QTableWdiget 单元格中的 QLineEdit 不会失去焦点

Question

我目前正在尝试使用 PyQt5 制作图形界面。到目前为止，一切都运行良好（毕竟我在这方面有一些经验），但是我已经为这个问题苦苦挣扎了几天，我在任何地方都找不到解决方案。

在我的应用程序中，我显示了来自 matplotlib 的 FigureCanvas（以及各种其他小部件），其中我有一个连接到函数的键事件，该函数从鼠标单击中选择一个点并将该点保存在 QTableWidget 中。但是，我希望用户能够编辑使用验证器获取的 y 值，因此我将第二列从持有 QTableWidgetItem 更改为 QLineEdit 小部件。一切正常，除了当我在表格中编辑 QLineEdit 小部件后按 Enter 键时，焦点没有按预期改变（我将焦点设置为返回画布，但单元格保持活动状态，光标闪烁）。

在同一个应用程序中，我在布局的其他地方有另一个 QLineEdit 小部件，它按预期工作。当我在此框中按 enter 时，连接到其 returnPressed 信号的函数将焦点发送回画布。

谁能帮我弄清楚这是怎么回事？

另外，当我在创建主框架时明确将焦点设置到画布时，我不明白为什么应用程序启动时焦点位于 QLineEdit 上。你知道如何解决这个问题吗？

我已将我的应用程序剥离为粘贴在下面的最小示例，并且行为保持不变。

总结一下：

1. 我在画布上单击并按“a”，调用函数“add_point”。
2. 然后我单击绘图中的一个点，该点在小部件中创建一个新行并将焦点设置到第二列。
3. 我在这里输入我想要的任何浮点值，然后按 Enter。

4. 然后调用函数“print_val”，但焦点没有按预期返回到画布。光标在表格单元格中一直闪烁。

5. 当我编辑最左边的 QLineEdit（表格外）并按 Enter 键时，会调用函数 'func' 并将焦点正确地发送回画布。

为什么 QLineEdit 的两个实例行为不同？

作为参考，函数“print_val”的输出给了我： TableWidget 有焦点？错误的 单元格编辑器有焦点？假的

提前致谢！

import sys
from matplotlib.backends.backend_qt5agg import FigureCanvas, NavigationToolbar2QT as NavigationToolbar
from matplotlib.figure import Figure

from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *



class GraphicInterface(QMainWindow):
    def __init__(self, parent=None):
        QMainWindow.__init__(self, parent)
        self.setWindowTitle('Test')
        self._main = QWidget()
        self.setCentralWidget(self._main)

        # Create Toolbar and Menubar
        toolbar = QToolBar()
        toolbar.setMovable(False)
        toolbar_fontsize = QFont()
        toolbar_fontsize.setPointSize(14)

        quit_action = QAction("Close", self)
        quit_action.setFont(toolbar_fontsize)
        quit_action.setStatusTip("Quit the application")
        quit_action.triggered.connect(self.close)
        quit_action.setShortcut("ctrl+Q")
        toolbar.addAction(quit_action)


        # =============================================================
        # Start Layout:
        layout = QHBoxLayout(self._main)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.setSpacing(0)

        self.line_editor = QLineEdit("3")
        self.line_editor.setValidator(QIntValidator(1, 100))
        self.line_editor.returnPressed.connect(self.func)
        layout.addWidget(self.line_editor)

        # Create Table for Pixel Identifications:
        pixtab_layout = QVBoxLayout()
        label_pixtab_header = QLabel("Pixel Table\n")
        label_pixtab_header.setAlignment(Qt.AlignCenter)
        self.linetable = QTableWidget()
        self.linetable.verticalHeader().hide()
        self.linetable.setColumnCount(2)
        self.linetable.setHorizontalHeaderLabels(["Pixel", "Wavelength"])
        self.linetable.setColumnWidth(0, 80)
        self.linetable.setColumnWidth(1, 90)
        self.linetable.setFixedWidth(180)
        pixtab_layout.addWidget(label_pixtab_header)
        pixtab_layout.addWidget(self.linetable)
        layout.addLayout(pixtab_layout)

        # Create Figure Canvas:
        right_layout = QVBoxLayout()
        self.fig = Figure(figsize=(6, 6))
        self.canvas = FigureCanvas(self.fig)
        self.canvas.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding)
        self.canvas.updateGeometry()
        self.canvas.mpl_connect('key_press_event', self.on_key_press)
        self.canvas.setFocusPolicy(Qt.StrongFocus)
        self.canvas.setFocus()
        right_layout.addWidget(self.canvas)
        self.mpl_toolbar = NavigationToolbar(self.canvas, self)
        right_layout.addWidget(self.mpl_toolbar)
        layout.addLayout(right_layout)

        # Plot some random data:
        self.ax = self.fig.add_subplot(111)
        self.ax.plot([0, 1, 5, 10, 20], [-1, 2, -4, 5, -2])

    def on_key_press(self, e):
        if e.key == "a":
            self.add_point()

    def add_point(self):
        print("Select point...")
        point = self.fig.ginput(1)
        x0, _ = point[0]
        rowPosition = self.linetable.rowCount()
        self.linetable.insertRow(rowPosition)
        item = QTableWidgetItem("%.2f" % x0)
        item.setFlags(Qt.ItemIsEnabled)
        item.setBackground(QColor('lightgray'))
        self.linetable.setItem(rowPosition, 0, item)

        y_item = QLineEdit("")
        y_item.setValidator(QDoubleValidator())
        y_item.returnPressed.connect(self.print_val)
        self.linetable.setCellWidget(rowPosition, 1, y_item)
        self.linetable.cellWidget(rowPosition, 1).setFocus()

    def print_val(self):
        rowPosition = self.linetable.rowCount()
        editor = self.linetable.cellWidget(rowPosition-1, 1)
        y_in = float(editor.text())
        print(" Table value: %.2f" % y_in)
        # and set focus back to canvas:
        self.canvas.setFocus()
        # Check which widget has focus:
        focus_widget = self.focusWidget()
        print(focus_widget.__class__)
        print("TableWidget has focus?  %r" % self.linetable.hasFocus())
        print("Cell editor has focus?  %r" % editor.hasFocus())

    def func(self):
        # dome some stuff
        print(self.line_editor.text())
        # and set focus back to canvas:
        self.canvas.setFocus()


if __name__ == '__main__':
    # Launch App:
    qapp = QApplication(sys.argv)
    app = GraphicInterface()
    app.show()
    qapp.exec_()

Answer 1

如果您想验证 QTableWidget 的信息，则无需插入 QLineEdit，而是使用委托创建的并在那里设置 QValidator：

class ValidatorDelegate(QtWidgets.QStyledItemDelegate):
    def createEditor(self, parent, option, index):
        editor = super(ValidatorDelegate, self).createEditor(parent, option, index)
        if isinstance(editor, QtWidgets.QLineEdit):
            editor.setValidator(QtGui.QDoubleValidator(editor))
        return editor

然后用视图的edit方法打开编辑器，改变焦点可以使用delegate的closeEditor信号：

import sys
from matplotlib.backends.backend_qt5agg import (
    FigureCanvas,
    NavigationToolbar2QT as NavigationToolbar,
)
from matplotlib.figure import Figure


from PyQt5 import QtCore, QtGui, QtWidgets


class ValidatorDelegate(QtWidgets.QStyledItemDelegate):
    def createEditor(self, parent, option, index):
        editor = super(ValidatorDelegate, self).createEditor(parent, option, index)
        if isinstance(editor, QtWidgets.QLineEdit):
            editor.setValidator(QtGui.QDoubleValidator(editor))
        return editor


class GraphicInterface(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(GraphicInterface, self).__init__(parent)
        self.setWindowTitle("Test")
        self._main = QtWidgets.QWidget()
        self.setCentralWidget(self._main)

        # Create Toolbar and Menubar
        toolbar = QtWidgets.QToolBar(movable=False)
        toolbar_fontsize = QtGui.QFont()
        toolbar_fontsize.setPointSize(14)

        quit_action = QtWidgets.QAction("Close", self)
        quit_action.setFont(toolbar_fontsize)
        quit_action.setStatusTip("Quit the application")
        quit_action.triggered.connect(self.close)
        quit_action.setShortcut("ctrl+Q")
        toolbar.addAction(quit_action)

        self.line_editor = QtWidgets.QLineEdit("3")
        self.line_editor.setValidator(QtGui.QIntValidator(1, 100))

        label_pixtab_header = QtWidgets.QLabel(
            "Pixel Table\n", alignment=QtCore.Qt.AlignCenter
        )

        self.linetable = QtWidgets.QTableWidget()
        self.linetable.verticalHeader().hide()
        self.linetable.setColumnCount(2)
        self.linetable.setHorizontalHeaderLabels(["Pixel", "Wavelength"])
        self.linetable.setColumnWidth(0, 80)
        self.linetable.setColumnWidth(1, 90)
        self.linetable.setFixedWidth(180)

        delegate = ValidatorDelegate(self.linetable)
        self.linetable.setItemDelegate(delegate)

        layout = QtWidgets.QHBoxLayout(self._main)
        layout.setContentsMargins(0, 0, 0, 0)
        layout.setSpacing(0)
        layout.addWidget(self.line_editor)

        pixtab_layout = QtWidgets.QVBoxLayout()
        pixtab_layout.addWidget(label_pixtab_header)
        pixtab_layout.addWidget(self.linetable)
        layout.addLayout(pixtab_layout)

        # Create Figure Canvas:
        right_layout = QtWidgets.QVBoxLayout()
        self.fig = Figure(figsize=(6, 6))
        self.canvas = FigureCanvas(self.fig)
        self.canvas.setSizePolicy(
            QtWidgets.QSizePolicy.Expanding, QtWidgets.QSizePolicy.Expanding
        )
        self.canvas.updateGeometry()
        self.canvas.mpl_connect("key_press_event", self.on_key_press)
        self.canvas.setFocusPolicy(QtCore.Qt.StrongFocus)
        self.canvas.setFocus()
        right_layout.addWidget(self.canvas)
        self.mpl_toolbar = NavigationToolbar(self.canvas, self)
        right_layout.addWidget(self.mpl_toolbar)
        layout.addLayout(right_layout)

        delegate.closeEditor.connect(self.canvas.setFocus)

        # Plot some random data:
        self.ax = self.fig.add_subplot(111)
        self.ax.plot([0, 1, 5, 10, 20], [-1, 2, -4, 5, -2])

    def on_key_press(self, e):
        if e.key == "a":
            self.add_point()

    def add_point(self):
        print("Select point...")
        point = self.fig.ginput(1)
        if not point:
            return
        x0, _ = point[0]

        row = self.linetable.rowCount()
        self.linetable.insertRow(row)

        item = QtWidgets.QTableWidgetItem("%.2f" % x0)
        item.setFlags(QtCore.Qt.ItemIsEnabled)
        item.setBackground(QtGui.QColor("lightgray"))
        self.linetable.setItem(row, 0, item)

        index = self.linetable.model().index(row, 1)

        self.linetable.edit(index)


if __name__ == "__main__":
    # Launch App:
    qapp = QtWidgets.QApplication(sys.argv)
    app = GraphicInterface()
    app.show()
    qapp.exec_()