qt 绘制表盘

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#include "widget.h"
#include "ui_widget.h"
#include <QPainter>

Widget::Widget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::Widget)
{
    ui->setupUi(this);

    ui->horizontalSlider->setMaximum(300);
    ui->horizontalSlider->setMinimum(0);
    connect(ui->horizontalSlider,SIGNAL(valueChanged(int)),this,SLOT(hSliderValueChangedSlot(int)));
}

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



void Widget::paintEvent(QPaintEvent *event)
{
    double R = this->width()/3;
    double r = this->width()/3;
    QPainter p(this);
    p.translate(this->width()/2, this->height()/2);
    p.setBrush(brush);
    p.drawPixmap(-R,-R, 2*R,2*R,QPixmap(":/rs/Pan.png"));
    p.rodate(120);

     p.rotate(   ui->horizontalSlider->value()    );//旋转
     p.drawPixmap(-20,-25,r/1.2,r/6,QPixmap(":/rs/Point.png"));



}
void Widget::hSliderValueChangedSlot(int)
{
    update();// 要求重绘
}

运行结果