PyQt5 – 为不可编辑的组合框的行编辑部分添加边框

为不可编辑的组合框的行编辑部分添加边框可以使用PyQt5中提供的QProxyStyle类。该类继承自QStyle类，它可以自定义组件的外观，包括颜色、大小、边框等。

完整使用攻略如下：

Step 1: 导入必要模块

首先，需要导入PyQt5中的必要模块，代码如下：

from PyQt5.QtWidgets import QComboBox, QStyleOptionComboBox, QProxyStyle
from PyQt5.QtCore import QSize

其中，QComboBox是组合框控件，QStyleOptionComboBox是样式选项接口，QProxyStyle是QStyle的子类，QSize控制控件大小。

Step 2: 自定义样式

接下来，需要通过自定义样式来添加QComboBox的边框。代码如下：

class ComboboxStyle(QProxyStyle):
    def subControlRect(self, control, option, subcontrol, widget=None):
        rect = super(ComboboxStyle, self).subControlRect(control, option, subcontrol, widget)
        if subcontrol == QStyle.SC_ComboBoxEditField:
            rect.adjust(3, 3, -3, -3)
        return rect

    def drawComplexControl(self, control, option, painter, widget=None):
        if control == QStyle.CC_ComboBox and option.currentIcon.isNull():
            comboRect = option.rect.adjusted(2, 2, -20, -2)
            arrowRect = QRect(option.rect.right() - 20, option.rect.top() + 2, 20, option.rect.height() - 4)
            fieldRect = QRect(comboRect.right() + 1, comboRect.top(), arrowRect.left() - comboRect.right() - 1, comboRect.height())

            pen = painter.pen()
            pen.setWidth(1)
            painter.setPen(pen)
            painter.drawRoundedRect(comboRect, 3, 1)
            painter.drawRoundedRect(fieldRect, 3, 1)
            painter.drawPolygon(QPoint(arrowRect.left() + 6, arrowRect.top() + 10),
                                QPoint(arrowRect.right() - 10, arrowRect.top() + 10),
                                QPoint(arrowRect.left() + 13, arrowRect.top() + 17))

            option_copy = QStyleOptionComboBox(option)
            option_copy.rect = fieldRect
            super(ComboboxStyle, self).drawComplexControl(control, option_copy, painter, widget)

这里自定义的ComboboxStyle类继承自QProxyStyle类，成为QComboBox的代理类，可以使用proxy()函数将其应用到QComboBox上。

subControlRect()函数是一个Qt中的虚函数，用于设定组件的边框。在这里，通过对QStyle的SC_ComboBoxEditField子控件的rect进行调整，来添加QComboBox的边框。

drawComplexControl()函数是用于绘制复杂控件，包括组合框、下拉框等。在这里，通过获取COMBOBOX字段的当前状态，来绘制框架、箭头和文本部分。

Step 3: 设置代理

最后，使用该代理类将样式应用于QComboBox上，代码如下：

combo = QComboBox()
combo.setEditable(True)
combo.lineEdit().setReadOnly(True)
combo.setItemDelegate(QStyledItemDelegate())
combo.setFixedHeight(30)
combo.setFixedWidth(150)
combo.currentIndexChanged.connect(lambda: print(combo.currentText()))

combo.setStyle(ComboboxStyle())

在这里，combo.setEditable(True)设置QComboBox的文本框为可编辑状态，combo.lineEdit().setReadOnly(True)设置为不可编辑状态，combo.setItemDelegate(QStyledItemDelegate())设置QComboBox的ItemDelegate为空，combo.setFixedHeight(30)设置高度为30，combo.setFixedWidth(150)设置宽度为150，combo.currentIndexChanged.connect(lambda: print(combo.currentText()))设置响应combo的值改变事件。

最后一行combo.setStyle(ComboboxStyle())将自定义的ComboboxStyle样式代理设置到QComboBox上。

示例1：自定义的ComboboxStyle应用到QComboBox上

from PyQt5.QtWidgets import QApplication, QWidget, QVBoxLayout, QComboBox, QStyleOptionComboBox, QProxyStyle, QStyledItemDelegate
from PyQt5.QtCore import QSize, QRect, QPoint
import sys

class ComboboxStyle(QProxyStyle):
    def subControlRect(self, control, option, subcontrol, widget=None):
        rect = super(ComboboxStyle, self).subControlRect(control, option, subcontrol, widget)
        if subcontrol == QStyle.SC_ComboBoxEditField:
            rect.adjust(3, 3, -3, -3)
        return rect

    def drawComplexControl(self, control, option, painter, widget=None):
        if control == QStyle.CC_ComboBox and option.currentIcon.isNull():
            comboRect = option.rect.adjusted(2, 2, -20, -2)
            arrowRect = QRect(option.rect.right() - 20, option.rect.top() + 2, 20, option.rect.height() - 4)
            fieldRect = QRect(comboRect.right() + 1, comboRect.top(), arrowRect.left() - comboRect.right() - 1, comboRect.height())

            pen = painter.pen()
            pen.setWidth(1)
            painter.setPen(pen)
            painter.drawRoundedRect(comboRect, 3, 1)
            painter.drawRoundedRect(fieldRect, 3, 1)
            painter.drawPolygon(QPoint(arrowRect.left() + 6, arrowRect.top() + 10),
                                QPoint(arrowRect.right() - 10, arrowRect.top() + 10),
                                QPoint(arrowRect.left() + 13, arrowRect.top() + 17))

            option_copy = QStyleOptionComboBox(option)
            option_copy.rect = fieldRect
            super(ComboboxStyle, self).drawComplexControl(control, option_copy, painter, widget)

app = QApplication(sys.argv)
widget = QWidget()
layout = QVBoxLayout(widget)

combo = QComboBox()
combo.setEditable(True)
combo.lineEdit().setReadOnly(True)
combo.setItemDelegate(QStyledItemDelegate())
combo.setFixedHeight(30)
combo.setFixedWidth(150)
combo.currentIndexChanged.connect(lambda: print(combo.currentText()))

combo.setStyle(ComboboxStyle())

layout.addWidget(combo)
widget.show()
sys.exit(app.exec_())

示例2：自定义的ComboboxStyle应用到多个QComboBox上

from PyQt5.QtWidgets import QApplication, QWidget, QVBoxLayout, QComboBox, QStyleOptionComboBox, QProxyStyle, QStyledItemDelegate
from PyQt5.QtCore import QSize, QRect, QPoint
import sys

class ComboboxStyle(QProxyStyle):
    def subControlRect(self, control, option, subcontrol, widget=None):
        rect = super(ComboboxStyle, self).subControlRect(control, option, subcontrol, widget)
        if subcontrol == QStyle.SC_ComboBoxEditField:
            rect.adjust(3, 3, -3, -3)
        return rect

    def drawComplexControl(self, control, option, painter, widget=None):
        if control == QStyle.CC_ComboBox and option.currentIcon.isNull():
            comboRect = option.rect.adjusted(2, 2, -20, -2)
            arrowRect = QRect(option.rect.right() - 20, option.rect.top() + 2, 20, option.rect.height() - 4)
            fieldRect = QRect(comboRect.right() + 1, comboRect.top(), arrowRect.left() - comboRect.right() - 1, comboRect.height())

            pen = painter.pen()
            pen.setWidth(1)
            painter.setPen(pen)
            painter.drawRoundedRect(comboRect, 3, 1)
            painter.drawRoundedRect(fieldRect, 3, 1)
            painter.drawPolygon(QPoint(arrowRect.left() + 6, arrowRect.top() + 10),
                                QPoint(arrowRect.right() - 10, arrowRect.top() + 10),
                                QPoint(arrowRect.left() + 13, arrowRect.top() + 17))

            option_copy = QStyleOptionComboBox(option)
            option_copy.rect = fieldRect
            super(ComboboxStyle, self).drawComplexControl(control, option_copy, painter, widget)

app = QApplication(sys.argv)
widget = QWidget()
layout = QVBoxLayout(widget)

combo1 = QComboBox()
combo1.setEditable(True)
combo1.lineEdit().setReadOnly(True)
combo1.setItemDelegate(QStyledItemDelegate())
combo1.setFixedHeight(30)
combo1.setFixedWidth(150)
combo1.currentIndexChanged.connect(lambda: print(combo1.currentText()))

combo2 = QComboBox()
combo2.setEditable(True)
combo2.lineEdit().setReadOnly(True)
combo2.setItemDelegate(QStyledItemDelegate())
combo2.setFixedHeight(30)
combo2.setFixedWidth(150)
combo2.currentIndexChanged.connect(lambda: print(combo2.currentText()))

ComboboxStyleInstance = ComboboxStyle()
combo1.setStyle(ComboboxStyleInstance)
combo2.setStyle(ComboboxStyleInstance)

layout.addWidget(combo1)
layout.addWidget(combo2)
widget.show()
sys.exit(app.exec_())

以上就是在PyQt5中为不可编辑的组合框的行编辑部分添加边框的完整使用攻略。