在自定义树视图中显示QCombobox向下箭头

from PyQt5.QtWidgets import QTreeView, QStyledItemDelegate, QComboBox, QApplication
from PyQt5.QtCore import Qt

class CustomTreeView(QTreeView):
    def __init__(self):
        super().__init__()
        self.setItemDelegate(CustomDelegate(self))

class CustomDelegate(QStyledItemDelegate):
    def paint(self, painter, option, index):
        if index.column() == 0:  # 判断需要显示QComboBox的列
            # 绘制QComboBox外观
            combo_rect = option.rect
            combo_rect.setWidth(combo_rect.width() - 20)  # 减去箭头的宽度
            QStyleOptionComboBox().rect = combo_rect
            self.parent().style().drawComplexControl(QStyle.CC_ComboBox, QStyleOptionComboBox(), painter)

            # 绘制箭头
            arrow_rect = option.rect
            arrow_rect.setX(arrow_rect.x() + arrow_rect.width() - 20)  # 箭头的起始位置
            arrow_rect.setWidth(20)  # 箭头的宽度
            QStyleOptionComboBox().rect = arrow_rect
            self.parent().style().drawPrimitive(QStyle.PE_IndicatorArrowDown, QStyleOptionComboBox(), painter)

            # 绘制文本
            text_rect = option.rect
            text_rect.setWidth(text_rect.width() - 20)  # 减去箭头的宽度
            text = index.data(Qt.DisplayRole)
            painter.drawText(text_rect, Qt.AlignVCenter, text)

        else:
            super().paint(painter, option, index)

if __name__ == '__main__':
    app = QApplication([])
    tree_view = CustomTreeView()
    tree_view.show()
    app.exec_()