reading android jpeg EXIF metadata from picture callback

Question

Background: I am writing a camera app for a messenger program. I cannot save the captured image to persistent disk at any time. The camera must support all orientations.

Answer 1

If you want a way to read EXIF data that wont be so dependent on where your URI came from you you could use the exif support library and read it from a stream. For example this is how I get the orientation of the image.

build.gradle

dependencies {
...    
compile "com.android.support:exifinterface:25.0.1"
...
}

Example code:

import android.support.media.ExifInterface;
...
try (InputStream inputStream = context.getContentResolver().openInputStream(uri)) {
      ExifInterface exif = new ExifInterface(inputStream);
      int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_NORMAL);
    } catch (IOException e) {
      e.printStackTrace();
    }

The reason I had to do it this way once we started targeting api 25 (maybe a problem on 24+ also) but still supporting back to api 19, on android 7 our app would crash if I passed in a URI that was just referencing a file. Hence I had to create a URI to pass to the camera intent like this.

FileProvider.getUriForFile(context, context.getApplicationContext().getPackageName() + ".fileprovider", tempFile);

The issue there is that file its not possible to turn the URI into a real file path (other than holding on to the temp file path).

Answer 2

If you have a content:// type of Uri, android provides APIs through ContentResolver and there’s no need to use external libraries:

public static int getExifAngle(Context context, Uri uri) {
    int angle = 0;
    Cursor c = context.getContentResolver().query(uri,
            new String[] { MediaStore.Images.ImageColumns.ORIENTATION },
            null,
            null,
            null);

    if (c != null && c.moveToFirst()) {
        int col = c.getColumnIndex( MediaStore.Images.ImageColumns.ORIENTATION );
        angle = c.getInt(col);
        c.close();
    }
    return angle;
}

You can also read any other value you find in MediaStore.Images.ImageColumns, like latitude and longitude.

This currently doesn’t work with file:/// Uris but can be easily tweaked.