如何在子类化QRubberBand时使paintEvent工作？

Question

目前，我使用PySide在Ubuntu 14.04 LTS下进行图像裁剪。我在answer中遇到了post，它描述了如何进行图像裁剪的粗略概念。现在我想改变裁剪矩形的宽度和颜色。在this之后，我理解我应该创建一个子类QRubberBand并覆盖paintEvent方法。所以我在底部得到了python代码。如您所见，我在pen.setWidth(5)中进行了paintEvent。但是，当我进行图像裁剪时，线宽不会改变（默认情况下似乎保持1）。请参阅以下红色矩形。

请帮忙。谢谢！

import sys
from PyQt4 import QtGui, QtCore

class MyRubberBand(QtGui.QRubberBand):
    def __init__(self, QRubberBand_Shape, QWidget_parent=None):
        super(MyRubberBand, self).__init__(QRubberBand_Shape, QWidget_parent)
        palette = QtGui.QPalette()
        palette.setBrush(QtGui.QPalette.WindowText, QtGui.QBrush(QtCore.Qt.red))
        self.setPalette(palette)

    def paintEvent(self, QPaintEvent):
        painter = QtGui.QStylePainter(self)
        # painter.begin(self)
        pen = QtGui.QPen()
        # pen.setStyle(QtCore.Qt.SolidLine)
        # pen.setColor(QtGui.QColor(QtCore.Qt.red))
        pen.setWidth(5)
        painter.setPen(pen)

        option = QtGui.QStyleOptionFocusRect()
        option.initFrom(self)
        painter.drawControl(QtGui.QStyle.CE_FocusFrame, option)

class QExampleLabel (QtGui.QLabel):
    def __init__(self, parentQWidget = None):
        super(QExampleLabel, self).__init__(parentQWidget)
        self.initUI()

    def initUI (self):
        self.setPixmap(QtGui.QPixmap('images/3.png'))
        self.currentQRubberBand = MyRubberBand(QtGui.QRubberBand.Rectangle, self)

    def mousePressEvent (self, eventQMouseEvent):
        print 'mouse pressed'
        self.originQPoint = eventQMouseEvent.pos()
        self.currentQRubberBand.setGeometry(QtCore.QRect(self.originQPoint, QtCore.QSize()))
        self.currentQRubberBand.show()

    def mouseMoveEvent (self, eventQMouseEvent):
        self.currentQRubberBand.setGeometry(QtCore.QRect(self.originQPoint, eventQMouseEvent.pos()).normalized())

    def mouseReleaseEvent (self, eventQMouseEvent):
        print 'mouse released'
        # self.currentQRubberBand.hide()
        currentQRect = self.currentQRubberBand.geometry()
        # self.currentQRubberBand.deleteLater()
        cropQPixmap = self.pixmap().copy(currentQRect)
        cropQPixmap.save('output.png')

if __name__ == '__main__':
    myQApplication = QtGui.QApplication(sys.argv)
    myQExampleLabel = QExampleLabel()
    myQExampleLabel.show()
    sys.exit(myQApplication.exec_())

Answer 1

我知道这个问题很旧，但是最近我试图做同样的事情并且看到了这个问题，所以我想为其他可能遇到此问题的人发布一些代码。

您的代码已更新paintEvent。

PySide2：

import sys
from PySide2.QtCore import Qt, QRect, QSize
from PySide2.QtGui import QColor, QPen, QBrush, QPixmap, QPainter, QPalette
from PySide2.QtWidgets import QApplication, QLabel, QRubberBand

class MyRubberBand(QRubberBand):
    def __init__(self, QRubberBand_Shape, QWidget_parent=None):
        super(MyRubberBand, self).__init__(QRubberBand_Shape, QWidget_parent)
        palette = QPalette()
        palette.setBrush(QPalette.WindowText, QBrush(Qt.red))
        self.setPalette(palette)

    def paintEvent(self, QPaintEvent):
        ###QRubberBand with black border and transparent background###
        painter = QPainter(self)
        ###Border Color with width set at 6###
        pen_color = QColor(0, 0, 0, 255)
        painter.setPen(QPen(pen_color, 6))
        ###Transparent background###
        brush_color = QColor(Qt.transparent)
        ###Or to use solid background color###
        # brush_color = QColor(Qt.red)
        painter.setBrush(QBrush(brush_color))
        painter.drawRect(QPaintEvent.rect())

class QExampleLabel (QLabel):
    def __init__(self, parentQWidget = None):
        super(QExampleLabel, self).__init__(parentQWidget)
        self.initUI()

    def initUI (self):
        self.setPixmap(QPixmap('images/3.png'))
        self.currentQRubberBand = MyRubberBand(QRubberBand.Rectangle, self)

    def mousePressEvent (self, eventQMouseEvent):
        print('mouse pressed')
        self.originQPoint = eventQMouseEvent.pos()
        self.currentQRubberBand.setGeometry(QRect(self.originQPoint, QSize()))
        self.currentQRubberBand.show()

    def mouseMoveEvent (self, eventQMouseEvent):
        self.currentQRubberBand.setGeometry(QRect(self.originQPoint, eventQMouseEvent.pos()).normalized())

    def mouseReleaseEvent (self, eventQMouseEvent):
        print('mouse released')
        # self.currentQRubberBand.hide()
        currentQRect = self.currentQRubberBand.geometry()
        # self.currentQRubberBand.deleteLater()
        cropQPixmap = self.pixmap().copy(currentQRect)
        cropQPixmap.save('output.png')

if __name__ == '__main__':
    myQApplication = QApplication(sys.argv)
    myQExampleLabel = QExampleLabel()
    myQExampleLabel.resize(800, 600)
    myQExampleLabel.show()
    sys.exit(myQApplication.exec_())

PyQt5：

import sys
from PyQt5.QtCore import Qt, QRect, QSize
from PyQt5.QtGui import QColor, QPen, QBrush, QPixmap, QPainter, QPalette
from PyQt5.QtWidgets import QApplication, QLabel, QRubberBand

class MyRubberBand(QRubberBand):
    def __init__(self, QRubberBand_Shape, QWidget_parent=None):
        super(MyRubberBand, self).__init__(QRubberBand_Shape, QWidget_parent)
        palette = QPalette()
        palette.setBrush(QPalette.WindowText, QBrush(Qt.red))
        self.setPalette(palette)

    def paintEvent(self, QPaintEvent):
        ###QRubberBand with black border and transparent background###
        painter = QPainter(self)
        ###Border Color with width set at 6###
        pen_color = QColor(0, 0, 0, 255)
        painter.setPen(QPen(pen_color, 6))
        ###Transparent background###
        brush_color = QColor(Qt.transparent)
        ###Or to use solid background color###
        # brush_color = QColor(Qt.red)
        painter.setBrush(QBrush(brush_color))
        painter.drawRect(QPaintEvent.rect())

class QExampleLabel (QLabel):
    def __init__(self, parentQWidget = None):
        super(QExampleLabel, self).__init__(parentQWidget)
        self.initUI()

    def initUI (self):
        self.setPixmap(QPixmap('images/3.png'))
        self.currentQRubberBand = MyRubberBand(QRubberBand.Rectangle, self)

    def mousePressEvent (self, eventQMouseEvent):
        print('mouse pressed')
        self.originQPoint = eventQMouseEvent.pos()
        self.currentQRubberBand.setGeometry(QRect(self.originQPoint, QSize()))
        self.currentQRubberBand.show()

    def mouseMoveEvent (self, eventQMouseEvent):
        self.currentQRubberBand.setGeometry(QRect(self.originQPoint, eventQMouseEvent.pos()).normalized())

    def mouseReleaseEvent (self, eventQMouseEvent):
        print('mouse released')
        # self.currentQRubberBand.hide()
        currentQRect = self.currentQRubberBand.geometry()
        # self.currentQRubberBand.deleteLater()
        cropQPixmap = self.pixmap().copy(currentQRect)
        cropQPixmap.save('output.png')

if __name__ == '__main__':
    myQApplication = QApplication(sys.argv)
    myQExampleLabel = QExampleLabel()
    myQExampleLabel.resize(800, 600)
    myQExampleLabel.show()
    sys.exit(myQApplication.exec_())