Drag photos to sort order in slide show

[tedbarnett]

Users should be able to press-hold, then drag photos into a new position in the slide show. The slide show should always read from top left to right, then down each row (as a user would read text).

[prempratapsingh]

Added the desired drag and drop feature to the photos' grid view. Now slide show will follow the same order as set by user with drag and drop behaviour.

However, since the order is set temporarily in memory, the order is lost when the app is closed. Please suggest, if we need to retain the order of photos even after the app is closed. It would require saving the order on Firebase and thus would require additional work.

This is how the drag and drop works in the app,
https://drive.google.com/file/d/1NNATLZwbNGJIEoxrKgXbVB1xQ5i-bX_N/view?usp=sharing