如何通过QItemDelegate为QTableView指定行添加粗下划线？

我需要实现：根据每行第一列的内容（如'revenue avg 3'、'tangible book'），为对应整行的所有单元格文本添加粗下划线。尝试用QItemDelegate实现，但当前自定义Delegate完全无效，不知道问题出在哪。

原代码如下：

模型与视图代码 #

import pandas as pd
from PySide6 import QtCore, QtWidgets
from PySide6.QtCore import Qt
from PySide6.QtGui import QColor, QPen, QBrush
from PySide6.QtWidgets import QStyle


class TickerTableModel(QtCore.QAbstractTableModel):

    def __init__(self,  parent=None, *args):
        super(TickerTableModel,  self).__init__(parent,  *args)
        self._filters = {}
        self._sortBy = []
        self._sortDirection = []
        self._dfSource = pd.DataFrame()
        self._dfDisplay = pd.DataFrame()

    def rowCount(self,  parent=QtCore.QModelIndex()):
        if parent.isValid():
            return 0
        return self._dfDisplay.shape[0]

    def columnCount(self,  parent=QtCore.QModelIndex()):
        if parent.isValid():
            return 0
        return self._dfDisplay.shape[1]

    def data(self, index, role):
        if index.isValid() and role == QtCore.Qt.ItemDataRole.DisplayRole:
            return self._dfDisplay.values[index.row()][index.column()]
        return None

    def headerData(self, col, orientation=QtCore.Qt.Orientation.Horizontal, role=QtCore.Qt.ItemDataRole.DisplayRole):
        if orientation == QtCore.Qt.Orientation.Horizontal and role == QtCore.Qt.ItemDataRole.DisplayRole:
            return str(self._dfDisplay.columns[col])
        return None

    def setupModel(self, data):
        self._dfSource = data
        self._sortBy = []
        self._sortDirection = []
        self.setFilters({})

    def setFilters(self, filters):
        self.modelAboutToBeReset.emit()
        self._filters = filters
        self.updateDisplay()
        self.modelReset.emit()

    def updateDisplay(self):

        dfDisplay = self._dfSource.copy()

        # Filtering
        cond = pd.Series(True, index=dfDisplay.index)
        for column, value in self._filters.items():
            cond = cond & \
                   (dfDisplay[column].str.lower().str.find(str(value).lower()) >= 0)
        dfDisplay = dfDisplay[cond]

        # Sorting
        if len(self._sortBy) != 0:
            dfDisplay.sort_values(by=self._sortBy,
                                  ascending=self._sortDirection,
                                  inplace=True)

        # Updating
        self._dfDisplay = dfDisplay


class TickerTableView(QtWidgets.QTableView):
    def setupUi(self, TickerTableWidget):
        self.verticalLayout = QtWidgets.QVBoxLayout(TickerTableWidget)
        self.tableView = QtWidgets.QTableView(TickerTableWidget)
        self.tableView.setSortingEnabled(True)
        self.tableView.setAlternatingRowColors(True)
        self.verticalLayout.addWidget(self.tableView)
        QtCore.QMetaObject.connectSlotsByName(TickerTableWidget)


class TickerTableWidget(QtWidgets.QWidget):
    def __init__(self, data, parent=None):
        super(TickerTableWidget, self).__init__(parent)

        self.ui = TickerTableView()
        self.ui.setupUi(self)

        self.tableModel = TickerTableModel()
        self.tableModel.setupModel(data)
        self.ui.tableView.setModel(self.tableModel)

        # Set delegate here
        self.delegate = TickerTableDelegate(self.ui)
        self.ui.setItemDelegate(self.delegate)


class TickerTableDelegate(QtWidgets.QItemDelegate):
    def __init__(self,  parent=None, *args):
        QtWidgets.QItemDelegate.__init__(self, parent, *args)

    def paint(self, painter, option, index):
        painter.save()

        # set text color
        painter.setPen(QPen(Qt.black))
        text = index.data(Qt.DisplayRole)

        if text:
            painter.setPen(QPen(Qt.red))

        painter.drawText(option.rect, Qt.AlignCenter, text)
        painter.restore()

主函数代码 #

if __name__ == '__main__':
    app = QApplication(sys.argv)
    df = pd.DataFrame({'revenue avg 3' : [1,5,10], 'profit': [5, 4, 5], 'income': [3,5,6]})
    window = TickerTableWidget(df)
    window.show()
    sys.exit(app.exec())

问题分析与修复 #

1. Delegate设置错误 #

原代码中self.ui.setItemDelegate(self.delegate)是给TickerTableView实例设置Delegate，但实际需要给内部的tableView控件设置，应该改为：

self.ui.tableView.setItemDelegate(self.delegate)

2. Delegate的paint方法未实现下划线逻辑 #

修改TickerTableDelegate的paint方法，先获取当前行第0列的内容，判断是否需要添加下划线，同时保留表格原有样式：

class TickerTableDelegate(QtWidgets.QItemDelegate):
    def __init__(self,  parent=None, *args):
        super().__init__(parent, *args)
        # 定义需要添加下划线的首列关键词
        self.target_labels = ['revenue avg 3']

    def paint(self, painter, option, index):
        painter.save()

        # 获取当前行第0列的内容
        row = index.row()
        first_col_index = index.model().index(row, 0)
        first_col_text = index.model().data(first_col_index, Qt.DisplayRole)

        # 获取单元格文本
        text = index.data(Qt.DisplayRole) or ""

        # 保留默认的背景和焦点样式（选中、交替行颜色等）
        self.drawBackground(painter, option, index)
        self.drawFocus(painter, option, option.rect)

        # 设置画笔：目标行启用粗下划线
        pen = QPen(Qt.black)
        if first_col_text in self.target_labels:
            pen.setUnderline(True)
            pen.setWeight(2)  # 设置下划线粗细
        painter.setPen(pen)

        # 绘制居中文本
        painter.drawText(option.rect, Qt.AlignCenter, str(text))

        painter.restore()

修改后的完整代码 #

import pandas as pd
from PySide6 import QtCore, QtWidgets
from PySide6.QtCore import Qt
from PySide6.QtGui import QColor, QPen, QBrush
from PySide6.QtWidgets import QStyle


class TickerTableModel(QtCore.QAbstractTableModel):

    def __init__(self,  parent=None, *args):
        super(TickerTableModel,  self).__init__(parent,  *args)
        self._filters = {}
        self._sortBy = []
        self._sortDirection = []
        self._dfSource = pd.DataFrame()
        self._dfDisplay = pd.DataFrame()

    def rowCount(self,  parent=QtCore.QModelIndex()):
        if parent.isValid():
            return 0
        return self._dfDisplay.shape[0]

    def columnCount(self,  parent=QtCore.QModelIndex()):
        if parent.isValid():
            return 0
        return self._dfDisplay.shape[1]

    def data(self, index, role):
        if index.isValid() and role == QtCore.Qt.ItemDataRole.DisplayRole:
            return self._dfDisplay.values[index.row()][index.column()]
        return None

    def headerData(self, col, orientation=QtCore.Qt.Orientation.Horizontal, role=QtCore.Qt.ItemDataRole.DisplayRole):
        if orientation == QtCore.Qt.Orientation.Horizontal and role == QtCore.Qt.ItemDataRole.DisplayRole:
            return str(self._dfDisplay.columns[col])
        return None

    def setupModel(self, data):
        self._dfSource = data
        self._sortBy = []
        self._sortDirection = []
        self.setFilters({})

    def setFilters(self, filters):
        self.modelAboutToBeReset.emit()
        self._filters = filters
        self.updateDisplay()
        self.modelReset.emit()

    def updateDisplay(self):

        dfDisplay = self._dfSource.copy()

        # Filtering
        cond = pd.Series(True, index=dfDisplay.index)
        for column, value in self._filters.items():
            cond = cond & \
                   (dfDisplay[column].str.lower().str.find(str(value).lower()) >= 0)
        dfDisplay = dfDisplay[cond]

        # Sorting
        if len(self._sortBy) != 0:
            dfDisplay.sort_values(by=self._sortBy,
                                  ascending=self._sortDirection,
                                  inplace=True)

        # Updating
        self._dfDisplay = dfDisplay


class TickerTableView(QtWidgets.QTableView):
    def setupUi(self, TickerTableWidget):
        self.verticalLayout = QtWidgets.QVBoxLayout(TickerTableWidget)
        self.tableView = QtWidgets.QTableView(TickerTableWidget)
        self.tableView.setSortingEnabled(True)
        self.tableView.setAlternatingRowColors(True)
        self.verticalLayout.addWidget(self.tableView)
        QtCore.QMetaObject.connectSlotsByName(TickerTableWidget)


class TickerTableWidget(QtWidgets.QWidget):
    def __init__(self, data, parent=None):
        super(TickerTableWidget, self).__init__(parent)

        self.ui = TickerTableView()
        self.ui.setupUi(self)

        self.tableModel = TickerTableModel()
        self.tableModel.setupModel(data)
        self.ui.tableView.setModel(self.tableModel)

        # 修复：给tableView设置Delegate
        self.delegate = TickerTableDelegate(self.ui)
        self.ui.tableView.setItemDelegate(self.delegate)


class TickerTableDelegate(QtWidgets.QItemDelegate):
    def __init__(self,  parent=None, *args):
        super().__init__(parent, *args)
        # 定义需要添加下划线的首列关键词
        self.target_labels = ['revenue avg 3']

    def paint(self, painter, option, index):
        painter.save()

        # 获取当前行第0列的内容
        row = index.row()
        first_col_index = index.model().index(row, 0)
        first_col_text = index.model().data(first_col_index, Qt.DisplayRole)

        # 获取单元格文本
        text = index.data(Qt.DisplayRole) or ""

        # 保留默认的背景和焦点样式
        self.drawBackground(painter, option, index)
        self.drawFocus(painter, option, option.rect)

        # 设置画笔样式
        pen = QPen(Qt.black)
        if first_col_text in self.target_labels:
            pen.setUnderline(True)
            pen.setWeight(2)  # 加粗下划线
        painter.setPen(pen)

        # 绘制居中文本
        painter.drawText(option.rect, Qt.AlignCenter, str(text))

        painter.restore()


if __name__ == '__main__':
    import sys
    from PySide6.QtWidgets import QApplication
    app = QApplication(sys.argv)
    df = pd.DataFrame({'revenue avg 3' : [1,5,10], 'profit': [5, 4, 5], 'income': [3,5,6]})
    window = TickerTableWidget(df)
    window.show()
    sys.exit(app.exec())

修改后，首列内容为'revenue avg 3'的整行都会显示粗下划线文本，同时保留表格原有选中、交替行颜色等样式，Delegate可正常生效。

内容的提问来源于stack exchange，提问作者David Frick