Tkinter canvas: Drawing in the Tkinter interface with canvas. Example from (Langtangen, 2005, pages 527+)

gistfile1.py

from Tkinter import *

root = Tk()

canvas = Canvas(root, width=400, height=200)
canvas.pack()
canvas.create_oval(10, 10, 110, 60, fill="grey")
canvas.create_text(60, 35, text="Oval")
canvas.create_rectangle(10, 100, 110, 150, outline="blue")
canvas.create_text(60, 125, text="Rectangle")
canvas.create_line(60, 60, 60, 100, width=3)

class MouseMover():
    def __init__(self):
        self.item = 0; self.previous = (0, 0)
    def select(self, event):
        widget = event.widget           # Get handle to canvas
        # Convert screen coordinates to canvas coordinates
        xc = widget.canvasx(event.x); yc = widget.canvasx(event.y)
        self.item = widget.find_closest(xc, yc)[0]      # ID for closest
        self.previous = (xc, yc)
        print((xc, yc, self.item))
    def drag(self, event):
        widget = event.widget
        xc = widget.canvasx(event.x); yc = widget.canvasx(event.y)
        canvas.move(self.item, xc-self.previous[0], yc-self.previous[1])
        self.previous = (xc, yc)


# Get an instance of the MouseMover object
mm = MouseMover()

# Bind mouse events to methods (could also be in the constructor)
canvas.bind("<Button-1>", mm.select)
canvas.bind("<B1-Motion>", mm.drag)