【Qt】paintEvent实现动画旋转

头文件：

#ifndef CIRCLEWIDGET_H
#define CIRCLEWIDGET_H
 
#include <QWidget>
 
class QTimer;
 
class CircleWidget : public QWidget
{
    Q_OBJECT
public:
    explicit CircleWidget(QWidget *parent = 0);
 
    void startCircle();
 
protected:
    void paintEvent(QPaintEvent *e);
 
private slots:
    void onTimeout();
 
private:
    QImage m_bg;
    QTimer *m_pCircleTimer = Q_NULLPTR;
    int m_nCirleCount = 0;
    bool m_bCircle = false;
    int m_nAngle = 0;
 
};
 
#endif // CIRCLEWIDGET_H

cpp文件：

#include "circlewidget.h"
 
#include <QPainter>
#include <QTimer>
 
CircleWidget::CircleWidget(QWidget *parent):
    QWidget(parent)
{
    m_bg = QImage(":/skin/btn_Reconnecting.png");
 
    m_pCircleTimer = new QTimer(this);
    m_pCircleTimer->setInterval(50);
    connect(m_pCircleTimer, &QTimer::timeout, this, &CircleWidget::onTimeout);
}
 
void CircleWidget::startCircle()
{
    m_pCircleTimer->start();
    m_bCircle = true;
}
 
void CircleWidget::paintEvent(QPaintEvent *e)
{
    QPainter painter(this);
    painter.setPen(Qt::NoPen);
    painter.setBrush(Qt::NoBrush);
    painter.setRenderHint(QPainter::SmoothPixmapTransform);
 
    if(m_bCircle)
    {
        painter.translate(this->width() / 2, this->height() / 2);          //设置旋转中心
        painter.rotate(m_nAngle);          //旋转
        painter.translate(-(this->width() / 2), -(this->height() / 2));        //将原点复位
    }
    painter.drawImage(this->rect(), m_bg);
 
    QWidget::paintEvent(e);
}
 
void CircleWidget::onTimeout()
{
    ++m_nCirleCount;
    if(m_nAngle == 360)
    {
        m_nAngle = 0;
    }
    m_nAngle += 10;
 
    if(m_nCirleCount == 600)
    {
        m_pCircleTimer->stop();
        m_bCircle = false;
        m_nCirleCount = 0;
    }
    update();
}