PyQt5 QTableWidget嵌入控件时focusWidget().pos()始终返回0

将组合了QCheckBox与QLineEdit的自定义QWidget通过setCellWidget()嵌入QTableWidget使用时，切换复选框状态、修改输入框文本，程序始终返回错误的单元格坐标(0,0)：操作第3行（索引为2）的复选框时预期输出2 0，实际输出0 0；修改第3行输入框文本时，同样返回0行0列的单元格信息。
排查确认问题根源：QApplication.focusWidget().pos()始终返回坐标值0，导致QTableWidget.indexAt()方法定位到错误单元格。

import sys
from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import QWidget, QHBoxLayout, QTableWidget, \
    QApplication, QTableWidgetItem, QLineEdit, QCheckBox
from PyQt5 import QtGui

class SimpleTable(QTableWidget):
    def __init__(self,window):
        QTableWidget.__init__(self)
        self.window = window
        

class myWidget(QWidget):
    def __init__(self,parent=None):
        super(myWidget,self).__init__()
        self.Layout1 = QHBoxLayout()
        self.item = QLineEdit("My custom text")
        
        self.Checkbox = QCheckBox()
        self.Checkbox.setCheckState(Qt.CheckState.Unchecked)

        self.Layout1.addWidget(self.Checkbox)
        self.Layout1.addWidget(self.item)

        self.item.home(True)
        
        self.setLayout(self.Layout1)
        
class Window(QWidget):
    def __init__(self):
        super(Window, self).__init__()
        layout = QHBoxLayout()
        self.setLayout(layout)
        
        self.table_widget = SimpleTable(window=self)
        layout.addWidget(self.table_widget)
        self.table_widget.setColumnCount(3)
        self.table_widget.setHorizontalHeaderLabels(['Colour', 'Model'])

        items = [('Red', 'Toyota'), ('Blue', 'RV'), ('Green', 'Beetle')]
        for i in range(len(items)):
            c = QTableWidgetItem(items[i][0])
            m = QTableWidgetItem(items[i][1])
             
            self.table_widget.insertRow(self.table_widget.rowCount())
            self.table_widget.setItem(i, 1, c)
            self.table_widget.setItem(i, 2, m)

            myWidget1 = myWidget()
            myWidget1.Checkbox.stateChanged.connect(self.handleButtonClicked)
            myWidget1.item.editingFinished.connect(self.handle_cell_edited)      
            self.table_widget.setCellWidget(i,0,myWidget1)
            myWidget1.Layout1.setContentsMargins(50*i+10,0,0,0)

        self.show()

        self.table_widget.itemChanged.connect(self.handle_cell_edited)


    def handleButtonClicked(self):   
        button = QApplication.focusWidget()
        index = self.table_widget.indexAt(button.pos())
        if index.isValid():
            print(index.row(), index.column())
    
    def handle_cell_edited(self):
        if QApplication.focusWidget() != None:
            index = self.table_widget.indexAt(QApplication.focusWidget().pos())
            x,y = index.column(),index.row()
            if index.isValid():
                print("Handle Cell Edited",index.row(), index.column())
            if self.table_widget.item(y,x)!= None:
                print(f"Cell {x},{y} was changed to {self.table_widget.item(y,x).text()}.")

def main():
    app = QApplication(sys.argv)
    window = Window()
    sys.exit(app.exec_())
main()

Qt表格嵌入元素有两类常规实现，均无法完全满足需求：

• 通过setItem()添加QTableWidgetItem：可设置Qt.ItemFlag.ItemIsUserCheckable标志实现单元格复选框，但无法自定义复选框缩进，也不能在同一单元格内同时组合复选框与可编辑文本框。
  该方案的实现代码如下：

  import sys
  from PyQt5.QtCore import Qt
  from PyQt5.QtWidgets import QWidget, QHBoxLayout, QTableWidget, \
      QApplication, QTableWidgetItem, QLineEdit, QCheckBox
  from PyQt5 import QtGui
  
  class SimpleTable(QTableWidget):
      def __init__(self,window):
          QTableWidget.__init__(self)
          self.window = window
          
  class Window(QWidget):
      def __init__(self):
          super(Window, self).__init__()
          layout = QHBoxLayout()
          self.setLayout(layout)
          
          self.table_widget = SimpleTable(window=self)
          layout.addWidget(self.table_widget)
          self.table_widget.setColumnCount(3)
          self.table_widget.setHorizontalHeaderLabels(['Colour', 'Model'])
  
          items = [('Red', 'Toyota'), ('Blue', 'RV'), ('Green', 'Beetle')]
          for i in range(len(items)):
              c = QTableWidgetItem(items[i][0])
              m = QTableWidgetItem(items[i][1])
               
              self.table_widget.insertRow(self.table_widget.rowCount())
              self.table_widget.setItem(i, 1, c)
              self.table_widget.setItem(i, 2, m)
              
              item = QTableWidgetItem("My Custom Text")
              item.setFlags(Qt.ItemFlag.ItemIsUserCheckable| Qt.ItemFlag.ItemIsEnabled)
              item.setCheckState(Qt.CheckState.Unchecked)
              self.table_widget.setItem(i,0,item)
  
          self.show()
          self.table_widget.itemChanged.connect(self.handle_cell_edited)
  
      def handleButtonClicked(self):    
          button = QApplication.focusWidget()
          index = self.table_widget.indexAt(button.pos())
          if index.isValid():
              print(index.row(), index.column())
      
      def handle_cell_edited(self):
          if QApplication.focusWidget() != None:
              index = self.table_widget.indexAt(QApplication.focusWidget().pos())
              x,y = index.column(),index.row()
              if index.isValid():
                  print("Handle Cell Edited",index.row(), index.column())
              if self.table_widget.item(y,x)!= None:
                  print(f"Cell {x},{y} was changed to {self.table_widget.item(y,x).text()}.")
  
  def main():
      app = QApplication(sys.argv)
      window = Window()
      sys.exit(app.exec_())
  main()
  

• 通过自定义QItemDelegate实现灵活的单元格控件配置：该方案可满足所有自定义需求，但实现复杂度高，优先不考虑。

错误原因 #

原代码直接调用子控件（QCheckBox/QLineEdit）的pos()方法获取坐标，该坐标是**相对于子控件直接父容器（自定义myWidget）**的局部坐标，永远在(0,0)附近，并非相对于QTableWidget视口的全局坐标，因此传给indexAt()会永远定位到(0,0)单元格。

最简实现（无需自定义委托） #

不需要做坐标转换，直接在创建单元格控件时给控件实例绑定行列属性，槽函数中通过信号发送者（sender()）找到对应控件实例，直接读取存储的行列值即可，无坐标计算误差：

1. 首先修改myWidget类，增加行列属性存储：

class myWidget(QWidget):
    def __init__(self, row, col, parent=None):
        super(myWidget,self).__init__(parent)
        # 存储自身所在行列
        self.row = row
        self.col = col
        self.Layout1 = QHBoxLayout()
        self.item = QLineEdit("My custom text")
        
        self.Checkbox = QCheckBox()
        self.Checkbox.setCheckState(Qt.CheckState.Unchecked)

        self.Layout1.addWidget(self.Checkbox)
        self.Layout1.addWidget(self.item)
        self.item.home(True)
        # 消除控件周围默认边距，避免单元格显示错位
        self.Layout1.setContentsMargins(2,2,2,2)
        self.setLayout(self.Layout1)

2. 创建控件实例时传入当前行列，修改槽函数逻辑，直接从控件实例读行列：

# 循环中创建控件的代码修改为
for i in range(len(items)):
    c = QTableWidgetItem(items[i][0])
    m = QTableWidgetItem(items[i][1])
     
    self.table_widget.insertRow(self.table_widget.rowCount())
    self.table_widget.setItem(i, 1, c)
    self.table_widget.setItem(i, 2, m)
    # 传入当前行列i,0
    myWidget1 = myWidget(i, 0)
    myWidget1.Checkbox.stateChanged.connect(self.handleButtonClicked)
    myWidget1.item.editingFinished.connect(self.handle_cell_edited)      
    self.table_widget.setCellWidget(i,0,myWidget1)
    myWidget1.Layout1.setContentsMargins(50*i+10,0,0,0)

# 槽函数修改为
def handleButtonClicked(self):
    # 拿到发信号的checkbox
    checkbox = self.sender()
    # 找到其父容器即myWidget实例
    cell_widget = checkbox.parent()
    while not isinstance(cell_widget, myWidget):
        cell_widget = cell_widget.parent()
    print(cell_widget.row, cell_widget.col)

def handle_cell_edited(self):
    sender = self.sender()
    # 判断是输入框发的信号还是表格item发的信号
    if isinstance(sender, QLineEdit):
        cell_widget = sender.parent()
        while not isinstance(cell_widget, myWidget):
            cell_widget = cell_widget.parent()
        row, col = cell_widget.row, cell_widget.col
        print("Handle Cell Edited", row, col)
        # 直接读取输入框文本即可，不需要额外读table item
        print(f"Cell {col},{row} was changed to {sender.text()}.")
    else:
        # 处理普通QTableWidgetItem的编辑信号
        item = self.table_widget.currentItem()
        if item:
            print("Handle Cell Edited", item.row(), item.column())
            print(f"Cell {item.column()},{item.row()} was changed to {item.text()}.")

如果表格后续有插入、删除行的操作，只需要遍历所有单元格的setCellWidget实例，更新它们存储的row属性即可，逻辑非常简单。

内容的提问来源于stack exchange，提问作者spamme180