class EmittingStream(QtCore.QObject): textWritten = QtCore.pyqtSignal(str) def write(self, text): self.textWritten.emit(str(text))

这是一个 Python 中使用 PyQt 模块的类，它继承自 QObject 类。它定义了一个 textWritten 信号（使用 PyQt 的信号槽机制），并且重写了 write() 方法，将传入的文本转换成字符串并发射 textWritten 信号。这个类的主要作用是将 Python 中的 print 输出重定向到 PyQt 应用程序的窗口中，使得 print 输出可以在应用程序中显示。

相关问题

import sys from PyQt5.QtCore import * from PyQt5.QtGui import * from PyQt5.QtWidgets import * from PyQt5.QtChart import * class RandomGenerator(QObject): dataReady = pyqtSignal(int) stopSignal = pyqtSignal() def init(self): super().init() self.queue = [] self.count = 0 def start(self): while True: val = random.randint(1, 100) if val < 50: self.queue.append(val) if len(self.queue) == 1: self.dataReady.emit(val) else: self.count += 1 if self.count >= 2: self.stopSignal.emit() break class ChartDrawer(QObject): finished = pyqtSignal() def init(self, queue): super().init() self.queue = queue self.series = QLineSeries() def start(self): while True: if len(self.queue) > 0: val = self.queue.pop(0) self.series.append(self.series.count(), val) else: break self.finished.emit() class MainWindow(QMainWindow): def init(self): super().init() self.generator = RandomGenerator() self.drawer = ChartDrawer(self.generator.queue) self.chartView = QChartView() self.chart = QChart() self.chart.addSeries(self.drawer.series) self.chart.createDefaultAxes() self.chartView.setChart(self.chart) self.startButton = QPushButton("Start") self.startButton.clicked.connect(self.start) self.stopButton = QPushButton("Stop") self.stopButton.clicked.connect(self.stop) self.stopButton.setEnabled(False) self.statusBar().showMessage("Ready") layout = QVBoxLayout() layout.addWidget(self.chartView) layout.addWidget(self.startButton) layout.addWidget(self.stopButton) widget = QWidget() widget.setLayout(layout) self.setCentralWidget(widget) def start(self): self.statusBar().showMessage("Running") self.generatorThread = QThread() self.generator.moveToThread(self.generatorThread) self.generatorThread.started.connect(self.generator.start) self.generator.dataReady.connect(self.handleDataReady) self.generator.stopSignal.connect(self.handleStopSignal) self.generatorThread.start() self.drawerThread = QThread() self.drawer.moveToThread(self.drawerThread) self.drawer.finished.connect(self.handleDrawerFinished) self.drawerThread.start() self.startButton.setEnabled(False) self.stopButton.setEnabled(True) def stop(self): self.statusBar().showMessage("Stopping") self.generator.stopSignal.emit() self.generatorThread.quit() self.drawerThread.quit() self.startButton.setEnabled(True) self.stopButton.setEnabled(False) def handleDataReady(self, val): self.drawer.series.append(self.drawer.series.count(), val) def handleStopSignal(self): self.generatorThread.quit() def handleDrawerFinished(self): self.chartView.update() self.statusBar().showMessage("Finished") self.startButton.setEnabled(True) self.stopButton.setEnabled(False) if name == 'main': app = QApplication(sys.argv) window = MainWindow() window.show() sys.exit(app.exec_()) 请检查上述代码为何没有画图并展示

这段代码缺少了一些必要的部分，例如 `random` 模块的导入，以及 `RandomGenerator` 类中 `init` 方法的名称错误。此外，`ChartDrawer` 的构造函数应该接受 `queue` 参数并将其存储为实例属性。

另外，`MainWindow` 类中 `start` 方法的最后一行应该是 `self.chartView.show()`，而不是 `self.chartView.update()`。

以下是修改后的代码，应该可以正确地显示图表：

import random
import sys
from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *
from PyQt5.QtChart import *

class RandomGenerator(QObject):
    dataReady = pyqtSignal(int)
    stopSignal = pyqtSignal()

    def __init__(self):
        super().__init__()
        self.queue = []
        self.count = 0

    def start(self):
        while True:
            val = random.randint(1, 100)
            if val < 50:
                self.queue.append(val)
            if len(self.queue) == 1:
                self.dataReady.emit(val)
            else:
                self.count += 1
            if self.count >= 2:
                self.stopSignal.emit()
                break

class ChartDrawer(QObject):
    finished = pyqtSignal()

    def __init__(self, queue):
        super().__init__()
        self.queue = queue
        self.series = QLineSeries()

    def start(self):
        while True:
            if len(self.queue) > 0:
                val = self.queue.pop(0)
                self.series.append(self.series.count(), val)
            else:
                break
        self.finished.emit()

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.generator = RandomGenerator()
        self.drawer = ChartDrawer(self.generator.queue)

        self.chartView = QChartView()
        self.chart = QChart()
        self.chart.addSeries(self.drawer.series)
        self.chart.createDefaultAxes()
        self.chartView.setChart(self.chart)

        self.startButton = QPushButton("Start")
        self.startButton.clicked.connect(self.start)

        self.stopButton = QPushButton("Stop")
        self.stopButton.clicked.connect(self.stop)
        self.stopButton.setEnabled(False)

        self.statusBar().showMessage("Ready")

        layout = QVBoxLayout()
        layout.addWidget(self.chartView)
        layout.addWidget(self.startButton)
        layout.addWidget(self.stopButton)

        widget = QWidget()
        widget.setLayout(layout)
        self.setCentralWidget(widget)

    def start(self):
        self.statusBar().showMessage("Running")

        self.generatorThread = QThread()
        self.generator.moveToThread(self.generatorThread)
        self.generatorThread.started.connect(self.generator.start)
        self.generator.dataReady.connect(self.handleDataReady)
        self.generator.stopSignal.connect(self.handleStopSignal)
        self.generatorThread.start()

        self.drawerThread = QThread()
        self.drawer.moveToThread(self.drawerThread)
        self.drawer.finished.connect(self.handleDrawerFinished)
        self.drawerThread.start()

        self.startButton.setEnabled(False)
        self.stopButton.setEnabled(True)

    def stop(self):
        self.statusBar().showMessage("Stopping")
        self.generator.stopSignal.emit()
        self.generatorThread.quit()
        self.drawerThread.quit()
        self.startButton.setEnabled(True)
        self.stopButton.setEnabled(False)

    def handleDataReady(self, val):
        self.drawer.series.append(self.drawer.series.count(), val)

    def handleStopSignal(self):
        self.generatorThread.quit()

    def handleDrawerFinished(self):
        self.chartView.show()
        self.statusBar().showMessage("Finished")
        self.startButton.setEnabled(True)
        self.stopButton.setEnabled(False)

if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())

import random import sys from PyQt5.QtCore import * from PyQt5.QtGui import * from PyQt5.QtWidgets import * from PyQt5.QtChart import * class RandomGenerator(QObject): dataReady = pyqtSignal(int) stopSignal = pyqtSignal() def init(self): super().init() self.queue = [] self.count = 0 def start(self): while True: val = random.randint(1, 49) if val < 50: self.queue.append(val) print(self.queue) if len(self.queue) == 1: self.dataReady.emit(val) else: self.count += 1 if self.count >= 2: self.stopSignal.emit() break class ChartDrawer(QObject): finished = pyqtSignal() def init(self, queue): super().init() self.queue = queue self.series = QLineSeries() def start(self): while True: if len(self.queue) > 0: print("start draw") val = self.queue.pop(0) self.series.append(self.series.count(), val) else: break self.finished.emit() print('end draw') class MainWindow(QMainWindow): def init(self): super().init() self.generator = RandomGenerator() self.drawer = ChartDrawer(self.generator.queue) self.chartView = QChartView() self.chart = QChart() self.chart.addSeries(self.drawer.series) self.chart.createDefaultAxes() self.chartView.setChart(self.chart) self.startButton = QPushButton("Start") self.startButton.clicked.connect(self.start) self.stopButton = QPushButton("Stop") self.stopButton.clicked.connect(self.stop) self.stopButton.setEnabled(False) self.statusBar().showMessage("Ready") layout = QVBoxLayout() layout.addWidget(self.chartView) layout.addWidget(self.startButton) layout.addWidget(self.stopButton) widget = QWidget() widget.setLayout(layout) self.setCentralWidget(widget) def start(self): self.statusBar().showMessage("Running") self.generatorThread = QThread() self.generator.moveToThread(self.generatorThread) self.generatorThread.started.connect(self.generator.start) self.generator.dataReady.connect(self.handleDataReady) self.generator.stopSignal.connect(self.handleStopSignal) self.generatorThread.start() self.drawerThread = QThread() self.drawer.moveToThread(self.drawerThread) self.drawer.finished.connect(self.handleDrawerFinished) self.drawerThread.start() self.startButton.setEnabled(False) self.stopButton.setEnabled(True) def stop(self): self.statusBar().showMessage("Stopping") self.generator.stopSignal.emit() self.generatorThread.quit() self.drawerThread.quit() self.startButton.setEnabled(True) self.stopButton.setEnabled(False) def handleDataReady(self, val): self.drawer.series.append(self.drawer.series.count(), val) def handleStopSignal(self): self.generatorThread.quit() def handleDrawerFinished(self): self.chartView.show() self.statusBar().showMessage("Finished") self.startButton.setEnabled(True) self.stopButton.setEnabled(False) if name == 'main': app = QApplication(sys.argv) window = MainWindow() window.show() sys.exit(app.exec_()) 检查上述代码为何在点击start按钮后只生成三个随机数后就停止生成数据，且未画图

在上述代码中，当随机数生成的值大于等于50时，没有将这个值加入到队列中。因此，队列中的随机数数量不足以绘制图表。解决方法是将第11行代码修改为`if val <= 50:`。另外，在 `RandomGenerator` 类的 `start` 方法中，当队列中只有一个随机数时，应该使用 `self.queue[0]` 而不是 `val`。这些修改后，点击 start 按钮后，会绘制出完整的图表。