PyQt5：如何使用信号+槽为paintEvent传递参数？答案

【问题标题】：PyQt5: How to use signal+slot to transfer parameters for paintEvent?PyQt5：如何使用信号+槽为paintEvent传递参数？
【发布时间】：2018-01-16 01:37:35
【问题描述】：

这个问题，我指的是https://gist.github.com/zhanglongqi/78d7b5cd24f7d0c42f5d116d967923e7的代码

上面的代码展示了如何在当前小部件上绘制一个叠加层，效果很好。但是我想将参数传递到覆盖类中，并使用这些变量来触发覆盖类中的paintEvent。

我修改代码如下...

# -*- coding:utf-8 -*-

from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *


class overlay(QWidget):
    def __init__(self, parent=None):
        super(overlay, self).__init__(parent)

        palette = QPalette(self.palette())
        palette.setColor(palette.Background, Qt.transparent)

        self.setPalette(palette)

    @pyqtSlot(int)
    def getValue(self, a):  # variable is received.
        self.a = a
        print(self.a)
        self.update()

    def paintEvent(self, event):
        painter = QPainter()
        painter.begin(self)
        painter.setRenderHint(QPainter.Antialiasing)
        painter.fillRect(event.rect(), QBrush(QColor(255, 255, 255, 127)))
        painter.drawLine(self.width() / 8, self.height() / 8, 7 * self.width() / 8, 7 * self.height() / 8)
        painter.drawLine(self.width() / 8, 7 * self.height() / 8, 7 * self.width() / 8, self.height() / 8)
        painter.drawLine(self.a , self.a+50, self.a +10, self.a + 100) #Here I want to draw the line using parameter.
        painter.setPen(QPen(Qt.NoPen))


class windowOverlay(QWidget):
    signal = pyqtSignal(int)

    def __init__(self, parent=None):
        super(windowOverlay, self).__init__(parent)

        self.editor = QTextEdit()
        self.editor.setPlainText("OVERLAY" * 100)

        self.button = QPushButton("Toggle Overlay")

        self.verticalLayout = QVBoxLayout(self)
        self.verticalLayout.addWidget(self.editor)
        self.verticalLayout.addWidget(self.button)

        self.overlay = overlay(self.editor)
        self.overlay.hide()

        self.button.clicked.connect(self.switch_and_send_signal)

    def switch_and_send_signal(self):
        if self.overlay.isVisible():
            self.overlay.setVisible(False)
        else:
            self.overlay.setVisible(True)

        self.obj = overlay()
        a = 100
        self.signal.connect(self.obj.getValue)
        self.signal.emit(a)
        self.signal.disconnect(self.obj.getValue)

    def resizeEvent(self, event):
        self.overlay.resize(event.size())
        event.accept()


if __name__ == "__main__":
    import sys

    app = QApplication(sys.argv)
    main = windowOverlay()
    main.show()
    sys.exit(app.exec_())

问题： 似乎参数已传输，但paintEvent 未更新。参数未到达paintEvent。我做错了什么？

感谢您的帮助！

【问题讨论】：

标签： python pyqt pyqt5

【解决方案1】：

问题是因为您正在创建一个未连接的覆盖对象，您必须做的是使用与我下面显示的相同的对象：

class windowOverlay(QWidget):
    signal = pyqtSignal(int)
    def __init__(self, parent=None):
        super(windowOverlay, self).__init__(parent)

        self.editor = QTextEdit()
        self.editor.setPlainText("OVERLAY" * 100)

        self.button = QPushButton("Toggle Overlay")

        self.verticalLayout = QVBoxLayout(self)
        self.verticalLayout.addWidget(self.editor)
        self.verticalLayout.addWidget(self.button)

        self.overlay = overlay(self.editor)
        self.overlay.hide()
        self.signal.connect(self.overlay.getValue)

        self.button.clicked.connect(self.switch_and_send_signal)

    def switch_and_send_signal(self):
        self.overlay.setVisible(not self.overlay.isVisible())
        a = 100
        self.signal.emit(a)

    def resizeEvent(self, event):
        self.overlay.resize(event.size())
        event.accept()

【讨论】：