#!python
# -*- mode: python; Encoding: utf-8; coding: utf-8 -*-
# Last updated: <2022/04/07 06:45:33 +0900>
"""
tkinter.PhotoImage zoom sample.

* Windows10 x64 21H2 + Python 3.9.12 64bit + Pillow 9.1.0
* Windows10 x64 21H2 + Python 2.7.18 32bit + Pillow 6.2.2

Python 2.7.18 32bit ... Success up to 10x, failure 11x.
"""

try:
    import Tkinter as tk
except Exception:
    import tkinter as tk

from PIL import Image, ImageTk


class App(tk.Frame):

    def __init__(self, master=None):
        tk.Frame.__init__(self, master)

        self.frm = tk.Frame(self.master)
        self.frm.pack(expand=1, fill=tk.BOTH)
        self.frm.rowconfigure(1, weight=1)
        self.frm.columnconfigure(2, weight=1)

        self.btn0 = tk.Button(self.frm, text="-", command=lambda: self.dec_ratio())
        self.btn1 = tk.Button(self.frm, text="+", command=lambda: self.inc_ratio())
        self.zoomstr = tk.StringVar()
        self.zoomlbl = tk.Label(self.frm, textvariable=self.zoomstr)
        self.btn0.grid(row=0, column=0, ipadx=4)
        self.btn1.grid(row=0, column=1, ipadx=4)
        self.zoomlbl.grid(row=0, column=2)

        self.canvas = tk.Canvas(self.frm, bg="#666666")
        self.canvas.grid(row=1, column=0, columnspan=3, sticky=tk.N + tk.S + tk.W + tk.E)

        self.im = Image.open("tex_1024.png")
        self.photo_image = ImageTk.PhotoImage(image=self.im)

        self.ratio = 1
        self.set_image()

    def set_image(self):
        self.canvas.delete("all")
        if self.ratio == 1:
            # 1:1
            self.zoomstr.set("%d%%" % (self.ratio * 100))
            self.zoom_image = self.photo_image
        elif self.ratio > 1:
            # zoom (x 2, 3, 4, ...)
            zm = int(self.ratio)
            self.zoomstr.set("%d%%" % (self.ratio * 100))
            self.zoom_image = self.photo_image._PhotoImage__photo.zoom(zm)
        else:
            # subsample (/ 2, 3, 4, ...)
            zm = -self.ratio
            r = int(100 / zm)
            self.zoomstr.set("%d%%" % r)
            self.zoom_image = self.photo_image._PhotoImage__photo.subsample(zm)

        self.canvas.create_image(0, 0, image=self.zoom_image, anchor=tk.NW)

    def inc_ratio(self):
        maxratio = 16
        if self.ratio < maxratio:
            self.ratio = self.ratio + 1
            self.ratio = min([maxratio, self.ratio])
            if -1 <= self.ratio <= 1:
                self.ratio = 1
            self.set_image()

    def dec_ratio(self):
        minratio = -10
        if self.ratio > minratio:
            self.ratio = self.ratio - 1
            self.ratio = max([minratio, self.ratio])
            if -1 <= self.ratio <= 0:
                self.ratio = -2
            self.set_image()


def main():
    root = tk.Tk()
    app = App(master=root)
    app.mainloop()


if __name__ == '__main__':
    main()