Python四步设置与进度条

Question

我在下面的代码上遇到了一个问题。当我运行它的时候，进度条会像预期那样闪烁大约10秒，然后开始下载，并显示进度。但是下载完成后，它不会继续到下一步，而是卡住了。

import sys
import time
import pygtk
import gtk
import gobject
import threading
import urllib
import urlparse

class WorkerThread(threading.Thread):

    def __init__ (self, function, parent, arg = None):
        threading.Thread.__init__(self)
        self.function = function
        self.parent = parent
        self.arg = arg
        self.parent.still_working = True

    def run(self): # when does "run" get executed?
        self.parent.still_working = True      
        if self.arg == None:
            self.function()
        else:
            self.function(self.arg)

        self.parent.still_working = False    

    def stop(self):
        self = None

class MainWindow:
    def __init__(self):
        gtk.gdk.threads_init()
        self.wTree = gtk.Builder()
        self.wTree.add_from_file("gui.glade")
        self.mainWindows()

    def mainWindows(self):
        self.mainWindow = self.wTree.get_object("frmMain")

        dic = { 
            "on_btnNext_clicked" : self.mainWindowNext,
        }
        self.wTree.connect_signals(dic)

        self.mainWindow.show()
        self.installerStep = 0 # 0 = none, 1 = preinstall, 2 = download, 3 = install info, 4 = install
        #gtk.main()
        self.mainWindowNext()

    def pulse(self):
        self.wTree.get_object("progress").pulse()

        if self.still_working == False:
            self.mainWindowNext()

        return self.still_working

    def preinstallStep(self):
        self.wTree.get_object("progress").set_fraction(0)
        self.wTree.get_object("btnNext").set_sensitive(0)
        self.wTree.get_object("notebook1").set_current_page(0)
        self.installerStep = 1
        WT = WorkerThread(self.heavyWork, self) #Would do a heavy function here like setup some thing
        WT.start()

        gobject.timeout_add(75, self.pulse)

    def downloadStep(self):
        self.wTree.get_object("progress").set_fraction(0)
        self.wTree.get_object("btnNext").set_sensitive(0)
        self.wTree.get_object("notebook1").set_current_page(0)
        self.installerStep = 2
        urllib.urlretrieve('http://mozilla.mirrors.evolva.ro//firefox/releases/3.6.3/win32/en-US/Firefox%20Setup%203.6.3.exe', '/tmp/firefox.exe', self.updateHook)

        self.mainWindowNext()

    def updateHook(self, blocks, blockSize, totalSize):
        percentage = float ( blocks * blockSize ) / totalSize
        if percentage > 1:
            percentage = 1

        self.wTree.get_object("progress").set_fraction(percentage)

        while gtk.events_pending():
            gtk.main_iteration()

    def installInfoStep(self):
        self.wTree.get_object("btnNext").set_sensitive(1)
        self.wTree.get_object("notebook1").set_current_page(1)
        self.installerStep = 3

    def installStep(self):
        self.wTree.get_object("progress").set_fraction(0)
        self.wTree.get_object("btnNext").set_sensitive(0)
        self.wTree.get_object("notebook1").set_current_page(0)
        self.installerStep = 4

        WT = WorkerThread(self.heavyWork, self) #Would do a heavy function here like setup some thing
        WT.start()

        gobject.timeout_add(75, self.pulse)

    def mainWindowNext(self, widget = None):
        if self.installerStep == 0:
            self.preinstallStep()
        elif self.installerStep == 1:
            self.downloadStep()
        elif self.installerStep == 2:
            self.installInfoStep()
        elif self.installerStep == 3:
            self.installStep()
        elif self.installerStep == 4:
            sys.exit(0)

    def heavyWork(self):
        time.sleep(10)

if __name__ == '__main__':
    MainWindow()
    gtk.main()

我感觉这可能和以下内容有关：

while gtk.events_pending():
    gtk.main_iteration()

有没有更好的方法来实现这个？

Answer 1

千万不要这样做：

while gtk.events_pending():
   gtk.main_iteration()

除非你真的非常清楚自己在做什么。如果你真的知道，那就这样做：

def refresh_gui(delay=0.0001, wait=0.0001):
    """Use up all the events waiting to be run

    :param delay: Time to wait before using events
    :param wait: Time to wait between iterations of events

    This function will block until all pending events are emitted. This is
    useful in testing to ensure signals and other asynchronous functionality
    is required to take place.

    (c) PyGTKHelpers Authors 2005-2010
    """
    time.sleep(delay)
    while gtk.events_pending():
        gtk.main_iteration_do(block=False)
        time.sleep(wait)

使用block=False和一些延迟。

如果你想使用线程，我个人不推荐像那样去继承Thread（这样做没有意义），相反，我建议你采用这种方法，里面有更新进度条的例子。