def add_grid(self, cell_callback):
grid = GridLayout(cols=len(self.field[0]), rows=len(self.field))
for i, line in enumerate(self.field):
for j, cell in enumerate(line):
btn = ToggleButton(background_color=self.BLUE,
background_normal='',
on_press=cell_callback)
if cell == 1:
btn = ToggleButton(background_normal='',
background_color=self.BLUE,
state='down',
on_press=cell_callback)
btn.coordinates = (i, j)
grid.add_widget(btn)
return grid
