#ifndef WHIRLBUTTON_H
#define WHIRLBTUUON_H#include <QColor>
#include <QImage>
#include <QWidget>#define whirlbuttonHeigth   130
#define whirlbuttonWidth    120class whirlbutton : public QWidget
{Q_OBJECT
public:void  paintEvent(QPaintEvent *event);whirlbutton();~whirlbutton();void setDegree(int deg);int getDegree();signals:void updateDegree();
protected:void mousePressEvent(QMouseEvent *event);void mouseMoveEvent(QMouseEvent *event);void mouseReleaseEvent(QMouseEvent *event);void mouseToPosion(QMouseEvent *event);QSize sizeHint() const;QSize minimumSizeHint() const;
private:int degree;};#endif

#include "whirlbutton.h"
#include <QPainter>
#include <QMouseEvent>
#include <math.h>whirlbutton::whirlbutton()
{//   setMouseTracking(true);
    setSizePolicy(QSizePolicy::Minimum,QSizePolicy::Minimum);degree = 90;
}whirlbutton::~ whirlbutton()
{
}void whirlbutton::setDegree(int deg)
{this->degree = deg;this->update();
}
void whirlbutton::paintEvent(QPaintEvent *event)
{QPainter painter(this);QTransform tranform1;int originY = whirlbuttonHeigth/2;int originX = whirlbuttonWidth/2;const int triangle[3][2] ={{ originX-2, 0 },{ originX+2, 0 },{ originX, 7 }};painter.setPen(QPen(Qt::red));//painter.setBrush(palette().foreground());
    painter.setBrush(QBrush(Qt::red));//draw polygon,triangle.painter.drawPolygon(QPolygon(3, &triangle[0][0]));//   painter.setWindow(0,0,150,150);
    tranform1.translate(originX,originY);tranform1.rotate(degree);tranform1.translate(-(originX),-(originY));painter.setWorldTransform(tranform1);QPen thickPen(palette().foreground(), 1.5);QPen midPen(palette().foreground(), 1.0);QPen thinPen(palette().foreground(), 0.5);QColor niceBlue(150, 150, 200);painter.setPen(thinPen);//gradually change with degreeQConicalGradient coneGradient(originX, originY, -90.0);coneGradient.setColorAt(0.0, Qt::darkGray);coneGradient.setColorAt(0.2, niceBlue);coneGradient.setColorAt(1.0, Qt::white);coneGradient.setColorAt(1.0, Qt::darkGray);unsigned r = 56;painter.setBrush(coneGradient);painter.drawEllipse((originX-r), (originY-r), r*2, r*2);r = 24;QRadialGradient haloGradient(originX, originY, r, originX, originY);haloGradient.setColorAt(0.0, Qt::lightGray);haloGradient.setColorAt(0.8, Qt::darkGray);haloGradient.setColorAt(0.9, Qt::white);haloGradient.setColorAt(1.0, Qt::black);painter.setPen(Qt::NoPen);painter.setBrush(haloGradient);painter.drawEllipse(originX-r, originY-r, r*2, 2*r);unsigned rx = 30,ry = 8;QLinearGradient knobGradient(originX-rx, originY-ry,originX-rx, originY+ry);knobGradient.setColorAt(0.0, Qt::black);knobGradient.setColorAt(0.2, niceBlue);knobGradient.setColorAt(0.3, Qt::lightGray);knobGradient.setColorAt(0.8, Qt::white);knobGradient.setColorAt(1.0, Qt::black);painter.setBrush(knobGradient);painter.setPen(thinPen);painter.drawRoundRect(originX-rx,originY-ry, rx*2, ry*2, 49, 99);for (int i = 0; i < 36; ++i){if (i%6){painter.setPen(midPen);painter.drawLine(5,originY, 10,originY);}else{painter.setPen(thickPen);painter.drawLine(5,originY, 13,originY);tranform1.translate(25,originY);tranform1.rotate(-90);tranform1.translate(-25,-originY);painter.setWorldTransform(tranform1);painter.drawText(22, originY,QString::number(i/6));tranform1.translate(25,originY);tranform1.rotate(90);tranform1.translate(-25,-originY);painter.setWorldTransform(tranform1);}tranform1.translate(originX,originY);tranform1.rotate(-10);tranform1.translate(-originX,-originY);painter.setWorldTransform(tranform1);}
}
QSize whirlbutton::sizeHint() const
{QSize size = QSize(whirlbuttonHeigth,whirlbuttonWidth);return size;
}
QSize whirlbutton::minimumSizeHint() const
{QSize size = QSize(whirlbuttonHeigth,whirlbuttonWidth);return size;
}
void whirlbutton::mousePressEvent(QMouseEvent *event)
{mouseToPosion(event);this->update();
}
int whirlbutton :: getDegree()
{return(degree);
}
void whirlbutton::mouseMoveEvent(QMouseEvent * event)
{mouseToPosion(event);this->update();
}
void whirlbutton::mouseReleaseEvent(QMouseEvent * event)
{mouseToPosion(event);this->updateDegree();
}
void whirlbutton:: mouseToPosion(QMouseEvent * event)
{QPoint currentPoint = event->pos();double pi = 3.1415927;double  x = currentPoint.x() - whirlbuttonHeigth/2;double  y = currentPoint.y() - whirlbuttonWidth/2;if((x ==0)&&(y<=0))degree = 90;else if((x==0)&&(y<0))degree = 270;else if(x>0)degree = atan(y/x)*180/pi + 180;else if(y>0)degree = atan(y/x)*180/pi + 360;elsedegree = atan(y/x)*180/pi;
}