从子程序到 pyQT Widget 的标准输出的实时输出

Question

您好，我已经看到关于这个问题已经有很多问题了，但是似乎没有一个回答我的问题。

根据下面的链接，我什至在使用 windows 时尝试了 winpexpect，但它似乎对我有用。 Getting realtime output from ffmpeg to be used in progress bar (PyQt4, stdout)

我正在使用 subprocess.Popen 运行一个子程序，并希望在 pyQt Widget 中查看实时结果。目前它在 pyQt 小部件中显示结果，但仅在子命令执行完成之后。我需要知道是否有一种方法可以将子进程的输出实时获取到窗口中。请参阅下面的代码，我尝试了所有这些。

import sys
import os
from PyQt4 import QtGui,QtCore
from threading import Thread
import subprocess
#from winpexpect import winspawn



class EmittingStream(QtCore.QObject):
    textWritten = QtCore.pyqtSignal(str)

    def write(self, text):
        self.textWritten.emit(str(text))

class gui(QtGui.QMainWindow):

    def __init__(self):
    # ...
        super(gui, self).__init__()
    # Install the custom output stream
        sys.stdout = EmittingStream(textWritten=self.normalOutputWritten)
        self.initUI()

    def normalOutputWritten(self, text):
        cursor = self.textEdit.textCursor()
        cursor.movePosition(QtGui.QTextCursor.End)
        cursor.insertText(text)
        self.textEdit.ensureCursorVisible()

    def callProgram(self):

        command="ping 127.0.0.1"
        #winspawn(command)
              py=subprocess.Popen(command.split(),stdout=subprocess.PIPE,stderr=subprocess.PIPE,shell=True)
        result,_=py.communicate()
        for line in result:
            print line
        print result


    def initUI(self):
        self.setGeometry(100,100,300,300)
        self.show()

        self.textEdit=QtGui.QTextEdit(self)
        self.textEdit.show()
        self.textEdit.setGeometry(20,40,200,200)

        print "changing sys.out"
        print "hello"

        thread = Thread(target = self.callProgram)
        thread.start()


#Function Main Start
def main():
    app = QtGui.QApplication(sys.argv)
    ui=gui()
    sys.exit(app.exec_())
#Function Main END

if __name__ == '__main__':
    main()

Answer 1

这是对 PyQt5 接受答案的改编。

import sys

# On Windows it looks like cp850 is used for my console. We need it to decode the QByteArray correctly.
# Based on https://forum.qt.io/topic/85064/qbytearray-to-string/2
import ctypes
CP_console = "cp" + str(ctypes.cdll.kernel32.GetConsoleOutputCP())

from PyQt5 import QtCore, QtGui, QtWidgets

class gui(QtWidgets.QMainWindow):
    def __init__(self):
        super(gui, self).__init__()
        self.initUI()

    def dataReady(self):
        cursor = self.output.textCursor()
        cursor.movePosition(cursor.End)

        # Here we have to decode the QByteArray
        cursor.insertText(str(self.process.readAll().data().decode(CP_console)))
        self.output.ensureCursorVisible()

    def callProgram(self):
        # run the process
        # `start` takes the exec and a list of arguments
        self.process.start('ping',['127.0.0.1'])

    def initUI(self):
        # Layout are better for placing widgets
        layout = QtWidgets.QVBoxLayout()
        self.runButton = QtWidgets.QPushButton('Run')
        self.runButton.clicked.connect(self.callProgram)

        self.output = QtWidgets.QTextEdit()

        layout.addWidget(self.output)
        layout.addWidget(self.runButton)

        centralWidget = QtWidgets.QWidget()
        centralWidget.setLayout(layout)
        self.setCentralWidget(centralWidget)

        # QProcess object for external app
        self.process = QtCore.QProcess(self)
        # QProcess emits `readyRead` when there is data to be read
        self.process.readyRead.connect(self.dataReady)

        # Just to prevent accidentally running multiple times
        # Disable the button when process starts, and enable it when it finishes
        self.process.started.connect(lambda: self.runButton.setEnabled(False))
        self.process.finished.connect(lambda: self.runButton.setEnabled(True))


#Function Main Start
def main():
    app = QtWidgets.QApplication(sys.argv)
    ui=gui()
    ui.show()
    sys.exit(app.exec_())
#Function Main END

if __name__ == '__main__':
    main() 

Answer 2

QProcess 与subprocess 非常相似，但在 (Py)Qt 代码中使用要方便得多。因为它利用信号/插槽。此外，它以异步方式运行该过程，因此您无需使用QThread。

我已经修改（并清理）了您的 QProcess 代码：

import sys
from PyQt4 import QtGui,QtCore

class gui(QtGui.QMainWindow):
    def __init__(self):
        super(gui, self).__init__()
        self.initUI()

    def dataReady(self):
        cursor = self.output.textCursor()
        cursor.movePosition(cursor.End)
        cursor.insertText(str(self.process.readAll()))
        self.output.ensureCursorVisible()

    def callProgram(self):
        # run the process
        # `start` takes the exec and a list of arguments
        self.process.start('ping',['127.0.0.1'])

    def initUI(self):
        # Layout are better for placing widgets
        layout = QtGui.QHBoxLayout()
        self.runButton = QtGui.QPushButton('Run')
        self.runButton.clicked.connect(self.callProgram)

        self.output = QtGui.QTextEdit()

        layout.addWidget(self.output)
        layout.addWidget(self.runButton)

        centralWidget = QtGui.QWidget()
        centralWidget.setLayout(layout)
        self.setCentralWidget(centralWidget)

        # QProcess object for external app
        self.process = QtCore.QProcess(self)
        # QProcess emits `readyRead` when there is data to be read
        self.process.readyRead.connect(self.dataReady)

        # Just to prevent accidentally running multiple times
        # Disable the button when process starts, and enable it when it finishes
        self.process.started.connect(lambda: self.runButton.setEnabled(False))
        self.process.finished.connect(lambda: self.runButton.setEnabled(True))


#Function Main Start
def main():
    app = QtGui.QApplication(sys.argv)
    ui=gui()
    ui.show()
    sys.exit(app.exec_())
#Function Main END

if __name__ == '__main__':
    main()