qt loading

#ifndef LOADING_H
#define LOADING_H

#include <QWidget>
#include <QPainter>
#include <QTimer>
#include <QMap>

struct Location
{
public:
    explicit Location(float _x,float _y){x=_x;y=_y;}
    float x;
    float y;
};

class Loading : public QWidget
{
    Q_OBJECT
public:
    explicit Loading(QWidget *parent = nullptr);
    //设置圆点个数
    void setDotCount(int);
    //设置点颜色
    void setDotColor(const QColor&);
    //开始
    void start();
    //设置圆点最大直径
    void setMaxDiameter(float);
    //设置圆点最小直径
    void setMinDiameter(float);

private:
    //刷新计数
    int _index;
    //点的颜色
    QColor _dotColor;
    //点的个数
    int _count;
    //圆点最小直径
    float _minDiameter;
    //圆点最大直径
    float _maxDiameter;
    //绘制圆点
    void paintDot(QPainter &);
    //计数
    int _i;
    //时间间隔 单位：毫秒(ms)
    int _interval;
    //定时器
    QTimer timer;
    //绘制区域边长
    float _squareWidth;
    //圆的直径
    float _centerDistance;
    //直径列表
    QList<float> radiiList;
    //圆点坐标列表
    QList<Location> locationList;

    //计算
    void caculate();

protected:
    void paintEvent(QPaintEvent *event);
    void resizeEvent(QResizeEvent *event);
signals:

public slots:

private slots:
    void refresh();
};

#endif // LOADING_H

#include "Loading.h"
#include "qmath.h"
#include <QDebug>

Loading::Loading(QWidget *parent) : QWidget(parent),_i(0),_interval(50),_index(0)
{
    //设置背景透明
    //this->setWindowFlags(Qt::FramelessWindowHint | Qt::WindowSystemMenuHint | Qt::WindowMinMaxButtonsHint);
    //this->setAttribute(Qt::WA_TranslucentBackground, true);

    setDotColor(QColor(49, 177, 190));
    setDotCount(20);
    connect(&timer,&QTimer::timeout,this,&Loading::refresh);
    setMaxDiameter(30);
    setMinDiameter(5);
}

//********************************************** 设置部分 *************************************
//设置点的个数
void Loading::setDotCount(int count)
{
    _count=count;
}

//设置点的颜色
void Loading::setDotColor(const QColor & color)
{
    _dotColor=color;
}

//开始动画
void Loading::start()
{
    timer.setInterval(_interval);
    timer.start();
}

//设置最大直径
void Loading::setMaxDiameter(float max)
{
    _maxDiameter=max;
}

//设置最小直径
void Loading::setMinDiameter(float min)
{
    _minDiameter=min;
}
//********************************************** 绘制部分 *************************************
//刷新界面
void Loading::refresh()
{
    repaint();
}

void Loading::resizeEvent(QResizeEvent *event)
{
    Q_UNUSED(event)
    caculate();
}

void Loading::paintEvent(QPaintEvent *event)
{
    Q_UNUSED(event)
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing);

    painter.setPen(_dotColor);
    painter.setBrush(_dotColor);

    //绘制点
    paintDot(painter);
}

//计算绘制正方形区域
void Loading::caculate()
{
    _squareWidth=qMin(this->width(),this->height());
    float half=_squareWidth/2;
    _centerDistance=half-_maxDiameter/2-1;

    float gap=(_maxDiameter-_minDiameter)/(_count-1)/2;
    float angleGap=(float)360/_count;

    locationList.clear();
    radiiList.clear();

    for(int i=0;i<_count;i++)
    {
        radiiList<<_maxDiameter/2-i*gap;
        float radian=qDegreesToRadians(-angleGap*i);
        locationList.append(Location(half+_centerDistance*qCos(radian),half-_centerDistance*qSin(radian)));
    }
}

//绘制圆点
void Loading::paintDot(QPainter& painter)
{
    for(int i=0;i<_count;i++)
    {
        painter.setPen(_dotColor);
        //半径
        float radii=radiiList.at((_index+_count-i)%_count);

        //绘制圆点
        painter.drawEllipse(QPointF(locationList.at(i).x,locationList.at(i).y),radii,radii);
        //绘制正方形
        //painter.drawRect(locationList.at(i).x,locationList.at(i).y,radii,radii);
        //绘制文字
        //QFont font("Microsoft YaHei",radii*1.2,75);
        //painter.setFont(font);
        //painter.drawText(QPointF(locationList.at(i).x,locationList.at(i).y),u8"霞");
    }
    _index++;
}

    Loading* loading1;

    //********************** Loading *************************
    loading1=new Loading(this);
    loading1->start();
    ui->gridLayout_2->addWidget(loading1,0,0);