31.QPainter-rotate()函数分析-文字旋转不倾斜,图片旋转实现等待

void QPainter::drawPixmap ( int x, int y, int w, int h, 
   const QPixmap & pixmap, int sx, int sy, int sw, int sh );
    //绘画pixmap
    // x y w h:表示本身的绘画面积
    //sx sy sw sh:表示pixmap的绘画面积
  

void QPainter::drawPixmap ( int x, int y, const QPixmap & pixmap, int sx, int sy, int sw, int sh  );
    //绘画pixmap
    // x y 表示绘画起始位置
    //sx sy sw sh:表示pixmap的绘画面积

drawTiledPixmap ( int x, int y, int width, int height, const QPixmap & pixmap, 
int sx = 0, int sy = 0 )；
        //平铺pixmap

void QPainter::translate ( qreal dx, qreal dy );
        //将坐标(dx,dy)设置显示原点

void  scale ( qreal sx, qreal sy )
       //设置图片缩放,sx(横坐标放大系数),sy(纵坐标放大系数)

void  rotate ( qreal angle );  //旋转绘画区域(比如斜文本),angle=90,则表示90度
        //以时针方向旋转(顺时针)

   QPainter painter(this);

    for(int i=0;i<10;i++)
     {
        painter.save();
        painter.rotate(i*10);
        painter.drawText(100,100,"123");
        painter.restore();
    }

    static int rotate = 0;
    QPainter painter(this);

    painter.setRenderHint(QPainter::Antialiasing,true);

    painter.translate(width()/2,height()/2);

    painter.drawRect(-2,-2,4,4);

    painter.setFont(QFont(0,11));

    for(int i=0;i<10;i++)
    {
        painter.save();

        painter.rotate(i*36);

        painter.drawText(100,0,20,20,Qt::AlignCenter,QString("%1").arg(i));

        painter.restore();
}

/*  point: 文字所在的点
 *  from_angle : 文字所在的度数
 *  rotate : 需要旋转的角度,值为-360~360(为负数表示逆时针旋转,为正数表示顺时针旋转)
 */
QPoint Widget::CustomRotate(QPointF point,qreal from_angle,qreal rotate)
{
    qreal PI=3.141592653589;
    QPointF Tmp; 
    qreal arc = (rotate-from_angle)/180*PI;
    qreal Length = qSqrt(point.x()*point.x() +point.y()*point.y());
    Tmp.setX(Length*qCos(arc));
    Tmp.setY(Length*qSin(arc));
    return Tmp.toPoint();
}
void Widget::paintEvent(QPaintEvent *)
{
    int angle = 0;
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing,true);
    painter.translate(width()/2,height()/2);
    painter.drawRect(-2,-2,4,4);
    painter.setFont(QFont(0,11));
    QPoint point(100,0);        //从(100,0)开始填文字

    for(int i=0;i<10;i++)
    {
       painter.drawText(point.x()-10,point.y()-10,20,20,Qt::AlignCenter,QString("%1").arg(i));
       point=CustomRotate(point,angle, 36);         //以当前angle度,顺时针旋转36度
       angle -=36;                                  //更新度数,由于顺时针,所以用减
    }  
}

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    m_rotate(false)
{
    resize(300,300);
    connect(&timer,SIGNAL(timeout()),this,SLOT(timerout()));
    timer.start(40);
}

void Widget::timerout()
{
    m_rotate =true;
    update();
}

void Widget::paintEvent(QPaintEvent *)
{
    static int rotate = 0;
    QPainter painter(this);
    painter.setRenderHint(QPainter::Antialiasing,true);
    painter.translate(width()/2,height()/2);

    if(m_rotate)
    {
       rotate = (rotate+5)%360;
       m_rotate =false;
    }

 
    painter.rotate(rotate);
    QPixmap pix(":wait"); 
    painter.drawPixmap(-pix.width()/2,-pix.height()/2,pix);
}