我正在尝试使用stdlib InteractiveConsole为我的PyQt5应用程序构建一个python shell，这样我就可以让用户编写实时脚本了。我使用QTextEdit来显示shell中的标准输出。
当我在shell中执行for循环时，应用程序会冻结，因为insertPlainText() QTextEdit太快了。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，只要在for循环中运行time.sleep()之类的任何阻塞函数，它就会冻结。所以for循环中的打印只会在循环完成后显示。如果缓冲区被禁用，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。
这是我根据MVCE指南编写的最小版本。
以下是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>
以下是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()
主线程和解释器之间的通信需要类BaseSignals。以下是transcript有关实施此原因的原因。
此行负责插入纯文本self.output.signal_str.emit(data)。这个emit()发生在QThread内。因此，在完成多个self.buffer.write()之前，emit()将无法处理。我想在QApplication.processEvents()中添加DelayedBuffer.process()会有所帮助。它没有。我承认我可能错了。
任何帮助表示赞赏。 提前谢谢。
答案 0 :(得分：3)
您的解释器线程在<div class="ds">
<span id="dsspan">
This line is longer than the rest.
<ul>
<li>Text</li>
<li>Text</li>
<li>Text</li>
<li>Text</li>
<li>Text</li>
</ul>
</span>
<a href="example.com">Hover Here</a>
</div>电话上被阻止。在此调用完成之前，它将无法处理任何信号。这就是你看到延迟输出的原因。
您可以通过更改
来获得您之后的效果InteractiveConsole.runcode()到
self.interpreter.output.connect(self.send_console_log)
对于一些旧学校的调试，断开你的stderr处理，并在周围洒一些打印声明......
self.interpreter.stream.output.signal_str.connect(self.send_console_log)