设置QPainter背景

Question

大家好，我正在使用QPainter和鼠标事件，我想将QPainter的背景设置为黑色，我使用了这段代码，但没有工作，谢谢提前

class Drawer(QWidget):

    newPoint = pyqtSignal(QPoint)
    def __init__(self, parent=None):
        QWidget.__init__(self, parent)
        self.path = QPainterPath()    

    def paintEvent(self, event):
        painter = QPainter(self)
        painter.setPen(QColor(168, 34, 3))
        painter.setFont(QFont('Decorative', 10))
        bbrush = QtGui.QBrush( QtGui.QColor(0,0,0),QtCore.Qt.SolidPattern)
        painter.setBackground(painter,bbrush)
        painter.drawPath(self.path)

    def mousePressEvent(self, event):
        self.path.moveTo(event.pos())
        self.update()

    def mouseMoveEvent(self, event):
        self.path.lineTo(event.pos())
        self.newPoint.emit(event.pos())
        self.update()

    def sizeHint(self):
        return QSize(400, 400)   

class MyWidget(QWidget):

    def __init__(self, parent=None):
        QWidget.__init__(self, parent)
        self.setLayout(QVBoxLayout())
        label = QLabel(self)
        drawer = Drawer(self)
        drawer.newPoint.connect(lambda p: label.setText(
                        'Coordinates: ( %d : %d )' % (p.x(), p.y())))
        self.layout().addWidget(label)
        self.layout().addWidget(drawer)

Answer 1

如果你只是想得到一个黑色的背景，你可以得到没有paintEvent。

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


class Drawer(QWidget):

    newPoint = pyqtSignal(QPoint)

    def __init__(self, parent=None):
        QWidget.__init__(self, parent)
        self.path = QPainterPath()    

        # set black background
        pal = self.palette()
        pal.setColor(QPalette.Background, Qt.black)
        self.setAutoFillBackground(True)
        self.setPalette(pal)

    def mousePressEvent(self, event):
        self.path.moveTo(event.pos())
        self.update()

    def mouseMoveEvent(self, event):
        self.path.lineTo(event.pos())
        self.newPoint.emit(event.pos())
        self.update()

    def sizeHint(self):
        return QSize(400, 400)


class MyWidget(QWidget):

    def __init__(self, parent=None):
        QWidget.__init__(self, parent)
        self.setLayout(QVBoxLayout())
        label = QLabel(self)
        drawer = Drawer(self)
        drawer.newPoint.connect(lambda p: label.setText(
                        'Coordinates: ( %d : %d )' % (p.x(), p.y())))
        self.layout().addWidget(label)
        self.layout().addWidget(drawer)


app = QApplication(sys.argv)
widget = MyWidget()
widget.show()

sys.exit(app.exec_())