qt开发：QWidget中有一个QLabel，当鼠标点击到QLabel的区域内时，QLabel显示，当鼠标点击QLabel区域外时，QLabel隐藏

代码：

MyWidget.h

#include 
#include 
#include 

class MyWidget : public QWidget
{
    Q_OBJECT

public:
    MyWidget(QWidget *parent = nullptr);
    ~MyWidget();
    
protected:
    bool eventFilter(QObject *obj, QEvent *event) override;

private:
    Ui::MyWidget *ui;
    QLabel* m_label;
};

MyWidget.cpp
MyWidget::MyWidget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::MyWidget)
{
	m_label = new QLabel("this is a label.",this);
	m_label->setGeometry(100, 100, 200, 200);
	m_label->setStyleSheet("background: red;");
    QApplication::instance()->installEventFilter(this);
}

bool MyWidget::eventFilter(QObject *obj, QEvent *event)
{
if (event->type() == QEvent::MouseButtonPress && ((QMouseEvent*)event)->button() == Qt::LeftButton)
    {
        if(m_label != nullptr)
        {
            if(m_label->underMouse())//判断鼠标是否在m_label控件上
            {
                m_label->show();
            }
            else
            {
                m_label->hide();
            }
        }
    }
    return QObject::eventFilter(obj, event);
}

效果

QQ录屏20230825171229