Paint_box.py

from tkinter import *
from tkinter.colorchooser import askcolor

class Paint(object):
    DEFAULT_PEN_SIZE=5.0
    DEFAULT_COLOR='black'

    def __init__ (self):
        self.root=Tk()

        self.pen_button=Button(self.root,text='Pen',command=self.use_pen)
        self.pen_button.grid(row=0,column=0)

        self.brush_button=Button(self.root,text='Brush',command=self.use_brush)
        self.brush_button.grid(row=0,column=1)

        self.color_button=Button(self.root,text='Color',command=self.choose_color)
        self.color_button.grid(row=0,column=2)

        self.eraser_button=Button(self.root,text='Eraser',command=self.use_eraser)
        self.eraser_button.grid(row=0,column=3)

        self.choose_size_button=Scale(self.root,from_=1,to=10,orient=HORIZONTAL)
        self.choose_size_button.grid(row=0,column=4)

        self.c=Canvas(self.root,bg='white',width=1000, height=1000)
        self.c.grid(row=1,columnspan=5)

        self.setup()
        self.root.mainloop()

    def setup(self):
        self.old_x=None
        self.old_y=None
        self.line_width=self.choose_size_button.get()
        self.color=self.DEFAULT_COLOR
        self.eraser_on=False
        self.active_button=self.pen_button
        self.c.bind('<B1-Motion>',self.paint)
        self.c.bind('<ButtonRelease-1>',self.reset)


    def use_pen(self):
        self.activate_button(self.pen_button)

    def use_brush(self):
        self.activate_button(self.brush_button)

    def choose_color(self):
        self.eraser_on=False
        self.color=askcolor(color=self.color)[1]

    def use_eraser(self):
        self.activate_button(self.eraser_button)


    def activate_button(self,some_button,eraser_mode=False):
        self.activate_button.config(relief=RAISED)
        some_button.config(relief=SUNKEN)
        self.activate_button=some_button
        self.eraser_on=eraser_mode


    def paint(self,event):
        self.line_width=self.choose_size_button.get()
        paint_color='white' if self.eraser_on else self.color
        if self.old_x and self.old_y:
            self.c.create_line(self.old_x,self.old_y,event.x,event.y,width=self.line_width,fill=paint_color,capstyle=ROUND,smooth=TRUE,splinesteps=36)
        self.old_x=event.x
        self.old_y=event.y

    def reset(self,event):
        self.old_x,self.old_y=None,None



if __name__=='__main__':
    Paint()