Python 更换画笔不更新外部线程中的QGraphicsLineItem

我正在通过在QGraphicsLine的子类中编程的方法更新画笔颜色，甚至QGraphicsLine对象的画笔颜色。问题在于，当我设置新笔时，当我从线程调用它时，该行消失

import sys
from PyQt5.QtGui import QColor, QBrush, QPen, QPainter
from PyQt5.QtWidgets import QGraphicsScene, QGraphicsEllipseItem, QGraphicsSceneMouseEvent, \
    QGraphicsSceneHoverEvent, QGraphicsLineItem, QApplication, QMainWindow, QGraphicsView, QToolBar, QAction
from threading import Thread
from time import sleep
from random import randint


class GraphicsLine(QGraphicsLineItem):
    def __init__(self, x1: float, y1: float, x2: float, y2: float):
        super(GraphicsLine, self).__init__(x1, y1, x2, y2)

        pen = QPen(QColor(0, 0, 0))
        pen.setWidth(5)
        self.setPen(pen)
        self.setZValue(5)

    def change_color(self):
        pen = QPen(QColor(randint(0, 255), randint(0, 255), randint(0, 255)))
        pen.setWidth(5)
        self.setPen(pen)


class GraphicsNode(QGraphicsEllipseItem):
    def __init__(self, x: float, y: float, size: int):
        super(GraphicsNode, self).__init__(x - size/2, y - size/2, size, size)
        self.setAcceptHoverEvents(True)
        self.setZValue(10)
        brush = QBrush(QColor(0, 0, 0))
        pen = QPen(QColor(0, 0, 0))
        pen.setWidth(0)
        self.setBrush(brush)
        self.setPen(pen)

    def mousePressEvent(self, event: QGraphicsSceneMouseEvent) -> None:
        pass

    def hoverEnterEvent(self, event: QGraphicsSceneHoverEvent) -> None:
        self.setBrush(QColor(0, 255, 0))

    def hoverLeaveEvent(self, event: QGraphicsSceneHoverEvent) -> None:
        self.setBrush(QColor(0, 0, 0))


class MainWindow(QMainWindow):
    def __init__(self, *args, **kwargs):
        super(MainWindow, self).__init__(*args, **kwargs)
        self.width = 600
        self.height = 500
        self.thread_stop = False

        self.toolbar = QToolBar()
        self.action_color = QAction('Change Color', self)
        self.action_color.triggered.connect(self.__change_color)
        self.toolbar.addAction(self.action_color)
        self.action_stop = QAction('Stop Thread', self)
        self.action_stop.triggered.connect(self.__stop_thread)
        self.toolbar.addAction(self.action_stop)
        self.addToolBar(self.toolbar)

        self.scene = QGraphicsScene()
        self.graphics_view = QGraphicsView(self.scene, self)
        self.graphics_view.setRenderHints(QPainter.Antialiasing | QPainter.HighQualityAntialiasing)
        self.graphics_view.setGeometry(0, 20, 600, 500)
        self.__create_graphs()
        self.show()

    def __create_graphs(self):
        self.nodes = [GraphicsNode(0, 0, 20), GraphicsNode(0, 100, 20)]
        self.lines = [GraphicsLine(0, 0, 0, 100)]
        for node in self.nodes:
            self.scene.addItem(node)
        for line in self.lines:
            self.scene.addItem(line)
        self.thread = Thread(target=self.__color_changer_thread)
        self.thread.start()

    def __color_changer_thread(self):
        while not self.thread_stop:
            for line in self.lines:
                line.change_color()
            sleep(5)

    def __change_color(self):
        for line in self.lines:
            line.change_color()

    def __stop_thread(self):
        self.thread_stop = True


if __name__ == '__main__':
    app = QApplication(sys.argv)

    window = MainWindow()
    app.exec_()

单击工具栏中的“操作”时，对象图形线的颜色会更改，但该线程会使项目不可见。如果对线程进行了注释，则操作底部会毫无问题地更改颜色

---

提前谢谢。

非常感谢@musicamante

解决方案 解决方案包括创建一个QThread而不是POSIX线程，在QThread子类中创建一个信号并将其连接到小部件中创建的插槽。 （参考号：）

---

请提供（例如，什么是

列表

，

可选

和

图形节点

？）。另外，您在

set\u linked

中调用

self.hide（）

，设置画笔后不应调用

self.update（self.boundingRect（））

，因为项目会自动更新自身。@musicamante抱歉，复制代码时出错，self.hide（）是为了调试而在调试器停止后调用self.show（），但结果是一样的。所有方法中的行为都是相同的（set_linked、set_freezed和set_disabled）。还有一个列表，可选的是来自键入（键入提示）和GraphicsNode是来自QGraphicsSellipseitem的一个类子类。请仔细阅读我第一条评论中的链接。你的例子必须是最小的和可复制的。什么是

Callout

和

NetworkNode

？创建这些图形项的零件在哪里？不要只是复制粘贴你的代码，确保它是可复制的，因为我们必须能够复制、粘贴和运行它，可能只需要很少的修改（或者根本没有修改）；你不能期望我们编辑一个完整的150行的例子来让它运行。请帮助我们帮助您。@musicamante我很抱歉您的代码是正确的，代码不清楚。我希望这个新版本更容易理解，您应该从一开始就指定使用线程来实现这一点。只允许从主Qt线程访问小部件，任何其他方式都是非常不鼓励的，因为它通常会导致错误或意外行为，就像您的情况一样。如果要修改GUI中的任何内容，需要使用QThread的子类，并使用信号和插槽与主线程通信。看看吧，即使在这里也有很多问题和答案。

import sys
from PyQt5.QtCore import QThread, pyqtSlot, pyqtSignal
from PyQt5.QtGui import QColor, QBrush, QPen, QPainter
from PyQt5.QtWidgets import QGraphicsScene, QGraphicsEllipseItem, QGraphicsSceneMouseEvent, \
    QGraphicsSceneHoverEvent, QGraphicsLineItem, QApplication, QMainWindow, QGraphicsView, QToolBar, QAction
from threading import Thread
from time import sleep
from random import randint


class ColorChangingThread(QThread):
    signal_color_change = pyqtSignal(int, name='Scheduled color change')

    def __init__(self):
        super(ColorChangingThread, self).__init__()
        self.stop_thread = False

    def run(self) -> None:
        while not self.stop_thread:
            self.signal_color_change.emit(0)
            self.sleep(5)


class GraphicsLine(QGraphicsLineItem):
    def __init__(self, x1: float, y1: float, x2: float, y2: float):
        super(GraphicsLine, self).__init__(x1, y1, x2, y2)

        pen = QPen(QColor(0, 0, 0))
        pen.setWidth(5)
        self.setPen(pen)
        self.setZValue(5)

    def change_color(self):
        pen = QPen(QColor(randint(0, 255), randint(0, 255), randint(0, 255)))
        pen.setWidth(5)
        self.setPen(pen)


class GraphicsNode(QGraphicsEllipseItem):
    def __init__(self, x: float, y: float, size: int):
        super(GraphicsNode, self).__init__(x - size/2, y - size/2, size, size)
        self.setAcceptHoverEvents(True)
        self.setZValue(10)
        brush = QBrush(QColor(0, 0, 0))
        pen = QPen(QColor(0, 0, 0))
        pen.setWidth(0)
        self.setBrush(brush)
        self.setPen(pen)

    def mousePressEvent(self, event: QGraphicsSceneMouseEvent) -> None:
        pass

    def hoverEnterEvent(self, event: QGraphicsSceneHoverEvent) -> None:
        self.setBrush(QColor(0, 255, 0))

    def hoverLeaveEvent(self, event: QGraphicsSceneHoverEvent) -> None:
        self.setBrush(QColor(0, 0, 0))


class MainWindow(QMainWindow):
    def __init__(self, *args, **kwargs):
        super(MainWindow, self).__init__(*args, **kwargs)
        self.width = 600
        self.height = 500
        self.thread = ColorChangingThread()
        self.thread.signal_color_change.connect(self.slot_color_change)

        self.toolbar = QToolBar()
        self.action_color = QAction('Change Color', self)
        self.action_color.triggered.connect(self.__change_color)
        self.toolbar.addAction(self.action_color)
        self.action_stop = QAction('Stop Thread', self)
        self.action_stop.triggered.connect(self.__stop_thread)
        self.toolbar.addAction(self.action_stop)
        self.addToolBar(self.toolbar)

        self.scene = QGraphicsScene()
        self.graphics_view = QGraphicsView(self.scene, self)
        self.graphics_view.setRenderHints(QPainter.Antialiasing | QPainter.HighQualityAntialiasing)
        self.graphics_view.setGeometry(0, 20, 600, 500)
        self.__create_graphs()
        self.show()

    def __create_graphs(self):
        self.nodes = [GraphicsNode(0, 0, 20), GraphicsNode(0, 100, 20)]
        self.lines = [GraphicsLine(0, 0, 0, 100)]
        for node in self.nodes:
            self.scene.addItem(node)
        for line in self.lines:
            self.scene.addItem(line)
        self.thread.start()

    @pyqtSlot(int)
    def slot_color_change(self, value):
        print('Received signal with value %d' % value)
        self.__change_color()

    def __change_color(self):
        for line in self.lines:
            line.change_color()

    def __stop_thread(self):
        self.thread.stop_thread = True


if __name__ == '__main__':
    app = QApplication(sys.argv)

    window = MainWindow()
    app.exec_()