用qt4和c++实现QScrollArea实现鼠标滑动

可以使用Qt的事件过滤器来实现鼠标滑动。

首先，将QScrollArea设置为可滚动：

QScrollArea *scrollArea = new QScrollArea(this);
scrollArea->setWidgetResizable(true);

然后，在构造函数中安装事件过滤器：

scrollArea->viewport()->installEventFilter(this);

接下来，重写事件过滤器函数：

bool YourClassName::eventFilter(QObject *obj, QEvent *event)
{
    if (obj == scrollArea->viewport() && event->type() == QEvent::Wheel) {
        // 鼠标滚轮事件
        QWheelEvent *wheelEvent = static_cast<QWheelEvent*>(event);
        int delta = wheelEvent->delta();
        int scrollBarValue = scrollArea->verticalScrollBar()->value();
        scrollArea->verticalScrollBar()->setValue(scrollBarValue - delta);
        return true;
    }
    return false;
}

在这个事件过滤器函数中，我们捕获QScrollArea的视口（viewport）的鼠标滚轮事件，并获取滚动的距离delta，计算出当前滚动条的值，然后设置滚动条的值为当前值减去delta。

最后，在类的头文件中声明事件过滤器函数：

protected:
    bool eventFilter(QObject *obj, QEvent *event) override;

完整示例代码：

#include <QtWidgets>

class Widget : public QWidget
{
public:
    Widget(QWidget *parent = nullptr) : QWidget(parent)
    {
        QVBoxLayout *layout = new QVBoxLayout(this);
        QScrollArea *scrollArea = new QScrollArea(this);
        scrollArea->setWidgetResizable(true);

        QWidget *widget = new QWidget(scrollArea);
        QVBoxLayout *widgetLayout = new QVBoxLayout(widget);
        for (int i = 0; i < 100; ++i) {
            QLabel *label = new QLabel(QString("Label %1").arg(i + 1), widget);
            widgetLayout->addWidget(label);
        }
        widget->setLayout(widgetLayout);

        scrollArea->setWidget(widget);
        layout->addWidget(scrollArea);

        scrollArea->viewport()->installEventFilter(this);
    }

protected:
    bool eventFilter(QObject *obj, QEvent *event) override
    {
        QScrollArea *scrollArea = qobject_cast<QScrollArea*>(obj);
        if (scrollArea && event->type() == QEvent::Wheel) {
            QWheelEvent *wheelEvent = static_cast<QWheelEvent*>(event);
            int delta = wheelEvent->delta();
            int scrollBarValue = scrollArea->verticalScrollBar()->value();
            scrollArea->verticalScrollBar()->setValue(scrollBarValue - delta);
            return true;
        }
        return false;
    }
};

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    Widget w;
    w.show();
    return a.exec();
}