Plant with purple/white/yellow flower
The plant is Convolvulus tricolor, the dwarf morning-glory. It belongs to the family Convolvulaceae.Blue, white, red and pink flowering cultivars of this plant are available$^1$. It is a annual/perennial growing to 0.3 m (1ft) by 0.2 m (0ft 8in) at a medium rate$^2$.


Image source
References:

Plantasm

PFAF database