Python PyQT：如何从工作线程调用 GUI 函数？

Question

我有一个 pyqt gui 并调用一个长进程 (ffmpeg)，我把它放在一个单独的线程上以不阻塞 gui。然后，我想在更长的命令列表中的一个命令完成时更新进度条。问题是，我无法从工作线程中调用 gui 线程中的函数。所以我让在工作线程中运行一个ticker，但是当我用while循环更新进度条并读取ticker值时，gui再次被阻塞。我该如何解决这个问题。我目前使用的是 python 线程而不是 Qthread。 感谢您的帮助！

import threading, pexpect

self.cmd_list = ['ffmpeg -i file outfile','and so on']

self.stop_proc = False
self.executeCMD()

def spawn_ffmpeg_cmd(self):
    for cmd in self.cmd_list:
        if self.stop_proc == False:
            thread = pexpect.spawn(cmd)
            print "\nstarted: %s" % cmd
            cpl = thread.compile_pattern_list([pexpect.EOF,"frame= *\d+ fps=*\d+",'(.+)'])

            while True:
                i = thread.expect_list(cpl, timeout=None)
                if i == 0: # EOF
                    print "the sub process exited"
                    self.pgticker += 1
                    break
                elif i == 1:
                    frame_number_fps = thread.match.group(0)
                    print frame_number_fps
                    thread.close
                elif i == 2:
                    pass
    self.startButton.setEnabled(True)


def executeCMD(self):
    self.startButton.setEnabled(False)
    self.pgticker = 0
    threading.Thread(target=self.spawn_ffmpeg_cmd, name="_proc").start()


def stopprocess(self):
    self.stop_proc = True
    self.cmd_list = []
    os.system('pkill ffmpeg') 
    self.pgticker = len(self.cmd_list)
    self.startButton.setEnabled(True)


def updateProgress(self):  
    pgfactor = 100 / len(self.cmd_list)
    progress = 0.0
    progress = pgfactor*int(self.pgticker)
    self.progressBar.setProperty("value", progress)

Answer 1

简而言之：移动到QThread 并使用Qt 的信号和槽，它们是线程间通信的首选方式。

此答案提供了一些示例： https://stackoverflow.com/a/6789205/2319400

在您的情况下，使用上面的“SomeObject”版本可能如下所示：

class Worker(QtCore.QObject):

    madeProgress = QtCore.pyqtSignal([int])
    finished = QtCore.pyqtSignal()

    def __init__(self, cmdlist):
        self.cmdlist = cmdlist

    def run(self):
        for icmd, cmd in enumerate(self.cmdlist):
            # execute your work
            # processCommand(cmd)

            # signal that we've made progress
            self.madeProgress.emit(icmd)

        # emit the finished signal - we're done
        self.finished.emit()

然后将此工作器移动到您创建的QThread 实例。 按照链接答案中的模式，您可以连接 madeProgress 信号 到进度条的setValue 槽：

workerThread = QThread()
workerObject = Worker(cmdlist)
workerObject.moveToThread(workerThread)
workerThread.started.connect(workerObject.run)
workerObject.finished.connect(workerThread.quit)

# create a progressbar with min/max according to
# the length of your cmdlist
progressBar = QProgressBar()
progressBar.setRange(0, len(cmdlist))

# connect the worker's progress signal with the progressbar
workerObject.madeProgress.connect(progressBar.setValue)

# start the thread (starting your worker at the same time)
workerThread.start()