# tk_canvas_zoom.py

# tk_canvas_zoom.py

import tkinter as tk

def create_xcanvas(rootwin, **opt):
    width = opt.get("width", 1000)
    height = opt.get("height", 600)
    bg = opt.get("bg", "white")
    scrollbars = opt.get("scrollbars", True)
    scalewidget = opt.get("scalewidget", True)
    x_axis = opt.get("x_axis", 7)
    y_axis = opt.get("y_axis", 7)

    region = (-50, -50, width, height)
    rootframe = tk.Frame(rootwin, width=width, height=height, bg=bg)
    rootframe.pack(expand=True, fill=tk.BOTH)

    canvas = tk.Canvas(rootframe, width=width, height=height, bg=bg, scrollregion=region)
    canvas.config(highlightthickness=0)

    if scrollbars:
        setup_scrollbars(canvas, rootframe)

    canvas.pack(side=tk.LEFT, expand=True, fill=tk.BOTH)

    scalewidget_obj = tk.Scale(rootframe, from_=1, to=3000, length=500,
                               orient=tk.VERTICAL, font="Consolas 6",
                               command=lambda p: resize_canvas(canvas, region, p))
    scalewidget_obj.set(100)

    if scalewidget:
        scalewidget_obj.pack(side=tk.TOP, fill=tk.Y, expand=False)
    else:
        scalewidget_obj.place(x=100000, y=100000)

    canvas.xview_moveto(0)
    canvas.yview_moveto(0)

    if x_axis or y_axis:
        draw_axis(canvas, x_axis, y_axis)

    setup_bindings(canvas, rootwin, scalewidget_obj)

    canvas.region = region
    canvas.rootwin = rootwin
    canvas.scalewidget = scalewidget_obj

    return canvas

def setup_scrollbars(canvas, rootframe):
    sbarV = tk.Scrollbar(rootframe, orient=tk.VERTICAL)
    sbarH = tk.Scrollbar(rootframe, orient=tk.HORIZONTAL)
    sbarV.config(command=canvas.yview)
    sbarH.config(command=canvas.xview)
    canvas.config(yscrollcommand=sbarV.set)
    canvas.config(xscrollcommand=sbarH.set)
    sbarV.pack(side=tk.RIGHT, fill=tk.Y)
    sbarH.pack(side=tk.BOTTOM, fill=tk.X)

def setup_bindings(canvas, rootwin, scalewidget):
    canvas.bind("<Control-MouseWheel>", lambda e: on_ctrl_mousewheel(e, scalewidget))
    canvas.bind("<Alt-MouseWheel>", lambda e: on_alt_mousewheel(e, scalewidget))
    canvas.bind("<MouseWheel>", lambda e: canvas.yview_scroll(int(-1*(e.delta/120)), "units"))
    canvas.bind("<Shift-MouseWheel>", lambda e: canvas.xview_scroll(int(-1*(e.delta/120)), "units"))
    canvas.bind("f", lambda e: scalewidget.set(100))
    canvas.bind("<Home>", lambda e: scalewidget.set(100))
    canvas.bind("<Up>", lambda e: canvas.yview_scroll(-1, "units"))
    canvas.bind("<Down>", lambda e: canvas.yview_scroll(1, "units"))
    canvas.bind("<Left>", lambda e: canvas.xview_scroll(-1, "units"))
    canvas.bind("<Right>", lambda e: canvas.xview_scroll(1, "units"))
    canvas.bind("<Prior>", lambda e: canvas.yview_scroll(-1, "pages"))
    canvas.bind("<Next>", lambda e: canvas.yview_scroll(1, "pages"))
    canvas.bind("<Shift-Prior>", lambda e: canvas.xview_scroll(1, "pages"))
    canvas.bind("<Shift-Next>", lambda e: canvas.xview_scroll(-1, "pages"))

def on_ctrl_mousewheel(event, scalewidget):
    s = scalewidget.get()
    s += 15 if event.delta > 0 else -15
    scalewidget.set(s)

def on_alt_mousewheel(event, scalewidget):
    s = scalewidget.get()
    s += 5 if event.delta > 0 else -5
    scalewidget.set(s)

def resize_canvas(canvas, region, percent):
    x1, y1, x2, y2 = region
    canvas_breadth = max(x2-x1, y2-y1)
    _region = canvas.config('scrollregion')[4].split()
    region_vals = tuple(float(x) for x in _region)
    x1, y1, x2, y2 = region_vals
    breadth = max(x2-x1, y2-y1)

    if breadth == 0:
        return

    r = float(percent) / 100
    if r < 0.01 or r > 30:
        return

    s = r / (float(breadth) / canvas_breadth)
    canvas.scale('all', 0, 0, s, s)
    nregion = tuple(x*r for x in region)
    canvas.config(scrollregion=nregion)

def draw_axis(canvas, m, n):
    canvas.create_line(-40, 0, 100*m, 0, width=1, fill='black', arrow='last')
    canvas.create_line(0, -40, 0, 100*n, width=1, fill='black', arrow='last')
    for i in range(1, m):
        canvas.create_line(100*i, -5, 100*i, 0, width=1, fill='black')
        canvas.create_text(100*i, -5, text=str(100*i), font='Consolas 8', anchor='s')
    for i in range(1, n):
        canvas.create_line(-5, 100*i, 0, 100*i, width=1, fill='black')
        canvas.create_text(-7, 100*i, text=str(100*i), font='Consolas 8', anchor='e')

def show_canvas(canvas, force=False):
    if force or not canvas.winfo_ismapped():
        canvas.rootwin.iconify()
        canvas.rootwin.update()
        canvas.rootwin.deiconify()
        canvas.rootwin.lift()

def hide_canvas(canvas):
    canvas.rootwin.iconify()

def xcanvas_test():
    rootwin1 = tk.Tk()
    c1 = create_xcanvas(rootwin1, width=1000, height=800, bg="white")
    c1.create_rectangle(100, 120, 400, 230, width=2, outline='blue', fill='yellow')
    c1.create_rectangle(400, 320, 600, 530, width=2, outline='blue', fill='yellow')
    c1.create_oval(400, 320, 600, 530, width=2, outline='blue', fill='cyan')
    c1.create_line(200, 50, 500, 430, width=3, fill='blue')

    rootwin2 = tk.Tk()
    c2 = create_xcanvas(rootwin2, scrollbars=False, scalewidget=False, x_axis=0, y_axis=0, width=1000, height=800, bg="cornsilk")
    c2.create_rectangle(100, 120, 400, 230, width=2, outline='red', fill='yellow')
    c2.create_oval(100, 120, 400, 230, width=2, outline='red', fill='cyan')
    c2.create_rectangle(400, 320, 600, 530, width=2, outline='red', fill='yellow')
    c2.create_line(200, 50, 500, 430, width=3, fill='red')

    tk.mainloop()

xcanvas_test()