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@TargetApi(Build.VERSION_CODES.KITKAT)
static class DocumentExifTransformation implements Transformation {
private static final String[] CONTENT_ORIENTATION = new String[] {
MediaStore.Images.ImageColumns.ORIENTATION
};
final Context context;
final Uri uri;
DocumentExifTransformation(Context context, Uri uri) {
this.context = context;
this.uri = uri;
}
@Override public Bitmap transform(Bitmap source) {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) return source;
if (!DocumentsContract.isDocumentUri(context, uri)) return source;
int exifRotation = getExifOrientation(context, uri);
if (exifRotation != 0) {
Matrix matrix = new Matrix();
matrix.preRotate(exifRotation);
Bitmap rotated =
Bitmap.createBitmap(source, 0, 0, source.getWidth(), source.getHeight(), matrix, true);
if (rotated != source) {
source.recycle();
}
return rotated;
}
return source;
}
@Override public String key() {
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) return "documentTransform()";
return "documentExifTransform(" + DocumentsContract.getDocumentId(uri) + ")";
}
static int getExifOrientation(Context context, Uri uri) {
ContentResolver contentResolver = context.getContentResolver();
Cursor cursor = null;
try {
String id = DocumentsContract.getDocumentId(uri);
id = id.split(":")[1];
cursor = contentResolver.query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
CONTENT_ORIENTATION, MediaStore.Images.Media._ID + " = ?", new String[] { id }, null);
if (cursor == null || !cursor.moveToFirst()) {
return 0;
}
return cursor.getInt(0);
} catch (RuntimeException ignored) {
// If the orientation column doesn't exist, assume no rotation.
return 0;
} finally {
if (cursor != null) {
cursor.close();
}
}
}
}

cool. what is the Transformation interface?

Owner

Picasso allows to pass in custom transformations for your loading task. You can apply anything you want such as crop the image, add effects, color overlay etc.

NemSim commented Apr 6, 2016

Thanks for writing this class up! It's helping me a great deal so far.

Something to look out for, I had to update the key method to guard against non-document IDs:

@Override
public String key() {
        if ((Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) || 
                !DocumentsContract.isDocumentUri(context, uri)) return "documentTransform()";
        return "documentExifTransform(" + DocumentsContract.getDocumentId(uri) + ")";
    }
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