网上视频抄的，用来自己看一下，看完就删掉

ui

 mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
#include <QDebug>
#include <QtMath>
#include <QDialog>
#include <QPainter>
#include <QPaintEvent>
#include <QPainterPath>
#include <QRadialGradient>#include <QTimer>
#include <QKeyEvent>QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow
{Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();QTimer *myTimer;int radius;//仪表盘的中心位置int direction;//指针运动的方向,1为前进，0为后退protected:void paintEvent(QPaintEvent*);
private:int degRotate =0;private:void DrawPoint(QPainter&,int);void DrawDigital(QPainter&,int);void DrawCircle(QPainter&,int);void DrawSmallScale(QPainter&,int);void DrawBigScale(QPainter&,int);void DrawUnit(QPainter&,int);void DrawNum(QPainter&,int);void DrawPointer(QPainter&,int);void drawIndicator(QPainter *painter);void DrawCircle_line(QPainter& painter,int radius);void DrawCircle_bom(QPainter& painter,int radius);void DrawCircle_bom_big(QPainter& painter,int radius);void DrawCircle_bom_shine(QPainter& painter,int radius);void DrawCircle_bom_small(QPainter& painter,int radius);void DrawCircle_arc(QPainter& painter,int radius);void keyPressEvent(QKeyEvent *event);void keyReleaseEvent(QKeyEvent *event);private slots:void slot_speed_changed();private:Ui::MainWindow *ui;
};
#endif // MAINWINDOW_H

 mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"MainWindow::MainWindow(QWidget *parent): QMainWindow(parent), ui(new Ui::MainWindow)
{ui->setupUi(this);// setFixedSize() 函数是 QWidget 类的一个成员函数，用于设置窗口的固定大小。// 该函数接受两个参数，分别是窗口宽度和高度。// 设置后无法通过拖拽窗口的边缘来改变窗口大小，而且，即使添加的控件超出了窗口大小，也不会出现滚动条。setFixedSize(1280,800);//定时器动态增加时速myTimer = new QTimer(this);connect(myTimer,SIGNAL(timeout()),this,SLOT(slot_speed_changed()));}void MainWindow::paintEvent(QPaintEvent*)
{QPainter painter(this);int width=this->width();int height=this->height() - 100;//移动仪表盘的高度int radius=((width>height)?height:width)/2.0;//仪表盘的中心位置//移动画笔到中下方painter.translate(width/2,height*0.6);//启用反锯齿painter.setRenderHint(QPainter::Antialiasing, true);painter.setPen(Qt::NoPen);//设置画刷颜色painter.setBrush(QColor(138,43,226));DrawSmallScale(painter,radius-60);//刻度线DrawDigital(painter,radius-90);//刻度数字/*所有形状绘画*/// DrawCircle_bom(painter,radius-40);  //扇形大圆DrawCircle(painter,radius-35);      //渐变发光外扇形DrawCircle_arc(painter,radius - 40);//动态扇形环DrawPointer(painter,radius-130);//指针DrawCircle_line(painter,radius-35); //最外细圆线DrawCircle_bom_big(painter,radius-150);//中间大圆DrawCircle_bom_shine(painter,radius - 230);//渐变发光内圈DrawCircle_bom_small(painter,radius - 200);//中间小圆DrawUnit(painter,radius - 390);//单位DrawNum(painter,radius-300);//时速
}
//绘制外圈点
void MainWindow::DrawPoint(QPainter& painter,int radius)
{//组装点的路径图QPainterPath pointPath;pointPath.moveTo(-2,-2);pointPath.lineTo(2,-2);pointPath.lineTo(2,2);pointPath.lineTo(0,4);pointPath.lineTo(-2,2);//绘制13个小点for(int i=0;i<13;++i){QPointF point(0,0);painter.save();painter.setBrush(QColor(250,252,78));//计算并移动绘图对象中心点point.setX(radius*qCos(((210-i*20)*M_PI)/180));point.setY(radius*qSin(((210-i*20)*M_PI)/180));//计算并移动绘图对象的中心点painter.translate(point.x(),-point.y());//计算并选择绘图对象坐标painter.rotate(-120+i*20);//绘制路径painter.drawPath(pointPath);painter.restore();}
}//刻度数字
void MainWindow::DrawDigital(QPainter& painter,int radius)
{//设置画笔，画笔默认NOPENpainter.setPen(QColor(255,255,255));QFont font;font.setFamily("Arial");font.setPointSize(15);font.setBold(true);painter.setFont(font);for(int i=0;i<13;++i){QPointF point(0,0);painter.save();point.setX(radius*qCos(((210-i*20)*M_PI)/180));point.setY(radius*qSin(((210-i*20)*M_PI)/180));painter.translate(point.x(),-point.y());painter.rotate(-120+i*20);painter.drawText(-25, 0, 50, 20,Qt::AlignCenter,QString::number(i*20));painter.restore();}//还原画笔painter.setPen(Qt::NoPen);
}//扇形大圆
void MainWindow::DrawCircle_bom(QPainter& painter,int radius)
{//保存绘图对象painter.save();//计算大小圆路径QPainterPath outRing;outRing.moveTo(0,0);outRing.arcTo(-radius,-radius, 2*radius,2*radius,-30,240);outRing.closeSubpath();//设置画刷painter.setBrush(QColor(14,15,33));painter.drawPath(outRing);painter.restore();
}//渐变发光内圈
void  MainWindow::DrawCircle_bom_shine(QPainter& painter,int radius)
{painter.save();QRadialGradient radialGradient(0,0,radius,0,0);
//    radialGradient.setColorAt(0.5,QColor(8,77,197));radialGradient.setColorAt(0.5,QColor(10,68,185,150));radialGradient.setColorAt(1.0,Qt::transparent);painter.setBrush(QBrush(radialGradient));painter.drawRect(-radius,-radius,2*(radius),2*(radius));painter.restore();}//中间大圆
void  MainWindow::DrawCircle_bom_big(QPainter& painter,int radius)
{//保存绘图对象painter.save();//计算大小圆路径QPainterPath inRing;inRing.moveTo(0,0);inRing.addEllipse(-radius+50,-radius + 50,2*(radius-50),2*(radius-50));//设置画刷painter.setBrush(QColor(10,20,30));painter.drawPath(inRing);painter.restore();
}void  MainWindow::DrawCircle_bom_small(QPainter& painter,int radius)
{//保存绘图对象painter.save();//计算大小圆路径QPainterPath inRing;inRing.moveTo(0,0);inRing.addEllipse(-radius+50,-radius + 50,2*(radius-50),2*(radius-50));//设置画刷painter.setBrush(QColor(10,20,30));painter.drawPath(inRing);painter.restore();
}void MainWindow::DrawCircle_arc(QPainter& painter,int radius)
{QRect rect(-radius,-radius,2*radius,2*radius);QConicalGradient Conical(0,0,-70);Conical.setColorAt(0.1,QColor(255,88,127,200));//红色Conical.setColorAt(0.5,QColor(53,179,251,150));//蓝色painter.setBrush(Conical);painter.drawPie(rect,210*16,-(degRotate)*16);
}//渐变发光外扇形
void MainWindow::DrawCircle(QPainter& painter,int radius)
{//保存绘图对象painter.save();//计算大小圆路径QPainterPath outRing;QPainterPath inRing;outRing.moveTo(0,0);inRing.moveTo(0,0);outRing.arcTo(-radius,-radius, 2*radius,2*radius,-30,240);inRing.addEllipse(-radius+50,-radius + 50,2*(radius-50),2*(radius-50));outRing.closeSubpath();//设置渐变色kQRadialGradient radialGradient(0,0,radius,0,0);radialGradient.setColorAt(1,QColor(0,82,199));radialGradient.setColorAt(0.92,Qt::transparent);//设置画刷painter.setBrush(radialGradient);//大圆减小圆painter.drawPath(outRing.subtracted(inRing));painter.restore();
}//最外细圆线
void MainWindow::DrawCircle_line(QPainter& painter,int radius)
{//保存绘图对象painter.save();//计算大小圆路径QPainterPath outRing;QPainterPath inRing;outRing.moveTo(0,0);inRing.moveTo(0,0);outRing.arcTo(-radius,-radius, 2*radius,2*radius,-30,240);inRing.addEllipse(-radius+2,-radius+2,2*(radius-2),2*(radius-2));outRing.closeSubpath();//设置画刷painter.setBrush(QColor(5,228,255));//大圆减小圆painter.drawPath(outRing.subtracted(inRing));painter.restore();
}//绘制刻度
void MainWindow::DrawSmallScale(QPainter& painter,int radius)
{//组装点的路径图QPainterPath pointPath_small;pointPath_small.moveTo(-2,-2);pointPath_small.lineTo(2,-2);pointPath_small.lineTo(2,8);pointPath_small.lineTo(-2,8);QPainterPath pointPath_big;pointPath_big.moveTo(-2,-2);pointPath_big.lineTo(2,-2);pointPath_big.lineTo(2,20);pointPath_big.lineTo(-2,20);//绘制121个小点for(int i=0;i<121;i+=2){QPointF point(0,0);painter.save();point.setX(radius*qCos(((210-i*2)*M_PI)/180));point.setY(radius*qSin(((210-i*2)*M_PI)/180));painter.translate(point.x(),-point.y());painter.rotate(-120+i*2);if(i<80){painter.setBrush(QColor(255,255,255));}if(i>=80){painter.setBrush(QColor(235,70,70));}if(i%5 == 0){painter.drawPath(pointPath_big);//绘画大刻度}else{painter.drawPath(pointPath_small);//绘画小刻度}painter.restore();}
}//绘制文字
void MainWindow::DrawUnit(QPainter& painter,int radius)
{painter.save();painter.setPen(QColor(255,255,255));QFont font;font.setFamily("Arial");font.setPointSize(16);font.setBold(true);painter.setFont(font);painter.drawText(-50, -radius, 100, 20,Qt::AlignCenter,QString("km/h"));painter.drawText(-60, -radius + 130, 120, 40,Qt::AlignCenter,QString("当前车速"));painter.setPen(QColor(255,255,255,50));painter.drawText(-120, -radius + 280, 250, 40,Qt::AlignCenter,QString("-请按space键加速-"));painter.restore();
}//绘制实时时速数字
void MainWindow::DrawNum(QPainter& painter,int radius)
{painter.save();painter.setPen(QColor(255,255,255));QFont font;font.setFamily("Arial");font.setPointSize(45);painter.setFont(font);painter.drawText(-75, -radius - 20, 150, 100,Qt::AlignCenter,QString::number(degRotate));painter.restore();
}//绘制指针
void MainWindow::DrawPointer(QPainter& painter,int radius)
{//组装点的路径图QPainterPath pointPath;pointPath.moveTo(10,0);pointPath.lineTo(1,-radius);pointPath.lineTo(-1,-radius);pointPath.lineTo(-10,0);pointPath.arcTo(-10,0,20,20,180,180);QPainterPath inRing;inRing.addEllipse(-5,-5,10,10);painter.save();//计算并选择绘图对象坐标painter.rotate(degRotate - 120);painter.setBrush(QColor(255,255,255));painter.drawPath(pointPath.subtracted(inRing));painter.restore();
}//动态增加时速画面效果
void MainWindow::slot_speed_changed()
{if(direction == 1)//加速{degRotate++;if(degRotate > 240)degRotate = 240;}else if(direction == 0)//减速{degRotate--;if(degRotate < 0){degRotate = 0;myTimer->stop();}}update();//刷新画面。很重要！
}//按键按下事件
void MainWindow::keyPressEvent(QKeyEvent *event)
{if(event->key() == Qt::Key_Space){if(direction == 0){myTimer->start(1);direction = 1;}}
}
//按键释放事件
void MainWindow::keyReleaseEvent(QKeyEvent *event)
{if(event->key() == Qt::Key_Space){direction = 0;}
}MainWindow::~MainWindow()
{delete ui;
}

main.cpp

#include "mainwindow.h"#include <QApplication>int main(int argc, char *argv[])
{QApplication a(argc, argv);MainWindow w;w.show();return a.exec();
}