一.效果

二.实现

roller.h

#ifndef ROLLER_H
#define ROLLER_H

#include <QWidget>
#include <QPaintEvent>
#include <QShowEvent>
#include <QHideEvent>
#include <QTimer>

class Roller : public QWidget
{
public:
    explicit Roller(QWidget *parent = nullptr);

    void setText(const QString &text);

protected:
    QSize sizeHint() const override;
    void paintEvent(QPaintEvent* event) override;
    void showEvent(QShowEvent* event) override;
    void hideEvent(QHideEvent* event) override;

private:
    QString m_text;
    int m_offset;
    QTimer m_timer;
};

#endif // ROLLER_H

roller.cpp

#include "roller.h"

#include <QPainter>
#include <QFontMetrics>

Roller::Roller(QW