本文实例为大家分享了Qt实现圆圈加载进度条的具体代码，供大家参考，具体内容如下

先看效果图：

思路：画一个占270度的圆弧，然后定义一个定时器，定时旋转坐标系，实现旋转的效果。圆弧需要使用渐变色，实现颜色越来越浅的效果

关键代码：CMProcessBar1.cpp

CMProcessBar1::CMProcessBar1(QWidget *parent) :
  QWidget(parent),
  ui(new Ui::CMProcessBar1)
{
  ui->setupUi(this);
  QTimer *timer = new QTimer;
  connect(timer,QTimer::timeout,this,updaterRotation);// 定时旋转坐标系
  timer->start(3);//定时3毫秒
}

CMProcessBar1::~CMProcessBar1()
{
  delete ui;
}

void CMProcessBar1::updaterRotation(){ //循环360度旋转坐标系
  rotation++;
  if(rotation == 360){
    rotation = 0;
  }
  update();
}

void CMProcessBar1::paintEvent(QPaintEvent *event){//根据QPaintPath画出渐变色的圆弧
  int width = this->width();
  int height = this->height();
  int side = qMin(width, height);

  QPainter painter(this);
  painter.setRenderHints(QPainter::Antialiasing | QPainter::TextAntialiasing);
  painter.translate(width / 2, height / 2);
  painter.scale(side / 200.0, side / 200.0);

  QConicalGradient gra(QPoint(0,0),0);
  gra.setColorAt(0,QColor("#3BB6FE"));
  gra.setColorAt(1,QColor("#FFFFFF"));
  QBrush brush(gra);

  int radis = 40;
  int sider = 5;
  QRect rect(-radis,-radis,radis*2,radis*2);
  QPainterPath path;
  path.arcTo(rect,0, 270);

  QPainterPath subPath;
  subPath.addEllipse(rect.adjusted(sider, sider, -sider, -sider));

  path = path-subPath;
  painter.setBrush(brush);//QColor("#66CFFF")
  painter.setPen(Qt::NoPen);
  painter.rotate(rotation);
  painter.drawPath(path);


}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持IIS7站长之家。