PyQt5 – 从未选中的复选框为已按下的指示器设置背景图片

要实现从未选中的复选框为已按下的指示器设置背景图片，需要使用PyQt5中的QSS（Qt Style Sheet）来设置样式。以下是详细的使用攻略：

1. 导入必要的依赖项

from PyQt5.QtCore import Qt
from PyQt5.QtGui import QPixmap
from PyQt5.QtWidgets import QCheckBox, QApplication

1. 创建自定义复选框类

class CustomCheckBox(QCheckBox):
    def __init__(self):
        super().__init__()

        # 设置复选框的默认样式
        self.setStyleSheet("QCheckBox::indicator {width: 20px; height: 20px;}");

1. 重写paintEvent方法

def paintEvent(self, event):
    # 绘制复选框指示器的背景
    if self.isChecked():
        bg_image = QPixmap('checked.png')
    else:
        bg_image = QPixmap('unchecked.png')

    painter = QPainter(self)
    painter.drawPixmap(0, 0, bg_image.width(), bg_image.height(), bg_image)

    # 使用默认的绘制方法
    super().paintEvent(event)

1. 设置样式表

app = QApplication(sys.argv)
checkbox = CustomCheckBox()
checkbox.setStyleSheet(
    "QCheckBox::indicator:checked {background-color: transparent;}"
    "QCheckBox::indicator:unchecked {background-color: transparent;}"
)

在这里，我们使用了两个样式表来覆盖复选框指示器的背景为透明，否则会和背景图片冲突。

接下来是两个示例说明：

示例1：用PyQt5设置具有背景图片的复选框

app = QApplication(sys.argv)

checkbox = CustomCheckBox()
checkbox.setGeometry(50, 50, 100, 100)
checkbox.show()

app.setStyleSheet(
    "QCheckBox::indicator:checked {background-color: transparent;}"
    "QCheckBox::indicator:unchecked {background-color: transparent;}"
)

sys.exit(app.exec_())

示例2：用PyQt5为复选框应用动画

app = QApplication(sys.argv)

checkbox = CustomCheckBox()
checkbox.setGeometry(50, 50, 100, 100)
checkbox.show()

app.setStyleSheet(
    "QCheckBox::indicator:checked {background-color: transparent;}"
    "QCheckBox::indicator:unchecked {background-color: transparent;}"
    "QCheckBox::indicator:checked {"
    "   border: 0px solid #2f9e99;"
    "   border-radius: 10px;"
    "   background-color: #2f9e99;"
    "   width: 20px;"
    "   height: 20px;"
    "}"
    "QCheckBox::indicator:checked:pressed {"
    "   background-color: #19ad9d;"
    "   border: 1px solid #19ad9d;"
    "}"
    "QCheckBox::indicator:hover {"
    "   border: 2px solid #19ad9d;"
    "}"
)

animation1 = QPropertyAnimation(checkbox, b"geometry")
animation1.setDuration(500)
animation1.setStartValue(QRect(50, 50, 100, 100))
animation1.setEndValue(QRect(150, 50, 100, 100))
animation1.setEasingCurve(QEasingCurve.OutQuad)

animation2 = QPropertyAnimation(checkbox, b"geometry")
animation2.setDuration(500)
animation2.setStartValue(QRect(150, 50, 100, 100))
animation2.setEndValue(QRect(50, 50, 100, 100))
animation2.setEasingCurve(QEasingCurve.InQuad)

animation_group = QSequentialAnimationGroup()
animation_group.addAnimation(animation1)
animation_group.addAnimation(animation2)
animation_group.setLoopCount(-1)
animation_group.start()

sys.exit(app.exec_())

此示例使用了QPropertyAnimation和QSequentialAnimationGroup来实现动画效果。