && cursor.moveToFirst()) {
        int imageId = cursor.getInt(0);
        cursor.close();

        return Uri.withAppendedPath(IMAGE_PROVIDER_URI, Integer.toString(imageId));
    } 

    if (new File(imagePath).exists()) {
        ContentValues values = new ContentValues();
        values.put(MediaStore.Images.Media.DATA, imagePath);

        return context.getContentResolver().insert(
                    MediaStore.Images.Media.EXTERNAL_CONTENT_URI, values);
    } 

    return null;
}

回答3:

For a quick fix you can check if image's width is bigger than image's height. it means it's landscape and you can change it to portrait.

private Bitmap fromGallery(final Uri selectedImageUri) {
        try {
            Bitmap bm = MediaStore.Images.Media.getBitmap(this.getContentResolver(), selectedImageUri);

            ExifInterface exif = new ExifInterface(selectedImageUri.getPath());
            int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);

            int angle = 0;
            switch (orientation) {
                case ExifInterface.ORIENTATION_ROTATE_90:
                    angle = 90;
                    break;
                case ExifInterface.ORIENTATION_ROTATE_180:
                    angle = 180;
                    break;
                case ExifInterface.ORIENTATION_ROTATE_270:
                    angle = 270;
                    break;
                default:
                    angle = 0;
                    break;
            }
            Matrix mat = new Matrix();
            if (angle == 0 && bm.getWidth() > bm.getHeight())
                mat.postRotate(90);
            else
                mat.postRotate(angle);

            return Bitmap.createBitmap(bm, 0, 0, bm.getWidth(), bm.getHeight(), mat, true);

        } catch (IOException e) {
            Log.e("", "-- Error in setting image");
        } catch (OutOfMemoryError oom) {
            Log.e("", "-- OOM Error in setting image");
        }
        return null;
    }

回答4:

I used a file provider and nothing worked except making a temporary copy and reading the data from it.

public static int getOrientation(Context context, Uri uri) {

    int rotate = 0;

    try {

        ParcelFileDescriptor parcelFileDescriptor =
                context.getContentResolver().openFileDescriptor(uri, "r");

        FileDescriptor fileDescriptor = parcelFileDescriptor.getFileDescriptor();

        FileInputStream input = new FileInputStream(fileDescriptor);

        File tempFile = File.createTempFile("exif", "tmp");

        String tempFilename = tempFile.getPath();

        FileOutputStream output = new FileOutputStream(tempFile.getPath());

        int read;

        byte[] bytes = new byte[4096];

        while ((read = input.read(bytes)) != -1) {
            output.write(bytes, 0, read);
        }

        input.close();
        output.close();

        ExifInterface exif = new ExifInterface(tempFile.getAbsolutePath());
        int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);

        switch (orientation) {
            case ExifInterface.ORIENTATION_ROTATE_270:
                rotate = 270;
                break;
            case ExifInterface.ORIENTATION_ROTATE_180:
                rotate = 180;
                break;
            case ExifInterface.ORIENTATION_ROTATE_90:
                rotate = 90;
                break;
        }

    } catch (Exception e) {
        Log.i(TAG, e.getLocalizedMessage());
    }

    return rotate;
}

bonus rotate function

public static Bitmap rotateImage(Context context, Uri uri, int orientation) throws IOException {

    ParcelFileDescriptor parcelFileDescriptor =
            context.getContentResolver().openFileDescriptor(uri, "r");
    FileDescriptor fileDescriptor = parcelFileDescriptor.getFileDescriptor();
    Bitmap bitmap = BitmapFactory.decodeFileDescriptor(fileDescriptor);
    parcelFileDescriptor.close();

    if (orientation > 0) {
        Matrix matrix = new Matrix();
        matrix.postRotate(orientation);

        return Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(), bitmap.getHeight(), matrix, true);
    }

    return bitmap;
}