PyQt5 – 复选框中未被选中的指标的背景颜色

介绍PyQt5中如何修改复选框中未被选中的指标的背景颜色，主要涉及到QProxyStyle和QStyleOptionViewItem两个类。步骤如下：

1.创建一个自定义类，继承自QProxyStyle，并且重写drawPrimitive方法：

from PyQt5.QtWidgets import QProxyStyle
from PyQt5.QtGui import QPainter, QColor, QPalette, QBrush, QPen
from PyQt5.QtCore import Qt

class CheckboxStyle(QProxyStyle):
    def drawPrimitive(self, element, option, painter, widget=None):
        if element == QStyle.PE_IndicatorCheckBox:
            checked = option.state & QStyle.State_On
            palette = option.palette
            if not checked and not option.state & QStyle.State_NoChange:
                new_palette = QPalette(palette)
                new_palette.setColor(QPalette.Window, QColor(255, 0, 0)) # 未选中时显示为红色
                option = QStyleOptionViewItem(option)
                option.palette = new_palette
        super().drawPrimitive(element, option, painter, widget)

2.创建QTreeView控件，并将它的样式设置为自定义类

from PyQt5.QtWidgets import QTreeView, QApplication
from PyQt5.QtGui import QStandardItemModel, QStandardItem

app = QApplication([])
treeview = QTreeView()

model = QStandardItemModel()
rootNode = model.invisibleRootItem()
node1 = QStandardItem("Node 1")
node2 = QStandardItem("Node 2")

rootNode.appendRow(node1)
rootNode.appendRow(node2)

treeview.setModel(model)
treeview.setStyle(CheckboxStyle()) # 设置样式

treeview.show()
app.exec_()

示例1：将复选框未选中时的背景颜色设置为红色

class RedCheckBoxStyle(QProxyStyle):
    def drawPrimitive(self, element, option, painter, widget=None):
        if element == QStyle.PE_IndicatorCheckBox:
            checked = option.state & QStyle.State_On
            palette = option.palette
            if not checked and not option.state & QStyle.State_NoChange:
                new_palette = QPalette(palette)
                new_palette.setColor(QPalette.Window, QColor(255, 0, 0)) # 未选中时显示为红色
                option = QStyleOptionViewItem(option)
                option.palette = new_palette
        super().drawPrimitive(element, option, painter, widget)

if __name__ == '__main__':
    app = QApplication([])
    treeview = QTreeView()

    model = QStandardItemModel()
    rootNode = model.invisibleRootItem()
    node1 = QStandardItem("Node 1")
    node2 = QStandardItem("Node 2")

    rootNode.appendRow(node1)
    rootNode.appendRow(node2)

    treeview.setModel(model)
    treeview.setStyle(RedCheckBoxStyle()) # 设置样式

    treeview.show()
    app.exec_()

示例2：将复选框未选中时的背景颜色设置为蓝色

class BlueCheckBoxStyle(QProxyStyle):
    def drawPrimitive(self, element, option, painter, widget=None):
        if element == QStyle.PE_IndicatorCheckBox:
            checked = option.state & QStyle.State_On
            palette = option.palette
            if not checked and not option.state & QStyle.State_NoChange:
                new_palette = QPalette(palette)
                new_palette.setColor(QPalette.Window, QColor(0, 0, 255)) # 未选中时显示为蓝色
                option = QStyleOptionViewItem(option)
                option.palette = new_palette
        super().drawPrimitive(element, option, painter, widget)

if __name__ == '__main__':
    app = QApplication([])
    treeview = QTreeView()

    model = QStandardItemModel()
    rootNode = model.invisibleRootItem()
    node1 = QStandardItem("Node 1")
    node2 = QStandardItem("Node 2")

    rootNode.appendRow(node1)
    rootNode.appendRow(node2)

    treeview.setModel(model)
    treeview.setStyle(BlueCheckBoxStyle()) # 设置样式

    treeview.show()
    app.exec_()