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Question

应用程序

我正在尝试使用stdlib为我的PyQt5应用程序构建一个python shell,InteractiveConsole这样我就可以让用户编写实时脚本了.我正在使用a QTextEdit来显示shell中的stdout.

问题

当我在外壳循环做,应用程序冻结,因为insertPlainText()对QTextEdit太快.所以我写了一个缓冲区,可以将插入延迟几毫秒.但是,我注意到,只要我time.sleep()在for循环中运行任何阻塞函数,它就会冻结.所以for循环中的打印只会在循环完成后显示.如果禁用缓冲区,则不会发生这种情况.

例如,如果我在shell中执行此操作:

>>>for i in range(10):
...    time.sleep(1)
...    print(i)
...

这只会在10秒后打印.

码

这是我根据MVCE指南编写的最小版本.

这是main.ui文件:

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>main_window</class>
 <widget class="QMainWindow" name="main_window">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="sizePolicy">
   <sizepolicy hsizetype="Preferred" vsizetype="Preferred">
    <horstretch>0</horstretch>
    <verstretch>0</verstretch>
   </sizepolicy>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <property name="tabShape">
   <enum>QTabWidget::Rounded</enum>
  </property>
  <widget class="QWidget" name="central_widget">
   <layout class="QHBoxLayout" name="horizontalLayout">
    <item>
     <layout class="QVBoxLayout" name="console_layout">
      <item>
       <widget class="QTextEdit" name="console_log">
        <property name="undoRedoEnabled">
         <bool>false</bool>
        </property>
       </widget>
      </item>
      <item>
       <layout class="QHBoxLayout" name="horizontalLayout_4">
        <item>
         <widget class="QLabel" name="console_prompt">
          <property name="text">
           <string/>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QLineEdit" name="console_input">
          <property name="frame">
           <bool>true</bool>
          </property>
         </widget>
        </item>
       </layout>
      </item>
     </layout>
    </item>
   </layout>
  </widget>
  <widget class="QMenuBar" name="menu_bar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>800</width>
     <height>26</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="status_bar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

这是main.py文件:

import sys
from code import InteractiveConsole
from io import StringIO
from queue import Queue, Empty

from PyQt5 import uic
from PyQt5.QtCore import pyqtSlot, QThread, QObject, pyqtSignal, QTimer
from PyQt5.QtGui import QTextOption, QTextCursor
from PyQt5.QtWidgets import QApplication

__author__ = "daegontaven"
__copyright__ = "daegontaven"
__license__ = "gpl3"


class BaseSignals(QObject):
    """
    Standard set of pyqtSignals.
    """
    signal_str = pyqtSignal(str)
    signal_int = pyqtSignal(int)
    signal_float = pyqtSignal(float)
    signal_list = pyqtSignal(list)
    signal_tuple = pyqtSignal(tuple)
    signal_dict = pyqtSignal(dict)
    signal_object = pyqtSignal(object)

    def __init__(self):
        QObject.__init__(self)


class DelayedBuffer(QObject):
    """
    A buffer that uses a queue to store strings. It removes the
    first appended string first in a constant interval.
    """
    written = pyqtSignal(str)

    def __init__(self, output, delay):
        """
        :param output: used to access BaseSignals
        :param delay: delay for emitting
        """
        super().__init__()
        self.output = output

        # Set Delay
        self.delay = delay
        self.queue = Queue()
        self.timer = QTimer()
        self.timer.timeout.connect(self.process)
        self.timer.start(self.delay)

    def write(self, string):
        self.queue.put(string)

    def process(self):
        """
        Try to send the data to the stream
        """
        try:
            data = self.queue.get(block=False)
            self.written.emit(data)
        except Empty:
            pass

    def emit(self, string):
        """
        Force emit of string.
        """
        self.output.signal_str.emit(string)


class ConsoleStream(StringIO):
    """
    Custom StreamIO class that emits a signal on each write.
    """
    def __init__(self, enabled=True, *args, **kwargs):
        """
        Starts a delayed buffer to store writes due to UI
        refresh limitations.

        :param enabled: set False to bypass the buffer
        """
        StringIO.__init__(self, *args, **kwargs)
        self.enabled = enabled
        self.output = BaseSignals()

        # Buffer
        self.thread = QThread()
        self.buffer = DelayedBuffer(self.output, delay=5)
        self.buffer.moveToThread(self.thread)
        self.buffer.written.connect(self.get)
        self.thread.start()

    def write(self, string):
        """
        Overrides the parent write method and emits a signal
        meant to be received by interpreters.

        :param string: single write output from stdout
        """
        if self.enabled:
            self.buffer.write(string)
        else:
            self.output.signal_str.emit(string)

    def get(self, string):
        self.output.signal_str.emit(string)


class PythonInterpreter(QObject, InteractiveConsole):
    """
    A reimplementation of the builtin InteractiveConsole to
    work with threads.
    """
    output = pyqtSignal(str)
    push_command = pyqtSignal(str)
    multi_line = pyqtSignal(bool)

    def __init__(self):
        QObject.__init__(self)
        self.l = {}
        InteractiveConsole.__init__(self, self.l)
        self.stream = ConsoleStream()
        self.stream.output.signal_str.connect(self.console)
        self.push_command.connect(self.command)

    def write(self, string):
        self.output.emit(string)

    def runcode(self, code):
        """
        Overrides and captures stdout and stdin from
        InteractiveConsole.
        """
        sys.stdout = self.stream
        sys.stderr = self.stream
        sys.excepthook = sys.__excepthook__
        result = InteractiveConsole.runcode(self, code)
        sys.stdout = sys.__stdout__
        sys.stderr = sys.__stderr__
        return result

    @pyqtSlot(str)
    def command(self, command):
        """
        :param command: line retrieved from console_input on
                        returnPressed
        """
        result = self.push(command)
        self.multi_line.emit(result)

    @pyqtSlot(str)
    def console(self, string):
        """
        :param string: processed output from a stream
        """
        self.output.emit(string)


class MainWindow:
    """
    The main GUI window. Opens maximized.
    """
    def __init__(self):

        self.ui = uic.loadUi("main.ui")
        self.ui.showMaximized()

        # Console Properties
        self.ui.console_log.document().setMaximumBlockCount(1000)
        self.ui.console_log.setWordWrapMode(QTextOption.WrapAnywhere)

        self.ps1 = '>>>'
        self.ps2 = '...'
        self.ui.console_prompt.setText(self.ps1)

        # Spawn Interpreter
        self.thread = QThread()
        self.thread.start()

        self.interpreter = PythonInterpreter()
        self.interpreter.moveToThread(self.thread)

        # Interpreter Signals
        self.ui.console_input.returnPressed.connect(self.send_console_input)
        self.interpreter.output.connect(self.send_console_log)
        self.interpreter.multi_line.connect(self.prompt)

    def prompt(self, multi_line):
        """
        Sets what prompt to use.
        """
        if multi_line:
            self.ui.console_prompt.setText(self.ps2)
        else:
            self.ui.console_prompt.setText(self.ps1)

    def send_console_input(self):
        """
        Send input grabbed from the QLineEdit prompt to the console.
        """
        command = self.ui.console_input.text()
        self.ui.console_input.clear()
        self.interpreter.push_command.emit(str(command))

    def send_console_log(self, command):
        """
        Set the output from InteractiveConsole in the QTextEdit.
        Auto scroll scrollbar.
        """
        # Checks if scrolled
        old_cursor = self.ui.console_log.textCursor()
        old_scrollbar = self.ui.console_log.verticalScrollBar().value()
        new_scrollbar = self.ui.console_log.verticalScrollBar().maximum()
        if old_scrollbar == new_scrollbar:
            scrolled = True
        else:
            scrolled = False

        # Sets the text
        self.ui.console_log.insertPlainText(command)

        # Scrolls/Moves cursor based on available data
        if old_cursor.hasSelection() or not scrolled:
            self.ui.console_log.setTextCursor(old_cursor)
            self.ui.console_log.verticalScrollBar().setValue(old_scrollbar)
        else:
            self.ui.console_log.moveCursor(QTextCursor.End)
            self.ui.console_log.verticalScrollBar().setValue(
                self.ui.console_log.verticalScrollBar().maximum()
            )


def main():
    app = QApplication(sys.argv)
    window = MainWindow()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()

BaseSignals主线程和解释器之间的通信需要该类.以下是有关实施此原因的成绩单.

我知道的

该行负责插入纯文本self.output.signal_str.emit(data).这emit()发生在一个QThread.因此,在self.buffer.write()完成倍数之前,emit()将不会处理.我想加入QApplication.processEvents()的DelayedBuffer.process()会有所帮助.它没有.我承认我可能错了.

任何帮助赞赏.提前致谢.

Answer 1

您的解释器线程在调用时被阻塞InteractiveConsole.runcode()。在该调用完成之前，它将无法处理任何信号。这就是您看到延迟输出的原因。

您可以通过更改来获得您想要的效果

self.interpreter.output.connect(self.send_console_log)

到

self.interpreter.stream.output.signal_str.connect(self.send_console_log)

对于一些老式的调试，断开你的 stderr 处理并散布一些打印语句，例如......

print('runcode after', file=sys.stderr)