# coding: utf-8
from tkinter import *
import tkinter.filedialog
from PIL import Image,ImageTk
import os

def CALSIZE(ppix,img):
    width=0
    height=0
    if img.size[0]<=ppix and img.size[1]<ppix:
        width=img.size[0]
        height=img.size[1]
    elif img.size[0]<img.size[1]:
        height=ppix
        width=int(float(height)/float(img.size[1])*float(img.size[0]))
    else:
        width=ppix
        height=int(float(width)/float(img.size[0])*float(img.size[1]))
    return width,height

def SHOW_PIC(num):
    global fn
    img = Image.open(fn[num], 'r')
    info=fn[num]+' ('+str(img.size[0])+' x '+str(img.size[1])+')'
    width,height=CALSIZE(600,img)
    img.thumbnail((width, height), Image.ANTIALIAS)
    img2=ImageTk.PhotoImage(img)
    sub_win = Toplevel()
    Label(sub_win,text=info).pack()
    w=Label(sub_win, image = img2)
    w.img = img2
    w.pack()

def NEXTVIEW():
    global fn
    pix=150
    cols=6
    # create scrolled canvas
    vscrollbar = AutoScrollbar(root)
    vscrollbar.grid(row=0, column=1, sticky=N+S)
    hscrollbar = AutoScrollbar(root, orient=HORIZONTAL)
    hscrollbar.grid(row=1, column=0, sticky=E+W)
    canvas = Canvas(root,width=pix*cols+40,height=pix*4,
                    yscrollcommand=vscrollbar.set,
                    xscrollcommand=hscrollbar.set)
    canvas.grid(row=0, column=0, sticky=N+S+E+W)
    vscrollbar.config(command=canvas.yview)
    hscrollbar.config(command=canvas.xview)
    # make the canvas expandable
    root.grid_rowconfigure(0, weight=1)
    root.grid_columnconfigure(0, weight=1)
    # create canvas contents
    frame = Frame(canvas)
    frame.rowconfigure(1, weight=1)
    frame.columnconfigure(1, weight=1)

    dir_name=tkinter.filedialog.askdirectory(initialdir='C:/')
    os.chdir(dir_name)
    files=os.listdir(dir_name)
    root.title(dir_name)
    fn=[]
    for file in files:
        if '.JPG' in file: fn=fn+[file]
        if '.jpg' in file: fn=fn+[file]
        if '.png' in file: fn=fn+[file]
    n=len(fn)
#    print(dir_name,n)
    if n==0:
        Label(frame,text='No JPG, jpg, png image file!', font=('Arial', 32)).pack()
    else:
        bt=[0]*n
        for k in range(0,n):
            img = Image.open(fn[k],'r')
            ppix=pix
            width,height=CALSIZE(ppix,img)
            img.thumbnail((width, height), Image.ANTIALIAS)
            img1=ImageTk.PhotoImage(img)
            i=k//cols+1
            j=int(k%cols)+1
            bt[k] = Button(frame, padx=0, pady=0, image=img1,relief=RAISED,command=lambda kk=k: SHOW_PIC(kk))
            bt[k].img=img1
            bt[k].grid(row=i, column=j, sticky='news')
#            print(k,fn[k],width,height)
    canvas.create_window(0, 0, anchor=NW, window=frame)
    frame.update_idletasks()
    canvas.config(scrollregion=canvas.bbox("all"))

class AutoScrollbar(Scrollbar):
    # a scrollbar that hides itself if it's not needed.  only
    # works if you use the grid geometry manager.
    def set(self, lo, hi):
        if float(lo) <= 0.0 and float(hi) >= 1.0:
            # grid_remove is currently missing from Tkinter!
            self.tk.call("grid", "remove", self)
        else:
            self.grid()
        Scrollbar.set(self, lo, hi)
#    def pack(self, **kw):
#        raise TclError, "cannot use pack with this widget"
#    def place(self, **kw):
#        raise TclError, "cannot use place with this widget"

#--------------------------------------------------------

root = Tk()
menu = Menu()
root.config(menu=menu)
file_menu = Menu(menu, tearoff=0)
file_menu.add_command(label='Open', command=NEXTVIEW)
file_menu.add_separator()
file_menu.add_command(label='Exit', command=root.destroy)
menu.add_cascade(label='File', menu=file_menu)

root.mainloop()