Real time drawing with mouse in Tkinter-CodePudding

I am fairly comfortable with drawing in Tkinter but you only see the shape once you release the mouse button. How do you see the shape as you drag the mouse? I am half way there with the below code but if you run it you will see it doesn't update to remove each drawing made by the motion function.

from tkinter import *

window = Tk()

canvas = Canvas(bg='black')
canvas.pack()

def locate_xy(event):
    global current_x, current_y
    current_x, current_y = event.x, event.y

def draw_circle(event):
    global current_x, current_y
    canvas.create_oval((current_x, current_y, event.x, event.y), outline='white')
    current_x, current_y = event.x, event.y

def update_circle(event):
    global current_x, current_y
    canvas.create_oval((current_x, current_y, event.x, event.y), outline='white')

canvas.bind('<ButtonPress-1>', locate_xy)
canvas.bind('<ButtonRelease-1>', draw_circle)
canvas.bind('<B1-Motion>', update_circle)

window.mainloop()

CodePudding user response：

You just need to create the oval inside locate_xy() and update its coordinates inside update_circle(). The binding of <ButtonRelease-1> is not necessary:

def locate_xy(event):
    global current_x, current_y, current_item
    current_x, current_y = event.x, event.y
    # create the oval item and save its ID
    current_item = canvas.create_oval((current_x, current_y, event.x, event.y), outline='white')

def update_circle(event):
    # update coords of the oval item
    canvas.coords(current_item, (current_x, current_y, event.x, event.y))

canvas.bind('<ButtonPress-1>', locate_xy)
canvas.bind('<B1-Motion>', update_circle)

CodePudding user response：

You are already tracking mouse move with left button pressed by event <B1-Motion>, so just add drawing there:

from tkinter import *

window = Tk()

canvas = Canvas(bg='black')
canvas.pack()

def draw_line(event):
    x, y = event.x, event.y
    canvas.create_oval((x-2, y-2, x 2, y 2), outline='white')

canvas.bind('<B1-Motion>', draw_line)

window.mainloop()