non continuous line user draw tkinter python

Question

So here's the code for a program where the user can click on a point and it draws a point and then subsequent clicks draw more lines all attached to the previous line. How would I edit this program to just let the user press down on the button and have like (xp1, yp1) and then drag some where and release at (xp2, yp2) then draw a line between (xp1, yp1) and (xp2, yp2). Finally it would let the user create many different lines then eventually be able to clear the canvas screen by pressing "c". Like I know the last thing would have to bind some function to "c" but I don't know what it is.

from Tkinter import Canvas, Tk, mainloop
import Tkinter as tk

# Image dimensions
w,h = 640,480

# Create canvas
root = Tk()
canvas = Canvas(root, width = w, height = h, bg = 'white')
canvas.pack()

# Create poly line
class PolyLine(object):
    def __init__(x, canvas):
        x.canvas = canvas
        x.start_coords = None # first click
        x.end_coords = None # subsequent clicks
    def __call__(x, event):
        coords = event.x, event.y # coordinates of the click
        if not x.start_coords:
            x.start_coords = coords
            return
        x.end_coords = coords # last click
        x.canvas.create_line(x.start_coords[0], # first dot x
                                x.start_coords[1], # first dot y
                                x.end_coords[0], # next location x
                                x.end_coords[1]) # next location y
        x.start_coords = x.end_coords

canvas.bind("<Button-1>", PolyLine(canvas)) # left click is used
mainloop()

Thank you so much for your time! I really appreciate it!

j_4321 · Accepted Answer · 2017-03-04 11:11:45Z

2

For the drawing line part, I use a global list variable to store the line points. If the list is empty, then I store the line starting point coordinates inside the list. Otherwise, I draw the line between the starting point and the current cursor position and I reset the list.

For the clearing part, what you need is to bind the canvas.delete method to "c" key press.

from Tkinter import Canvas, Tk

line = []

def on_click(event):
    global line
    if len(line) == 2:
        # starting point has been defined
        line.extend([event.x, event.y])
        canvas.create_line(*line)
        line = []   # reset variable
    else:
        # define line starting point
        line = [event.x, event.y]

def clear_canvas(event):
    canvas.delete('all')

root = Tk()
canvas = Canvas(root, bg='white')
canvas.pack()

canvas.bind("<Button-1>", on_click) 
root.bind("<Key-c>", clear_canvas)

root.mainloop()

edited Mar 4, 2017 at 11:11

answered Mar 3, 2017 at 10:08

j_4321

16.2k4 gold badges38 silver badges67 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

MissSprezzatura Over a year ago

Oh sorry I worded my question wrong, what if I wanted to click two points and have a line drawn in between them? Not click drag and release... The clear worked fantastic, thank you

3141 · Accepted Answer · 2017-12-27 17:18:49Z

1

import tkinter as tk
from time import sleep

def getpoint1(event):
    global x, y
    x, y = event.x, event.y

def getpoint2(event):
    global x1, y1
    x1, y1 = event.x, event.y

def drawline(event):
    canvas.create_line(x, y, x1, y1)



root = tk.Tk()

canvas = tk.Canvas(root, width=400, height=400)
canvas.pack()

root.bind('q', getpoint1)
root.bind('w', getpoint2)
root.bind('<Button-1>', drawline)


root.mainloop()

This is pretty much what you asked for on your comment, but with different keys.

answered Dec 27, 2017 at 17:18

3141

4091 gold badge6 silver badges23 bronze badges

Collectives™ on Stack Overflow

non continuous line user draw tkinter python

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related