# Tk_scroll_by_mouse_angle.py

# Tk_scroll_by_mouse_angle.py

# ZZZ

from tkinter import *
from math import *
from time import *

def mouse_down(e):
    cv.px = int(e.x/unit) * unit
    cv.py = int(e.y/unit) * unit
def mouse_up(e):
    cv.x = 0
    cv.y = 0
def mouse_move(e):
    cv.x = e.x
    cv.y = e.y
def scroll_dist():
    return sqrt((cv.x - cv.width/2)**2 + (cv.y - cv.height/2)**2)
def draw_grid():
    for x in range(0, sq_units, unit*2):
        canvas.create_line([(x, 0), (x, sq_units)], fill='lightblue', tags=('mv','g'))
    for y in range(0, sq_units, unit*2):
        canvas.create_line([(0, y), (sq_units, y)], fill='lightblue', tags=('mv','g'))
root = Tk()
root.geometry('+-10+0')
root.title("Tk_scroll_by_mouse_angle")

class Cv(): 0
cv = Cv()

cv.x = 0
cv.y = 0
cv.px = 0
cv.py = 0
cv.x2 = 0
cv.y2 = 0
cv.prev = 0
cv.timer = time()

unit = 50

sq_units = 10000

cv.width = 1280
cv.height = 640

cv.ww = 4000
cv.hh = 3000

vectors = []

frame = Frame(root)
frame.pack()

# create canvas with scrollbars
canvas = Canvas(frame, width=cv.width, height=cv.height, bg='white')
canvas.pack(side=LEFT, expand=True, fill=BOTH)
canvas.pack_propagate(False)

draw_grid()

# create scrollbars
vbar = Scrollbar(canvas)
vbar.pack(side=RIGHT, fill=Y)
hbar = Scrollbar(canvas, orient=HORIZONTAL)
hbar.pack(side=BOTTOM, fill=X)

# attach canvas to scrollbars
canvas.config(xscrollcommand=hbar.set, yscrollcommand=vbar.set)

# bind scrollbars to the canvas
hbar.config(command=canvas.xview)
vbar.config(command=canvas.yview)

# set the scrollregion to all
canvas.config(scrollregion=(0,0,sq_units,sq_units))
'''
'''

canvas.bind("<Button-1>", mouse_down)
canvas.bind("<B1-Motion>", mouse_move)
canvas.bind("<ButtonRelease-1>", mouse_up)

'''
            canvas.move('mv', cv.x2, cv.y2)
            vectors.append((cx+cv.x, cy+cv.y))
            canvas.update()
    canvas.after(1, move_canvas)

move_canvas()

root.mainloop()
'''

# to keep moving canvas by mouse position from center of the screen while it draws a line
def move_canvas():
    if cv.x:
        canvas.delete('line')
        canvas.delete('coord')
        cv.timer = time()
        cx, cy,_ ,_ = canvas.coords('g')
        cx, cy = cx*-1, cy*-1
        cv.x2 = (cv.x - cv.width/2)*-0.2
        cv.y2 = (cv.y - cv.height/2)*-0.2
        canvas.create_text(cv.x, cv.y+10, text=list(map(int ,(cx, cy, cv.x2, cv.y2))), tags=('coord'))
        # move canvas with cv.x2 and cv.y2 while keeping the coords within (0, 0, cv.ww, cv.hh)
        if cx-cv.x2 < 0:
            cv.x2 = cx
        elif cx-cv.x2 > cv.ww:
            0
            # cv.x2 = cv.ww ### ???
        if cy-cv.y2 < 0:
            cv.y2 = -cx
        elif cy-cv.y2 > cv.hh:
            0
            # cv.y2 = cv.hh ### ???
        canvas.move('mv', cv.x2, cv.y2)
        vectors.append((cv.x, cv.y))
        #canvas.place_configure('mv', x=cv.x2, y=cv.y2)
        try:
            canvas.create_line(vectors, fill='red', tags=('mv', 'line'))
        except: 0
        cv.px, cv.py = cx+cv.x, cy+cv.y
        canvas.update()
    canvas.after(100, move_canvas)

move_canvas()

root.mainloop()