Tkinter Python：在函数中调用时找不到模块？

Question

为什么我得到这个错误：

File "exampleTreeCanvas.py", line 59, in treeImageSelect 
    theImage = ImageTK.PhotoImage(Image.open(imageWhere)) #this line produces the error 
NameError: name 'ImageTK' is not defined 

当我运行下面的代码，并通过单击在TreeView .png文件（其中我想作为一个文件浏览器来使用）的触发treeImageSelect功能该程序？

import os 
import glob 
import tkinter 
from tkinter import * 
from tkinter import ttk 
from PIL import Image, ImageTk 

root = Tk() 

def on_vertical(event): 
    picCanvas.yview_scroll(-event.delta, 'units') 

def on_horizontal(event): 
    picCanvas.xview_scroll(-event.delta, 'units') 

def populate_tree(tree, node): 
    if tree.set(node, "type") != 'directory': 
     return 

    path = tree.set(node, "fullpath") 
    tree.delete(*tree.get_children(node)) 

    parent = tree.parent(node) 
    special_dirs = [] if parent else glob.glob('.') + glob.glob('..') 

    for p in special_dirs + os.listdir(path): 
     ptype = None 
     p = os.path.join(path, p).replace('\\', '/') 
     if os.path.isdir(p): ptype = "directory" 
     elif os.path.isfile(p): ptype = "file" 

     fname = os.path.split(p)[1] 
     id = tree.insert(node, "end", text=fname, values=[p, ptype]) 

     if ptype == 'directory': 
      if fname not in ('.', '..'): 
       tree.insert(id, 0, text="dummy") 
       tree.item(id, text=fname) 
     elif ptype == 'file': 
      size = os.stat(p).st_size 
      tree.set(id, "size", "%d bytes" % size) 

def populate_roots(tree): 
    dir = os.path.abspath('.').replace('\\', '/') 
    node = tree.insert('', 'end', text=dir, values=[dir, "directory"]) 
    populate_tree(tree, node) 

def update_tree(event): 
    tree = event.widget 
    populate_tree(tree, tree.focus()) 

def treeImageSelect(event): 
    if len(tree.selection()) == 1: 
     filename, file_extension = os.path.splitext(tree.item(tree.selection()).get('values')[0]) 
     if file_extension == ".png": 
      global imageWhere 
      global theImage 
      imageWhere = tree.item(tree.selection()).get('values')[0] 
      theImage = ImageTK.PhotoImage(Image.open(imageWhere)) #this line produces the error 
      picCanvas.itemconfigure(canvasImage, image = theImage) 
      picCanvas.config(scrollregion=(0,0, theImage.width(), theImage.height())) 

def autoscroll(sbar, first, last): 
    """Hide and show scrollbar as needed.""" 
    first, last = float(first), float(last) 
    if first <= 0 and last >= 1: 
     sbar.grid_remove() 
    else: 
     sbar.grid() 
    sbar.set(first, last) 

contents = ttk.Frame(root, padding=(3,3,3,3), width=200, height=200) 
treecontent = ttk.Frame(contents, padding=(3,3,3,3), width=200, height=200) 
picFrame = ttk.Frame(contents, padding=(3,3,3,3), width=200, height=200) 

hp = Scrollbar(picFrame, orient=HORIZONTAL) 
vp = Scrollbar(picFrame, orient=VERTICAL) 

picCanvas = Canvas(picFrame, scrollregion=(0, 0, 1000, 1000), yscrollcommand=vp.set, xscrollcommand=hp.set) 

hp['command'] = picCanvas.xview 
vp['command'] = picCanvas.yview 

imageWhere = 'example.png' 
theImage = ImageTk.PhotoImage(Image.open(imageWhere)) 
canvasImage = picCanvas.create_image(0,0,image=theImage, anchor='nw') 
picCanvas.config(scrollregion=(0,0,theImage.width(), theImage.height())) 

contents.grid(column=0, row=0, sticky=(N,S,W,E)) 
hp.grid(column=0, row=1, sticky=(W,E)) 
vp.grid(column=1, row=0, sticky=(N,S)) 
picFrame.grid(column=1, row=0, sticky=(N,S,E,W)) 
picCanvas.grid(column=0, row=0, sticky=(N,S,E,W)) 

tree = ttk.Treeview(treecontent, columns=("fullpath", "type", "size"), displaycolumns="size", yscrollcommand=lambda f, l: autoscroll(vsb, f, l), xscrollcommand=lambda f, l:autoscroll(hsb, f, l)) 
vsb = ttk.Scrollbar(treecontent, orient="vertical") 
hsb = ttk.Scrollbar(treecontent, orient="horizontal") 

vsb['command'] = tree.yview 
hsb['command'] = tree.xview 

tree.heading("#0", text="Directory Structure", anchor='w') 
tree.heading("size", text="File Size", anchor='w') 
tree.column("size", stretch=0, width=100) 

populate_roots(tree) 
tree.bind('<<TreeviewOpen>>', update_tree) 
tree.bind('<<TreeviewSelect>>', treeImageSelect) 

tree.grid(column=0, row=0, sticky='nswe') 
vsb.grid(column=1, row=0, sticky='ns') 
hsb.grid(column=0, row=1, sticky='ew') 
treecontent.grid(column=0, row=0, rowspan=4, sticky='nesw') 

root.columnconfigure(0, weight=1) 
root.rowconfigure(0, weight=1) 
contents.columnconfigure(0, weight=1) 
contents.columnconfigure(1, weight=1) 
contents.rowconfigure(0, weight=1) 
treecontent.rowconfigure(0, weight=1) 
treecontent.columnconfigure(0, weight=1) 
picFrame.columnconfigure(0, weight=1) 
picFrame.rowconfigure(0, weight=1) 

picCanvas.bind('<MouseWheel>', on_vertical) 
picCanvas.bind('<Shift-MouseWheel>', on_horizontal) 

root.mainloop() 

对不起，这是很长的，但我想不出如何缩短它，而不会打破它。

为了增加混乱，当我运行此类似（但更短）的代码，我没有错误可言：

from tkinter import * 
import tkinter.ttk as ttk 
from PIL import Image, ImageTk 

def on_vertical(event): 
    canvas.yview_scroll(-event.delta, 'units') 

def on_horizontal(event): 
    canvas.xview_scroll(-event.delta, 'units') 

def getImage(): 
    global imageWhere 
    theImage = ImageTk.PhotoImage(Image.open(imageWhere)) 
    return theImage 

root = Tk() 
h = Scrollbar(root, orient=HORIZONTAL) 
v = Scrollbar(root, orient=VERTICAL) 
canvas = Canvas(root, scrollregion=(0, 0, 1000, 1000), yscrollcommand=v.set, xscrollcommand=h.set) 
h['command'] = canvas.xview 
v['command'] = canvas.yview 
imageWhere = 'example.png' 
theImage = getImage() 
canvas.create_image(0,0,image=theImage, anchor='nw') 
canvas.grid(column=0, row=0, sticky=(N,W,E,S)) 

canvas.bind_all('<MouseWheel>', on_vertical) 
canvas.bind_all('<Shift-MouseWheel>', on_horizontal) 

h.grid(column=0, row=1, sticky=(W,E)) 
v.grid(column=1, row=0, sticky=(N,S)) 
root.grid_columnconfigure(0, weight=1) 
root.grid_rowconfigure(0, weight=1) 
root.mainloop() 

是什么造成的问题？为什么除了treeView调用的函数外，我都可以使用ImageTK？

背景：我使用Python 3.4，Tkinter 8.5.18，Pillow（不知道该版本）和Mac OS X 10.9.5。这里的想法是让程序将Canvas的图像更改为用户在Treeview中选择的任何.png文件。我是Python和Tkinter的完全新手。

Answer 1

你有一个错字：它是ImageTk，而不是ImageTK。