Python进度条Variable class版

from Tkinter import *
import ttk
import threading
import random
import time

class PgBarFrm(Frame):
    def __init__(self, root, max_len):
        self.root = root
        Frame.__init__(self, root)

        self.pb_val = IntVar()  # pbar variable
        self.pb_max = max_len   # pbar maximum
        
        self.lb_str = StringVar()   # label string
        self.update_label()
        
        self.pack(side=TOP, expand=1, fill=X)

        self.initUI()

    def initUI(self):
        self.label = Label(self, textvariable=self.lb_str)
        self.label.pack(side=LEFT)

        self.pbar = ttk.Progressbar(self, length=300, maximum=self.pb_max, variable=self.pb_val)
        self.pbar.pack(side=LEFT, expand=1, fill=BOTH)

    def update_label(self):
        self.lb_str.set('%d/%d' % (self.pb_val.get(), self.pb_max))

    def clear(self):
        self.pb_val.set(0)
        self.update_label()

    def step(self):
        new_val = (self.pb_val.get()+1)
        if new_val>self.pb_max:
            self.clear()
            self.step()
        else:
            self.pb_val.set(new_val)
            self.update_label()



class DualWork:
    def __init__(self):
        self.N1 = 5
        self.N2 = 7
        self.frm1 = PgBarFrm(root, self.N1)
        self.frm2 = PgBarFrm(root, self.N2)

    def work(self):
        for i in xrange(self.N1):            
            for j in xrange(self.N2):
                rnd_t = random.uniform(0, 1)
                print threading.currentThread().getName(), i, j, rnd_t
                
                self.frm2.step()
                time.sleep(rnd_t)

            self.frm1.step()

    def start(self):
        w_td = threading.Thread(target=self.work)
        w_td.start()

if __name__=='__main__':
    root = Tk()
    
    w = DualWork()
    w.start()

    root.mainloop()