如何消除QBoxLayout（TopToBottom）中组件间的间距

我用PyQt5创建了一个QBoxLayout.TopToBottom方向的QBoxLayout，想完全消除组件之间的间距，但试过QBoxLayout.setSpacing(0)、QBoxLayout.setContentsMargins(0,0,0,0)，甚至自定义QBoxLayout类在初始化时设置这两个属性，都没解决问题。下方组件是QProgressBar。

附上代码 #

自定义布局类代码：

class LearnLeftPanelQBox(QBoxLayout):
        def __init__(self):
            super().__init__(QBoxLayout.TopToBottom)
            self.setContentsMargins(0,0,0,0)
            self.setSpacing(0)

self.learnLeftPanelTitle=QLabel("Correct:")
            self.learnLeftPanelTopLayout.addWidget(self.learnLeftPanelTitle)
            self.learnLeftPanelTitle.setStyleSheet("font: 20pt Comic Sans MS; color: white;")
            self.learnLeftPanelTopLayout.addWidget(self.learnLeftPanelTitle)
            self.learnLeftPanelProgressCorrect=QProgressBar()
            self.learnLeftPanelProgressCorrect.setStyleSheet("font: 20pt Comic Sans MS; color: green;")
            self.learnLeftPanelTopLayout.addWidget(self.learnLeftPanelProgressCorrect)
            self.learnLeftPanelTitle=QLabel("Incorrect:")
            self.learnLeftPanelTopLayout.addWidget(self.learnLeftPanelTitle)
            self.learnLeftPanelTitle.setStyleSheet("font: 20pt Comic Sans MS; color: white;")
            self.learnLeftPanelProgressIncorrect=QProgressBar()
            self.learnLeftPanelProgressIncorrect.setStyleSheet("font: 20pt Comic Sans MS; color: red;")
            self.learnLeftPanelTopLayout.addWidget(self.learnLeftPanelProgressIncorrect)
            self.learnLeftPanelLayout.addWidget(self.learnLeftPanelTop)
            self.learnLeftPanelSettingsButton=QPushButton("Settings")
            self.learnLeftPanelSettingsButton.setStyleSheet("QPushButton{font: 20pt Comic Sans MS; color: white;border-style: outset; border-width: 2px; border-radius: 10px;border-color:white;} QPushButton::hover{background-color: white; color: black;}")
            self.learnLeftPanelSettingsButton.clicked.connect(self._showLearnSettings)
            self.learnLeftPanelLayout.addWidget(self.learnLeftPanelSettingsButton)

注：代码缩进格式存在问题，但不影响逻辑，代码位于独立函数中，其余部分无关。

可复现代码：

# Purpose: Stack layout example
from PyQt5.QtWidgets import QWidget, QLabel,QProgressBar,QApplication,QBoxLayout
class main(QWidget):
    def __init__(self) -> None:
        super().__init__()
        self.showFullScreen()
        layout=QBoxLayout(QBoxLayout.TopToBottom)
        layout.setContentsMargins(0,0,0,0)
        firstLabel=QLabel("First Label")
        firstBar=QProgressBar()
        secondLabel=QLabel("Second Label")
        secondBar=QProgressBar()
        layout.addWidget(firstLabel)
        layout.addWidget(firstBar)
        layout.addWidget(secondLabel)
        layout.addWidget(secondBar)
        self.setLayout(layout)
if __name__=="__main__":
    import sys
    app = QApplication(sys.argv)
    win = main()
    win.show()
    sys.exit(app.exec_())

解决办法 #

问题不在布局本身，而是QLabel和QProgressBar组件自身带有默认的边距（margin）和内边距（padding），导致看起来有间距。需要给这些组件设置样式表，强制清除边距和内边距：

• 给QLabel添加样式：margin:0; padding:0;
• 给QProgressBar添加样式：margin:0; padding:0;，同时可以调整其内容区域的边距（如果需要）。

修改后的可复现代码示例：

# Purpose: Stack layout example
from PyQt5.QtWidgets import QWidget, QLabel,QProgressBar,QApplication,QBoxLayout
class main(QWidget):
    def __init__(self) -> None:
        super().__init__()
        self.showFullScreen()
        layout=QBoxLayout(QBoxLayout.TopToBottom)
        layout.setContentsMargins(0,0,0,0)
        layout.setSpacing(0)  # 补充设置spacing为0

        firstLabel=QLabel("First Label")
        firstLabel.setStyleSheet("margin:0; padding:0;")  # 清除标签边距
        firstBar=QProgressBar()
        firstBar.setStyleSheet("margin:0; padding:0;")  # 清除进度条边距
        secondLabel=QLabel("Second Label")
        secondLabel.setStyleSheet("margin:0; padding:0;")
        secondBar=QProgressBar()
        secondBar.setStyleSheet("margin:0; padding:0;")

        layout.addWidget(firstLabel)
        layout.addWidget(firstBar)
        layout.addWidget(secondLabel)
        layout.addWidget(secondBar)
        self.setLayout(layout)
if __name__=="__main__":
    import sys
    app = QApplication(sys.argv)
    win = main()
    win.show()
    sys.exit(app.exec_())

另外，如果你使用了自定义样式，需要把margin:0; padding:0;合并到已有的样式表中，比如你的自定义代码里的QLabel样式可以改成：

font: 20pt Comic Sans MS; color: white; margin:0; padding:0;

这样就能完全消除组件之间的额外间距了。

内容的提问来源于stack exchange，提问作者user19926715