# Tk_image_scrollbars_zoom_and_drag.py ZZZ

# Tk_image_scrollbars_zoom_and_drag.py ZZZ ??? quite confusing

from Tkinter import *
import os

import tkFileDialog
from tkFileDialog import askopenfilename

import random
from PIL import Image, ImageTk

class Cv(): 0
cv=Cv()

def hide_scroll(tScrollbar, lo, hi):
    ''' scrollbar hides if it's not needed.
        Works only if you use the grid geometry manager '''
    if float(lo) <= 0.0 and float(hi) >= 1.0:
        grid_remove()
    else:
        grid()
    tScrollbar.set(root, lo, hi)

def zoom():
    ''' Simple drag and zoom with mouse wheel '''

    def mouse_wheel(event):
        ''' Zoom with mouse wheel '''
        # Respond to Linux (event.num) or Windows (event.delta) wheel event
        if event.num == 5 or event.delta == -120:
            cv.scale += (0.1*cv.scale)
        if event.num == 4 or event.delta == 120:
            cv.scale -= (0.1*cv.scale)
        cv.scale = max(0.001,min(2,cv.scale))
        # Rescale image on canvas
        xi,yi = canvas.coords('photoID')
        xc = canvas.canvasx(event.x)
        yc = canvas.canvasy(event.y)
        x = xc-cv.scale*xc
        y = yc-cv.scale*yc
        canvas.delete('photoID')
        newsize = (int(img.size[0]*cv.scale), int(img.size[1]*cv.scale))
        print newsize
        scaledImg = img.resize(newsize, Image.ANTIALIAS)
        cv.imgTk = ImageTk.PhotoImage(scaledImg)
        canvas.create_image((x, y), anchor='nw', image=cv.imgTk, tag='photoID')
        canvas.lift('info')
        canvas.configure(scrollregion=canvas.bbox("all"))
        # canvas.configure(scrollregion=canvas.bbox(cv.imgTk))

    def move_from(event):
        ''' Remember previous coordinates for scrolling with the mouse '''
        canvas.scan_mark(event.x, event.y)

    def move_to(event):
        ''' Drag (move) canvas to the new position '''
        if min(event.x, event.y) > 15:
            canvas.scan_dragto(event.x, event.y, gain=1)

    # Bind events to the Canvas
    root.bind('<ButtonPress-1>', move_from)
    root.bind('<B1-Motion>',       move_to)
    root.bind('<Button-5>',    mouse_wheel)  # only with Linux, wheel scroll down
    root.bind('<Button-4>',    mouse_wheel)  # only with Linux, wheel scroll up
    root.bind("<MouseWheel>",  mouse_wheel)  # with Windows and MacOS, but not Linux

    # Show image and plot some random test rectangles on the canvas
    cv.scale = 1.0
    cv.x, cv.y = 0, 0

root = Tk()
ww,hh=500,400
#root.geometry('{}x{}+{}+{}'.format(ww,hh,0,0))
root.title('Simple Zoom With Mouse Wheel')

f = askopenfilename(filetypes=[("png files","*.png"),("all files","*.*")])
img = Image.open(f)


# Lock the canvas size
root.resizable(0,0)

frame = Frame(root, bd=2, relief=SUNKEN)

frame.grid_rowconfigure(0, weight=1)
frame.grid_columnconfigure(0, weight=1)

xscrollbar = Scrollbar(frame, orient=HORIZONTAL)
xscrollbar.grid(row=1, column=0, sticky=E+W)

yscrollbar = Scrollbar(frame)
yscrollbar.grid(row=0, column=1, sticky=N+S)

canvas = Canvas(frame, bd=0, scrollregion=(0, 0, 1000, 1000),
        width=ww, height=hh,
        xscrollcommand=xscrollbar.set,
        yscrollcommand=yscrollbar.set)
canvas.grid(row=0, column=0, sticky=N+S+E+W)


cv.imgTk = ImageTk.PhotoImage(img)
canvas.create_image((0, 0), anchor='nw', image=cv.imgTk, tag='photoID')

xscrollbar.config(command=canvas.xview)
yscrollbar.config(command=canvas.yview)
canvas.config(scrollregion=canvas.bbox(ALL))

canvas.create_text(200, 40, font=('courier', 20, 'bold'), text='Scroll Wheel To Zoom', tag='info')

frame.pack()
zoom()

root.mainloop()