如何使用pyqt4创建圆形图像？

Question

我在这里编写了这段代码，但是没有用：

import sys
from PyQt4 import QtGui, QtCore

class CricleImage(QtCore.QObject):
    def __init__(self):
        super(CricleImage, self).__init__()

        self.pix = QtGui.QGraphicsPixmapItem(QtGui.QPixmap("bird(01).jpg"))

        #drawRoundCircle
        rect = self.pix.boundingRect()
        self.gri = QtGui.QGraphicsRectItem(rect)
        self.gri.setPen(QtGui.QColor('red'))


if __name__ == '__main__':

    myQApplication = QtGui.QApplication(sys.argv)

    IMG = CricleImage()
    #scene
    scene = QtGui.QGraphicsScene(0, 0, 400, 300)
    scene.addItem(IMG.pix)
    #view
    view = QtGui.QGraphicsView(scene)
    view.show()
    sys.exit(myQApplication.exec_())

Answer 1

一种可能的解决方案是覆盖QGraphicsPixmapItem的paint（）方法并使用setClipPath来限制绘画区域：

from PyQt4 import QtCore, QtGui


class CirclePixmapItem(QtGui.QGraphicsPixmapItem):
    @property
    def radius(self):
        if not hasattr(self, "_radius"):
            self._radius = 0
        return self._radius

    @radius.setter
    def radius(self, value):
        if value >= 0:
            self._radius = value
            self.update()

    def paint(self, painter, option, widget=None):
        painter.save()
        rect = QtCore.QRectF(QtCore.QPointF(), 2 * self.radius * QtCore.QSizeF(1, 1))
        rect.moveCenter(self.boundingRect().center())
        path = QtGui.QPainterPath()
        path.addEllipse(rect)
        painter.setClipPath(path)
        super().paint(painter, option, widget)
        painter.restore()


if __name__ == "__main__":
    import sys

    app = QtGui.QApplication(sys.argv)

    pixmap = QtGui.QPixmap("logo.jpg")

    scene = QtGui.QGraphicsScene()
    view = QtGui.QGraphicsView(scene)
    view.setRenderHints(
        QtGui.QPainter.Antialiasing | QtGui.QPainter.SmoothPixmapTransform
    )

    it = CirclePixmapItem(pixmap)
    scene.addItem(it)

    it.radius = pixmap.width() / 2

    view.show()
    sys.exit(app.exec_())