from tkinter import *
 
a = 0
 
def inc():
     
    v = infos['value']
    v += 1
    infos['value'] = v
     
    can.itemconfig(text, text=str(v)) 
 
infos = {'value': a}
 
f = Tk()
 
can= Canvas(f, width=150, height=150)
can.pack()
text = can.create_text((50, 50), text=a) 
 
button = Button(f, text='incrémenter', command=inc)
button.pack()
 
f.mainloop()