Android : Cropping an image and setting it as background

Whenever I select a picture from gallery to set it as a background, it shrinks (if size exceeds the device resolution). So I cropped the selected image before setting it as a background. But somehow its not setting it as background after cropping. Must be a silly mistake I know but I'm not able to figure it out right now.

Thanks.

Can someone point out what's the problem?

private void wallp() // For changing wallpaper
    {
        Intent intent = new Intent();
        intent.setType("image/*");

        startActivityForResult(Intent.createChooser(intent, "Select Picture"),
                SELECT_PICTURE);

    }
    private void crop(Uri photoUri) {
        Intent intent = new Intent();
        intent.setData(photoUri);
        intent.putExtra("outputX", 1256);
        intent.putExtra("outputY", 720);
        intent.putExtra("aspectX", 1);
        intent.putExtra("aspectY", 1);
        intent.putExtra("scale", true);
        intent.putExtra("return-data", true);

        startActivityForResult(intent, RESULT_CROP);
    }

ActivityForResult:

case SELECT_PICTURE:
            if (resultcode == RESULT_OK) {
                  Uri photoUri = data.getData();
                    if (photoUri != null) {
                        crop(photoUri);
                    }
                } else if (resultcode == RESULT_CROP) {
                    Uri myimage = data.getData();

                    File f = new File(getIntent().getExtras().containsKey(key));
                    if (f.exists()) {
                        Drawable img = Drawable.createFromPath(f.getAbsolutePath());

                        l.setBackgroundDrawable(img); <-- Why is this not working?||||||

                        store = PreferenceManager.getDefaultSharedPreferences(this);
                        edit = store.edit();
                        edit.putString("my_image", f.getAbsolutePath());
                        edit.commit();
                    }

getRealPathFromUri:

private String getRealPathFromUri(Uri contentURI) // For Changing Wallpaper
{
    Cursor cursor = getContentResolver().query(contentURI, null, null,
            null, null);
    if (cursor == null) {
        return contentURI.getPath();
    } else {
        cursor.moveToFirst();
        int idx = cursor
                .getColumnIndex(MediaStore.Images.ImageColumns.DATA);
        return cursor.getString(idx);

    }
}
}