With just your thumb, without any need of looking at the screen, this app has the same function of a finger rosary.
The user will find a nice collection of art pieces, one for each mystery of the Rosary. Thus, with these representations, the app indicates the mystery which is being prayed.
4 Finger gestures are recognized to easily use it.
The original artworks can be found in the Shrine of Our Lady of Torreciudad, in Northern Spain (+info: torreciudad.org). Permission for using those images has been granted to this application -thanks!